Recherche avancée

Sur d’autres sites (4018)

• Decoding m4a and dumping PCM data gives back noise

  7 décembre 2013, par lynnard

  I'm using the code below (modified from the examples given in libavcodec) to decode audio files

  int main(int argc, char **argv)
  
  {
  
      av_register_all();
  
      avcodec_register_all();
  
  
  
      char *filename = argv[1];
  
      char *outfilename = argv[2];
  
  
  
      FILE *outfile;
  
  
  
      AVCodec *codec;
  
      AVCodecContext *c= NULL;
  
      AVPacket avpkt;
  
      AVFrame *frame = av_frame_alloc();
  
  
  
      printf("Decode audio file %s to %s\n", filename, outfilename);
  
  
  
      outfile = fopen(outfilename, "wb");
  
      if (!outfile) {
  
          fprintf(stderr, "Could not write to %s\n", outfilename);
  
          av_free(c);
  
          exit(1);
  
      }
  
  
  
      AVFormatContext *format_context = NULL;
  
      avformat_open_input(&format_context, filename, NULL, NULL);
  
      printf("Opened format input\n");
  
  
  
      int find_result = avformat_find_stream_info(format_context, NULL);
  
      if (find_result < 0) {
  
          fprintf(stderr, "Cannot find stream info\n");
  
          avformat_close_input(&format_context);
  
          exit(-1);
  
      }
  
  
  
      int audio_stream_idx = av_find_best_stream(format_context, AVMEDIA_TYPE_AUDIO, -1, -1, &codec, 0);
  
  
  
      if (audio_stream_idx < 0) {
  
          fprintf(stderr,"Couldn't find stream information\n");
  
          exit(-1);
  
      }
  
  
  
      // Get a pointer to the codec context for the audio stream
  
      c = format_context->streams[audio_stream_idx]->codec;
  
      av_opt_set_int(c, "refcounted_frames", 1, 0);
  
  
  
      if (avcodec_open2(c, codec, NULL) < 0) {
  
          fprintf(stderr, "Could not open codec\n");
  
          exit(-1);
  
      }
  
  
  
      // read the audio frames
  
      int ret, got_frame;
  
      while (1) {
  
          if ((ret = av_read_frame(format_context, &avpkt)) < 0)
  
              break;
  
          if (avpkt.stream_index == audio_stream_idx) {
  
              avcodec_get_frame_defaults(frame);
  
              got_frame = 0;
  
              ret = avcodec_decode_audio4(c, frame, &got_frame, &avpkt);
  
              if (ret < 0) {
  
                  fprintf(stderr, "Error decoding audio\n");
  
                  continue;
  
              }
  
  
  
              if (got_frame) {
  
                  // write to disk
  
                  fwrite(frame->extended_data[0], 1, frame->linesize[0], outfile);
  
              }
  
          }
  
          av_free_packet(&avpkt);
  
      }
  
  
  
      fclose(outfile);
  
  
  
      printf("Finished\n");
  
      if (c) 
  
          avcodec_close(c);
  
      avformat_close_input(&format_context);
  
      av_frame_free(&frame);
  
  }

  I tried .mp3 and .m4a files ; .mp3 files work fine but not for .m4a files. Any help ?

• Android Samsung Galaxy S2 / S3 device bitmap rendering to ImageView issue

  18 décembre 2014, par Steve

  I am stuck in a very strange Bitmap rendering issue with Samsung Android devices. Let me discuss in brief what I have done.

  I am taking frame from a video and rendering it in a ImageView using ffmpeg. Following code gives me a bitmap object in return from JNI callback.

      img_convert_ctx = sws_getContext(pCodecCtx->width,
  
              pCodecCtx->height, pCodecCtx->pix_fmt, target_width,
  
          target_height, PIX_FMT_RGB24, SWS_BICUBIC, NULL, NULL,NULL);
  
  
  
      sws_scale(img_convert_ctx,(const uint8_t* const *) 
  
          pFrame->data,pFrame->linesize, 0, pCodecCtx->height,pFrameRGB->data, 
  
  pFrameRGB->linesize);

  Next, I’m just setting the Bitmap to ImageView. Now the issue is the Bitmap I get is rendering very well in maximum devices except Samsung S2/S3.

  A>Working well In :- Screen Shot 1

  1. Nexus 4
  2. HTC One / HTC One x
  3. LG Optimus
  4. Sony Experia
  5. Samsung Galaxy S Plus / Samsung Exhibit (Android 2.3)

  Issue With :-
  B>Samsung Galaxy S2 & S3 : The second screen shot.

  For Case B, A part of the video is rendering at the right side if you notice.

  I have tried saving the Bitmap I get from JNI as jpg in SD card and read that again to set the ImageView and it works. I Don’t understand what is going wrong with the raw Bitmap that I get from JNI callback, is it with Samsung S2 Hardware ? Please someone help me on this.

  

  

• Revision fe2fd37bb2 : vp8 : Updates to noise level estimate. -Use full bandwidth (when temporal layers

  24 octobre 2014, par Marco

  Changed Paths :
   Modify /vp8/encoder/denoising.c

  
   Modify /vp8/encoder/onyx_if.c

  
  
  vp8 : Updates to noise level estimate.

   Use full bandwidth (when temporal layers is on) for checking switching.
   Normalize metric wrt num_blocks.
   Rounding fix to update of average noise level metric.
   Make default internal denoiser mode == kDenoiserOnYUV (in denoiser
  set_parameters()).
   Adjust some thresholds.

  Change-Id : Ib827512b25a7bf1f66c76d3045f3a68ce56b1cd2