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• Ble with record video

  24 juillet 2017, par Vitaly

  I’m working on rpi3.
  When I try to run the command :

  sudo ffmpeg -f video4linux2 -i /dev/video0 -video_size 640x480 -r 25 output.avi

  to record a video using ffmpeg.

  In this time,I try to connect with Bluetooth.

  The BT cannot connect.

  the exception I get is :
  A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.

  top result :

  1156 root 20 0 299860 197172 137736 S 80.6 20.9 40:21.35 ffmpeg

  80.6 % cpu and 20.9 % mem.

  all the other processes take less than 1%.

  Did you encounter with this ?
  Do you have a clue what can be done ?

  Thanks

• Concatenate two mp4 files using ffmpeg

  24 mars 2018, par Mark L

  I’m trying to concatenate two mp4 files using ffmpeg. I need this to be an automatic process hence why I chose ffmpeg. I’m converting the two files into .ts files and then concatenating them and then trying to encode that concated .ts file. The files are h264 and aac encoded and I’m hoping to keep the quality the same or as close to original as possible.

  ffmpeg -i part1.mp4 -vcodec copy -vbsf h264_mp4toannexb -acodec copy part1.ts
  
  ffmpeg -i part2.mp4 -vcodec copy -vbsf h264_mp4toannexb -acodec copy part2.ts
  
  cat part1.ts part2.ts > parts.ts
  
  ffmpeg -y -i parts.ts -acodec copy -ar 44100 -ab 96k -coder ac -vbsf h264_mp4toannexb parts.mp4

  Unfortunately I’m getting the following error message coming back from ffmpeg during encoding :

  [h264 @ 0x1012600]sps_id out of range
  
  [h264 @ 0x1012600]non-existing SPS 0 referenced in buffering period
  
  [h264 @ 0x1012600]sps_id out of range
  
  [h264 @ 0x1012600]non-existing SPS 0 referenced in buffering period
  
  [NULL @ 0x101d600]error, non monotone timestamps 13779431 >= 13779431kbits/s    
  
  av_interleaved_write_frame(): Error while opening file

  This happens about half way through encoding which makes me think that you can’t concat two .ts files together and have it work.

• Make ffmpeg keep silence in generated audio files when RTP input is paused

  19 septembre 2017, par Iñaki Baz Castillo

  I run ffmpeg as follows in order to capture an audio RTP input stream :

  ffmpeg -protocol_whitelist file,udp,rtp -acodec opus -i sdp output.wav

  It works. However, if the RTP stream is paused for some seconds (so no RTP packets are received during that period) and is later resumed, the generated output.wav files does not contain such a pause/silence. Instead, no paused period exists at all in the output.wav file.

  The RTP packets have a proper timestamp RTP header field. I mean, the first RTP packet after the paused period has a timestamp value MUCH higher than the latest packet before the paused period. This makes me think that ffmpeg just ignores the RTP timestamp header.

  I do know that this would work if I generate "silence" RTP packets (with just padding, for example), but I want to avoid such a hack. I hope there is a way to tell ffmpeg "hey, don’t stop filling the WAV file (with silence) in periods where no RTP packets are received".

  Any help ?