No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
HDTV subjective quality of H.264 vs. MPEG-2, with and without packet loss
Abstract
The intent of H.264 (MPEG-4 Part 10) was to achieve equivalent quality to previous standards (e.g., MPEG-2) at no more than half the bit-rate. H.264 is commonly felt to have achieved this objective. This document presents results of an HDTV subjective experiment that compared the perceptual quality of H.264 to MPEG-2. The study included both the coding-only impairment case and a coding plus packet loss case, where the packet loss was representative of a well managed network (0.02% random packet loss rate). Subjective testing results partially uphold the commonly held claim that H.264 provides quality similar to MPEG-2 at no more than half the bit rate for the coding-only case. However, the advantage of H.264 diminishes with increasing bit rate and all but disappears when one reaches about 18 Mbps. For the packet loss case, results from the study indicate that H.264 suffers a large decrease in quality whereas MPEG-2 undergoes a much smaller decrease.
... However, there also may be a drawback arising from greater When considering higher resolutions, the video quality after packet losses can be affected by changes in encoding format. Thus, it has previously been demonstrated [47] that H.264/ AVC HD video quality falls dramatically for even very low packet loss rates (PLRs) (0.02%), while for MPEG-2 encoding of the same video, the quality drops by much less. The finding was, therefore, that for equivalent transmitted HD video quality [47] the older codec achieves a better quality at the receiver, once packet loss is factored in. ...
... Thus, it has previously been demonstrated [47] that H.264/ AVC HD video quality falls dramatically for even very low packet loss rates (PLRs) (0.02%), while for MPEG-2 encoding of the same video, the quality drops by much less. The finding was, therefore, that for equivalent transmitted HD video quality [47] the older codec achieves a better quality at the receiver, once packet loss is factored in. Notice, however, that the Pinson et al. [47] experiments adjusted for the expected coding gain between MPEG-2 and H.264/ AVC to allow the PLV of video of equal expected quality to be compared. ...
... The finding was, therefore, that for equivalent transmitted HD video quality [47] the older codec achieves a better quality at the receiver, once packet loss is factored in. Notice, however, that the Pinson et al. [47] experiments adjusted for the expected coding gain between MPEG-2 and H.264/ AVC to allow the PLV of video of equal expected quality to be compared. MPEG-2 encoded video at 6 Mbps was compared with an H.264/AVC bit-rate of 2 Mbps. ...
Ultra High Definition (UHD) video streaming to portable devices has become topical. Two standardized codecs are current, H.264/Advanced Video Coding (AVC) and the more recent High Efficiency Video Coding (HEVC). This paper compares the two codecs’ robustness to packet loss, after making allowances for relative coding gain. A significant finding from the comparison is that the H.264/AVC codec is less impacted by packet loss than HEVC, despite their differing coding efficiencies and including at low levels of packet loss. The results will be especially relevant to those designing portable devices with 4K UHD video display capability, allowing them to estimate the level of error concealment necessary. The paper also includes the results of HEVC compressed UHD video streaming over an IEEE 802.11ad wireless link operating at 60 GHz as a pointer to future performance in an error-prone channel.
... (Objectified MOS, herein, results from a direct mapping from either the Structural SIMilarity (SSIM) index [4] or the Video Quality Metric (VQM) [5].) In fact, PLV also may change in response to variations in: bitrate; content type; and codec [6]. However, in this paper, the main focus is upon the relationship between spatial-resolution and PLV, because the current trend is towards video streaming at ever higher resolutions, including HD (1280 × 720 pixels/frame progressive (p) scanning), 3D (both Standard Definition (SD) (480 × 720p) and HD), and 4k Ultra High Definition (UHD)(4096 × 2160p ) [7]. ...
... Nevertheless, there is indirect evidence that changes in coding format result in differing responses to packet loss. Thus, [6] showed that H.264/AVC quality drops dramatically for even low packet loss rates (0.02%), while MPEG-2 quality drops by much less. The implication is that for equivalent transmitter HD quality the older codec achieves a better receiver quality once packet loss is taken into account. ...
... The implication is that for equivalent transmitter HD quality the older codec achieves a better receiver quality once packet loss is taken into account. It is also important to notice that Pinson et al. [6] did this with experiments that adjusted for the expected coding gain between MPEG-2 and H.264/AVC to allow the PLV of video of expected equal quality to be compared. Thus, for MPEG-2 a bitrate of 6 Mbps was compared with an H.264/AVC bit-rate of 2 Mbps amongst others. ...
The trend towards video streaming with increased spatial resolutions and dimensions, SD, HD, 3D, and 4kUHD, even for portable devices has important implications for displayed video quality. There is an interplay between packetization, packet loss visibility, choice of codec, and viewing conditions, which implies that prior studies at lower resolutions may not be as relevant. This paper presents two sets of experiments, the one at a Variable BitRate (VBR) and the other at a Constant BitRate (CBR), which highlight different aspects of the interpretation. The latter experiments also compare and contrast encoding with either an H.264 or an High Efficiency Video Coding (HEVC) codec, with all results recorded as objective Mean Opinion Score (MOS). The video quality assessments will be of interest to those considering: the bitrates and expected quality in error-prone environments; or, in fact, whether to use a reliable transport protocol to prevent all errors, at a cost in jitter and latency, rather than tolerate low levels of packet errors.
... Third, dataset NTIA/Verizon [21] compares the performance of MPEG-2 and AVC/H.264 on HDTV, both coding only and in the presence of transmission errors. This experiment contains a partial matrix design, drawn from 12 SRCs and 9 HRCs, for a total of 144 PVSs. ...
... The obtained equation has two possible solutions (20) or (21) In the case of derivative over we have (22) or (23) The above equations generated many alternative sets of equations that are different by the choice of the indexes of and , which are zeros. From those equations the optimal solution can be found. ...
... Transforming (21) and (23) we obtain ...
How accurately are people able to use the absolute category rating (ACR) 5-level scale? Put another way, how repeatable are an individual subject's scores? Several subjective experiments have asked subjects to rate the same sequences a couple of times. Analyses indicate that none of the subjects exactly repeated their prior scores for these sequences. We would like to better understand this imperfection. This paper uses ACR subjective video quality tests to explore the precision of subjective ratings. To make formal measurements possible, we propose a theoretical subject model that is the main contribution of this paper. The proposed subject model indicates three major factors that influence accuracy: subject bias, subject inaccuracy, and stimulus scoring difficulty. These appear to be separate random effects and their existence is a reason why none of the subjects were able to perfectly repeat scores. There are three key consequences. First, subject scoring behavior includes a random component that spans approximately half of the rating scale. Second, the sensitivity and accuracy of most subjective analyses can be improved if the subject scores are normalized by removing subject bias. Third, to some extent, multiple subjects can be replaced with a single subject who rates each sequence multiple times.
... Jusmisko et al. [10] Some studies that have addressed the quality of video for H.264, mention the profile used. For example, [11] and [13] used the high profile, [14] used the main profile, and Ries et al. [15] used the baseline profile for quality estimation based in motion characteristics. ...
... Human perception involves various aspects of human psychology and viewing conditions, such as vision ability; lighting conditions; preference for content; displaying devices; and understanding of the rating criteria [22]. Absolute Category Rating (ACR) is considered to be well-suited for qualification tests [5] and was applied in several studies [23], [14], [13]. ...
