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• Transcode to ogg or webm, writing the file as it goes

  22 juillet 2020, par Mark Smith

  I need to transcode files (mp3, flac, m4a and others) to ogg or webm. (This is because I need them to play on Firefox 60.9 which does not support most of these, and flacs are too large. I cannot update the browser.)

  


  ffmpeg can do the transcoding, but when transcoding to ogg or webm, depending on the exact configuration, either 0 bytes or a few kB is written immediately, and then nothing more until the transcoding is complete (even using -flush_packets 1) — hence I cannot start playing the audio.

  


  By comparison, if I transcode to mp3, the file is written progressively and I can start playing immediately.

  


  Is it possible to transcode to ogg or webm in such a way that the file is written as the transcoding happens, and I can start playing it (almost) immediately ?

  


  Configurations I have tried :

  


  ffmpeg -i orig.m4a -c:a libvorbis -flush_packets 1 vorbis.ogg
ffmpeg -i orig.m4a -c:a libopus -flush_packets 1 opus.ogg
ffmpeg -i orig.m4a -c:a libvorbis -flush_packets 1 vorbis.webm
ffmpeg -i orig.m4a -c:a libopus -flush_packets 1 opus.webm


  


  This is running on Debian (Raspian stretch, specifically) and I would like to do it without adding dependencies from outside of the Debian/Raspian archives, if possible. Sticking with ffmpeg would be my ideal choice but will consider others.

  


• avformat/dashdec : drop arbitrary DASH manifest size limit

  3 septembre 2020, par Jan Ekström

  avformat/dashdec : drop arbitrary DASH manifest size limit
  Currently the utilized AVBPrint API is internally limited to unsigned
  
  integers, so if we limit the file size as well as the amount to read
  
  to UINT_MAX - 1, we do not require additional limiting to be performed
  
  on the values.
  This change is based on the fact that initially the 8*1024 value added
  
  in 96d70694aea64616c68db8be306c159c73fb3980 was only for the case where
  
  the file size was not known. It was not a maximum file size limit.
  In 29121188983932f79aef8501652630d322a9974c this was reworked to be
  
  a maximum manifest file size limit, while its commit message appears
  
  to only note that it added support for larger manifest file sizes.
  This should enable various unfortunately large MPEG-DASH manifests,
  
  such as Youtube's multi-megabyte live stream archives to load up
  
  as well as bring back the original intent of the logic.
  

  • [DH] libavformat/dashdec.c

• ffmpeg : Add an option "qsv_device" to choose proper node for QSV child device (vaapi...

  5 janvier 2017, par Zhengxu

  ffmpeg : Add an option "qsv_device" to choose proper node for QSV child device (vaapi or dxva2)
  Reason : For some cases, such as 2 or more graphics cards existing, the
  
  default command line may fail because ffmpeg does not open the correct
  
  device node :
  
      ffmpeg -hwaccel qsv -c:v h264_qsv -i test.264 -c:v h264_qsv out.264
  
  Let user choose the proper one by running like below :
  
      ffmpeg -hwaccel qsv -qsv_device /dev/dri/renderD128 -c:v h264_qsv \
  
   i test.264 -c:v h264_qsv out.264
  Signed-off-by : ChaoX A Liu <chaox.a.liu@gmail.com>
  
  Signed-off-by : Huang, Zhengxu <zhengxu.maxwell@gmail.com>
  
  Signed-off-by : Andrew, Zhang <huazh407@gmail.com>
  
  Signed-off-by : Mark Thompson <sw@jkqxz.net>
  

  • [DH] ffmpeg.h
  • [DH] ffmpeg_opt.c
  • [DH] ffmpeg_qsv.c