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• How to detect Audio or Video or Both exist in converted file

  28 juillet 2016, par Khaja Hussain

  I am trying to convert mp4 or 3gp video files into Flash (flv) format (using Perl script), using following (mencoder) command :

  mencoder test.mp4 -of lavf -ovc lavc -lavcopts vcodec=flv:vbitrate=1000:mbd=2 -fps 20.80 -ofps 20.80 -oac mp3lame -lameopts abr:br=32 -srate 22050 -o test.flv

  It works fine, but some files which comes as attachments from mobile phone has problem, the converted FLV file has only audio.

  I also used ffmpeg command as follows :

  ffmpeg -i test.mp4 -ar 22050 -acodec libmp3lame -ab 32K -r 25 -vcodec flv test.flv

  This ffmpeg command helps to convert to flv, which is failed by mencoder.

  I am thinking some solution like, need to check whether converted flv has audio and video then will take action depends on it. Could you help me to solve this issue ?

  Here is some more info (log) :

  [mov,mp4,m4a,3gp,3g2,mj2 @ 0xb6b9a3a0]multiple edit list entries, a/v desync might occur, patch welcome
  ** MUXER_LAVF *************************************
  REMEMBER : MEncoder’s libavformat muxing is presently broken and can generate
  INCORRECT files in the presence of B-frames. Moreover, due to bugs MPlayer
  will play these INCORRECT files as if nothing were wrong !

  ---

  Unsupported PixelFormat 61
  Unsupported PixelFormat 53
  Unsupported PixelFormat 81
  [flv @ 0xb6b9a3a0]Codec for stream 0 does not use global headers but container format requires global headers
  [flv @ 0xb6b9a3a0]Codec for stream 1 does not use global headers but container format requires global headers
  [flv @ 0xb6b9a3a0]pts < dts in stream 0
  Error while writing frame.

  [flv @ 0xb6b9a3a0]pts < dts in stream 0
  Error while writing frame.

  [flv @ 0xb6b9a3a0]pts < dts in stream 0
  Error while writing frame.

  [flv @ 0xb6b9a3a0]pts < dts in stream 0
  Error while writing frame.

  [flv @ 0xb6b9a3a0]pts < dts in stream 0
  Error while writing frame.

  Skipping frame !

  .........................

• ffmpeg split avi into frames with known frame rate

  31 mai 2016, par Myx

  I posted this as comments under this related thread. However, they seem to have gone unnoticed =(

  I’ve used

  ffmpeg -i myfile.avi -f image2 image-%05d.bmp

  to split myfile.avi into frames stored as .bmp files. It seemed to work except not quite. When recording my video, I recorded at a rate of 1000fps and the video turned out to be 2min29sec long. If my math is correct, that should amount to a total of 149,000 frames for the entire video. However, when I ran

  ffmpeg -i myfile.avi -f image2 image-%05d.bmp

  I only obtained 4472 files. How can I get the original 149k frames ?

  I also tried to convert the frame rate of my original AVI to 1000fps by doing

  ffmpeg -i myfile.avi -r 1000 otherfile.avi

  but this didn’t seem to fix my concern.

• Change volume of audio file to be merged with video using ffmpeg

  15 juin 2017, par 1234567

  Change volume of audio file to be merged with video using ffmpeg

  I am using this command to merge audio into a video file

  String[] complexCommand = {"-ss", "" + startMs / 1000, "-y", "-i", videopath, "-i", audiopath, "-t", "" + (endMs - startMs) / 1000, "-s", "320x240", "-vcodec", "mpeg4", "-b:v", "2097152", "-b:a", "48000", "-ac", "2", "-ar", "22050", filePath};

  How can we control the volume of audio to be merged