Streaming PulseAudio to file (possibly with GStreamer)

I'm on Ubuntu and I want to record PulseAudio output to a file, to make a recording of a pygame program. The format doesn't matter, because I can change it afterward, so raw audio is fine.

Looking around, it seems like GStreamer may be able to handle this, 开发者_运维知识库but I'm not familiar with it, and extensive searching has not yielded an answer. So answers involving GStreamer or otherwise are welcome.

Thanks!

There is a monitor for each pulseaudio sink. You just need to get it's name:

$ pactl list
...
Sink #0
    State: RUNNING
    Name: alsa_output.pci-0000_00_1b.0.analog-stereo
    Description: Internal Audio Analog Stereo
    Driver: module-alsa-card.c
    Sample Specification: s16le 2ch 44100Hz
    Channel Map: front-left,front-right
    Owner Module: 4
    Mute: no
    Volume: 0:  40% 1:  40%
            0: -23.87 dB 1: -23.87 dB
            balance 0.00
    Base Volume:  96%
                 -1.00 dB
    Monitor Source: alsa_output.pci-0000_00_1b.0.analog-stereo.monitor
    Latency: 119973 usec, configured 210000 usec
    Flags: HARDWARE HW_MUTE_CTRL HW_VOLUME_CTRL DECIBEL_VOLUME LATENCY 
    ...

Note line Monitor Source: alsa_output.pci-0000_00_1b.0.analog-stereo.monitor. It is your monitor source.

First, you need to unmute it:

$ pacmd
Welcome to PulseAudio! Use "help" for usage information.
>>> set-source-mute alsa_output.pci-0000_00_1b.0.analog-stereo.monitor false
>>> exit

And now you can record sound form it:

$ parec \
>     --format=s16le \
>     --device=alsa_output.pci-0000_00_1b.0.analog-stereo.monitor \
> | oggenc --raw --quiet -o dump.ogg -

Or with lame:

$ parec \
>    --format=s16le \
>    --device=alsa_output.pci-0000_00_1b.0.analog-stereo.monitor \
> | lame -r - dump.mp3

The same could be done with gstreamer, but there is not much sense in it if you don't need some complex processing:

$ gst-launch-0.10 \
>  pulsesrc device=alsa_output.pci-0000_00_1b.0.analog-stereo.monitor \
>  ! lame \
>  ! filesink location=dump.mp3