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• Capture camera + mic and encode to h264/aac on macOS

  16 décembre 2018, par Flock Dawson

  I’m having trouble capturing and encoding audio+video on-the-fly on macOS.

  I tried two options :

  1. ffmpeg

     ffmpeg -threads 0 -f avfoundation -s 1920x1080 -framerate 25 -I 0:0 -async 441 -c:v libx264 -preset medium -pix_fmt yuv420p -crf 22 -c:a libfdk_aac -aq 95 -y

  2. gstreamer

     gst-launch-1.0 -ve avfvideosrc device-index=0 ! video/x-raw,width=1920,height=1080,framerate=25/1 ! vtenc_h264 ! queue ! mp4mux name=mux ! filesink location=out.mp4  osxaudiosrc device=0 ! audio/x-raw ! faac midside=false ! queue ! mux.

  The ffmpeg option works, but only for lower resolutions. With higher resolutions, the Mac mini (2018 gen) can’t do the heavy lifting. I think because I installed ffmpeg with brew, so it wasn’t compiled on my machine, meaning it doesn’t use the h264 hardware encoder in the Mac ?

  The gstreamer option works as well, but there’s a slight audio/video sync issue (audio is 100ms ahead of the video). I can’t seem to add delay to the GStreamer queue (it ignores it) :

  queue max-size-buffers=0 max-size-time=0 max-size-bytes=0 min-threshold-time=100000000

  Anyone who has any experience with this ? Thanks !

• FFMPEG streaming RTP : time base not set

  15 novembre 2016, par Managarm

  I’m trying to create a small demo to get a feeling for streaming programmatically with ffmpeg. I’m using the code from this question as a basis. I can compile my code, but when I try to run it I always get this error :

  [rtp @ 0xbeb480] time base not set

  The thing is, I have set the time base parameters. I even tried setting them for the stream (and the codec associated with the stream) as well, even though this should not be necessary as far as I understand it. This is the relevant section in my code :

  AVCodec* codec = avcodec_find_encoder(AV_CODEC_ID_H264);
  
  AVCodecContext* c = avcodec_alloc_context3(codec);
  
  c->pix_fmt = AV_PIX_FMT_YUV420P;
  
  c->flags = CODEC_FLAG_GLOBAL_HEADER;
  
  c->width = WIDTH;
  
  c->height = HEIGHT;
  
  c->time_base.den = FPS;
  
  c->time_base.num = 1;
  
  c->gop_size = FPS;
  
  c->bit_rate = BITRATE;
  
  
  
  avcodec_open2(c, codec, NULL);
  
  struct AVStream* stream = avformat_new_stream(avctx, codec);
  
  
  
  // TODO: causes an error
  
  avformat_write_header(avctx, NULL);

  The error occurs when calling "avformat_write_header" near the end. All methods that can fail (like avcodec_open2) are checked, I just removed the checks to make the code more readable.

  Digging through google and the ffmpeg source code didn’t yield any useful results. I think it’s really basic, but I’m stuck. Who can help me ?

• FFMPEG streaming RTP : time base not set

  25 octobre 2020, par Managarm

  I'm trying to create a small demo to get a feeling for streaming programmatically with ffmpeg. I'm using the code from this question as a basis. I can compile my code, but when I try to run it I always get this error :

  



  


  [rtp @ 0xbeb480] time base not set

  


  



  The thing is, I have set the time base parameters. I even tried setting them for the stream (and the codec associated with the stream) as well, even though this should not be necessary as far as I understand it. This is the relevant section in my code :

  



  AVCodec* codec = avcodec_find_encoder(AV_CODEC_ID_H264);
AVCodecContext* c = avcodec_alloc_context3(codec);
c->pix_fmt = AV_PIX_FMT_YUV420P;
c->flags = CODEC_FLAG_GLOBAL_HEADER;
c->width = WIDTH;
c->height = HEIGHT;
c->time_base.den = FPS;
c->time_base.num = 1;
c->gop_size = FPS;
c->bit_rate = BITRATE;

avcodec_open2(c, codec, NULL);
struct AVStream* stream = avformat_new_stream(avctx, codec);

// TODO: causes an error
avformat_write_header(avctx, NULL);


  



  The error occurs when calling "avformat_write_header" near the end. All methods that can fail (like avcodec_open2) are checked, I just removed the checks to make the code more readable.

  



  Digging through google and the ffmpeg source code didn't yield any useful results. I think it's really basic, but I'm stuck. Who can help me ?