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• FFmpeg libavcodec.a Xcode linker issues - Undefined symbols for architecture arm64

  7 novembre 2016, par mahdiolfat

  I’ve build FFmpeg for iOS using this script :
  https://github.com/kewlbear/FFmpeg-iOS-build-script

  I built for all architectures, then I built again just for arm64 (as my desired arch), and I’ve even used other build scripts to build FFmpeg for iOS. However, I keep running into the same issues :

  Undefined symbols for architecture arm64:
  
    "_VTDecompressionSessionCreate", referenced from:
  
        _av_videotoolbox_default_init2 in libavcodec.a(videotoolbox.o)
  
    "_VTDecompressionSessionDecodeFrame", referenced from:
  
        _videotoolbox_common_end_frame in libavcodec.a(videotoolbox.o)
  
    "_VTDecompressionSessionInvalidate", referenced from:
  
        _av_videotoolbox_default_free in libavcodec.a(videotoolbox.o)
  
    "_VTDecompressionSessionWaitForAsynchronousFrames", referenced from:
  
        _videotoolbox_common_end_frame in libavcodec.a(videotoolbox.o)

  I’ve tried

  • changing the architecture settings in Build Settings of my project
  • setting Dead Code Stripping to NO
  • Double checked my library/linker search paths

  Note that all the linker errors come from the same static library (libavcodec.a). This leads me to believe that I’m missing some other library that the linker needs specifically for these symbols. I’ve added all the libraries that are mentioned for an FFmpeg build - see image below :

  

  Any help is appreciated. Thanks !

• Powershell script finishes after the first ffmpeg call

  25 mars 2014, par sk904861

  The following Powershell script only executes the first ffmpeg call, no matter which one is first. Both the ffmpeg and the powershell processes never finish. Stopping the server, however, leads to the processes finishing and suddenly the second picture also appears.

  Param($InputFile, $OutputFile, $Thumbnail, $Sprites)
  
  
  
  $ThumbnailWidth = 120
  
  $ThumbnailHeight = 120
  
  
  
  # Thumbnail
  
  ffmpeg -i $InputFile -f image2 -vframes 1 -filter:v "crop=min(iw\,ih):min(iw\,ih), scale=$($ThumbnailWidth):$($ThumbnailHeight)" -crf 18 "$($Thumbnail)\150x150.png"
  
  
  
  # Poster
  
  ffmpeg -i $InputFile -f image2 -vframes 1 -filter:v "crop=min(iw\,ih):min(iw\,ih), scale=$($PosterWidth):$($PosterHeight)" -crf 18 "$($Thumbnail)\1000x1000.png"

  The script gets called within an ASP.NET application as follows :

  ProcessStartInfo startInfo = new ProcessStartInfo();
  
  startInfo.FileName = "powershell.exe";
  
  startInfo.Arguments = String.Format("-executionpolicy RemoteSigned -file \"{0}\" \"{1}\" \"{2}\" \"{3}\" \"{4}\"", scriptPath, fullPath, videoPath, thumbnailPath, sprites);
  
  startInfo.RedirectStandardOutput = true;
  
  startInfo.RedirectStandardError = true;
  
  startInfo.UseShellExecute = false;
  
  startInfo.CreateNoWindow = true;
  
  Process process = new Process();
  
  process.StartInfo = startInfo;
  
  
  
  process.EnableRaisingEvents = true;
  
  process.Exited += delegate
  
  {
  
       // Do some cleaning up
  
  };
  
  
  
  process.Start();

  Does anyone have a clue, why only the first the two ffmpeg calls is working, while each call seems to be correct ?

  Adding process.StandardError.ReadToEnd(); makes the script finish as expected, but also makes it block, which is not acceptable.

• avformat/segment : Fix segfault when error happens and segment list is output

  5 septembre 2020, par Andreas Rheinhardt

  avformat/segment : Fix segfault when error happens and segment list is output
  The segment muxer has an option to output a file containing a list of
  
  the segments written. The AVIOContext used for writing this file is
  
  opened via the main AVFormatContext's io_open callback ; seg_free()
  
  meanwhile unconditionally closes this AVIOContext by calling
  
  ff_format_io_close() with the child muxer (the one for the actual output
  
  format) as AVFormatContext.
  The problem hereby is that the child AVFormatContext need not exist,
  
  even when the AVIOContext does. This leads to a segfault in
  
  ff_format_io_close() when the child muxer's io_close callback is called.
  Situations in which the AVFormatContext can be NULL range from an
  
  invalid reference stream parameter to an unavailable/bogus/unsupported
  
  output format to inability to allocate the AVFormatContext.
  The solution is to simply close the AVIOContext with the AVFormatContext
  
  that was used to open it : The main AVFormatContext.
  Reviewed-by : Ridley Combs <rcombs@rcombs.me>
  
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavformat/segment.c