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• What is the built-in microphone device for use with ffmpeg in OS X Mavericks

  5 janvier 2014, par tobinjim

  I will need to migrate a machine from 10.6.8/Podcast Producer to 10.9 in the near future. We were using the ad-hoc feature of Podcast Producer to record audio and then using ffmpeg to convert that to formats on our web server.

  The only Internet search I've come up with results pertinent to recording on a Mac have the command line argument to ffmpeg giving the input as hw:0,0,1 — which when I try that gives an error from ffmpeg that "hw:0,0,1 : No such file or directory"

  I have tried looking through the output of ioreg, grepping for audio, but frankly don't understand which item I'd use, nor how to refer to it.

• FFMPEG x264 encoding on Android - error with lookahead

  6 janvier 2013, par Tishu

  I am using FFMPEG + x264 on Android to encode YUV420 frames to a video file. I use the following code on each frame to encode them :

  avcodec_encode_video2(gVideoWriteCodecCtx, &packet, pCurrentFrame, &gotPacket);

  On the first few calls, the frame buffer gets filled and nothing is encoded. When the first encoding happens, a call is made to x264_lookahead_get_frames. I can see there that my frame array is correctly populated, but the first item is NULL. As a consequence, in x264_weights_analyse the reference frame gotten as frames[p0] is NULL and I get an exception there.

  slicetype.c, the first frame in "frames" is NULL

  if( h->param.analyse.i_weighted_pred && b == p1 )
  
      {
  
          x264_emms();
  
          x264_weights_analyse( h, fenc, frames[p0], 1 );
  
          w = fenc->weight[0];
  
      }

  And the exception happens there, ref is NULL

  static void x264_weights_analyse( x264_t *h, x264_frame_t *fenc, x264_frame_t *ref, int b_lookahead )
  
      {
  
          int i_delta_index = fenc->i_frame - ref->i_frame - 1;

  I surely am missing something as I am sure this encoder works for most people :) Does anyone have an idea why this first frame in the "frames" array is null ?

  Many thanks

• ios http live black screen

  11 mars 2013, par jagsler

  In my ios app I am trying to play videos using http live streaming. The playing goes well until I decide to use the scrubber and skip to some point that hasn't buffered yet. From that moment the audio goes on but the videos goes black.

  I've converted my .MP4 videos with the following command :

  avconv -y -i video.mp4 -f mpegts -acodec libmp3lame -ar 48000 -ab 64k -s 640x480 -vcodec libx264 -b 64k -flags +loop -cmp +chroma -partitions +parti4x4+partp8x8+partb8x8 -subq 7 -trellis 0 -refs 0 -coder 0 -me_range 16 -keyint_min 25 -sc_threshold 40 -i_qfactor 0.71 -bt 200k -maxrate 64k -bufsize 64k -rc_eq 'blurCplx^(1-qComp)' -qcomp 0.6 -qmin 30 -qmax 51 -qdiff 4 -level 30 -aspect 640:480 -g 30 -async 2 sample_64.ts

  I did this with multiple bitrates (64, 150, 240, 440 and 640) and created one .m3u8 that contains the different streams. After converting I used the mediafilesegmenter to split the video in segments of each 10 seconds.

  After scrubbing the following appears in the output window :

  2013-03-08 17:30:21.827 Geschiedenis Trainer[88129:19a03] [MPAVController] Autoplay: Disabling autoplay for pause
  
  2013-03-08 17:30:21.827 Geschiedenis Trainer[88129:19a03] [MPAVController] Autoplay: Disabling autoplay
  
  2013-03-08 17:30:21.977 Geschiedenis Trainer[88129:19a03] [MPAVController] Autoplay: _streamUnlikelyToKeepUp: 1 -> 0
  
  2013-03-08 17:30:21.978 Geschiedenis Trainer[88129:19a03] [MPAVController] Autoplay: Skipping autoplay, disabled (for current item: 1, on player: 0)
  
  2013-03-08 17:30:21.978 Geschiedenis Trainer[88129:19a03] [MPAVController] Autoplay: _streamRanDry: 0 -> 1
  
  2013-03-08 17:30:21.980 Geschiedenis Trainer[88129:19a03] [MPAVController] Autoplay: Took background task assertion (32) for playback stall
  
  2013-03-08 17:30:21.981 Geschiedenis Trainer[88129:19a03] [MPAVController] Autoplay: Skipping autoplay, disabled (for current item: 1, on player: 0)
  
  2013-03-08 17:30:22.634 Geschiedenis Trainer[88129:19a03] [MPAVController] Autoplay: _streamUnlikelyToKeepUp: 0 -> 0
  
  2013-03-08 17:30:22.634 Geschiedenis Trainer[88129:19a03] [MPAVController] Autoplay: _streamRanDry: 0 -> 1
  
  2013-03-08 17:30:22.667 Geschiedenis Trainer[88129:19a03] [MPAVController] Autoplay: Skipping autoplay, disabled (for current item: 1, on player: 0)
  
  2013-03-08 17:30:22.769 Geschiedenis Trainer[88129:19a03] [MPAVController] Autoplay: Ending background task assertion (32) for playback stall

  The code for my videoplayer :

  self.streamPlayer = [[MPMoviePlayerController alloc] initWithContentURL:movieURL];
  
  [self.view addSubview:self.streamPlayer.view];
  
  [self.streamPlayer setFullscreen:YES animated:YES];

  This problem does not occur when skipping to a point that has already been buffered.