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• Playback of FFMPEG Audio Using NAudio Has Lots of Noise

  28 août 2018, par Hrethric

  I have a video that I’m trying to play back using the FFMPEG framework, and NAudio to playback the audio frames. The video plays back just fine, but when I play back the audio using a BufferedWaveProvider while the underlying audio sounds correct, it has a ton of static/noise. What’s important to note in the attached code is when the events fire off from the managed C++ class, a C# class receives the event and then grabs the latest relevant AVFrame data. This works flawlessly for video, but like I said, when I try to play back the audio I have a bunch of noise. For now I’ve hardcoded the NAudio WaveFormat settings, but they should match the video’s audio.

      ///////////////////////// C# /////////////////////////////
  
  
  
      // Gets the size of the data from the audio AVFrame (audioFrame->linesize[0])
  
      int size = _Decoder.GetAVAudioFrameSize();
  
  
  
      if (!once)
  
      {
  
          managedArray = new byte[size];
  
          once = true;
  
      }
  
  
  
      // Gets the data array from the audio AVFrame
  
      IntPtr data = _Decoder.GetAVAudioFrameData();
  
  
  
      Marshal.Copy(data, managedArray, 0, size);
  
  
  
      if (_waveProvider == null)
  
      {
  
          _waveProvider = new BufferedWaveProvider(new WaveFormat(44100, 16, 2));
  
          _waveOut.NumberOfBuffers = 2;
  
          _waveOut.DesiredLatency = 300;
  
          _waveOut.Init(_waveProvider);
  
          _waveOut.Play();
  
      }
  
  
  
      _waveProvider.AddSamples(managedArray, 0, size);
  
  
  
  
  
      //////////////////////// Managed C++ /////////////////////////
  
      while (_shouldRead)
  
      {
  
          // if we're not initialized, sleep
  
          if (!_initialized || !_FFMpegObject->AVFormatContextReady())
  
          {
  
              Thread::Sleep(READ_INIT_WAIT_TIME);
  
          }
  
          else if (_sequentialFailedReadCount > MAX_SEQUENTIAL_READ_FAILS)
  
          {
  
              // we've failed a lot and probably lost the stream, try to reconnect.
  
              _sequentialFailedReadCount = 0;
  
              _initialized = false;
  
              StartInitThread();
  
              Thread::Sleep(READ_INIT_WAIT_TIME << 1);
  
          }
  
          else // otherwise, try reading one AV packet 
  
          {
  
              if (_FFMpegObject->AVReadFrame())
  
              {
  
                  if (_FFMpegObject->GetAVPacketStreamIndex() == _videoStreamIndex)
  
                  {
  
                      _sequentialFailedReadCount = 0;
  
  
  
                      // decode the video packet
  
                      _frameLock->WaitOne();
  
                      frameFinished = _FFMpegObject->AVCodecDecodeVideo2();
  
                      _frameLock->ReleaseMutex();
  
  
  
                      if (frameFinished)
  
                      {
  
                          _framesDecoded++;
  
  
  
                          if (!_isPaused) // If paused and AFAP playback, just don't call the callback
  
                          {
  
                              FrameFinished(this, EventArgs::Empty);
  
  
  
                              Thread::Sleep((int)(1000 / (GetFrameRate() * _speed)));
  
                          }
  
                      }
  
                  }
  
                  else if (_FFMpegObject->GetAVPacketStreamIndex() == _audioStreamIndex)
  
                  {
  
                      // decode the audio packet.
  
                      _frameLock->WaitOne();
  
                      audioFrameFinished = _FFMpegObject->AVCodecDecodeAudio4();
  
                      _frameLock->ReleaseMutex();
  
  
  
                      if (audioFrameFinished)
  
                      {
  
                          if (!_isPaused) // If paused and AFAP playback, just don't call the callback
  
                          {
  
                              // Fire the event - leaving it up to video to do the sleeps -- not sure if that will work or not
  
                              AudioFrameFinished(this, EventArgs::Empty);
  
                          }
  
                      }
  
                  }
  
  
  
                  _FFMpegObject->AVFreeFramePacket();
  
  
  
              }
  
              else // failed to read an AV packet
  
              {
  
                  _sequentialFailedReadCount++;
  
                  _failedReadCount++;
  
                  Thread::Sleep(READ_FAILED_WAIT_TIME);
  
              }
  
          }
  
      }

• lavfi/vf_colorchannelmixer : replace round by lrint

  16 décembre 2015, par Ganesh Ajjanagadde

  lavfi/vf_colorchannelmixer : replace round by lrint
  lrint is faster here on -ftree-vectorize with GCC. This is likely simply
  
  an artifact of GCC’s rather terrible auto-vectorizer, since as per the
  
  instruction set manuals cvtsd2si and cvttsd2si (or their vector equivalents)
  
  have identical cycle timings.
  Anyway, regardless of above, lrint is superior to round accuracy wise.
  Safety guaranteed as long int has at least 32 bits.
  Signed-off-by : Ganesh Ajjanagadde <gajjanagadde@gmail.com>
  

  • [DH] libavfilter/vf_colorchannelmixer.c

• WebM Encoding Available at encoding.com

  17 septembre 2010, par noreply@blogger.com (John Luther)

  Encoding.com, one of the world’s largest video transcoding services, has released WebM encoding support and also included six easy-to-use output presets. You can read more at the encoding.com blog.