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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 !

• Change bitrate of USB camera

  12 décembre 2018, par Nick Saw

  I use ELP USB camera with h264-codec output.

  Ffmpeg-command to take the video stream :

  ffmpeg -i /dev/video1 -c:v copy output.ts

  As result I have a video with 4Mb bitrate - this value is too high for my task.

  There is the same situation when I use GSTreamer :

  gst-launch-1.0 v4l2src device=/dev/video1 ! video/x-h264,width=1280,height=720,framerate=30/1 ! mpegtsmux ! filesink location=output.ts

  I know that it’s possible to change the bitrate if we decode h264 the stream firstly and then encode it to h264 again. This operation requires too much CPU-power of my NanoPI device.

  The main question is :
  Is it possible to change a USB-camera’s bitrate without decoding ?

  Thanks in advance !

• iOS : FFMPEG Camera stream to server gives 'Protocol not found' for RTSP

  15 novembre 2018, par John Mikelich

  I have a demo project which streams a local mp4 to a server using FFMPEG. An RTMP destination works, an RTSP does not.

  When attempting to use RTSP I get a ’Protocol not found’ error from

  ret = avio_open(&oc->pb, filename, AVIO_FLAG_WRITE);

  I have tried to rebuild my FFMPEG libraries and ensured I have the necessary protocols included
  (To my understanding RTSP is a muxer in FFMPEG, hence the muxer enabling)

  --enable-muxer=rtsp \
  
  --enable-muxer=rtp \
  
  --enable-protocol=rtp \
  
  --enable-protocol=rtsp \

  In the code, I’ve tried to add the appropriate AVOptions

  av_dict_set(&opt, "rtsp_transport", "udp", 0);
  
  av_dict_set(&opt, "announce_port", "1935", 0);
  
  av_dict_set(&opt, "enable-protocol", "rtsp", 0);
  
  av_dict_set(&opt, "protocol_whitelist","file,udp,tcp,rtp,rtsp", 0);
  
  av_dict_set(&opt, "enable-protocol", "rtp", 0);
  
  av_dict_set(&opt, "enable-protocol", "rtsp", 0);
  
  av_dict_set(&opt, "enable-protocol", "udp", 0);
  
  av_dict_set(&opt, "enable-muxer", "rtsp", 0);
  
  av_dict_set(&opt, "enable-muxer", "rtp", 0);

  This is called in my open codec calls.

  ret = avcodec_open2(c, codec, &opt);

  It feels like I’m missing something very basic, any help would be amazing !