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• How can I capture audio AND video simultenaous with ffmpeg from a linux USB capture device

  7 juin 2019, par oban

  I’m capturing a video by means of an USB Terratec Grabster AV350 (which is based on the em2860 chip).

  I don’t succeed to get the audio when it is played . If I play the captured video with vlc or with ffplay I got only 3 seconds sound and then a silence for the rest of the video ...

  During the capturing I don’t get any errors. At the end it indicates the size of the video and audio captured ....

  I’m using the ffmpeg command for this :

  ffmpeg -f alsa -ac 2 -i hw:3 -f video4linux2 -i /dev/video0 -acodec ac3 -ab 128k -vcodec mpeg4 -b 6000k -r 25 test5.avi

  The log is :

  [alsa @ 0x9bcd420]Estimating duration from bitrate, this may be inaccurate
  
  Input #0, alsa, from 'hw:3':
  
  Duration: N/A, start: 69930.998994, bitrate: N/A
  
  Stream #0.0: Audio: pcm_s16le, 44100 Hz, 2 channels, s16, 1411 kb/s
  
  [video4linux2 @ 0x9bf5d30]Estimating duration from bitrate, this may be inaccurate
  
  Input #1, video4linux2, from '/dev/video0':
  
  Duration: N/A, start: 1307111377.654173, bitrate: -2147483 kb/s
  
  Stream #1.0: Video: rawvideo, yuyv422, 720x576, -2147483 kb/s, 1000k tbr, 1000k tbn, 1000k tbc
  
  [ac3 @ 0x9bf9590]No channel layout specified. The encoder will guess the layout, but it might be incorrect.
  
  Output #0, avi, to 'test5.avi':
  
  Metadata:
  
  ISFT : Lavf52.64.2
  
  Stream #0.0: Video: mpeg4, yuv420p, 720x576, q=2-31, 6000 kb/s, 25 tbn, 25 tbc
  
  Stream #0.1: Audio: ac3, 44100 Hz, stereo, s16, 128 kb/s
  
  Stream mapping:
  
  Stream #1.0 -> #0.0
  
  Stream #0.0 -> #0.1
  
  Press [q] to stop encoding
  
  frame= 1283 fps= 25 q=2.3 Lsize= 38677kB time=51.32 bitrate=6173.9kbits/s
  
  **video:37755kB audio:846kB** global headers:0kB muxing overhead 0.198922%

  If I reduce the command for only capturing audio, then the audio file can be played successfully :

  ffmpeg -f alsa -ac 2 -i hw:3,0 -acodec ac3 -ab 128k test5.avi

  [alsa @ 0x8ede420]Estimating duration from bitrate, this may be inaccurate
  
  Input #0, alsa, from 'hw:3,0':
  
  Duration: N/A, start: 70395.998935, bitrate: N/A
  
  Stream #0.0: Audio: pcm_s16le, 44100 Hz, 2 channels, s16, 1411 kb/s
  
  [ac3 @ 0x8eebac0]No channel layout specified. The encoder will guess the layout, but it might be incorrect.
  
  Output #0, avi, to 'test5.avi':
  
  Metadata:
  
  ISFT : Lavf52.64.2
  
  Stream #0.0: Audio: ac3, 44100 Hz, stereo, s16, 128 kb/s
  
  Stream mapping:
  
  Stream #0.0 -> #0.0
  
  Press [q] to stop encoding
  
  size= 227kB time=13.62 bitrate= 136.8kbits/s
  
  **video:0kB audio:213kB** global headers:0kB muxing overhead 6.902375%

  If I run the command for only video capturing then vlc or ffplay can play the video successfully :

  ffmpeg -f video4linux2 -i /dev/video0 -vcodec mpeg4 -b 12000k -r 25 test5.avi

  [video4linux2 @ 0x91d6420]Estimating duration from bitrate, this may be inaccurate
  
  Input #0, video4linux2, from '/dev/video0':
  
  Duration: N/A, start: 1307112044.025687, bitrate: -2147483 kb/s
  
  Stream #0.0: Video: rawvideo, yuyv422, 720x576, -2147483 kb/s, 1000k tbr, 1000k tbn, 1000k tbc
  
  Output #0, avi, to 'test5.avi':
  
  Metadata:
  
  ISFT : Lavf52.64.2
  
  Stream #0.0: Video: mpeg4, yuv420p, 720x576, q=2-31, 12000 kb/s, 25 tbn, 25 tbc
  
  Stream mapping:
  
  Stream #0.0 -> #0.0
  
  Press [q] to stop encoding
  
  frame= 388 fps= 25 q=2.0 Lsize= 12963kB time=15.52 bitrate=6842.5kbits/s
  
  **video:12949kB audio:0kB** global headers:0kB muxing overhead 0.114584%

  Strange behaviour I noticed is that when I tried capturing video and audio, I can not capture the audio afterwards any more,
  unless I unplug the AV350 first.