... This shows that the viewers in some cases are reluctant to score the videos as "excellent." This behaviour was also found in other studies [14]. ...
With the growth of the mobile internet, the popularity of multimedia services and applications have increased rapidly. As a result, end-users become quality-conscious. To fulfill the users' expectations, the study of quality of experience (QoE) is becoming very important for both researchers and service providers. This paper analyses the impact on perceived quality of received videos encoded with the H.264 baseline profile, which is suitable for mobile video, and streamed through an emulated network with packet loss and packet delay variation. To evaluate the video QoE, tests are conducted on a mobile device and on a laptop. The users' responses show that the baseline profile of H.264 is very sensitive to packet loss and packet delay variation. Moreover, there is no considerable impact on users' perception either test is conducted on the mobile device or on the laptop by playing the same resolution video.
... However, a gap in the literature exists on the performance of best-effort transmission of LCEVC-coded video and in particular the impact of packet loss on the resulting visual quality. For example it was found that when packet loss is taken into account older video codecs achieve better receiver quality when compared with newer ones [8,9]. Furthermore, previous literature on LCEVC video compression has focused the use of constant bitrate (CBR) and constant quantization parameters (CQP), with minimal references to the use of constant rate factor (CRF). ...
... Therefore, due to these higher bitrates, high SI and TI sequences will exhibit better video quality. Figures 6,7,8,9,10 and 11 show the graphical representation of impact of packet loss on the video streams using the objective metrics (VMAF, SSIM and PSNR) for the individual sequnces. Overall, it was observed that, for all three metrics, once packet loss exceeds approximately 0.8-1%, there was a general reduction in the objective video quality seen across all [17] for HEVC, [28] for H.264 and [27] for both codecs. ...
This paper presents an evaluation of the latest MPEG-5 Part 2 Low Complexity Enhancement Video Coding (LCEVC) for video streaming applications using best effort protocols. LCEVC is a new video standard by MPEG, which enhances any base codec through an additional low bitrate stream, improving both video compression efficiency and and transmission. However, there is an interplay between packetization, packet loss visibility, choice of codec and video quality, which implies that prior studies with other codecs may be not as relevant. The contributions of this paper is, therefore in twofold: It evaluates the compression performance of LCEVC and then the impact of packet loss on its video quality when compared to H.264 and HEVC.The results from this evaluation suggest that, regarding compression, LCEVC outperformed its base codecs, overall in terms average encoding bitrate savings when using the constant rate factor (CRF) rate control. For example at a CRF of 19, the average encoding bitrate was reduced by 18.7% and 15.8% when compared with the base H.264 and HEVC codecs respectively. Furthermore, LCEVC produced better visual quality across the packet loss range compared to its base codecs and the quality only started to decrease once packet loss exceeded 0.8-1%, and decreases at a slower pace compared to its equivalent base codecs. This suggests that the LCEVC enhancement layer also provides error concealment. The results presented in this paper will be of interest to those considering the LCEVC standard and expected video quality in error-prone environments
... The studies also show that most long-lived failures that are caused by routing dynamics can be attributed to BGP. There are many studies that show the significant impact that packet loss has on video quality [12]- [16]. Some examples are [13], [14], in which the effects of packet loss on MPEG and MPEG-2 streams are analyzed. ...
... Some examples are [13], [14], in which the effects of packet loss on MPEG and MPEG-2 streams are analyzed. Other studies show the effects of packet loss on video-chat applications [15] or on HDTV [16]. ...
The Superbowl is one of the biggest entertainment events of the year in the United States. Given the rapid and large increase in the use of Internet streaming services for access to multimedia content - to the detriment of traditional cable, satellite and terrestrial-, it is to be expected that this traffic will affect the performance of the Internet at several levels. One is the communication between Autonomous Systems (ASs) which is primarily based on Border Gateway Protocol (BGP). The main focus of this paper is the analysis of the BGP updates registered during Superbowl 2016 in order to understand how a large streaming event affects the Internet at the BGP level. This paper shows the results of our analysis. Those results show that an increase in the number of updates happened during the key times in which a larger number of concurrent viewers connected to the game. Many dampening and flapping events were also observed which present some patterns at those instants. From these dampening or flapping events, the ASs potentially involved in the disruptions were detected and categorized. To evaluate what could have happened, the topology of the connections between the whole set of potential ASs was analyzed for each event. In order to show the conclusions obtained, an example of one of the most relevant events is provided.
... Nevertheless, there is indirect evidence that changes in coding format result in different responses to packet loss. Thus, [3] showed that H.264/AVC quality drops dramatically for even low packet loss rates (0.02%), while MPEG-2 quality drops by much less. The implication is that for equivalent transmitter HD quality the older codec achieves a better receiver quality once packet loss is taken into account. ...
... The implication is that for equivalent transmitter HD quality the older codec achieves a better receiver quality once packet loss is taken into account. In this paper, we follow that implication [3] by investigating whether the same may apply to H.264/AVC and HEVC codecs at higher spatial resolution. ...
After adjusting for coding gain between the H.264 and HEVC codecs, a comparison is made between the two codecs' robustness to packet loss. A counter-intuitive finding arises that the less efficient codec is less affected by packet loss than the more efficient codec, even at very low levels of packet loss. The findings will be of interest to those designing portable devices that can display up to 4kUHD video.
... Traditionally in network system the guaranteed bandwidth of channel facilitates with least risk in data flow error and non significant packet loss, thus not effecting the quality of service (QoS). But in modern network applications like multimedia over IP and video conferencing where dynamic and voluminous data flow is common across the network, may put forth the issue of (QoS) data quality maintenance during the network communication12345. Therefore, standardisation of QoS is a motivational domain to be resolved before research community. ...
... Earlier many authors conducted subjective experiments to analyze the impact of packet drop (resulting in frame drop) over the experienced quality [1, 4, 5, 7, 18, 25]. In our experiments, we have observed the impact of contiguous frame drop in five video sequences (Fig. 3) available at www.media.xiph.org. ...
Due to ever growing needs of multimedia data for various applications like video conferencing and
streaming, which involves human subjects, it is often desired to have good resumed perceptual quality
of videos, thus arises the need of quality assessment. This paper discusses involved steps during
subjective quality assessment and various available objective quality metrics like peak signal to noise
ratio (PSNR) and structural similarity index (SSIM) along with their performance with respect to
human visual system (HVS) models. This paper presents an HVS model which incorporates frame drop
distortion and its impact over subjective score. Simulation results show that PSNR and SSIM are
inefficient to analyse the quality deterioration due to frame drop.
... One of the design goals was to produce audio and video hypothetical reference circuits (HRCs) such that each set of [13] .) The video impairments were chosen from those used in [14], as this provided precise feedback on the expected mean opinion scores (MOS). Reference [14] found that AVC at 3.5 Mb/s was statistically equivalent to MPEG 2 at 8.5 Mb/s. ...
... The video impairments were chosen from those used in [14], as this provided precise feedback on the expected mean opinion scores (MOS). Reference [14] found that AVC at 3.5 Mb/s was statistically equivalent to MPEG 2 at 8.5 Mb/s. Both received an average MOS between fair and good on the Absolute Category Rating (ACR) scale; see [14,Fig. ...
The perceived quality of an audiovisual sequence is heavily influenced by both the quality of the audio and the quality of the video. The question then arises as to the relative importance of each factor and whether a regression model predicting audiovisual quality can be devised that is generally applicable.
