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• avformat/aviobuf : Avoid calling function twice due to FFMAX()

  4 août 2021, par Andreas Rheinhardt

  avformat/aviobuf : Avoid calling function twice due to FFMAX()
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavformat/aviobuf.c

• What is the correct way to write Frames in ffmpeg

  6 février 2020, par hagor

  I am working on some ffmpeg writer implementation and I can not undrestand what do I do wrong.
  I have a mdf (media digital file) file which I need to convert to avi and I have a software that does it. The test case : Avi file I get from my software and avi file I get from software are identical.
  I can get frames from input mdf file, and can convert them to bmps correctly. So I suppose I do something wrong with ffmpeg.
  I also need to use raw RGB codec in ffmpeg.

  Here is the code I wrote to fill avi files with frames :

  if (hOffLoaderDVR && m_hDeviceCollection && device && hDriveSetDVR && hFile)
  
                      { 
  
                          std::string camSuffix = "_cam_";
  
                          std::string cameraName = hFile->streamByIndex(streamC)->cameraPortName().c_str();
  
                          std::string fileName = pathToAviDir + hFile->parameters()->name.c_str() + camSuffix + cameraName + std::to_string(streamC).c_str() + ".avi";
  
  
  
                          Offload::Request request;
  
                          Common::DataTypeHandle cameraParams = hFile->streamByIndex(streamC)->streamView()->dataType();
  
  
  
                          AVFrame* frame = m_ffwriter.alloc_picture(AV_PIX_FMT_BGR24, cameraParams->width(), cameraParams->height());
  
  
  
                          size_t datasize = hFile->streamByIndex(streamC)->streamView()->frameAtIndex(0)->buffer()->size();  // size in bytes 
  
  
  
                          RecordingParams params(fileName, cameraParams->width(), cameraParams->height(), 50,
  
                              AV_PIX_FMT_BGR24, datasize);
  
  
  
                          frame->pkt_size = datasize;
  
                          m_ffwriter.delayedOpen(params);
  
  
  
                          for (unsigned int frameC = 0; frameC < hFile->streamByIndex(streamC)->streamView()->frameCount(); frameC++)
  
                          {
  
                              m_ffwriter.fill_rgb_image(frame, hFile->streamByIndex(streamC)->streamView()->frameAtIndex(frameC)->buffer()->data());
  
                              m_ffwriter.putImage(frame);
  
                          }
  
                          m_ffwriter.close();
  
                          av_frame_free(&frame);
  
  
  
                      }

  To open the AVI file I use the function ffmpegWriter::delayedOpen :

  bool FfmpegWriter::delayedOpen(const RecordingParams & params) {
  
  
  
      unsigned int w = params.getWidth();
  
      unsigned int h = params.getHeight();
  
      unsigned int framerate = params.getFramerate();
  
      unsigned int datasize = params.getDataSize();
  
      m_filename = params.getPath();
  
  
  
      unsigned int sample_rate = 0; //default 
  
      unsigned int channels = 0;    //default
  
  
  
      m_delayed = false;
  
      if (w <= 0 || h <= 0) {
  
          m_delayed = true;
  
          return true;
  
      }
  
      m_ready = true;
  
  
  
      // auto detect the output format from the name. default is mpeg.
  
      m_fmt = av_guess_format(nullptr, m_filename.c_str(), nullptr);
  
      m_fmt->video_codec = AV_CODEC_ID_RAWVIDEO; //can be moved to a parameter if required 
  
  
  
      if (!m_fmt) {
  
          printf("Could not deduce output format from file extension: using MPEG.\n");
  
          m_fmt = av_guess_format("mpeg", nullptr, nullptr);
  
      }
  
  
  
      if (!m_fmt) {
  
          fprintf(stderr, "Could not find suitable output format\n");
  
          ::exit(1);
  
      }
  
  
  
  
  
      // allocate the output media context 
  
      m_oc = avformat_alloc_context();
  
      if (!m_oc) {
  
          fprintf(stderr, "Memory error\n");
  
          ::exit(1);
  
      }
  
      m_oc->oformat = m_fmt;
  
      m_fmt->flags = AVFMT_NOTIMESTAMPS;
  
  
  
  
  
      snprintf(m_oc->filename, sizeof(m_oc->filename), "%s", m_filename.c_str());
  
  
  
      // add the audio and video streams using the default format codecs
  
      // and initialize the codecs 
  
      m_video_st = nullptr;
  
      m_audio_st = nullptr;
  
  
  
      if (m_fmt->video_codec != AV_CODEC_ID_NONE) {
  
          m_video_st = add_video_stream(m_oc, m_fmt->video_codec, w, h, framerate);
  
      }
  
  
  
      av_dump_format(m_oc, 0, m_filename.c_str(), 1);
  
  
  
      // now that all the parameters are set, we can open 
  
      // video codecs and allocate the necessary encode buffers 
  
  
  
      if (m_video_st) {
  
          open_video(m_oc, m_video_st, datasize);
  
      }
  
  
  
      // open the output file, if needed 
  
      if (!(m_fmt->flags & AVFMT_NOFILE)) {
  
          if (avio_open(&m_oc->pb, m_filename.c_str(), AVIO_FLAG_WRITE) < 0) {
  
              fprintf(stderr, "Could not open '%s'\n", m_filename.c_str());
  
              ::exit(1);
  
          }
  
      }
  
  
  
      // write the stream header, if any
  
      avformat_write_header(m_oc, NULL);
  
      return true;
  
  }

  And to fill images and put them into the AVI I use these functions :

  void FfmpegWriter::fill_rgb_image(AVFrame *pict, void *p)
  
  {
  
  
  
      memcpy(pict->data[0], p, pict->pkt_size);
  
  
  
  }
  
  bool FfmpegWriter::putImage(AVFrame * newFrame) {
  
      if (m_delayed) {
  
          // savedConfig.put("width",Value((int)image.width()));
  
         //  savedConfig.put("height",Value((int)image.height()));
  
      }
  
      if (!isOk()) {
  
          return false;
  
      }
  
  
  
      if (m_video_st) {
  
          m_video_pts = (double)av_stream_get_end_pts(m_video_st) *m_video_st->time_base.num / m_video_st->time_base.den;
  
      }
  
      else {
  
          m_video_pts = 0.0;
  
      }
  
  
  
      if (!(m_video_st)) {
  
          return false;
  
      }
  
  
  
      // write interleaved video frame
  
      write_video_frame(m_oc, m_video_st, newFrame);
  
  
  
      return true;
  
  }

  Do I not open context correctly ? Or where might be the problem ? The problems I can see are that the output AVI has around minute delay in the beginning with no frames changing, and the video channels behave differently(it seems that red and blue dissapeared). Does it make any difference to use other format ? I currently use AV_PIX_FMT_BGR24 which seems to be correct (I can visualize frames from the same pointer correctly).

  Thank you for your help !

• avformat/matroskadec : Read RealAudio extradata directly

  4 août 2021, par Andreas Rheinhardt

  avformat/matroskadec : Read RealAudio extradata directly
  Don't use the avio-API to read a few bytes at fixed offsets.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavformat/matroskadec.c