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• Merge commit ’c9478410c68c04261f9cfcd80474607e50bd1852’

  11 avril 2016, par Derek Buitenhuis

  Merge commit ’c9478410c68c04261f9cfcd80474607e50bd1852’
  * commit ’c9478410c68c04261f9cfcd80474607e50bd1852’ :
  
    avprobe : add local per-file state
  Merged-by : Derek Buitenhuis <derek.buitenhuis@gmail.com>
  

  • [DH] ffprobe.c

• Merge commit ’567d6d5f9d1400f00445183b3477391f58979aa3’

  11 avril 2016, par Derek Buitenhuis

  Merge commit ’567d6d5f9d1400f00445183b3477391f58979aa3’
  * commit ’567d6d5f9d1400f00445183b3477391f58979aa3’ :
  
    avprobe : add local per-stream state
  Merged-by : Derek Buitenhuis <derek.buitenhuis@gmail.com>
  

  • [DH] ffprobe.c

• Streaming Audio with OpenAL and FFMPEG

  28 janvier 2013, par Michael Barth

  Alright, basically I'm working on a simple video player and I'll probably be asking another question about lagging video\syncing to audio later, but for now I'm having a problem with audio. What I've managed to do to is go through all of the audio frames of a video and add them to a vector buffer then play the audio from that buffer using OpenAL.

  This is inefficient and memory hogging and so I need to be able stream it using what I guess is called a rotating buffer. I've ran into problems, one being that there's not a lot of information on streaming with OpenAL let alone the proper way to decode audio with FFMPEG and pipe it to OpenAL. I'm even less comfortable using a vector for my buffer because I honestly have no idea how vectors work in C++, but I some how managed to pull something out of my head to make it work.

  Currently I have a Video class that looks like this :

  class Video
  
  {
  
      public:
  
          Video(string MOV);
  
          ~Video();
  
          bool HasError();
  
          string GetError();
  
          void UpdateVideo();
  
          void RenderToQuad(float Width, float Height);
  
          void CleanTexture();
  
      private:
  
          string FileName;
  
          bool Error;
  
          int videoStream, audioStream, FrameFinished, ErrorLevel;
  
          AVPacket packet;
  
          AVFormatContext *pFormatCtx;
  
          AVCodecContext *pCodecCtx, *aCodecCtx;
  
          AVCodec *pCodec, *aCodec;
  
          AVFrame *pFrame, *pFrameRGB, *aFrame;
  
  
  
          GLuint VideoTexture;
  
          struct SwsContext* swsContext;
  
  
  
          ALint state;
  
          ALuint bufferID, sourceID;
  
          ALenum format;
  
          ALsizei freq;
  
  
  
          vector  bufferData;
  
  };

  The bottom private variables are the relevant ones. Currently I'm decoding audio in the class constructor to an AVFrame and adding the data to bufferData like so :

      av_init_packet(&packet);
  
  
  
      alGenBuffers(1, &bufferID);
  
      alGenSources(1, &sourceID);
  
  
  
      alListener3f(AL_POSITION, 0.0f, 0.0f, 0.0f);
  
  
  
      int GotFrame = 0;
  
  
  
      freq = aCodecCtx->sample_rate;
  
      if (aCodecCtx->channels == 1)
  
          format = AL_FORMAT_MONO16;
  
      else
  
          format = AL_FORMAT_STEREO16;
  
  
  
      while (av_read_frame(pFormatCtx, &packet) >= 0)
  
      {
  
          if (packet.stream_index == audioStream)
  
          {
  
              avcodec_decode_audio4(aCodecCtx, aFrame, &GotFrame, &packet);
  
              bufferData.insert(bufferData.end(), aFrame->data[0], aFrame->data[0] + aFrame->linesize[0]);
  
              av_free_packet(&packet);
  
          }
  
      }
  
      av_seek_frame(pFormatCtx, audioStream, 0, AVSEEK_FLAG_BACKWARD);
  
  
  
      alBufferData(bufferID, format, &amp;bufferData[0], static_cast<alsizei>(bufferData.size()), freq);
  
  
  
      alSourcei(sourceID, AL_BUFFER, bufferID);
  
  </alsizei>

  In my UpdateVideo() is where I'm decoding video to an OpenGL texture through the video stream, so it would make sense for me to decode my audio there and stream it :

  void Video::UpdateVideo()
  
  {
  
      alGetSourcei(sourceID, AL_SOURCE_STATE, &state);
  
      if (state != AL_PLAYING)
  
          alSourcePlay(sourceID);
  
      if (av_read_frame(pFormatCtx, &packet) >= 0)
  
      {
  
          if (packet.stream_index == videoStream)
  
          {
  
              avcodec_decode_video2(pCodecCtx, pFrame, &FrameFinished, &packet);
  
              if (FrameFinished)
  
              {
  
                  sws_scale(swsContext, pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameRGB->data, pFrameRGB->linesize);
  
                  av_free_packet(&packet);
  
              }
  
          }
  
          else if (packet.stream_index == audioStream)
  
          {
  
              /*
  
              avcodec_decode_audio4(aCodecCtx, aFrame, &FrameFinishd, &packet);
  
              if (FrameFinished)
  
              {
  
                  //Update Audio and rotate buffers here!
  
              }
  
              */
  
          }
  
          glGenTextures(1, &VideoTexture);
  
          glBindTexture(GL_TEXTURE_2D, VideoTexture);
  
          glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  
          glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  
          glTexImage2D(GL_TEXTURE_2D, 0, 3, pCodecCtx->width, pCodecCtx->height, 0, GL_RGB, GL_UNSIGNED_BYTE, pFrameRGB->data[0]);
  
      }
  
      else
  
      {
  
          av_seek_frame(pFormatCtx, videoStream, 0, AVSEEK_FLAG_BACKWARD);
  
      }
  
  }

  So I guess the big question is how do I do it ? I've got no clue. Any help is appreciated, thank you !