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• ffmpeg : Resampling with input channels greater than 2 unsupported ?

  13 septembre 2011, par user739711

  This question is already been asked but because that thread is old I am posting again.

  When a video file has 5.1 audio channels ffmpeg is not able to convert it to another format giving error :

  "Resampling with input channels greater than 2 unsupported"

  I saw some blogs saying I can modify the code and or patch ffmpeg for it.

  Any solution found yet ?

• Need to write to a file using fopen in a C++ class for iOS project

  2 mai 2014, par Chuck Mc Duran

  I have a project that uses C++ classes and FFmpeg, I need to use fopen and write a file to the app sandbox, so the code that I need to write in C++ is the equivalent of :

  NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
  
  NSString *docs_dir = [paths objectAtIndex:0];

  This would me to my app sandbox, where I can pretty much manipulate my files
  The question is how do I go about writing this code in C++ so that I can use fopen on a file ?

  This is the method that needs implementation :

  int testGrabAndWrite(const char* streamURL, bool decode, const char* filename)
  
  {
  
      FILE *outfile;
  
      int ret;
  
      int counter = 0;
  
      uint8_t *data;              // Pointer to the received audio mem
  
      int size;                   // Size of the received audio buffer
  
  
  
  
  
      outfile = fopen(filename, "w");
  
  
  
      if (outfile == NULL)
  
          exit(1);
  
  
  
      // Open the RTP stream
  
      if ((ret = openStream(streamURL, decode)) < 0)
  
          return ret;
  
  
  
      // Print out info about the stream found
  
      int tmpSampleRate, tmpBitRate, tmpChannels;
  
      ret = getStreamInfo(tmpSampleRate, tmpBitRate, tmpChannels);
  
      printf("\nSample rate:%d Bit rateL%d Channels:%d\n",tmpSampleRate,tmpBitRate, tmpChannels);
  
  
  
      // Grab some sample data and write it to file.
  
      while (counter < 500) 
  
      {
  
          ret = getStreamData(data, size);
  
          fwrite(data, 1, size, outfile);                             // Write RTP packets, i.e. mp3, to file.
  
          printf("Wrote packet %d with size %d which returned %d. ", ++counter, size, ret);
  
      }
  
  
  
      fclose(outfile);
  
      closeStream();
  
  
  
      return ret;
  
  }

• Python get Audio/Video frames separately from video file

  3 juillet 2016, par AlvaroAV

  What i’m trying to do :

  Hi !

  I’m trying to store the Video and Audio information from a video file. I would like to store video frames and audio frames separately in different variables.

  My intention is to manage video/files and do some actions with the audio and video frame list, but to do what I’m plannign to do I need to store this audio/video frames separately. I’ve read a lot of questions in StackOverflow about python and audio/video managing.

  Most people recommend to use OpenCV or ffmpeg to manage videos. I saw some scripts using these libraries to get video(only video) frames, but none of them are getting audio, most of them are just getting video frames and save them as RGB images. I also check some scripts where people get audio frames from a mp3 file, but I’m not sure if you can do that in a video file

  Most important thing to me is to know the best way to manage video and audio separately. I’m not looking for people to do my code, just asking to point me in a good direction.

  One of the things I’m trying to do is to send this information via socket, but as I said I need the audio and video frames to be in separated variables (yes, i’m wondering about an stream app, but that’s not the only thing I’m trying to do)

  I know I should give more information, and maybe show some code, but I don’t have any concret code I tried some things, but I’ve never been capable to separate audio and video. I know that each format has his own encryption, and at the end I decided to use "mp4" as video format but I don’t know neither if this is the best format for what I’m trying to do.

  Resume :

  Is openCV the best way to manage video and audio separately ?

  Wich is the easiest way to separate video and audio frames ? Is it possible ?

  Wich is the best documentation I should read to learn about video/audio management ?

  I would like to do the things with my own code, and use in the less way possible openCV or other libraries.

  My "basic" idea is to get a "list" of audio and video frames, and then I would like to do some operations, but right now I can’t find the best way for me to manage a vide using python. I even wonder if could be possible to manage a video as raw data

  I need to know wich is the best library to manage videos using python, for me the best library, will be the one that allows me to manage the videos more "freely"

  I’ve already checked :

  I’ve read too many questions on this theme, the most recent are :

  How to extract audio from video file

  Split audio video separately from given video using MLT

  Embed audio video in python gui