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• avformat/segafilmenc : Avoid seek when writing header

  17 juillet 2020, par Andreas Rheinhardt

  avformat/segafilmenc : Avoid seek when writing header
  Up until now, the Sega FILM muxer would first write all the packet data,
  
  then shift the data (in the muxer's write_trailer function) by the amount
  
  necessary to write the header at the front (which entails a seek to the
  
  front), then seek back to the beginning and actually write the header.
  This commit changes this : The dynamic buffer that is used to write the
  
  sample table (containing information about each sample in the file) is
  
  now used to write the complete header. This is possible because the size
  
  of everything in the header except the sample table is known in advance.
  
  Said buffer can then be used as one of the two temporary buffers used
  
  for shifting which also reduces the amount one has to allocate for this.
  
  Thereby the header will be written when shifting, so that the second
  
  seek to the beginning is unnecessary.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavformat/segafilmenc.c

• ffmpeg c++ seek performance

  30 juillet 2020, par thdemo

  I'm using ffmpeg for video playback, which works fine in itself, for many videos at once using HAP codec.

  


  The problem is when trying to play at faster speeds or reverse. The HAP codec only has full frames, so that should not be the problem. But apparently doing av_seek_frame and avcodec_flush_buffers is a big bottleneck. Not when playing a few videos, but I also want to be able to do it for 25 HD videos at once. Playing at normal speeds works fine for that many videos, but at higher speeds, the framerate becomes unusable.

  


  Is there a different way to handle playback speed and forward/backward direction anyone knows of that allows me to do this kind of playback at the same performance as normal playback ? A way to tell ffmpeg the playback speed and direction so that you don't need to seek and flush ?

  


• avformat/mpjpegdec : make sure we seek back to the ensured buffer

  26 septembre 2020, par Marton Balint

  avformat/mpjpegdec : make sure we seek back to the ensured buffer
  It was possible for the old code to seek back before the most recently read
  
  data if start of a new multipart was across read boundaries. Now we read some
  
  small sections multiple times to avoid this, but that is OK.
  Signed-off-by : Marton Balint <cus@passwd.hu>
  

  • [DH] libavformat/mpjpegdec.c