-
Trista Pei-chun Chen
[show abstract]
[hide abstract]
ABSTRACT: Video streaming over packet-loss networks faces the challenges that the networks are error-prone, transmission bandwidth is limited and fluctuating, the user device capabilities vary, and networks are heterogeneous. These challenges necessitate the need for smart adaptation of the precoded video. The focus of the thesis is error-resilient rate shaping for streaming precoded video over packet-loss networks. Given the packet-loss characteristic of the networks, the precoded video consists of channel-coded as well as source-coded bits. Error-resilient rate shaping is a filtering process that adapts the bit rates of the precoded video, in order to deliver the best video quality given the network condition at the time of delivery. We first illustrate "baseline rate shaping (BRS)" of the proposed error-resilient rate shaping as a baseline. Having introduced BRS with coarse decisions in rate adaptation, more sophisticated error-resilient rate shaping is proposed for layer-coded videos, namely, the enhancement layer video and the base layer video. "Fine-grained rate shaping (FGRS)" is proposed for streaming the enhancement layer video, and "errorconcealment aware rate shaping (ECARS)" is proposed for streaming the base layer video. FGRS and ECARS are formulated as rate-distortion (R-D) optimization problems. A two-stage R-D optimization approach is proposed to solve the R-D optimization problem in a fast and accurate manner. FGRS makes use of the fine granularity property of the MPEG-4 fine-granularityscalability bitstream and outperforms ad-hoc unequal packet-loss protection methods. ECARS takes into account error concealment (EC) performed at the receiver to deliver the part of precoded video that cannot be EC-reconstructed well. Frame dependency due to predictive coding and/...
04/2004;
-
[show abstract]
[hide abstract]
ABSTRACT: Video streaming over wireless networks faces challenges of time-varying packet loss rate and fluctuating bandwidth. In this paper, we focus on streaming precoded video that is both source and channel coded. Dynamic rate shaping has been proposed to “shape” the precompressed video to adapt to the fluctuating bandwidth. In our earlier work, rate shaping was extended to shape the channel coded precompressed video, and to take into account the time-varying packet loss rate as well as the fluctuating bandwidth of the wireless networks. However, prior work on rate shaping can only adjust the rate oarsely. In this paper, we propose “fine-grained rate shaping (FGRS)” to allow for bandwidth adaptation over a wide range of bandwidth and packet loss rate in fine granularities. The video is precoded with fine granularity scalability (FGS) followed by channel coding. Utilizing the fine granularity property of FGS and channel coding, FGRS selectively drops part of the precoded video and still yields decodable bit-stream at the decoder. Moreover, FGRS optimizes video streaming rather than achieves heuristic objectives as conventional methods. A two-stage rate-distortion (RD) optimization algorithm is proposed for FGRS. Promising results of FGRS are shown.
EURASIP Journal on Advances in Signal Processing. 01/2004;
-
EURASIP J. Adv. Sig. Proc. 01/2004; 2004:176-191.
-
[show abstract]
[hide abstract]
ABSTRACT: Streaming of precoded video, which is both source- and channelcoded, over packet-loss networks faces challenges of the timevarying packet loss rate and fluctuating bandwidth. Rate shaping has been proposed to reduce the bit rate of a precoded video bitstream to adapt to the real-time bandwidth variation. In our earlier work, rate shaping was extended to consider not only the bandwidth but also the packet loss rate variations. In practice, the reconstructed result of the previous frame will affect the following frames if the video is predictive coded, and/or the error concealment method performed at the receiver utilizes temporal information.
05/2003;
-
[show abstract]
[hide abstract]
ABSTRACT: We present in this paper an adaptive joint source-channel coding scheme using rate shaping on pre-coded video data. Rate shaping selectively drops portions of the video bitstream before transmitting them in order to satisfy the network bandwidth requirement. In wireless multimedia transport over heterogeneous networks, limited bandwidth is not the only issue. The high error rate of the channel should be considered as well, so channel coding is often applied. We propose a rate shaping method that drops not only the source-coding segments of the video bitstream, but also the channel-coding segments of the video bitstream, adaptively according to the network condition, in order to achieve the optimal rate-distortion performance. The proposed method is based on discrete rate-distortion combination to accomplish joint source-channel coding. We consider both the simulcast and multicast scenarios and show promising results.