  The G350 is located at card 3 :

  htpc@htpc-01:/proc/asound/G350/pcm0c$ more info
  
  card: 3
  
  device: 0
  
  subdevice: 0
  
  stream: CAPTURE
  
  id: USB Audio
  
  name: USB Audio
  
  subname: subdevice #0
  
  class: 0
  
  subclass: 0
  
  subdevices_count: 1
  
  subdevices_avail: 1

  The OS is a Linux 2.6.38-8-generic with the Ubuntu Natty Narwhal version

  Any help on how to tackle this issue would be great ....

  Thanks !

• Script to use ffmpeg or Liquidsoap as video automation broadcaster ?

  23 juillet 2017, par Ilimaan

  I would like to build a module to broadcast a fake-live playlist dynamically to an rtmp server. There are may playlist broadcaster like Xsplit, VirtualCam with FFMLE, Wirecast but each of them need a good graphical card to work while cloud server may not have graphical cards. I tried both Liquidsoap with the following congif :

  set("frame.video.width", 1280)
  
  set("frame.video.height", 720)
  
  set("frame.video.samplerate", 25)
  
  set("gstreamer.add_borders", false)
  
  
  
  s = single("/home/user/singlevideo.mp4")
  
  
  
  s = fallback([s, blank()])
  
  
  
  output.gstreamer.audio_video(
  
    video_pipeline=
  
      "videoconvert ! x264enc bitrate=2000 ! video/x-h264,profile=baseline ! queue ! mux.",
  
    audio_pipeline=
  
      "audioconvert ! voaacenc bitrate=96000 ! queue ! mux.",
  
    pipeline=
  
      "flvmux name=mux ! rtmpsink location=\"rtmp://127.0.0.1:1930/live/live live=1\"",
  
    s)

  This is working well, but when I change it from single to playlist("/home/user/playlist.m3u") I got only a black screen (which is the fallback). If someone ever used Liquidsoap with video playlist what to change in this config to get it working ?

  For FFMPEG also it’s working for single video file by cannot stream playlist. If someone have a script that can monitor ffmpeg process and change source 3 secs before end of current file or something like that ?

• Script to use ffmpeg or Liquidsoap as video automation broadcaster ?

  12 mars 2017, par Ilimaan

  I would like to build a module to broadcast a fake-live playlist dynamically to an rtmp server. There are may playlist broadcaster like Xsplit, VirtualCam with FFMLE, Wirecast but each of them need a good graphical card to work while cloud server may not have graphical cards. I tried both Liquidsoap with the following congif :

  set("frame.video.width", 1280)
  
  set("frame.video.height", 720)
  
  set("frame.video.samplerate", 25)
  
  set("gstreamer.add_borders", false)
  
  
  
  s = single("/home/user/singlevideo.mp4")
  
  
  
  s = fallback([s, blank()])
  
  
  
  output.gstreamer.audio_video(
  
    video_pipeline=
  
      "videoconvert ! x264enc bitrate=2000 ! video/x-h264,profile=baseline ! queue ! mux.",
  
    audio_pipeline=
  
      "audioconvert ! voaacenc bitrate=96000 ! queue ! mux.",
  
    pipeline=
  
      "flvmux name=mux ! rtmpsink location=\"rtmp://127.0.0.1:1930/live/live live=1\"",
  
    s)

  This is working well, but when I change it from single to playlist("/home/user/playlist.m3u") I got only a black screen (which is the fallback). If someone ever used Liquidsoap with video playlist what to change in this config to get it working ?

  For FFMPEG also it’s working for single video file by cannot stream playlist. If someone have a script that can monitor ffmpeg process and change source 3 secs before end of current file or something like that ?