Cost effective transcoding for QoS adaptive multimedia streaming
Proceedings of the 2004 ACM symposium on Applied computing
An efficient complexity-scalable video transcoder with mode refinement
Image Communication
Effective algorithms for fast transcoding of AVS to H.264/AVC in the spatial domain
Multimedia Tools and Applications
Efficient hybrid DCT-domain algorithm for video spatial downscaling
EURASIP Journal on Advances in Signal Processing
A fast MPEG-2 to H.264 downscaling transcoder
ISCGAV'08 Proceedings of the 8th conference on Signal processing, computational geometry and artificial vision
EURASIP Journal on Advances in Signal Processing
Mixed architectures for H.264/AVC digital video transrating
Multimedia Tools and Applications
Hybrid H.264 Video transcoding for bitrate reduction in wireless networks
WiCOM'09 Proceedings of the 5th International Conference on Wireless communications, networking and mobile computing
Effective drift reduction technique for reduced bit-rate video adaptation
PCM'04 Proceedings of the 5th Pacific Rim conference on Advances in Multimedia Information Processing - Volume Part III
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This paper discusses the problem of reduced-resolution transcoding of compressed video bitstreams. An analysis of drift errors is provided to identify the sources of quality degradation when transcoding to a lower spatial resolution. Two types of drift error are considered: a reference picture error, which has been identified in previous works, and error due to the noncommutative property of motion compensation and down-sampling, which is unique to this work. To overcome these sources of error, four novel architectures are presented. One architecture attempts to compensate for the reference picture error in the reduced resolution, while another architecture attempts to do the same in the original resolution. We present a third architecture that attempts to eliminate the second type of drift error and a final architecture that relies on an intrablock refresh method to compensate for all types of errors. In all of these architectures, a variety of macroblock level conversions are required, such as motion vector mapping and texture down-sampling. These conversions are discussed in detail. Another important issue for the transcoder is rate control. This is especially important for the intra-refresh architecture since it must find a balance between number of intrablocks used to compensate for errors and the associated rate-distortion characteristics of the low-resolution signal. The complexity and quality of the architectures are compared. Based on the results, we find that the intra-refresh architecture offers the best tradeoff between quality and complexity and is also the most flexible.