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• ffmpeg : Using with macos and swift

  22 février 2018, par jamesTMC

  I am trying to extract a thumbnail from the middle of a video. However, I am not sure if the issue lies within Swift or ffmpeg.

  The following code compiles but produces nothing.

      let frameCount = GetVideoFrameCount(itemPath: itemPath)
  
      let framesIn = frameCount / 2
  
      let framesInStr = "\(framesIn)"
  
  
  
      let thumbnailTask: Process = Process()
  
  
  
      thumbnailTask.launchPath = self.ffmpegLaunchPath
  
      thumbnailTask.arguments = ["-ss", framesInStr, "-i", itemPath.absoluteString.removingPercentEncoding!, "-vf", "scale=-1:120", "-frames:v", "1", thumbnailPath]
  
      thumbnailTask.standardInput = FileHandle.nullDevice
  
  
  
      thumbnailTask.launch()
  
      thumbnailTask.waitUntilExit()
  
  
  
      let thumbnailStatus = thumbnailTask.terminationStatus

  The "frameCount" variable does contain the number frames in the video. The Process "works" in that it doesn’t crash, the .terminationStatus = 0 but no thumbnail .jpg is produced.

  I have used the "-ss" option with String(framesIn), "\(framesIn)", I have changed the frameCount to an actual number (i.e., 10000), nothing. The "-ss" option ONLY works if I use String(10000) or any other number.

  Does anybody have a suggestion ?

  Thanks.

• FFmpeg reverse long audio hang randomly in Android

  23 mars 2021, par Michael

  I am writing an Android APP, underneath I simply use FFmpeg command to reverse the audio.

  


  The command is simple like :ffmpeg -loglevel debug -debug_ts -i /sdcard/.m4a -af areverse /sdcard/longaudio.aac

  


  If the audio is short, everything works fine, but if the audio longer than 10 mins, the thread will hang(sleep) randomly at some places. The log shows input processing stop in middle at some pkt_pts, every time stop at different ptk_pts. The whole app will therefore hang in there.

  


  If I simply do conversion "ffmpeg -loglevel debug -debug_ts -i /sdcard/.m4a -codec:a aac /sdcard/longaudio.aac" it will work.

  


  Some debug steps I did :

  


  


  1. The memory and cpu usage is normal, it seems the ffmpeg just suddenly decide to take a rest during reverse the long audio :(

     


  


  2. the IO shouldn't be fulled, I commented out the logs still not ok.

     


  


  3. I see a lot "cur_dts is invalid (this is harmless if it occurs once at the start per stream)", but it also showed in normal cases.

     


  


  


  I know the description is kind of ambiguous, but I am so desperate. Anything I don't know about the audio reverse is welcome.

  


• avformat/assenc : avoid incorrect copy of null terminator

  28 mars 2023, par Marton Balint

  avformat/assenc : avoid incorrect copy of null terminator
  When writing a subtitle SSA/ASS subtitle file, the AVCodecParameters::extradata
  
  buffer is written directly to the output.  In the case where the buffer is
  
  filled from a matroska source file produced by some older versions of
  
  Handbrake, this buffer ends with a null terminating character, which is then
  
  erroneously copied into the middle of the output file. The change here avoids
  
  this problem by treating it as a string rather than a raw buffer. This way it
  
  is agnostic as to whether the source buffer was null terminated or not.
  Fixes ticket #10203.
  Reported-by : Tim Angus <tim at ngus.net>
  
  Signed-off-by : Marton Balint <cus@passwd.hu>
  

  • [DH] libavformat/assenc.c