M. Gallant

McMaster University, Hamilton, Ontario, Canada

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Publications (13)13.24 Total impact

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    S. Shirani, M. Gallant, F. Kossentini
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    ABSTRACT: We address the problem of robust transmission of compressed visual information over unreliable networks. Our approach employs the principle of multiple descriptions, through pre- and post-processing of the image data, without modification to the source or channel codecs. We employ oversampling to add redundancy to the original image data followed by a partitioning of the oversampled image into “equal” sub-images which can be coded and transmitted over separate channels. Simulations using two descriptors show that this approach yields exceptional performance when only one descriptor is received and outperforms other popular multiple description approaches
    Information Technology: Coding and Computing, 2001. Proceedings. International Conference on; 05/2001
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    M. Gallant, F. Kossentini
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    ABSTRACT: We present an effective framework for increasing the error-resilience of low bit-rate video communications over an error-prone packet-switched network. Our framework is based on the principle of layered coding with transport prioritization. We introduce a rate-distortion optimized mode-selection algorithm for our prioritized layered framework. This algorithm is based on a joint source/channel-coding approach and trades off source coding efficiency for increased bitstream error-resilience to optimize the video coding mode selection within and across layers. The algorithm considers the channel conditions, as well as the error recovery and concealment capabilities, of the channel codec and source decoder, respectively. Important framework parameters including the packetization scheme, decoder error concealment method, and channel codec error-protection strength are considered. The effects of mismatch between the parameters employed by the encoder and the actual channel conditions are considered. Results are presented for a wide range of packet loss rates in order to illustrate the benefits of the proposed framework
    IEEE Transactions on Circuits and Systems for Video Technology 04/2001; · 1.82 Impact Factor
  • M. Gallant, S. Shirani, F. Kossentini
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    ABSTRACT: We address the problem of robust video transmission over unreliable networks. Our approach employs the principle of multiple-descriptions, through pre- and post-processing of the video data, without modification to the source or channel codecs. We employ oversampling to add redundancy to the original video data followed by a decomposition of the oversampled video frames into "equal" sub-images which can be coded and transmitted over separate channels. Simulations using two descriptions show that this approach maintains excellent reconstructed video quality when only one description is received
    Image Processing, 2001. Proceedings. 2001 International Conference on; 02/2001
  • M. Gallant, F. Kossentini
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    ABSTRACT: We present a rate-distortion optimal joint source/channel coding framework for efficient and robust low bit rate video communications in packet networks. The proposed algorithm combines layered coding with transport prioritization in a novel operational rate-distortion optimization framework that trades off source coding performance for channel coding protection. The system is demonstrated to achieve significant improvement in reconstructed video quality for a range of packet loss rates
    Image Processing, 2000. Proceedings. 2000 International Conference on; 02/2000
  • Source
    M. Gallant, G. Cote, F. Kossentini
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    ABSTRACT: We present an efficient computation constrained block-based motion vector estimation algorithm for low bit rate video coding that yields good tradeoffs between motion estimation distortion and number of computations. A reliable predictor determines the search origin, localizing the search process. An efficient search pattern exploits structural constraints within the motion field. A flexible cost measure used to terminate the search allows simultaneous control of the motion estimation distortion and the computational cost. Experimental results demonstrate the viability of the proposed algorithm in low bit rate video coding applications. The resulting low bit rate video encoder yields essentially the same levels of rate-distortion performance and subjective quality achieved by the UBC H.263+ video coding reference software. However, the proposed motion estimation algorithm provides substantially higher encoding speed as well as graceful computational degradation capabilities
    IEEE Transactions on Image Processing 01/2000; · 3.20 Impact Factor
  • G. Cote, M. Gallant, F. Kossentiai
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    ABSTRACT: We present a semi-fixed-length motion vector coding method for H.263-based low bit rate video compression. The method exploits structural constraints within the motion field. The motion vectors are encoded using semi-fixed-length codes, yielding essentially the same levels of rate-distortion performance and subjective quality achieved by H.263's Huffman-based variable length codes in a noiseless environment. However, such codes provide substantially higher error resilience in a noisy environment
    IEEE Transactions on Image Processing 11/1999; · 3.20 Impact Factor
  • M. Gallant, F. Kossentini
