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• Correctly Allocate And Fill Frame In FFmpeg

  24 février 2016, par mFeinstein

  I am filling a Frame with a BGR image for encoding, and I am getting a memory leak. I think I got to the source of the problem but it appears to be a library issue instead. Since FFmpeg is such a mature library, I think I am misusing it and I would like to be instructed on how to do it correctly.

  I am allocating a Frame using :

  AVFrame *bgrFrame = av_frame_alloc();

  And later I allocate the image in the Frame using :

  av_image_alloc(bgrFrame->data, bgrFrame->linesize, bgrFrame->width, bgrFrame->height, AV_PIX_FMT_BGR24, 32);

  Then I fill the image allocated using :

  av_image_fill_pointers(bgrFrame->data, AV_PIX_FMT_BGR24, bgrFrame->height, originalBGRImage.data, bgrFrame->linesize);

  Where originalBGRImage is an OpenCV Mat.

  And this has a memory leak, apparently, av_image_alloc() allocates memory, and av_image_fill_pointers() also allocates memory, on the same pointers (I can see bgrFrame->data[0] changing between calls).

  If I call

  av_freep(&bgrFrame->data[0]);

  After av_image_alloc(), it’s fine, but if I call it after av_image_fill_pointers(), the program crashes, even though bgrFrame->data[0] is not NULL, which I find very curious.

  Looking FFmpeg’s av_image_alloc() source code, I see it calls av_image_fill_pointers() twice inside it, once allocating a buffer buff....and later in av_image_fill_pointers() source code, data[0] is substituted by the image pointer, which is (I think) the source of the memory leak, since data[0] was holding buf from the previous av_image_alloc() call.

  So this brings the final question : What’s the correct way of filling a frame with an image ?.

• Mono : FFmpeg on Linux

  24 octobre 2016, par Robbertie

  I am using FFmpeg for my application on Windows.
  Now I would like it to work on Linux.
  On Windows I would use :

  var process = Process.Start(new ProcessStartInfo
  
          {
  
              FileName = "ffmpeg",
  
              Arguments = $"-i {pathOrUrl} -f s16le -ar 48000 -ac 2 pipe:1 -loglevel quiet",
  
              UseShellExecute = false,
  
              RedirectStandardOutput = true,
  
              RedirectStandardError = false,
  
              CreateNoWindow = true,
  
          });

  How would I do the same on Linux ?
  Because this is not working there.

• Linux NASM and ID3LIB

  21 novembre 2014, par Pablo Gaviria

  I need to call some procedures from the ID3LIB for MP3 process on Linux NASM X86 but I don’t have idea how should I do this.

  I already added the libid3-3.8.3-dev, libid3-3.8.3c2a and libid3-tools to my O.S (Linux Ubuntu 14.04) and the id3/ is callable from C and C++ IDEs (example id3/tag.h). I think that the EXTERN instruction maybe has something to do here but I don’t know how should I call it

  The main target of this code is to open a MP3 file using NASM and do modifications on his content

  HINT : I can do this job with ID3LIB or FFMPEG, Which could be the easier option ?