... In this way, the size of the video file decreases, and the required network bandwidth also decreases. It is worth mentioning that the H.264 codec is more sensitive to the network packet loss ratio [34]. The edge host sends the converted video to the data center gateway. ...
In recent years, surveillance systems have significantly increased in various environments. The Internet of Things (IoT), which interconnects objects through the Internet, enhances the capabilities of these systems. Typically, in IoT-enabled surveillance systems, the recorded videos should be processed and stored in cloud servers, which increases the system response time. Sending the videos to a cloud data center through the infrastructure network may also cause performance issues such as delay, jitter, and packet loss. Usually, edge computing is a viable solution to overcome these problems. This paper proposes a deep learning-based network traffic management policy for IoT-enabled surveillance systems in which the user's quality of experience (QoE) is a performance metric. For this purpose, first, a host in the edge data center preprocesses the video to reduce the video file size. Next, we designed a QoE-aware routing algorithm that uses a minimum delay-maximum mean opinion score heuristic algorithm to create a dataset that contains optimal routes with high QoE values. Then, it trains a sequential deep recurrent neural network (deep-RNN) on this dataset, and the trained model predicts the optimal routes between a source edge data center and a destination cloud center. Because software-defined networks (SDN) facilitate the execution of intelligent algorithms in networks, we implemented the proposed policy in the SDN controller of the infrastructure network. The simulation results showed that the proposed method could reduce the end-to-end packet loss ratio and increase the QoE values in IoT-enabled surveillance systems. Furthermore, converting the video codec on the edge layer reduces the video size, reducing the network latency by 50%. The experimental results also showed 94% accuracy using the proposed sequential deep RNN model.
... The Student's t-test can be used to compare individual systems, as per the comparison of H.264 and MPEG2 in [6]. P.913 recommends the Student's t-test for such analyses. ...
This paper calculates confidence intervals for 89 datasets that use the 5-level Absolute Category Rating (ACR) method to evaluate the quality of speech, video, images, and video with audio. This data allows us to compute the subjective test confidence interval
SCI) for 5-level ACR tests. We use a confusion matrix to compare conclusions reached by 88 lab-to-lab comparisons, 22 method-to-method comparisons, and 12 comparisons between expert and naïve subjects. We estimate the differences in conclusions reached by ad hoc evaluations, compared to subjective tests. We recommend using the
disagree
incidence rate to identify lab-to-lab differences (i.e., the likelihood that significantly different stimulus pairs receive opposing rank order from the two labs).
Disagree
incidence rates above 0.31% are unusual enough to warrant investigation and
disagree
incidence rates above 1.0% indicate differences in method, test environment, test implementation, or subject demographics. These incidence rates form the basis for a new statistical method that calculates the confidence interval of a metric (
MCI). When
MCI is used to make decisions, the equivalence to a video-quality test (EVQT) method determines whether a metric acts similarly to a subjective test. When
MCI is not used, the metric is likened to a certain number of people in a video-quality test (PVQT). This information will help users make the better decisions when applying quality metrics. The algorithm code is made available for any purpose. Most of the ratings used in this paper come from open datasets.
... Case 1 recording was encoded in MPEG2 while more recent Case 2 recording was encoded in MPEG4 format, both at high image quality. With high image quality, the encoding methods are unlikely to affect pixel-based measurements (Pinson et al., 2010). ...
Purpose
This research note illustrates the effects of video data with nonsquare pixels on the pixel-based measures obtained from videofluoroscopic swallow studies (VFSS).
Method
Six pixel-based distance and area measures were obtained from two different videoflouroscopic study units; both yielding videos with nonsquare pixels with different pixel aspect ratios (PARs). The swallowing measures were obtained from the original VFSS videos and from the videos after their pixels were squared.
Results
The results demonstrated significant multivariate effects both in video type (original vs. squared) and in the interaction between video type and sample (two video recordings of different patients, different PARs, and opposing tilt angles of the external reference). A wide range of variabilities was observed on the pixel-based measures between original and squared videos with the percent deviation ranging from 0.1% to 9.1% with the maximum effect size of 7.43.
Conclusions
This research note demonstrates the effect of disregarding PAR to distance and area pixel-based parameters. In addition, we present a multilevel roadmap to prevent possible measurement errors that could occur. At the planning stage, the PAR of video source should be identified, and, at the analyses stage, video data should be prescaled prior to analysis with PAR-unaware software. No methodology in prior absolute or relative pixel-based studies reports adjustment to the PAR prior to measurements nor identify the PAR as a possible source of variation within the literature. Addressing PAR will improve the precision and stability of pixel-based VFSS findings and improve comparability within and across clinical and research settings.
Supplemental Material
https://doi.org/10.23641/asha.21957134
... This data allows statistically significant comparisons between the codecs, encoding options, and network conditions. An example of a typical test can be found here [19]. A more detailed description is given in [22]. ...
The conventional video subjective test design, in which subjects view and rate multiple versions of each source video sequence, was used for decades. New technology, like adaptive streaming, makes it almost impossible to use this design since much longer sequences are needed. In this paper we examine three experiment designs: the conventional design and two alternatives that use each source sequence only once. Based on data collected by three laboratories, we compare the accuracy and scoring behavior of these three designs. We check whether there is a significant difference in scoring behavior between the experiment designs. One of the proposed experiment designs is proposed for immediate use.
... In [6], it was actually shown that increased HEVC compression of 4K UHD video causes greater loss of video quality compared to H.264/AVC, once coding gain is adjusted for. An earlier paper [66] made the same point when comparing MPEG-2 to H.264/AVC. The relative effect occurs because the increased compression of the later codecs makes them more vulnerable to packet loss, as the loss of a packet has more of an impact on the video quality. ...
From a review of the literature and a range of experiments, this paper demonstrates that live video streaming to mobile devices with pixel resolutions from Standard Definition up to 4K Ultra High Definition (UHD) is now becoming feasible by means of high-throughput IEEE 802.11ad at 60 GHz or 802.11ac at 5 GHz, and 4K UHD streaming is even possible with 802.11n operating at 5 GHz. The paper, by a customized implementation, also shows that real-time compression, assisted by graphical processing units at 4K UHD, is also becoming feasible. The paper further considers the impact of packet loss on H.264/AVC and HEVC codec compressed video streams in terms of structural similarity index video quality. It additionally gives an indication of wireless network latencies and currently feasible frame rates. Findings suggest that, for medium-range transmission, the video quality may be acceptable at low packet loss rates. For hardware-accelerated 4K UHD encoding, standard frame rates may be possible but appropriate higher frame rates are only just being reached in hardware implementations. The target bitrate was found to be important in determining the display quality, which depends on the coding complexity of the video content. Higher compressed bitrates are recommended, as video quality may improve disproportionately as a result.
... ITU-R BT.710 and ITU-T P.910 adapt the above procedures for high-definition displays and multimedia. With these methods, the authors in [13] analyze the impact of bit rate and packet loss rate on the mean opinion score (MOS) for MPEG-2 and MPEG-4 videos. This study is extended in [14][15][16] to 3D video sequences in wired and wireless networks, where other aspects has to be considered, such as depth perception and visual fatigue. ...
