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• libav* incorrect decode

  21 janvier 2012, par jjSunny

  Use libav to save frames from a video.

  The problem is that if you call the function decode a few times, then 2nd and then not correctly handled.

  1st time such a conclusion (all works fine) :

  [swscaler @ 0x8b48510]No accelerated colorspace conversion found from yuv420p to bgra.
  
  good

  2nd (can not find stream, but these are the same) :

  [mp3 @ 0x8ae5800]Header missing
  
  Last message repeated 223 times
  
  [mp3 @ 0x8af31c0]Could not find codec parameters (Audio: mp1, 0 channels, s16)
  
  [mp3 @ 0x8af31c0]Estimating duration from bitrate, this may be inaccurate
  
  av_find_stream_info

  Can you please tell where the error occurred.

  main.cpp

  avcodec_init();
  
  avcodec_register_all();
  
  av_register_all();
  
  char *data;
  
  int size;
  
  //fill data and size
  
  ...
  
  decode(data, size);
  
  decode(data, size);

  video.cpp

  int f_offset = 0;
  
  int f_length = 0;
  
  char *f_data = 0;
  
  
  
  int64_t seekp(void *opaque, int64_t offset, int whence)
  
  {
  
      switch (whence)
  
      {
  
      case SEEK_SET:
  
          if (offset > f_length || offset < 0)
  
              return -1;
  
          f_offset = offset;
  
          return f_offset;
  
      case SEEK_CUR:
  
          if (f_offset + offset > f_length || f_offset + offset < 0)
  
              return -1;
  
          f_offset += offset;
  
          return f_offset;
  
      case SEEK_END:
  
          if (offset > 0 || f_length + offset < 0)
  
              return -1;
  
          f_offset = f_length + offset;
  
          return f_offset;
  
      case AVSEEK_SIZE:
  
          return f_length;
  
      }
  
  
  
      return -1;
  
  }
  
  int readp(void *opaque, uint8_t *buf, int buf_size)
  
  {
  
      if (f_offset == f_length)
  
          return 0;
  
  
  
      int length = buf_size <= (f_length - f_offset) ? buf_size : (f_length - f_offset);
  
  
  
      memcpy(buf, f_data + f_offset, length);
  
      f_offset += length;
  
  
  
      return length;
  
  }
  
  
  
  bool decode(char *data, int length)
  
  {
  
      f_offset = 0;
  
      f_length = length;
  
      f_data = data;
  
  
  
      int buffer_read_size = FF_MIN_BUFFER_SIZE;
  
      uchar *buffer_read = (uchar *) av_mallocz(buffer_read_size + FF_INPUT_BUFFER_PADDING_SIZE);
  
  
  
      AVProbeData pd;
  
      pd.filename = "";
  
      pd.buf_size = 4096 < f_length ? 4096 : f_length;
  
      pd.buf = (uchar *) av_mallocz(pd.buf_size + AVPROBE_PADDING_SIZE);
  
      memcpy(pd.buf, f_data, pd.buf_size);
  
  
  
      AVInputFormat *pAVInputFormat = av_probe_input_format(&pd, 1);
  
      if (pAVInputFormat == NULL)
  
      {
  
          std::cerr << "AVIF";
  
          return false;
  
      }
  
      pAVInputFormat->flags |= AVFMT_NOFILE;
  
  
  
      ByteIOContext ByteIOCtx;
  
      if (init_put_byte(&ByteIOCtx, buffer_read, buffer_read_size, 0, NULL, readp, NULL, seekp) < 0)
  
      {
  
          std::cerr << "init_put_byte";
  
          return false;
  
      }
  
  
  
      AVFormatContext *pFormatCtx;
  
      if (av_open_input_stream(&pFormatCtx, &ByteIOCtx, "", pAVInputFormat, NULL) < 0)
  
      {
  
          std::cerr << "av_open_stream";
  
          return false;
  
      }
  
  
  
      if (av_find_stream_info(pFormatCtx) < 0)
  
      {
  
          std::cerr << "av_find_stream_info";
  
          return false;
  
      }
  
  
  
      int video_stream;
  
      video_stream = -1;
  
      for (uint i = 0; i < pFormatCtx->nb_streams; ++i)
  
          if (pFormatCtx->streams[i]->codec->codec_type == CODEC_TYPE_VIDEO)
  
          {
  
              video_stream = i;
  
              break;
  
          }
  
      if (video_stream == -1)
  
      {
  
          std::cerr << "video_stream == -1";
  
          return false;
  
      }
  
  
  
      AVCodecContext *pCodecCtx;
  
      pCodecCtx = pFormatCtx->streams[video_stream]->codec;
  
