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• avcodec/h264, videotoolbox : fix crash after VT decoder fails

  21 février 2017, par Aman Gupta

  avcodec/h264, videotoolbox : fix crash after VT decoder fails
  The way videotoolbox hooks in as a hwaccel is pretty hacky. The VT decode
  
  API is not invoked until end_frame(), so alloc_frame() returns a dummy
  
  frame with a 1-byte buffer. When end_frame() is eventually called, the
  
  dummy buffer is replaced with the actual decoded data from
  
  VTDecompressionSessionDecodeFrame().
  When the VT decoder fails, the frame returned to the h264 decoder from
  
  alloc_frame() remains invalid and should not be used. Before
  
  9747219958060d8c4f697df62e7f172c2a77e6c7, it was accidentally being
  
  returned all the way up to the API user. After that commit, the dummy
  
  frame was unref’d so the user received an error.
  However, since that commit, VT hwaccel failures started causing random
  
  segfaults in the h264 decoder. This happened more often on iOS where the
  
  VT implementation is more likely to throw errors on bitstream anomolies.
  
  A recent report of this issue can be see in
  
  http://ffmpeg.org/pipermail/libav-user/2016-November/009831.html
  The issue here is that the dummy frame is still referenced internally by the
  
  h264 decoder, as part of the reflist and cur_pic_ptr. Deallocating the
  
  frame causes assertions like this one to trip later on during decoding :
    Assertion h->cur_pic_ptr->f->buf[0] failed at src/libavcodec/h264_slice.c:1340
  With this commit, we leave the dummy 1-byte frame intact, but avoid returning it
  
  to the user.
  This reverts commit 9747219958060d8c4f697df62e7f172c2a77e6c7.
  Signed-off-by : wm4 <nfxjfg@googlemail.com>
  

  • [DH] libavcodec/h264_refs.c
  • [DH] libavcodec/h264dec.c
  • [DH] libavcodec/version.h
  • [DH] libavcodec/videotoolbox.c

• Ffprobe stopped working in a new environment ?

  4 avril 2017, par Neo Herakles

  so, I had this code to watermark my videos in time intervals but when I switched computers, it somehow stopped working, here’s what I have :

  @echo off
  
  setlocal
  
  for %%G in ("C:\Users\Administrator\Desktop\work\*.mp4") do (
  
      for /F "delims=" %%I in ('ffprobe.exe -v error -show_entries format^=duration -of default^=noprint_wrappers^=1:nokey^=1 %%G 2^>^&1') do (
  
      set duration=%%I
  
          ffmpeg.exe -i "%%G" -i white.png -filter_complex "[0:v]scale=iw:ih[v0];[1:v][v0]scale2ref=iw/6:ih/10[logo][0v];[0v][logo]overlay=W-w-3:H-h-3:enable='between(t,%%I*3/7,(%%I*3/7)+2)+between(t,%%I*5/7,(%%I*5/7)+2)'[v]" -map "[v]" -map 0:a -codec:v libx264 -preset ultrafast -crf 23 -codec:a copy "C:\Users\Administrator\Desktop\completed\%%~nG.mp4"
  
      )
  
  )
  
  endlocal
  
  pause

  I get an error that says that the video in the completed folder doesn’t exist, this seems to imply that there’s nothing to copy, so it means that nothing was processed by the ffmpeg.exe command, could you please help me find out what happened ?

• pthread_frame : fix uninitialized variable read

  27 mars 2017, par wm4

  pthread_frame : fix uninitialized variable read
  Could lead to random behavior. This possibly happened due to commit
  
  32a5b631267. This should/could probably be simplified, but for no apply
  
  a minimal fix to quell the errors.
  Tested-by : Michael Niedermayer <michael@niedermayer.cc>
  
  Reviewed-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/pthread_frame.c