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• avformat code produce slightly different output than ffmpeg with same parameters - why ?

  20 février 2020, par Daniel

  I would like to achieve the exact same result as this ffmpeg command line call does from code :

  ffmpeg -i CAMERARTSPLINK -c:v copy -an -movflags +frag_keyframe+empty_moov -f mp4

  When I run the above command it gives this binary result :

  got 36 bytes:  0, 0, 0, 36, 102, 116, 121, 112, ..., 111, 54, 109, 112, 52, 49, 
  
  got 512 bytes: 0, 0, 3, 76, 109, 111, 111, 118, 0, 0, 0, ..., 132, 0, 0, 3, 0, 4, 0, 0, 3, 0, 202,

  The code can utilize ffmpeg libraries and includes, but I don’t want to use ffmpeg as a program call (i.e. exec* functions are not preferred).

  I have created a small demonstration code example with avformat for an RTSP H264 to MP4 remux.
  The code is highly reuses horgh’s nice videostreamer library.

  I posted the sample code to pastebin.com (400 loc). It builds successfully but you need to link it against avformat, avdevice, avcodec and avutil.

  I tried to do my best to reach the same result, however when I run this code, the first few bytes after byte #38 are different (maybe not just those, I did not compare anything after byte #548) :

  writeOutput: writing 36 bytes: 0, 0, 0, 36, 102, 116, 121, 112, ..., 111, 54, 109, 112, 52, 49, 
  
  writeOutput: writing 512 bytes: 0, 0, 0, 0, 109, 111, 111, 118, 0, 0, 0, ..., 132, 0, 0, 3, 0, 4, 0, 0, 3, 0, 202, 

  You can see on the second line of my code’s output starts with 0 0 0 0 109,

  whereas the ffmpeg gave 0 0 3 76 109.

  All the rest (even the bytes are not pasted here) data are totally the same (at least for the first 548 bytes).

  What is wrong with my code ? These 2 bytes seems super-important for decoding this stream.

• ffmpeg code works in cmd but not as a batch [closed]

  13 novembre 2022, par BragonGod

  I'm trying to convert an image sequence to a video using ffmpeg.

  


  It works fine on CMD when I use this

  


  ffmpeg -r 23.976 -i frame_%d.png -pix_fmt yuv420p output.mp4


  


  My batch file code :

  


  cd path
ffmpeg -r 23.976 -i frame_%d.png -pix_fmt yuv420p output.mp4
Pause


  


  But when I'm using this command in a batch file, it says it can't recognize Frame.png/file_path.

  


  I think there's something wrong with the %d but I can't find a solution.

  


• Download FFMPEG source code and debug it [on hold]

  25 février 2017, par IPS

  I need to record a video from IP camera and currently I am using FFMPEG commands with a C# .Net application for that but we are facing issue with this as if we record a video of 300 seconds(5 Minutes) then 1 or 2 seconds video gets lost, don’t know why ?.

  So we need to check with source code of FFMPEG.

  I have downloaded the source code and I think it is written in "C/C++", so Can anyone guide me how to run and debug source code ?

  Or any other alternate way to record live video from IP camera RTSP stream.