From: Zhao Zhili <zhiliz...@tencent.com> v2: 1. Check vps_max_layers and vps_max_layer_id inside hevc decoder 2. Add hevc_extract_layer bsf to do the job rather than modifing hevc_metadata, 3. Check vps_max_layers_minus1 and vps_max_layer_id inside bsf 4. Update vps_max_layers_minus1 and vps_max_layer_id when rewrite as base layer 5. vps_extension should be updated rather than drop entirely, add a TODO
--------------------------------------------- 1. Don't drop nal->nuh_layer_id > 0 until decoder. 2. Make hevcdec able to decode a selected layer. 3. Add hevc_extract_layer bsf to extract a selected layer. Partially fix #7965. There is a sample in ticket #7965 which can be used to test the patchset. Or use videotoolbox encoder to create a sample (FFmpeg needs to be patched first, "avutil/hwcontext_videotoolbox: BGRA should be full range" http://ffmpeg.org/pipermail/ffmpeg-devel/2023-January/305252.html), e.g., ./ffmpeg -i cctv.mp4 \ -i pig.mp4 \ -c:v hevc_videotoolbox \ -alpha_quality 0.75 \ -filter_complex '[1:v]scale=640x480[v1];[0:v][v1]alphamerge[v2]' \ -map [v2] -an -t 60 \ -pix_fmt bgra \ -b:v 4M \ -tag:v hvc1 \ alpha.mp4 -y Now it's able to use two decoders to decode the base layer and alpha layer, and then combine the results, e.g., ./ffmpeg -i alpha.mp4 \ -strict -2 -nuh_layer_id 1 -i alpha.mp4 \ -frames 60 \ -filter_complex '[0:v][1:v]alphamerge[vout]' \ -map '[vout]' -an test-%d.png It only works with software decoder. hevc_extract_layer can be used together with hardware decoder. The following example is how to extract the alpha layer and rewrite as base layer: ./ffmpeg -i alpha.mp4 \ -an -c:v copy \ -bsf:v hevc_extract_layer=nuh_layer_id=1 \ test.mp4 Zhao Zhili (4): avcodec/hevc_parse: keep nal->nuh_layer_id > 0 avcodec/cbs_h2645: keep nal->nuh_layer_id > 0 avcodec/hevcdec: add nuh_layer_id option avcodec: add hevc_extract_layer bsf configure | 1 + doc/bitstream_filters.texi | 12 +++ libavcodec/Makefile | 1 + libavcodec/bitstream_filters.c | 1 + libavcodec/cbs_h2645.c | 3 - libavcodec/hevc_extract_layer_bsf.c | 126 ++++++++++++++++++++++++++++ libavcodec/hevc_parse.c | 2 - libavcodec/hevcdec.c | 56 ++++++++++++- libavcodec/version.h | 2 +- 9 files changed, 197 insertions(+), 7 deletions(-) create mode 100644 libavcodec/hevc_extract_layer_bsf.c -- 2.25.1 _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
