Hi all Kieran asked me about h264 ER TODO
so here are some ideas H264 features: Redundant pictures. It would be possible to encode a low bitrate image for each access unit and use it when the primary picture has lost slices. This can be limited to slices which would be concealed poorly if lost. This would increase the bitrate of the h264 stream Data partitioning. We support data partitioning for MPEG4(-ASP) and it provided there useful quality gains. This would seperate the high bitrate textures from low bitrate motion vectors. The later is much more important for maitaining ok looking images Error concealment features: Interlacing support is basically missing, this is obviously important when the input is interlaced Future frames are currently only used with B frames, but it would certainly improve other frames too. For example knowing the next P frame would mean we know the next frames motion vectors and the previous frames motion vectors which would help in estimating the motion vectors any lost area. This would require redecoding the next frame and thus possibly that is tricky Finer grained detection of initial error position, currently errors are detected during decoding and a heuristic is used to cover several previous MBs so as to cover the whole damaged area. But it would be possible to analyze the MBs itself to detect mismatches accorss MB edges and use this to better estimate from where concealing must start to maximize quality. Also if outside information as lost packets is known this too if it does not 1:1 match slices could be used to make the concealed area tighter Testing: We have little error concealment testing. A few more fate tests to cover various videos (high/low complexity motion/ no motion) with different errors (lost slices, reordered slices, damaged bytes/bits) and comparing (PSNR) vs undamaged input would be usefull. These could also be usefull to evaluate any changes done to the error concealment code. -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Opposition brings concord. Out of discord comes the fairest harmony. -- Heraclitus
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