1995 International Conference on Image Processing (ICIP'95) - Volume 2
Low bit rate model-assisted H.261-compatible coding of video
Washington D.C.
October 23-October 26
ISBN: 0-8186-7310-9
A. Jacquin, Dept. of Electr. Eng., Columbia Univ., New York, NY, USA
We describe a method of object-selective quantizer control in a standard coding system based on MC DCT-CCITT Recommendation H.261. The approach is based on two novel algorithms, namely buffer rate modulation and buffer size modulation. By forcing the rate control algorithm to transfer a relatively small fraction-about 10-15% on average-of the total available bit rate from the coding of the non-facial to that of the facial area, in head-and-shoulders videoteleconferencing sequences, images with better-rendered facial features are obtained, i.e. blocky artifacts in the facial area are less pronounced and eye contact and lip-sync are preserved. The improvement was found to be perceptually significant on video sequences coded at the rate of 64 kbps, with 48 kbps allocated for the input (color) video signal in QCIF format.
Index Terms:
code standards; telecommunication standards; video coding; teleconferencing; image sequences; motion estimation; motion compensation; image segmentation; discrete cosine transforms; transform coding; feature extraction; object-selective quantizer control; MC DCT-CCITT Recommendation H.261; buffer rate modulation; buffer size modulation; rate control algorithm; head-and-shoulders videoteleconferencing sequences; facial features; video sequences; QCIF format; video coding; low bit rate coding; 64 kbit/s
Citation:
A. Eleftheriadis, A. Jacquin, "Low bit rate model-assisted H.261-compatible coding of video," icip, vol. 2, pp.2418, 1995 International Conference on Image Processing (ICIP'95) - Volume 2, 1995