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In video coding systems using adaptive arithmetic coding to compress texture information, the employed symbol probability models need to be retrained every time the coding process moves into an area with different texture. To avoid this inefficiency, we propose to replace the probability models used in the original coder with multiple switchable sets of probability models. We determine the model set...
In this paper, we present motion-refined transcoding of H.264/AVC streams to SVC in the transform domain. By accurately taking into account both rate and distortion in the different layers on the one hand, and the SVC inter-layer motion prediction mechanisms on the other hand, the proposed transcoding architecture is able to improve rate-distortion performance over existing approaches. We propose...
When combining non-rectangular (shape-adaptive) partitioning of inter pictures with a rectangular block transform, some of the transforms will be applied to a residual signal which originates from two different predictions. This is a condition that is never encountered in any of the existing video coding standards, and the impact of this on the performance of the transform coder has not been investigated...
Requantization transcoding is a method for reducing the bit rate of compressed video bitstreams. Most research on requantization is concerned with the architectural design, the selection of a suitable quantizer, or the reduction of requantization errors. In this paper, we propose to incorporate a new dimension in requantization transcoding: the quantization offset. We compare two requantization methods:...
We present a family of new macroblock partitions for H.264/AVC inter prediction. These modes allow a macroblock to be bipartitioned along a horizontal, vertical, or diagonal edge with an arbitrary location within the block. These new partitioning modes allow an encoder to adapt more closely to the local motion characteristics and improve its rate-distortion performance. In order to quantify the improvements...
In this paper, we present a spatial resolution reduction transcoding architecture for H.264/AVC, which extends open-loop transcoding with a low-complexity compensation technique in the reduced-resolution domain. The proposed architecture removes visual artifacts from the transcoded sequence, while keeping complexity significantly lower than more traditional cascaded decoder-encoder architectures....
In this paper, dynamic rate shaping for H.264/AVC intra-coded video streams is investigated. An analysis of the distortion distinguishes different error components that lead to the degradation of the output video stream. Experimental results show that the propagation error due to intra prediction has a major impact on the visual quality. This results from the highly increased number of dependencies...
To attain efficient coding of sequences with complex motion activity, modern video coding standards allow variable block sizes to be employed in temporal prediction. A block with complex motion can be partitioned into two equal-sized halves or into four quadrants. In this paper we study the impact of allowing blocks to be partitioned in two unequal subpartitions. Additionally, we allow block partitioning...
Today's wireless networks suffer from high error rates in real-life conditions. Moreover errors tend to occur in large bursts. Multiple Description Coding (MDC) of digital video is a promising technique to overcome these problems in wireless environments by taking advantage of frequency or channel diversity. This papers proposes two low complexity MDC techniques for H.264/AVC at the Network Abstraction...
Transcoding is used in order to enable elegant adaptation of video sequences without fully decoding and recoding. For efficiency reasons, special attention is paid to transform-domain adaptation of video sequences, hereby avoiding the cost of forward and inverse DCT or, in the case of H.264/AVC, integer transforms. In this paper we compare different architectures for MPEG-2 to H.264/-AVC intra transcoding,...
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