Rate adaptation transcoding for precoded video streams
Proceedings of the tenth ACM international conference on Multimedia
Constrained and general dynamic rate shaping of compressed digital video
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An efficient complexity-scalable video transcoder with mode refinement
Image Communication
Digital Video Transcoding for Transmission and Storage
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Operational distortion-quantization curve-based bit allocation for smooth video quality
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Key techniques of bit rate reduction for h.264 streams
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Video transcoding: an overview of various techniques and research issues
IEEE Transactions on Multimedia
Performance evaluation of transcoding algorithms for H.264
IEEE Transactions on Consumer Electronics
Architectures for MPEG compressed bitstream scaling
IEEE Transactions on Circuits and Systems for Video Technology
A frequency-domain video transcoder for dynamic bit-rate reduction of MPEG-2 bit streams
IEEE Transactions on Circuits and Systems for Video Technology
Low-delay rate control for DCT video coding via ρ-domain source modeling
IEEE Transactions on Circuits and Systems for Video Technology
Optimum bit allocation and accurate rate control for video coding via ρ-domain source modeling
IEEE Transactions on Circuits and Systems for Video Technology
A linear source model and a unified rate control algorithm for DCT video coding
IEEE Transactions on Circuits and Systems for Video Technology
Overview of the H.264/AVC video coding standard
IEEE Transactions on Circuits and Systems for Video Technology
IEEE Transactions on Circuits and Systems for Video Technology
Transrating-assisted MPEG-4 video resizing with rate-distortion optimization
Proceedings of the 10th International Conference on Advances in Mobile Computing & Multimedia
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This paper presents a model-based transrating (bit-rate reduction) system for H.264 coded video via requantization. In works related to previous standards, optimal requantization step sizes were obtained via Lagrangian optimization that minimizes the distortion subject to a rate constraint. Due to H.264 advanced coding features, the choices of quantization step size and coding modes are dependent and the rate control becomes computationally expensive. Therefore, optimal requantization algorithms developed for previous standards cannot be applied as they are. Hence, previous works on transrating in H.264 focused on changing the input coding decisions rather than on rate control, while requantization was addressed by a simple one-pass algorithm. Here we propose new model-based optimal requantization algorithms for transrating of H.264 coded video. The optimal requantization goal is to achieve the target bit rate with minimal effect on video quality. Incorporation of the proposed models serves two goals. For intra-coded frames, a novel closed-loop statistical estimator that overcomes spatial neighbors dependencies is developed. For inter-coded frames, the proposed macroblock-Ievel models reduce the computational burden of the optimization. Overall, as compared to re-encoding (cascaded decoder-encoder), the proposed system reduces the computational complexity by a factor of about four, at an average PSNR loss of only 0.4 dB for transrating CIF/SIF sequences from 2 Mb/s to 1 Mb/s. In comparison with a simple one-pass requantization, the proposed algorithm achieves better performance (an average PSNR gain of 0.45 dB), at the cost of just twice the complexity.