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    ABSTRACT: Summary form only given. We present our work on rate-distortion (RD) optimized spatial scalability for MC-DCT based video coding. Extending our work on RD optimized coding from the single layered to the multi-layered framework, we incorporate the additional inter-layer coding dependencies present in a multilayered framework into the set of permissible coding parameters. We employ the Lagrangian rate-distortion functional as it provides an elegant framework for determining the optimal choice of motion vectors, coding modes, and quantized coefficient levels by weighting a distortion term against a resulting rate term. We obtain a simple relationship between the Lagrangian parameter λ, that controls rate-distortion tradeoffs, and the reference and enhancement layer quantization parameters QP, to allow the RD optimized framework to work easily in conjunction with rate control techniques that control the average bit rate by adjusting the quantization parameters. We then incorporate these relationships into our coder and generate two-layer bit streams with both the non-RD optimized coder and the RD optimized coder. We also generate RD optimized single-layer bit streams with the same resolution as the second layer of the two-layer bit streams. For the two-layer bit streams, we obtain a 0.6 to 1.4 dB improvement in PSNR by using RD optimization in both the base and enhancement layers. Compared to the single-layer bit stream, RD optimization in both the base and enhancement layers causes the decrease in PSNR to be reduced from 1.1 to 1.7 dB, to 0.3 to 0.5 dB
    Data Compression Conference, 1999. Proceedings. DCC '99; 04/1999
  • M. Gallant, F. Kossentini
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    ABSTRACT: It its well-known that flexibility and error resilience are significantly improved by employing a scalable bit stream. The major drawback of multi-layered representations within a motion compensated (MC) discrete cosine transform (DCT) based framework is the increase in bit rate as compared to a single-layered representation having the same frequency, spatial and temporal resolution as in the highest layer of the multi-layered representation. This increase in bit rate is due to side information overhead, variable-length coding inefficiencies, and the differing statistics of the error signal. Consequently, much of the research in the area of scalability has focused on non MC-DCT based techniques having inherently scalable properties, e.g. sub-band techniques. However, the ubiquity of MC-DCT based technology suggests that we also address the problem within the MC-DCT framework. This is further warranted given the inclusion of syntax extensions to support scalable coding within newer MC-DCT based video coding standards. In this paper we present a rate-distortion optimized SNR and spatially scalable framework for MC-DCT based video coding
    Electrical and Computer Engineering, 1999 IEEE Canadian Conference on; 02/1999
  • Source
    M. Gallant, F. Kossetini
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    ABSTRACT: It is well-known that flexibility and error resilience are significantly improved by employing a scalable bit stream. The major drawback of multi-layered representations within a motion compensated (MC) discrete cosine transform (DCT) based framework is the increase in bit rate as compared to a single-layered representation having the same frequency, spatial and temporal resolution as in the highest layer of the multi-layered representation. Using rate-distortion (RD) optimization techniques, we can improve the compression efficiency of MC-DCT based SNR and spatially scalable video coding framework. We first show how RD optimization techniques can be applied independently for each layer. We then extend the framework to consider coding decisions jointly across layers
    Image Processing, 1999. ICIP 99. Proceedings. 1999 International Conference on; 02/1999
  • Source
    B. Erol, M. Gallant, G. Cote, F. Kossentini
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    ABSTRACT: The emerging ITU-T H.263+ low bit-rate video coding standard is version 2 of the draft international standard ITU-T H.263. In this paper, we discuss this emerging video coding standard and present compression performance results based on our public domain implementation of H.263+
    Data Compression Conference, 1998. DCC '98. Proceedings; 12/1998
  • Source
    G. Cote, B. Erol, M. Gallant, F. Kossentini
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    ABSTRACT: We discuss the ITU-T H.263+ (or H.263 Version 2) low-bit-rate video coding standard. We first describe, briefly, the H.263 standard including its optional modes. We then address the 12 new negotiable modes of H.263+. Next, we present experimental results for these modes, based on our public-domain implementation (http:ilspmg.ece.ubc.ca). Tradeoffs among compression performance, complexity, and memory requirements for the H.263+ optional modes are discussed. Finally, results for mode combinations are presented
    IEEE Transactions on Circuits and Systems for Video Technology 12/1998; · 1.82 Impact Factor
  • Source
    M. Gallant, F. Kossentini
    [Show abstract] [Hide abstract]
    ABSTRACT: We present an efficient computation constrained block-based motion vector estimation algorithm for low bit rate video coding that offers good tradeoffs between motion estimation distortion and number of computations. A reliable predictor determines the search origin. An efficient search pattern exploits structural constraints within the motion field. A flexible cost measure used to terminate the search allows simultaneous control of the motion estimation distortion and the computational cost. Experimental results demonstrate the viability of the proposed algorithm in low bit rate video coding applications, achieving essentially the same levels of rate-distortion performance and subjective quality as that of the full search algorithm when used by the UBC H.263+ video coding reference software. However the proposed motion estimation algorithm provides substantially higher encoding speed as well as graceful computational degradation capabilities.
    Signals, Systems & Computers, 1998. Conference Record of the Thirty-Second Asilomar Conference on; 12/1998
  • M. Gallant, G. Cote, F. Kossentini
    IEEE Transactions on Image Processing 01/1997; · 3.20 Impact Factor