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• Extracting audio from video per video frame (C++) [on hold]

  5 septembre 2015, par PaulZyCZ

  Several days ago I had written an interface (in C) to simple DLL library which processes video in OpenCV using Qt5 framework. There is a function which takes frame ID and returns the raw picture data of the frame (so it can be played in Unity using C#). There is however no function to extract corresponding audio. So I am looking for a way to write such a function.

  I am thinking of a way to extract audio from video file (say MP4 with MPEG-4), with length of the corresponding video frame. But so far I have found only tutorials about extracting whole track (via FFMPEG) either to save or play the sound.

  Is there a way to extract only a "frame" (1/fps seconds of audio) ? Or would it be better to create indexes and extract whole track ?

  Thank you for answers.

  PS : Usual questions deal with whole track, not one frame-length sample specified by video frame ID. I have little knowledge of the FFMPEG and it has been several months since I used it last in uni project.

  I have frame, it’s ID, but no sound to it.

• Add random macro-blocking to video [duplicate]

  15 février 2018, par Grzegorzg

  This question already has an answer here :

  • Simulating TV noise
    
    3 answers
    

  For some reasons I need to add random macro-blocking to my video.

  Now I have clear representation, but I need to get something like this

  

• FFMpeg/libav set SEI unregistered user message per video frame

  17 décembre 2018, par maxhap

  I’m trying to set the SEI unregistered user message on a per video frame basis. I notice that libav has a H264MetadataContext structure which
  contains a const char *sei_user_data field. This seems to be exactly what I’m looking for. After poking around in the FFMpeg code I notice
  this structure is wrapped within the private data of the AVBSFContext. My knowledge is extremely limited so at this point I’m looking for an example
  or explanation on how to correctly access the H264MetadataContext structure. I presume I need a bit stream filter (based on the naming), but can’t
  find any examples of setting the H264MetadataContext.

  Can anyone help me with an explanation, code snippet or point me to an example I might have missed/overlooked ?

  Any general advice would also be appreciated. I have checked the few similar questions here on stackoverflow, they don’t seem to have any solid answers or explanations though (maybe due to my lack of understanding).

  Thanks in advanced !