[pulseaudio-discuss] Map sink-input to virtual microphone

[Arun Raghavan]

On Tue, 22 Dec 2020, at 2:04 AM, guest271314 wrote:
> This is the code that I cobbled together from your post, 
> https://askubuntu.com/questions/60837 and  
> https://aweirdimagination.net/2020/07/19/virtual-microphone-using-gstreamer-and-pulseaudio/
> 
> pactl load-module module-combine-sink \
> sink_name=Web_Speech_Sink slaves=$(pacmd list-sinks | grep -A1 "* 
> index" | grep -oP "<\K[^ >]+") \
> sink_properties=device.description="Web_Speech_Stream" \
> format=s16le \
> channels=1 \
> rate=22050
> 
> pactl move-sink-input $(pacmd list-sink-inputs|tac|perl 
> -E'undef$/;$_=<>;/speech-dispatcher-espeak-ng.*?index: (\d+)\n/s;say 
> $1') Web_Speech_Sink
> 
> pactl load-module module-remap-source \ master=Web_Speech_Sink.monitor 
> \ source_name=Web_Speech_Monitor \ 
> source_properties=device.description=Web_Speech_Output
> 
> Using this approach I am able to capture output from only 
> speech-dispatcher-espeak-ng module using
> 
> navigator.mediaDevices.getUserMedia({audio: true})
> .then(async stream => {
>   const [track] = stream.getAudioTracks();
>   const devices = await navigator.mediaDevices.enumerateDevices();
>   const device = devices.find(({label}) => label === 
> 'Web_Speech_Output');
>   track.stop();
>   console.log(devices, device);
>   return navigator.mediaDevices.getUserMedia({audio: {deviceId: {exact: 
> device.deviceId}}});
> })
> .then(stream => {
>   const recorder = new MediaRecorder(stream);
>   recorder.ondataavailable = e => 
> console.log(URL.createObjectURL(e.data));
>   const synth = speechSynthesis;
>   const u = new SpeechSynthesisUtterance('test, test, then test again');
>   u.onstart = e => {
>     recorder.start();
>     console.log(e);
>   }
>   u.onend = e => {
>     recorder.stop();
>     recorder.stream.getTracks().forEach(track => track.stop());
>     console.log(e);
>   }
>   synth.speak(u);
> });
> 
> Can the pactl and pacmd code be reduced?

Almost certainly. The module-combine-sink can probably get a manual list of slave devices if you know the name of the physical sink, and it should also be possible to use `pactl move-sink-input <sink name>` instead to avoid the second bit of Perl munging.

-- Arun