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• mov : Remove duration-of-last-frame heuristic hack

  24 décembre 2018, par Derek Buitenhuis

  mov : Remove duration-of-last-frame heuristic hack
  This breaks totally valid files that get caught in its heuristic.
  This, according to the commit message, is my own doing, having asked
  
  Michael to implement this check and providing a sample that was
  
  "wrong". I am now atoning for my sins, and removing this hack, having
  
  seen the light (aka that this was silly to do in the first place).
  Resotores correct behavior on valid files.
  This reverts commit 8e5e84c2a2a21a979b48e80c5a8dd44754ab3f21.
  Signed-off-by : Derek Buitenhuis <derek.buitenhuis@gmail.com>
  

  • [DH] libavformat/mov.c

• Send MP3 audio extracted from m3u8 stream to IBM Watson Speech To Text

  20 novembre 2018, par Link69

  I’m extracting audio in MP3 format from a M3U8 live url and the final goal is to send the live audio stream to IBM Watson Speech To Text. The m3u8 is obtained by calling an external script via a Process. Then I use FFMPEG script to get the audio in stdout. It works if I save the audio in a file but I don’t want to save the extracted audio, I need to send the datas directly to the STT service. So far I proceeded like this :

  SpeechToTextService speechToTextService = new SpeechToTextService(sttUsername, sttPassword);
  
  string m3u8Url = "https://something.m3u8";
  
  char[] buffer = new char[48000];
  
  Process ffmpeg = new ProcessHelper(@"ffmpeg\ffmpeg.exe", $"-v 0 -i {m3u8Url} -acodec mp3 -ac 2 -ar 48000 -f mp3 -");
  
  
  
  ffmpeg.Start();
  
  int count;
  
  while ((count = ffmpeg.StandardOutput.Read(buffer, 0, 48000)) > 0)
  
  {
  
      ffmpeg.StandardOutput.Read(buffer, 0, 48000);
  
      var answer = speechToTextService.RecognizeSessionless(
  
          audio: buffer.Select(c => (byte)c).ToArray(),
  
          contentType: "audio/mpeg",
  
          smartFormatting: true,
  
          speakerLabels: false,
  
          model: "en-US_BroadbandModel"
  
      );
  
      // Get answer.ResponseJson, deserializing, clean buffer, etc...
  
  }

  When requesting the transcribed audio I’m getting this error :

  An unhandled exception of type 'System.AggregateException' occurred in IBM.WatsonDeveloperCloud.SpeechToText.v1.dll: 'One or more errors occurred. (The API query failed with status code BadRequest: Bad Request | x-global-transaction-id: bd6cd203720a70d83b9a03451fe28973 | X-DP-Watson-Tran-ID: bd6cd203720a70d83b9a03451fe28973)'
  
   Inner exceptions found, see $exception in variables window for more details.
  
   Innermost exception     IBM.WatsonDeveloperCloud.Http.Exceptions.ServiceResponseException : The API query failed with status code BadRequest: Bad Request | x-global-transaction-id: bd6cd203720a70d83b9a03451fe28973 | X-DP-Watson-Tran-ID: bd6cd203720a70d83b9a03451fe28973
  
     at IBM.WatsonDeveloperCloud.Http.Filters.ErrorFilter.OnResponse(IResponse response, HttpResponseMessage responseMessage)
  
     at IBM.WatsonDeveloperCloud.Http.Request.<getresponse>d__30.MoveNext()
  
     at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
  
     at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
  
     at IBM.WatsonDeveloperCloud.Http.Request.<asmessage>d__23.MoveNext()
  
     at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
  
     at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
  
     at IBM.WatsonDeveloperCloud.Http.Request.<as>d__24`1.MoveNext()
  
  </as></asmessage></getresponse>

  ProcessHelper is just for convenience :

  class ProcessHelper : Process
  
  {
  
      private string command;
  
      private string arguments;
  
      public ProcessHelper(string command, string arguments, bool redirectStandardOutput = true)
  
      {
  
          this.command = command;
  
          this.arguments = arguments;
  
          StartInfo = new ProcessStartInfo()
  
          {
  
              FileName = this.command,
  
              Arguments = this.arguments,
  
              UseShellExecute = false,
  
              RedirectStandardOutput = redirectStandardOutput,
  
              CreateNoWindow = true
  
          };
  
      }
  
  }

  Pretty sure I’m doing it wrong, I’d love someone to shine a light on this. Thanks.

• Using ffmpeg to pipe Logitech C920 video to two outputs : re-encoded to RTMP stream and hardware-encoded to file

  18 décembre 2018, par Maros Hluska

  I’m trying to use ffmpeg to accept video from a Logitech C920 and broadcast it to an RTMP stream (e.g. Twitch). But there’s a twist : I would like to also save to file the original 1080p hardware-encoded video.

  So I would like to do both of these :

  1. Re-encode the input to 852x480 resolution and upload to an RTMP url with 1500 bitrate
  2. Save the original input to a file without re-encoding (C920 does hardware encoding with the h.264 codec)

  I’ve tried saving the video to file without re-encoding using the following :

  ffmpeg -s 1920x1080 -framerate 30 -pixel_format uyvy422 -vcodec h264 -f avfoundation -i 'HD Pro' -copyinkf -vcodec copy out.mp4

  This seems to almost work. The webcam light turns on and a few seconds of running this produces a massive file (1GB or so). However, I can’t seem to open the file with VLC. I do see a warning from ffmpeg :

  [AVBSFContext @ 0x7fbd4fc3e9c0] No start code is found.
  
  HD Pro: could not find codec parameters

  I’m on a Mac using ffmpeg 4.1.

  Edit :

  It seems the file that ffmpeg produces is not h264 encoded but rather raw pixel data. I’m starting to think that it’s not possible to set the webcam into the h264 mode with Mac (most other cases do it in Linux with v4l2).

  To anyone answering the question, I’d be happy with a solution that involves Linux as well. Especially if I can use a bootable live USB.