Piping Alsa output to ffmpeg and ffserver??

bastibasti · Guru Joined: 27 Nov 2006 Posts: 562

Hi I have a remote PC and some software that I use does not allow redirecting sound to network stream.
Is it possible that everything that the PC outputs (sound) is piped to a ffmpeg process? (Which will then use ffserver to forward the sound via network)??

wildhorse · Posted: Thu Jan 30, 2014 6:56 pm Post subject:

You did not provide us a lot of coherent information. Is this about gladiator movies? Perhaps PulseAudio is what you are looking for.

bastibasti · Guru Joined: 27 Nov 2006 Posts: 562

I use this machine as a remote sdr receiver. unfotunately not all software supports pulse. also if I could setup like a virtual soundcard that would pipe into ffmpeg, it would save a lot of messing about with each program.

Dominique_71 · Posted: Fri Jan 31, 2014 1:00 am Post subject:

What kind of network is it? If it is a fast network, you can try with netjack (part of jack-audio-connection-kit). With a few lines into ~/.asoundrc, it is possible to interface ALSA and JACK: Using the ALSA JACK PCM plugin.
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bastibasti · Guru Joined: 27 Nov 2006 Posts: 562

mmhh the line has 60kbytes upstream so it needs to be compressed

Dominique_71 · Posted: Fri Jan 31, 2014 6:37 pm Post subject:

JACK can use the opus codec. Anyway, with any ALSA software, the problem is you cannot redirect an ALSA output device to a software. But you can use the snd_loopback module to create a virtual sound card and define it as first sound card. That way, all the ALSA software will use it per default.

When done, you can use the other end of that virtual card to feed ffmpeg or mpd. With mpd, you can even use multiple outputs, as example 1 output for the second and regular ALSA card so you can hear the sound, and another one to stream on the network. I would use mpd for that: http://www.musicpd.org/
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bastibasti · Guru Joined: 27 Nov 2006 Posts: 562

Hi all,

I got it working using snd-aloop module and ffserver. Excellent!

pjp · Administrator Joined: 16 Apr 2002 Posts: 17202

Nice. Congratulations.
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