With the deployment of the first commercial long term evolution (LTE) networks, mobile operators need to understand how quality of service (QoS) network indicators and codec parameters affect subjective quality in video streaming services as perceived by customers. In this paper, the development of a testbed for evaluating the quality of experience (QoE) of 3D video streaming service over LTE is described. The proposed system consists of three elements: a streaming server, an internet protocol-level mobile network emulator, based on NetEm tool, and a streaming client. The main contribution of this testbed is the modification of NetEm code to model the impact of time correlation between packet arrivals on the packet delay in a video stream. In the testbed, different network conditions are configured by setting network emulator parameters based on the results obtained by a system-level LTE simulator. Results show how average network load and user position inside a cell have a strong impact on the QoS and QoE perceived by the end video user.
... The measured QoS parameters were weighted based on the class of service [e.g. standard-definition television (SDTV) and high-definition television (HDTV)], while in [10], a subjective quality assessment comparison of H.264/AVC and MPEG-2 was presented. The results suggested that higher bitrates provide reduced sensitivity to packet loss. ...
Networked visual applications such video streaming have grown exponentially in recent years, yet are known to be sensitive to network impairments. However, available measurement techniques that adopt a full reference model are impractical in real-time streaming because they require the original video sequence available at the receivers side. The primary aim of this study is to present a hybrid no-reference prediction model for the perceptual quality of 4kUHD H.265-coded video in the wireless domain. The contributions of this paper are two-fold: first, an investigation of the impact of quality of service (QoS) parameters on 4kUHD H.265-coded video transmission in an experimental environment; second, objective model based on fuzzy logic inference system is developed to predict the visual quality by mapping QoS parameters to the measured quality of experience. The model is evaluated in contrast to random neural networks. The results show that good prediction accuracy was obtained from the proposed hybrid prediction model. This study will help in the development of a reference-free video quality prediction model and QoS control methods for 4kUHD video streaming.
... Unfortunately when video is transmitted using UDP over wireless environment, the predictive coding strategies employed in techniques, such as MPEG-4, place a new set of constraints on traffic sequencing. For example, predictive coding introduces temporal dependencies into the video data that improve compression ratios, but can result in greater error propagation in the event of packet loss or late arrival[112] and it is further investigated in work[113], that demonstrate that H.264/MPEG4 provides quality similar to MPEG-2 at no more than half the bit rate for the coding-only case. Their assessment shows that the advantage of H.264 diminishes with increasing bit rate and all but disappears when one reaches about 18 Mbps. ...
Today, the fulfillment of customer demands and user experience requirements are becoming the main differentiators for gauging the effectiveness of telecom operators and service providers. In this competitive market, the poor Quality of Experience (QoE) leads to a chain reaction of negative word of mouth, pushing customers into the arms of waiting competitors. Therefore it is important for service providers to ensure superior quality of experience in order to avoid customer disloyalty and negative reputation. QoE is a fast emerging multi-disciplinary field focused on understanding overall human quality requirements from different angles such as technology, business and context of use. The first and foremost challenge is to understand how different influencing characteristics related to business, technology, and context influence human behavior. In this thesis, initial work addresses this challenge of understanding the influence of disparate domains over QoE. A consolidated QoE interaction model is proposed which links disparate domains (human, business, technology, and context) to understand overall human quality of experience requirements. Then taxonomy is presented for QoE interaction model. Second contribution in this thesis is based on the first and its main objective is to capture and analyze QoE data through user studies. Based on user data, the influence of technological, contextual and business parameters over QoE are evaluated. Different multimedia services were selected for user study such as video streaming service, telephony (VoIP and PSTN), and 3D audio teleconferencing service. Depending upon multimedia service, different aspects were considered during each user study such as types of multimedia service parameters (QoS, content, context), the types of QoE metrics (subjective, objective cognitive or both), human characteristics (age, gender etc), and human roles (user, or customer). These findings help in understanding the link between QoE and other influencing domains. The third contribution is based upon ongoing work of developing QoE based tools for video streaming services. Two QoE based tools for the assessment of multimedia services have been presented in this thesis, their main functions are to capture, analyze and report QoE metrics in real time. These QoE tools are useful for real time measurement of QoE metrics
... The results relate the number of frames affected by packet loss to the number of frames in the final degraded sequence that present artifacts, highlighting the nature and quantity of these artifacts. The effects of packet loss on video-chat applications [9] and HDTV [10] are also analysed. ...
Quality of experience is of critical importance in streaming video services, because the traditional quality of service cannot represent the quality perceived by viewers. This work evaluates several objective quality metrics under realistic bursty packet loss conditions in the network, with the support of a packet loss model. Alignment of reference and streamed video sequences (with different levels of spatial-temporal information) are also explored as a technique to prevent inaccurate computation of objective metrics due to frame loss. Finally, the correlation between subjective and objective metrics for each motion level and the computing time of metrics are analysed. The most suitable objective metrics to characterize the real degradation in the quality perceived by viewers, for both off-line and real-time assessment, are proposed. The integration of motion, busty packet loss, sequence alignment after frame loss and computing time of metrics are the main contributions of this research work.
... H.264/AVC는 매우 높은 데이터 압축률을 가지는 디 지털 비디오 코덱 표준으로 기존 표준인 MPEG-1, MPEG-2, MPEG-4 Part 2와 비교했을 때, 같은 화질에서 낮은 비트 레이트를 얻을 수 있도록 개발되었다123. ...
In this paper, an efficient hardware architecture is proposed for inverse transform and inverse quantization of H.264/AVC decoder. The previous inverse transform and quantization architecture has a different AC and DC coefficients decoding order. In the proposed architecture, IQ is achieved after IT regardless of the DC or AC coefficients. A common operation unit is also proposed to reduce the computational complexity of inverse quantization. Since division operation is included in the previous architecture, it will generate errors if the processing order is changed. In order to solve the problem, the division operation is achieved after IT to prevent errors in the proposed architecture. The architecture is implemented with 3-stage pipeline and a parallel vertical and horizontal IDCT is also implemented to reduce the operation cycle. As a result of analyzing the proposed ITIQ architecture operation cycle for one macroblock, the proposed one has improved by 45% than the previous one.
... Even if providers assure packet-level Quality of Service (QoS) on their networks, these services may suffer from poor perceptive quality. HD video contents, for example, show higher sensitivity to transmission anomalies compared to the legacy SD-based ones [1], since each key-frame in a high resolution video, due to the higher bit rate, spans more consecutive data packets. To objectively assess the service quality, flow-level network parameters, such as packet loss and jitter can be monitored at certain points of the transmission path [2]. ...
Finding the correlation among Quality of Experience (QoE) for video, measured Quality of Service (QoS) parameters in the network, and objective video performance metrics is a challenging task. This paper provides some analysis results on this issue. Our motivation is that streaming media content gets dominant position in the global traffic mix within the next few years. With the evolution of personal devices, demand for High Definition (HD) resolution contents is dynamically increasing. Traversing real-time media across public packet-switched networks is a complex task, especially if quality of service should be sustained. The issue gets more complicated when the traffic is forwarded through heterogeneous infrastructures. Media content with various resolutions and bit rates show different sensitivity to transmission anomalies. Our paper investigates the correlation between subjective quality assessment (i.e., Mean Opinion Score, MOS evaluation), measured QoS parameters (packet loss, jitter) and objective video performance metrics (Video Quality Metric - VQM, Structural Similarity - SSIM, Peak Signal Noise Ratio - PSNR) in the context of real-time HD video streaming (i.e., IPTV and MobileTV). In twelve scenarios, packet-level perturbations were emulated in our laboratory testbed during the transmission of short video sequences with three different resolutions (480p, 720p and 1080p). Later the videos were evaluated using subjective and objective assessment methods.