  
  
      AVCodec *pCodec;
  
      pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
  
      if (pCodec == NULL)
  
      {
  
          std::cerr << "pCodec == NULL";
  
          return false;
  
      }
  
  
  
      if (avcodec_open(pCodecCtx, pCodec) < 0)
  
      {
  
          std::cerr << "avcodec_open";
  
          return false;
  
      }
  
  
  
      AVFrame *pFrame;
  
      pFrame = avcodec_alloc_frame();
  
      if (pFrame == NULL)
  
      {
  
          std::cerr << "pFrame == NULL";
  
          return false;
  
      }
  
      AVFrame *pFrameRGB;
  
      pFrameRGB = avcodec_alloc_frame();
  
      if (pFrameRGB == NULL)
  
      {
  
          std::cerr << "pFrameRGB == NULL";
  
          return false;
  
      }
  
  
  
      int numBytes;
  
      numBytes = avpicture_get_size(PIX_FMT_RGB32, pCodecCtx->width, pCodecCtx->height);
  
      uint8_t *buffer;
  
      buffer = (uint8_t *) av_malloc(numBytes * sizeof(uint8_t));
  
      if (buffer == NULL)
  
      {
  
          std::cerr << "buffer == NULL";
  
          return false;
  
      }
  
  
  
      // Assign appropriate parts of buffer to image planes in pFrameRGB
  
      // Note that pFrameRGB is an AVFrame, but AVFrame is a superset
  
      // of AVPicture
  
      avpicture_fill((AVPicture *) pFrameRGB, buffer, PIX_FMT_RGB32, pCodecCtx->width, pCodecCtx->height);
  
  
  
      SwsContext *swsctx;
  
      swsctx = sws_getContext(
  
                  pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt,
  
                  pCodecCtx->width, pCodecCtx->height, PIX_FMT_RGB32,
  
                  SWS_BILINEAR, NULL, NULL, NULL);
  
      if (swsctx == NULL)
  
      {
  
          std::cerr << "swsctx == NULL";
  
          return false;
  
      }
  
  
  
      AVPacket packet;
  
      while (av_read_frame(pFormatCtx, &packet) >= 0)
  
      {
  
          if (packet.stream_index == video_stream)
  
          {
  
              int frame_finished;
  
              avcodec_decode_video2(pCodecCtx, pFrame, &frame_finished, &packet);
  
  
  
              if (frame_finished)
  
              {
  
                  sws_scale(swsctx, pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameRGB->data, pFrameRGB->linesize);
  
  
  
                  std::cerr << "good";
  
                  av_close_input_stream(pFormatCtx);
  
  
  
                  return true;
  
              }
  
              else
  
                  std::cerr << "frame_finished == 0";
  
          }
  
      }
  
  
  
      std::cerr << "av_read_frame < 0";
  
      return false;
  
  }

  ffmpeg -version

  FFmpeg 0.6.2-4:0.6.2-1ubuntu1
  
  libavutil     50.15. 1 / 50.15. 1
  
  libavcodec    52.72. 2 / 52.72. 2
  
  libavformat   52.64. 2 / 52.64. 2
  
  libavdevice   52. 2. 0 / 52. 2. 0
  
  libavfilter    1.19. 0 /  1.19. 0
  
  libswscale     0.11. 0 /  0.11. 0
  
  libpostproc   51. 2. 0 / 51. 2. 0

• FFMPEG terrible conversion quality when using -sameq (same quantizer as source) flag

  14 novembre 2015, par Brad

  I’m trying to convert .flv videos to .ogg format. After experimenting for a while, the ogg is always produced as very low quality. Even when I use the -sameq flag which uses the same quantizer as the input file, the quality is substantially worse.

  Since I am pretty new with ffmpeg, does anyone know some good options to convert video files with maximum quality ?

• FFMPEG RTMP Streaming to Android　Exec

  4 octobre 2012, par user1653922

  I have done in Android using FFMPEG RTMP streaming

  As a practical matter, an error is output when the RTMP streaming with Android.

  "rtmp :/ / ~ / oflaDemo / test live = 1": No such file or directory

  Command execution in Android is as follows.

  String [] command = new String [] {"/ directory / ffmpeg", "-vn", "-re", "-i", "\" rtmp :/ / ~ / oflaDemo / test live = 1 \ "" , "-loglevel", "debug", "pipe: 1"};
  
  Process process = Runtime.getRuntime () exec (command, null);

  Successfully decoded the above command on a FFMPEG on Windows.

  I would like you to tell me if it is good How can Android Can I run the above command.