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• Crash in ffmpeg avcodec_free_context in one application but not in other

  5 novembre 2017, par geekowl

  I am building an application in C++ on Windows 10 using Microsoft Visual Studio 2012 Professional.

  I have created a wrapper library around ffmpeg (libavcodec) to encode video in H.264 format using libx264. This wrapper contains following functions :

  Initialize()
  
  Open()
  
  EncodeFrame()
  
  Close()
  
  Uninitialize()

  I created a test application to test the wrapper library. The test application works perfectly fine.

  When I use the wrapper library in my actual main application, the main application crashes in Close() API. Inside close, it crashes in avcodec_free_context(). The difference between the main application and the test application is that the main application links with some more dependent libraries that test application does not link with.

  To debug the problem in the main application, I put avcodec_free_context() in Open() after the context is allocated. The crash occurs if avcodec_free_context() is put at a certain point as shown below.

  pCodecContext = avcodec_alloc_context3(pCodec);
  
  
  
  // <---- No crash here.
  
  
  
  pCodecContext->bit_rate = 200000;
  
  pCodecContext->width = 320;
  
  pCodecContext->height = 240;
  
  .
  
  .
  
  .
  
  if (pCodec->id == AV_CODEC_ID_H264)
  
  {
  
      av_opt_set(pCodecContext->priv_data, "preset", "slow", 0);
  
      av_opt_set(pCodecContext->priv_data, "tune", "zerolatency", 0);
  
  }
  
  
  
  pCodecContext->flags |= CODEC_FLAG_GLOBAL_HEADER;
  
  
  
  // <-- No crash here
  
  
  
  if (avcodec_open2(pCodecContext, pCodec, NULL) < 0)
  
  {
  
      return -1;
  
  }
  
  
  
  // <-- Crash here [avcodec_free_context(&pCodecContext);]

  What is a correct approach to identify and resolve this problem ?

  Thanks in advance.

  Update

  I found out that ffmpeg was built using gcc. That was causing the crash. I rebuilt ffmpeg using Visual Studio. That solved problem.

• avformat/wtvenc : pad judiciously when writing mpeg2 extradata

  30 mars 2014, par Peter Ross

  avformat/wtvenc : pad judiciously when writing mpeg2 extradata
  Padding rule described here http://msdn.microsoft.com/en-us/library/windows/desktop/dd390707(v=vs.85).aspx
  Signed-off-by : Peter Ross <pross@xvid.org>
  
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavformat/wtvenc.c
  • [DH] tests/ref/lavf/wtv
  • [DH] tests/ref/seek/lavf-wtv

• Audio offset get wrong after some time when streaming audios

  7 septembre 2024, par Antoine Grenard

  I use microsoft-cognitiveservices-speech-sdk (1.38.0) in order to do real time speech to text.
It seems like the offset is right when I send a full audio but it is wrong when I send it cut in a lot of audio chunks.

  


  The more there is audio chunks the more inaccurate the offset is :

  


  

  • No chunks : 1 726 300 000

  


  • 369 chunks of 0.5 seconds : 1 729 600 000

  


  • 923 chunks of 0.2 seconds : 1 744 600 000

  


  • 1443 chunks of 0.1 seconds : 1 757 900 000

  


  


  To reproduce here is some piece of code :

  


      const speechConfig = SpeechConfig.fromSubscription(<key>,  {console.log(event)}&#xA;    speechRecognizer.canceled = async (recognizer, event) => {console.log(event)}&#xA;    speechRecognizer.startContinuousRecognitionAsync();&#xA;&#xA;    for (let i = 1; i &lt;= 1443; i&#x2B;&#x2B;) {&#xA;      const formattedNumber = i.toString().padStart(4, &#x27;0&#x27;);&#xA;      const buffer = fs.readFileSync(`/var/tmp/chunks/output_${formattedNumber}.wav`);&#xA;      pushStream.write(buffer);&#xA;    }&#xA;</key>

  


  To create the audio chunks :

  


  ffmpeg -i  -f segment -segment_time 0.1 -c copy output_%04d.wav


  


  Here is the audio link : https://drive.google.com/file/d/1H_RJuqMiBaVkpo9XHrgp1bpuFdgQl64O/view?usp=sharing

  


  Thanks for your help