... It is known that even small percentages of IP packets loss with uniform distribution can produce high effects in the perceived video quality. Reference [9] describes a test performed transmitting H.264 streams over IP networks with 0.02% random packet loss rate. The authors report that higher levels of packet loss severely damage the user experience by freezing the receiver for long periods of time. ...
This paper presents a model to predict video quality perceived by the broadcast digital television (DTV) viewer. We present how noise on DTV can introduce individual transport stream (TS) packet losses at the receiver. The type of these errors is different than the produced on IP networks. Different scenarios of TS packet loss are analyzed, including uniform and burst distributions. The results show that there is a high variability on the perceived quality for a given percentage of packet loss and type of error. This implies that there is practically no correlation between the type of error or the percentage of packets loss and the perceived degradation. A new metric is introduced, the weighted percentage of slice loss, which takes into account the affected slice type in each lost TS packet. We show that this metric is correlated with the video quality degradation. A novel parametric model for video quality estimation is proposed, designed, and verified based on the results of subjective tests in SD and HD. The results were compared to a standard model used in IP transmission scenarios. The proposed model improves Pearson Correlation and root mean square error between the subjective and the predicted MOS.
... The relationship between bit rates and perceptual quality was investigated in [7], where the results showed that at low bit rates, even a small difference in bit rates is linked to a large difference in quality. The user experience study from [8] suggests that, in packet loss environments, a certain amount of channel rate should be assigned to forward error correction or another robust response to packet loss rather than to improve the coding accuracy in H.264. The results from [9] showed that users were more annoyed by long and widely spread packet losses than bursts. ...
Inspired by the rapidly increasing popularity of 3D movies, there is an industrial push for 3DTV services to the home. One important factor for the success and acceptance by the viewers is a positive quality of experience (QoE) of the new service when delivered. The questions of how to efficiently deliver 3DTV service to the home, and how to evaluate the visual quality perceived by end users are a recent research focus. We have investigated users' experience of stereoscopic 3D video quality by preparing two subjective assessment datasets. The first dataset aimed at the evaluation of efficient transmission in the transmission error free case, while the second focused on error concealment. A total of three subjective assessments, two for first dataset and one for the second, were performed using the Absolute Category Rating with Hidden unimpaired Reference video (ACR-HR) method. The experimental setup allows to show that the ACR-HR subjective method provides repeatable results across labs and across conditions for video quality. It was also verified that MVC is more efficient than H.264 simulcast coding. Furthermore it was discovered that based on the same level of quality of experience spatial down-sampling may lead to better bitrate efficiency while temporal down-sampling is not acceptable. When network impairments occur, traditional error 2D concealment methods need to be reinvestigated as they were outperformed by displaying the same view for both eyes (switching to 2D presentation).
... Additionally, the base view in MVC is also backwards compatible with H.264/AVC. While streaming video over Internet Protocol (IP) -based networks, impairments (such as packet loss) can severely degrade the perceived quality of the end-users [3]. The latter is also commonly referred to as Quality of Experience (QoE) [4]. ...
Thanks to the availability of 3D-capable televisions and blu-ray players, 3D content is made accessible in the home. Re-cently, an extension of the H.264/AVC video coding standard has been defined for encoding 3D video content. This exten-sion, called Multiview Video Coding, allows inter-view pre-diction resulting in a better compression efficiency. However, due to these inter-view dependencies impairments in one view caused by e.g. packet losses can lead to degradations in other views. Research has already been conducted towards estimat-ing packet loss visibility in H.264/AVC encoded sequences. In this paper, we investigate the possibility of using an exist-ing decision tree-based classifier for estimating impairment visibility in 3D MVC encoded sequences. Our results show that, in the case of losing entire pictures, it is possible to es-timate packet loss visibility in 3D MVC encoded sequences with a high accuracy by only taking into account a limited number of parameters.
... Apart from quality assessment due to spatial distortion, it is also required to analyse the quality deterioration due to temporal distortion. A video sequence can be temporally distorted by dropping frames or swapping frames or inserting average frames into reference video sequences[17][18][19]. These temporal distortions are context sensitive; therefore there impact over perceived visual quality varies in different context. ...
In last decade, ever growing internet technologies provided
platform to share the multimedia data among different
communities. As the ultimate users are human subjects who are
concerned about quality of visual information, it is often desired
to have good resumed perceptual quality of videos, thus arises
the need of quality assessment. This paper presents a full
reference hybrid video quality metric which is capable to analyse
the video quality for spatially or temporally (frame drop) or
spatio-temporally distorted video sequences. Simulated results
show that the metric efficiently analyses the quality degradation
and more closer to the developed human visual system.
... Distortions in a video stream appear either in intra frame or at inter-frame level. Intra frame distortions or spatial distortions (SD) arises due to change of pixel bits of a reference video frame; this might be multifactorial governed viz due to introduced bit error during communication, or other manipulation over pixel bits of a video frame like compression, bit inversion, acquisition, watermarking, editing, and storage while, inter frame distortions or temporal distortions (TD) arises with respect to time like, drop of video frames, swapping of video frames, and frame averaging8910.Figure 1 As frame drop is least desired, dropped frames identification in a video stream is always a challenging task for research community. There are significant work in terms of quality metrics which identify the dropped frames under full reference (FR), reduced reference (RR), and no reference (RR). ...
... Distortions in a video stream appear either in intra frame or at inter-frame level. Intra frame distortions or spatial distortions (SD) arises due to change of pixel bits of a reference video frame; this might be multifactorial governed viz due to introduced bit error during communication, or other manipulation over pixel bits of a video frame like compression, bit inversion, acquisition, watermarking, editing, and storage while, inter frame distortions or temporal distortions (TD) arises with respect to time like, drop of video frames, swapping of video frames, and frame averaging8910.Figure 1 As frame drop is least desired, dropped frames identification in a video stream is always a challenging task for research community. There are significant work in terms of quality metrics which identify the dropped frames under full reference (FR), reduced reference (RR), and no reference (RR). ...
Dropped frames identification in a given video stream is always a challenging task for research
community due to required heavy computation. To preserve the quality of service during any
processing over visual information, drop of frame is least desired. Many contemporary work identifies
the frame drop in terms of full reference algorithm (where reference and distorted video streams are
available for comparison), or reduced reference algorithm (where some information about reference
video are available) or no reference algorithm (where information about reference video are not
available). This paper presents a novel full reference heuristic approach using genetic algorithm which
identifies the dropped frame indices in a given distorted video stream with respect to original video
stream. The proposed algorithm efficiently identifies dropped frame indices even if reference video
stream contains repeated frames and spatially distorted too with low or high spatial distortions. The
proposed algorithm is simulated and tested with 12 video streams. Simulation results suggested that it
is more efficient with a video stream having lesser repeated frames.
... A small delay or drop of a certain packet of the compressed video stream can have a significant visual impact on the video depending on the type of packet that gets lost or delayed [3], [4]. Additional to the network characteristics, the type of video compression and the properties of the video stream highly influence the visual effect of network errors [5], [6]. In general, consumers expect less than one visual artifact per hour [7]. ...