04/2002;
-
[show abstract]
[hide abstract]
ABSTRACT: Video transport over error prone channels may result in loss or erroneous decoding of the video. Error concealment is an effective mechanism to reconstruct the video content. In this paper, we review different error concealment methods and introduce a new framework, which we refer to as second-generation error concealment. All the error concealment methods reconstruct the lost video content by making use of some a priori knowledge about the video content. First-generation error concealment builds such a priori in a heuristic manner. The proposed second-generation error concealment builds the a priori by modeling the statistics of the video content. Context-based models are trained with the correctly decoded video content, and then used to replenish the lost video content. Trained models capture the statistics of the video content and thus reconstruct the lost video content better than reconstruction by heuristics.
Image Processing. 2002. Proceedings. 2002 International Conference on; 02/2002
-
Recent Advances in Visual Information Systems, 5th International Conference, VISUAL 2002 Hsin Chu, Taiwan, March 11-13, 2002, Proceedings; 01/2002
-
01/2002
-
[show abstract]
[hide abstract]
ABSTRACT: We propose a general framework for blind watermark detection. This framework contains a maximum-likelihood detector that utilizes the probability distribution of the original image. Other watermark detectors in literature are shown to be special cases of this framework. We demonstrate this framework in both the pixel domain and the transform domain, and show that our detector outperforms others because of 1) better modeling of the probability distribution of the original image, and 2) consideration to the human visual system in this framework.
08/2001;
-
[show abstract]
[hide abstract]
ABSTRACT: Progressive transmission of images is very useful in many
applications, especially in image transmission over the Internet. To
view an image, people would want to see part of the image while the
image transmission is in progress, rather than having to wait until the
end of the image transmission. On the other hand, the ease of
transmission and copying of images creates the need to use digital
watermarking to embed the copyright information seamlessly into the
media. We propose a progressive image watermarking scheme. In this
scheme, the watermark is embedded in such a way that we can retrieve
part of it even when the watermarked image is still being transmitted.
As transmission progresses, the retrieved watermark has a decreasing bit
error rate. Our proposed methods not only transmit the watermarked image
progressively, but also intelligently select watermark embedding
locations robust to various attacks
Multimedia and Expo, 2000. ICME 2000. 2000 IEEE International Conference on; 02/2000
-
[show abstract]
[hide abstract]
ABSTRACT: Streaming of video, which is both source- and channel-coded, over wireless networks faces the challenge of time-varying packet loss rate and fluctuating bandwidth. Rate shaping (RS) has been proposed to reduce the bit-rate of a precoded video bitstream to adapt to the real-time bandwidth variation. In our earlier work, rate shaping was extended to consider not only the bandwidth but also the packet loss rate variations. Rate-distortion optimized rate adaptation is performed on the precoded video that is a scalable coded bitstream protected by forward error correction codes. In this paper, we propose an RS scheme that further takes into account the error concealment (EC) method used at the receiver. We refer to this scheme as EC aware RS (ECARS). When performing ECARS, first ECARS needs to know the benefit/gain of sending each part of the precoded video, as opposed to not sending it but reconstructing it by EC. Then given a certain packet loss probability, the expected gain can be derived and be included in the rate-distortion optimization problem formulation. Finally, ECARS performs rate-distortion optimization to adapt the rate of the precoded video. A two-stage rate-distortion optimization approach is proposed to solve the ECARS rate-distortion optimization problem. In addition to ECARS, the precoding process can be EC aware to prioritize the precoded video based on the gain. We present an example EC aware precoding process by means of macroblock prioritization. Experiment results of ECARS together with EC aware precoding are shown to have excellent performance.
Signal Processing: Image Communication.
