Empirical study of partial decoding for fast browsing of MPEG-2 compressed videos

Following a series of successful launch of MPEG standards on video compression, their applications reveal ever increasing needs for their content access without full decompression or in their compressed format. To this end, we further investigated a number of partial decoding schemes to address the issue of efficient content access to compressed video streams. By controlling the number of DCT coefficients involved in the inverse DCT, a number of partial decoding schemes can be designed featuring fast processing speed and low computing cost. By controlling the size of video frames, visually perceptual quality can be adjusted to suit various application including thumbnail image browsing, low resolution image processing, head tracking, skin detection, face recognition, and object segmentation etc. where full resolution frames are often not necessarily required. While achieving improved computing cost and processing speed, our work also features in: (i) reasonably good image quality for content browsing; (ii) compatibility with original MPEG-2 bit streams; and (iii) enormous potential for further application of MPEG-2 in video content management, content-based video frame retrieval, compressed video editing, and low bit-rate video communication such as those involving mobile phones and telephone networks etc. In addition, extensive experiments were carried out and reported to support our design.