For the purpose of automatic video quality evaluation, Peak Signal-to-Noise Ratio (PSNR) has been the most wellknown full reference quality metric since a long time. Improving on PSNR, several other pixel-based quality metrics have been developed, namely Structural SIMilarity (SSIM), Multi Scale-SSIM (MS-SSIM), and Video Quality Metric (VQM). The goal of these objective video quality metrics is to replace time-consuming and expensive subjective quality assessment experiments. These alternative objective metrics have already been evaluated on several video compression schemes, such as MPEG-2 and H.264/AVC, transported over different kinds of network protocols and under a large variation of network characteristics. In January 2013, the successor of the Advanced Video Coding (H.264/AVC) standard, named High Efficiency Video Coding (HEVC), has been finalized. Although HEVC is still a block based hybrid video compression standard, some radical changes are made to subjectively improve the compression efficiency compared to H.264/AVC. Until now, the alternative quality metrics have never been evaluated on this new compression scheme. Therefore, in this paper, we analyze the difference in performance of these full reference metrics. Based on subjective evaluations, a performance analysis is presented which shows the validity of these models when applied to HEVC compressed video content.
... In the 2D video case, it has been well studied in many publications, e.g. 6 , 7 , and several different methods for measuring the subjective quality have been developed and tested.In the 3D case, the most common approach is to use the Double-Stimulus Continuous Quality-Scale (DSCQS) method as specified in ITU-R BT.500 8 on stereoscopic displays 3, 4, 5 for 3D presentation. However, the DSCQS method is time consuming since each video sequence is played at least twice, which limits the number of test sequences that can be evaluated during the subjective test. ...
Broadcasting of high definition (HD) stereobased 3D (S3D) TV are planned, or has already begun, in Europe, the US, and Japan. Specific data processing operations such as compression and temporal and spatial resampling are commonly used tools for saving network bandwidth when IPTV is the distribution form, as this results in more efficient recording and transmission of 3DTV signals, however at the same time it inevitably brings quality degradations to the processed video. This paper investigated observers quality judgments of state of the art video coding schemes (simulcast H.264/AVC or H.264/MVC), with or without added temporal and spatial resolution reduction of S3D videos, by subjective experiments using the Absolute Category Rating method (ACR) method. The results showed that a certain spatial resolution reduction working together with high quality video compressing was the most bandwidth efficient way of processing video data when the required video quality is to be judged as "good" quality. As the subjective experiment was performed in two different laboratories in two different countries in parallel, a detailed analysis of the interlab differences was performed.
... From a research perspective, there are studies available [23] that compare the delay and bandwidth requirements for different multipoint topologies in the context of domestic videoconferencing, but these only consider 640x480 resolution. Quality assessment of high-definition video can be found in [24], but it does not target videoconferencing. The numbers in two papers match up, however, and suggest that transmitting 1280x720 at 30fps will require 2-3Mbit/s of bandwidth to be perceived as good quality. ...
This paper describes a videoconferencing system that meets performance constraints and functional requirements for use in consumer homes. Our system improves existing home technologies (such as video chat) by providing high-quality audio- visual communication, efficient encoding mechanisms, and low end-to-end delay. Moreover, the system includes a control inter- face that is capable of dynamically manipulating and compositing audiovisual content streams. This innovative architectural com- ponent is required for a domestic setting, where the television acts as the main screen and multiple people gather around it. Apart from the requirements and architecture, this paper analyses the performance of our system. The results validate our architectural decisions and provide a valuable input for further research in domestic videoconferencing. Index Terms—Compression and coding, consumer electronics and entertainment, presentation of content in multimedia sessions, standards and related issues, videoconferencing and collaboration environments.
... However, delivering high quality video services over existing IP-based networks can be a real challenge for video service providers, certainly when N. Staelens taking into account the packet-based, best-effort characteristics of such networks. In the event of network impairments, the perceived audiovisual quality can fluctuate significantly and drop below the acceptability thresholds [6], [7], [8]. To some extent, consumers tolerate minor impairments if the (discount) price for the provided service is acceptable and the error frequency remains low enough. ...
Ensuring and maintaining adequate Quality of Experience towards end-users are key objectives for video service providers, not only for increasing customer satisfaction but also as service differentiator. However, in the case of High Definition video streaming over IP-based networks, network impairments such as packet loss can severely degrade the perceived visual quality. Several standard organizations have established a minimum set of performance objectives which should be achieved for obtaining satisfactory quality. Therefore, video service providers should continuously monitor the network and the quality of the received video streams in order to detect visual degradations. Objective video quality metrics enable automatic measurement of perceived quality. Unfortunately, the most reliable metrics require access to both the original and the received video streams which makes them inappropriate for real-time monitoring. In this article, we present a novel no-reference bitstream-based visual quality impairment detector which enables real-time detection of visual degradations caused by network impairments. By only incorporating information extracted from the encoded bitstream, network impairments are classified as visible or invisible to the end-user. Our results show that impairment visibility can be classified with a high accuracy which enables real-time validation of the existing performance objectives.
Ideally, video streaming systems should provide the best quality video a user's device can handle without compromising on downloading speed. In this article, an improved video transmission system is presented which dynamically enhances the video quality based on a user's current network state and repairs errors from data lost in the video transmission. The system incorporates three main components: Scalable Video Coding (SVC) with three layers, multicast based on Receiver Layered Multicast (RLM) and an UnEqual Forward Error Correction (FEC) algorithm. The SVC provides an efficient method for providing different levels of video quality, stored as enhancement layers. In the presented system, a proportional-integral-derivative (PID) controller was implemented to dynamically adjust the video quality, adding or subtracting quality layers as appropriate. In addition, an FEC algorithm was added to compensate for data lost in transmission. A two dimensional FEC was used. The FEC algorithm came from the Pro MPEG code of practice #3 release 2. Several bit errors scenarios were tested (step function, cosine wave) with different bandwidth size and error values were simulated. The suggested scheme which includes SVC video encoding with 3 layers over IP Multicast with Unequal FEC algorithm was investigated under different channel conditions, variable bandwidths and different bit error rates. The results indicate improvement of the video quality in terms of PSNR over previous transmission schemes.
Fine-Grain parallelism is essential for real-time video encoding performance. This usually implies setting a fixed buffer size for each encoded block. The choice of this parameter is critical for both performance and hardware cost. In this paper we analyze the impact of buffer size on image subjective quality, and its relation with other encoding parameters. We explore the consequences on visual quality, when minimizing buffer size to the point of causing the discard of quantized coefficients for highest frequencies. Finally, we propose some guidelines for the choice of buffer size, that has proven to be heavily dependent, in addition to other parameters, on the type of sequence being encoded. These guidelines are useful for the design of efficient realtime encoders, both hardware and software.
We propose a model for rating behavior based on subject bias and subject error. Evidence for subject bias can be found in freely available subjective experiments. When subject bias is removed from ratings, the sensitivity of statistical comparisons between stimuli usually improves. According to our model, subject biases characterize the subject pool. These between-subject differences are important when analyzing and comparing people. On the other hand, it is advantageous to remove subject bias when analyzing mean opinion score. We conclude that bias acts like a random variable within ratings.
