[pulseaudio-discuss] Using PulseAudio's echo cancellation for a voice assistant

[Giovanni Campagna]

Hello all,

I'm the developer of Almond (https://almond.stanford.edu), an open-
source voice assistant, that is, an application that listens for
commands from the user in voice (continuously until a specific word is
heard) and then executes actions and replies.

Our assistant makes use of PulseAudio for audio frontend processing. I
have enabled echo cancellation by setting "filter.want=echo-cancel" on
both the record and playback streams, and the echo cancellation modules
seem to load correctly, but it seems that echo cancellation is only
performed between those two streams. Music or other audio that is not
assistant speech will not be echo cancelled.

For the voice assistant use case, we would like to echo cancel against
all outputs currently playing from the speaker where we're recording
audio, so we have the clearest input from the user to convert to text.

Is it possible to implement that using PulseAudio? What would be the
best way to do so?

Thanks in advance for the kind reply, and best,

Giovanni

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