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• fftools/ffmpeg_dec : move setting compute_edt to demuxer

  23 janvier 2024, par Anton Khirnov

  fftools/ffmpeg_dec : move setting compute_edt to demuxer
  It is done based on demuxer information, so that is the more appropriate
  
  place for this code.
  This is a step towards decoupling Decoder and InputStream.
  

  • [DH] fftools/ffmpeg_dec.c
  • [DH] fftools/ffmpeg_demux.c

• flvdec : Honor the "flv_metadata" option for the "datastream" metadata field

  9 février 2024, par Martin Storsjö

  flvdec : Honor the "flv_metadata" option for the "datastream" metadata field
  By default the option "flv_metadata" (internally using the field
  
  name "trust_metadata") is set to 0, meaning that we don't allocate
  
  streams based on information in the metadata, only based on
  
  actual streams we encounter. However the "datastream" metadata field
  
  still would allocate a subtitle stream.
  When muxing, the "datastream" field is added if either a data stream
  
  or subtitle stream is present - but the same metadata field is used
  
  to preemtively create a subtitle stream only. Thus, if the field
  
  was added due to a data stream, not a subtitle stream, the demuxer
  
  would create a stream which won't get any actual packets.
  If there was such an extra, empty subtitle stream, running
  
  avformat_find_stream_info still used to terminate within reasonable
  
  time before 3749eede66c3774799766b1f246afae8a6ffc9bb. After that
  
  commit, it no longer would terminate until it reaches the max
  
  analyze duration, which is 90 seconds for flv streams (see
  
  e6a084641aada7a2e4672172f2ee26642800a361,
  
  24fdf7334d2bb9aab0abdbc878b8ae51eb57c86b and
  
  f58e011a1f30332ba824c155078ca701e29aef63).
  Before that commit (which removed the deprecated AVStream.codec), the
  
  "st->codecpar->codec_id = AV_CODEC_ID_TEXT", set within the demuxer,
  
  would get propagated into st->codec->codec_id by numerous
  
  avcodec_parameters_to_context(st->codec, st->codecpar), then further
  
  into st->internal->avctx->codec_id by update_stream_avctx within
  
  read_frame_internal in libavformat/utils.c (demux.c these days).
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] libavformat/flvdec.c

• avcodec/mpegvideo_dec, mpeg12dec : Move MPEG1/2 code to mpeg12dec.c

  7 octobre 2023, par Andreas Rheinhardt

  avcodec/mpegvideo_dec, mpeg12dec : Move MPEG1/2 code to mpeg12dec.c
  Up until now, ff_mpv_frame_start() offsets the data of the current
  
  picture and doubles the linesizes of all pictures if the current
  
  picture is field-based so that data and linesize allow to address
  
  the current field only.
  This is done based upon the current picture_structure value.
  
  Only two mpegvideo-based decoders ever set this field : mpeg1/2
  
  and VC-1 ; but the latter only does it after ff_mpv_frame_start()
  
  (when using hardware-acceleration and in order to signal it to
  
  the DXVA2 hwaccel) in which case no offset is applied in
  
  ff_mpv_frame_start(). So only one decoder actually wants this
  
  offset* ; therefore move the code performing it to mpeg12dec.c.
  * : VC-1 doubles linesize when using field_mode (not only the picture's
  
  linesize, but also uvlinesize and linesize), yet it does not offset
  
  anything. This is further proof that this should not be performed
  
  generically.
  Also move MPEG-1/2 specific setting of the top-field-first flag.
  
  (The change here implies that the AVFrame in current_picture
  
  may have different top-field-first flags than the AVFrame
  
  from current_picture_ptr, but this doesn't matter as only
  
  the latter's are used.)
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavcodec/mpeg12dec.c
  • [DH] libavcodec/mpegvideo_dec.c