Internet video coding (IVC) is an exploration within MPEG to develop a video compression technology that is expected of royalty-free and targeted to the compression performance comparable to MPEG-4 AVC/H.264 Constrained Baseline Profile (CBP). IVC codec has been steadily enhanced since 2011, so it is valuable to report comparison results in the progress. In this paper, we evaluate the codec performance of IVC comparing with AVC CBP in terms of bitrate and PSNR together. Furthermore, we also evaluate the subjective quality of IVC with two types of viewers: MPEG experts and non-experts. The results show that the overall picture quality of IVC is comparable to AVC CBP except the subjective quality in low bitrate.
Multimode service (MMS) systems allow broadcasters to provide multichannel services using a single HD channel. Using these systems, it is possible to provide 3DTV programs that can be watched either in threedimensional (3-D) or two-dimensional (2-D) modes with backward compatibility. In the MMS system for 3DTV broadcasting using the Advanced Television Systems Committee standards, the left and the right views are encoded using MPEG-2 and H.264, respectively, and then transmitted using a dual HD streaming format. The left view, encoded using MPEG-2, assures 2-D backward compatibility while the right view, encoded using H.264, can be optionally combined with the left view to generate stereoscopic 3-D views. We analyze 2-D and 3-D perceptual quality when using the MMS system by comparing items in the frame-compatible format (top-bottom), which is a conventional transmission scheme for 3-D broadcasting. We performed perceptual 2-D and 3-D video quality evaluation assuming 3DTV programs are encoded using the MMS system and top-bottom format. The results show that MMS systems can be preferable with regard to perceptual 2-D and 3-D quality and backward compatibility.
This article describes how to perform a video quality subjective test. For companies, these tests can greatly facilitate video product development; for universities, removing perceived barriers to conducting such tests allows expanded research opportunities. This tutorial assumes no prior knowledge and focuses on proven techniques. (Certain commercial equipment, materials, and/or programs are identified in this article to adequately specify the experimental procedure. In no case does such identification imply recommendation or endorsement by the National Telecommunications and Information Administration, nor does it imply that the program or equipment identified is necessarily the best available for this application.)
Digital Television (DTV) is the communications service with higher penetration in society. Video content reaches households through different transmission channels, which add noise to transmitted signal, leading to bit errors in the received signal. DTV standards include error correction codes, which can correct bit errors at the receiver side. However, if these errors are large enough, original signal would not be recovered and some video packets will be lost. This will result in a degradation of received video quality. In this paper we discuss the incidence of packet loss on the video quality perceived by the DTV viewer and we present a novel model to measure video quality in DTV.
H.264/AVC is a widely used and very popular video compression format which is applied for compression and distribution of different multimedia contents. The main goal of the experiment presented in this paper is to compare possible differences in subjective assessment of full High Definition (HD) video sequences, encoded by H.264/AVC, when single and double stimulus methods are used. For this purpose, appropriate subjective test methods are chosen and applied. In order to compare the subjective scores with objective quality measures, we also provide an analysis of PSNR and SSIM metrics for the considered video sequences. Results show that the subjective assessments are in good agreement with objective ones.
To an end user, Quality of Experience (QoE) matters more than Quality of Ser-vice (QoS) because she is the owner of her experience, which is the result of her perception. In recent times, QoE got increasingly much attention from service providers, operators, manufacturers and researchers. Amongst others, they are in-terested to know how the users perceive the quality of multimedia streaming and how to predict the QoE by measuring network performance parameters. Below the network layer, different access networks can be used, but the internet and transport layers remain the same for everyone on best-effort internet. We highlight a set of possible factors that are contributing towards the QoE, from network via transport to application layer, including applications, codecs, middleware and devices. To investigate the relationship of QoS and QoE, emulation-based experiments were designed. For the purpose of emulation, different shapers are in use by the research community. We selected three popular shapers, NetEm, NISTnet and KauNet, and investigated their emulation capabilities with focus on delay, delay variation and bit rate in order to be able to select the best-suited shaper for future use. Then, we studied the effect of QoS parameters on mobile video QoE. To evaluate the video QoE, user tests were conducted. We observe a much larger sensitivity of users to freezes and their placement within the video than what is predicted by an objective video quality assessment tool that is recommended by the standardisation organization ITU. Furthermore, we investigated the role of codec and device on QoE in view of network-induced problems.
In video communications, the compressed video stream is very likely to be corrupted by channel errors. Recently, many error concealment algorithms have been proposed in order to combat channel errors. In this paper, we have combined two state-of-the-art motion vector recovery algorithms into a even better algorithm; we have modified the hybrid motion vector extrapolation (HMVE) algorithm and further improved the accuracy of the derived motion vectors by pixel-based MV correction using neighboring received MVs. Experimental results show that this method is able to provide better performance than existing algorithms subjectively and objectively.
Quality-of-Experience (QoE) is a human centric notion that produces the blue print of human perception, feelings, needs and intentions while Quality-of-Service (QoS) is a technology centric metric used to assess the performance of a multimedia application and/or network. To ensure superior video QoE, it is important to understand the relationship between QoE and QoS. To achieve this goal, we conducted a pilot subjective user study simulating a video streaming service over a broadband network with varying distortion scenarios, namely packet losses (0, 0.5, 1, 3,7, and 15%), packet reorder (0, 1, 5, 10, 20, and 30%), and coding bit rates (100, 400, 600, and 800 Kbps). Users were asked to rate their experience using a subjective quantitative metric (termed Perceived Video Quality, PVQ) and qualitative indicators of “experience.” Simulation results suggest a) an exponential relationship between PVQ and packet loss and between PVQ and packet reorder, and b) a logarithmic relationship between PVQ and video bit rate. Similar trends were observed with the qualitative indicators. Exploratory analysis with two objective video quality metrics suggests that trends similar to those obtained with the subjective ratings were obtained, particularly with a full-reference metric.
Subjective study was conducted for 4K (3840 × 2160) video content on a true 4K LCD display to determine required bitrates to achieve various levels of perceived visual quality. State-of-the-art H.264/ AVC and HEVC compression was used. Additionally performance of objective metrics for 4K video was evaluated.
Recently my family celebrated a couple of life cycle events. In both cases, we cooked up massive dairy meals for our nearest and dearest. At the second party, one of our friends came to me with a smile and said, "I see that you caved in again. First, you got a dog, and now you are making dairy parties." She knows that I do not like most dairy foods and that if we make a dairy meal, it is probably not because I suggested it. I responded, "I don't think of it as caving in; I think of it as being flexible."
Perceived video quality studies were performed on a number of key
classes of noise removal algorithms to determine viewer preference. The
noise removal algorithm classes represent increase in complexity from
linear filter to nonlinear filter to adaptive filter to spatio-temporal
filter. The subjective results quantify the perceived quality
improvements that can be obtained with increasing complexity. The
specific algorithm classes tested include: linear spatial one channel
filter, nonlinear spatial two-channel filter, adaptive nonlinear spatial
filter, multi-frame spatio-temporal adaptive filter. All algorithms were
applied on full HD (1080P) content. Our subjective results show that
spatio-temporal (multi-frame) noise removal algorithm performs best
amongst the various algorithm classes. The spatio-temporal algorithm
improvement compared to original video sequences is statistically
significant. On the average, noise-removed video sequences are preferred
over original (noisy) video sequences. The Adaptive bilateral and
non-adaptive bilateral two channel noise removal algorithms perform
similarly on the average thus suggesting that a non-adaptive parameter
tuned algorithm may be adequate.
