module-vchan-sink and alternate sample format (float32le specifically) question

[daltong defourne]

Hi!

I've been poking around trying to figure out why pulseaudio equalizer has such horrible underrun/hiccup issues, and I vaguely suspect it is due to format conversion (I have been able to replicate roughly same behavior with loopback interfaces by meddling with format conversions (s16le-float32le-s24le).

Also careful reading of pulse logs indicates that the equalizer LADSPA plugin only deals in float32le and it seems to me that the s16le->float32le->s16le conversion has something to do with it.

It *seems* to me that "pre-converting" stuff before the equalizer using a null sink and a loopback fixed the issue (but it's clumsy, hard to automate, and there seems to be an unrelated sampling issue with loopback where loopbacks resample sourse no matter what, even if it's "44100->44100" (mentiones speex instead of copy in log when initializing loopback interfaces) so I want to try sending audio from the VM to the ladspa plugin in float32le format

However, I'm not smart enough to actually read module-vchan-sink  source beyond   seeing that "format" option is supported.

So before I waste a day doing something damnably stupid, I'd like to ask:

Does module-vchan-sink support format float32le (rate being left at default 44100) ?

[Marek Marczykowski-Górecki]

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module-vchan-sink (and pacat-simple-vchan - the other end of connection)
have hardcoded s16le format and intentionally do not support any
negotiation - to keep the protocol as simple as possible. The protocol
consists of raw samples.

If you really need some other format, I think the way to go would be to
add module parameter, and similar option for pacat-simple-vchan. But
please, no in-band negotiation. Especially not in VM->dom0 direction.

- --
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
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