High Definition (HD) content delivery over IP networks is now a reality in the entertainment marketplace. Such networks can suffer packet loss, especially on the last mile link. This results in time-variant video quality. In this paper we first present an analysis of the human perception of network impairment on HD IPTV quality. Second, we propose a method, based on common objective measurements, to estimate subjective judgments of time-variant quality. A testbed was deployed to emulate a real use case of delivering high definition TV material over an IPTV network. The quality of the delivered H.264/AVC encoded video was evaluated objectively in an emulated environment where packet loss impairments were generated. Objective measurements were then compared to continuous subjective quality ratings. Based on the obtained results, highly correlated models were developed for the estimation of instantaneous user judgment of impaired HD broadcast IPTV.
How much bandwidth is required for good quality video for a given screen resolution? Data acquired during two Video Quality Experts Group (VQEG) projects allow at least a partial answer to this question. This international subjective testing produced large amounts of mean opinion score (MOS) data for the screen resolutions QIF, CIF, VGA, and HD; for H.264 and similar modern codecs; and for many bit rates. Those data are assembled in the present report. For each screen resolution, MOS is plotted as a function of bit rate. A plot of all four data sets together shows the bit rate that would be required to achieve a given level of video quality for a given screen resolution. Relations among the four data sets are regular, suggesting that interpolation across screen resolutions might be reasonable. Based on these data, it would be reasonable to choose a bit rate, given a screen resolution; it would not be reasonable to choose a screen resolution given a bit rate.
We propose a balanced multiple description coding framework using rate-distortion splitting for three dimensional DCT (3D DCT) coded video data. The proposed algorithm pro- duces correlated and balanced descriptions, with balancing in terms of bit rate and receiver distortion. Our description split- ting and balancing algorithm takes advantage of the structural properties of the 3D DCT video volume and the method of shifted compliment hyperboloid used in scanning and quantization of 3D DCT coefficients. Given the available bit rate and redundancy our simulations show high PSNR values for the reconstructed video. The proposed video codec requires a simple implementation, has a low complexity, and produces a high reconstruction quality. Comparative results with other schemes are included. IndexTerms—Errorresilience,multipledescriptioncoding,very low bit rate coding, 3D DCT.
In this paper, we evaluate the performances of SNR scalability provided by the scalable extension of the H.2641MPEG4 advanced video coding standard, also known as Scalable Video Coding (SVC), depending on the spatial resolution of the input video sequence. Preliminary simulation results show that SVC performances are directly related to spatial resolution of input video. In particular, video quality gains obtained by adding the enhancement layer to the base one, in terms of PSNR, are inferior when considering high resolution video contents in comparison with low ones, for similar bit rate ratios. We also propose a discussion on the consequences of this result on transmission schemes.
Importance of digitalization and compression of AV (audio/video) signals, produced in TV studios, and choose of optimal compression algorithm for different purposes, has been recognized long time ago, and in many countries, TV studios abandoned old analog transmission and storage of analog materials, leaving place for digital signal transmission and storage. In Bosnia and Herzegovina, TV studios are still producing, storing and broadcasting analog PAL signal, but according to recommendation, they should switch to DVB (digital video broadcasting) before 2012. One of DVB applications is VoD (video on demand), witch allows users to request specific AV material, stored on VoD servers, at any time they want. On order to provide that, TV studios must have VoD servers, with stored AV materials, witch they should stream to end users, on their request. Because of the actuality of this problem, the main idea of this paper was to make appropriate software solution for digitalization and trenscoding of analog PAL signal, or transcoding some digital formats, in order to produce AV file with optimal performance, according to QoS and file size, witch should be stored on VoD server. Using developed solutions, different types of compression algorithms, using different video transcoding bit rates, are tested, with the aim to recommend TV stations the solution for storage digital AV signals on VoD servers, with optimal performances, in future DVB network.
brief overview of H.264/AVC and MPEG-4 Part 2 standards is given in this paper with focus on differences between them. Experimental quality comparison of H.264/AVC and MPEG-2 Part 2 coded video is done for several sequences and bit rates. The codecs used in the experiment are JVT JM ver. 10.2, as implementation of H.264/AVC, andXviD ver. 1.1.0, as implementation of MPEG-4 Part 2. The peak signal-to-noise ratio (PSNR) and video quality model (VQM) are used as objective quality metrics. The results obtained show that JVT JM codec outperforms XviD codec both in objective and subjective quality.
The emerging ITU-T H.264 video coding standard has been developed to achieve significant improvements over the existing standards in the compression performance. Although the basic coding framework of the standard is similar to that of the existing standards, H.264 introduces many new features. The standard is close to completion, and preliminary tests were reported to give satisfactory results. However, thorough performance evaluations by independent parties have yet to come. In this paper, we provide an independent analysis of the coding performance improvement of H.264 over various other existing video coding standards. Our experiments demonstrated that the H.264 standard can achieve 50% coding gain over MPEG-2, 47% coding gain over H.263 baseline, and 24% coding gain over H.263 high profile encoders.
We examine the influence of scene-level content on the visibility of packet loss impairments in MPEG-2 and H.264 compressed video. We consider both global camera motion and proximity to a scene cut. We use Patient Rule Induction Method (PRIM) to pick out both highly visible and very invisible packet losses. We show that global camera motion significantly increases visibility relative to a still camera. Further, while packet losses that are concealed using a prior scene’s image are strongly visible, all other packet losses near a scene change are much less likely to be visible, all other factors being equal.
The Public Safety Statement of Requirements (PS-SoR) for Communications & Interoperability focuses on the needs of first responders to communicate and share information as authorized, when it is needed, where it is needed, and in a mode or form that allows the practitioners to effectively use it. PS-SoR Volume I defined functional communication and interoperability requirements. Published in September, 2006, PS-SoR Volume II identifies quantitative performance metrics, including minimum video performance requirements for public safety's tactical video applications. The goal was not to identify what is achievable with current technology but rather, looking towards the future, to investigate the minimum level of performance that first responders need in order to effectively use their video equipment. On behalf of the SAFECOM Program and the Office of Law Enforcement Standards, the Institute for Telecommunication Sciences (ITS) conducted subjective video quality testing to estimate the level of video quality that first responders find acceptable for tactical video applications. This subjective testing utilized source video content that is typical of public safety operations in structured subjective viewing experiments with 35 first responders. The evaluations from these first responders, in viewing high quality video (original video) and purposefully degraded video (using video compression and transmission equipment), allowed determination of basic quality thresholds for public safety tactical video applications. These perceptual quality thresholds have been translated into technical parameters for use by video equipment designers, manufacturers, and customers. This paper summarizes those findings. Other testing to evaluate requirements for other public safety applications is underway.
Subjective quality assessment of the emerging AVC/H.264 video coding standard
- T Oelbaum
- V Baroncini
- T K Tan
- C Fenimore
T. Oelbaum, V. Baroncini, T. K. Tan, and C. Fenimore, "Subjective
quality assessment of the emerging AVC/H.264 video coding standard,"
in Proc. International Broadcasting Convention (IBC), Amsterdam,
Netherlands, 2004.
Subjective Video Quality Assessment Methods for Multimedia Applications
ITU-T Recommendation P.910, "Subjective Video Quality Assessment
Methods for Multimedia Applications," Geneva, 2007 (available at
www.itu.int).