| module-vchan-sink and alternate sample format (float32le specifically) question | daltong defourne | 14/07/17 02:10 | 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) ? |
| Re: [qubes-devel] module-vchan-sink and alternate sample format (float32le specifically) question | Marek Marczykowski-Górecki | 17/07/17 04:06 | -----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256 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? -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAEBCAAGBQJZbJpMAAoJENuP0xzK19cs0mcH/jH6xc5nXCI/tNk5qXeymXeC NtTc87rThUbcagc9o1RokfGvcMJ07hkgmzY0mKM7EAjnt1yM8l5UprZ7sXeAO5Ly D3VC7oUmfDwZ5Tod6yL1Xh7dUHSzfzYRviYnEJ7BHN5Wqd1cvD5b+5q18TuOGfGq FCY/2Yp/3GfyJtkkbHGsxrEcd8hSKeSr9r6x0Kg6xu63QB5Cag4cmEw2jFvouSOo QLPXGPJHI4P6pkTV9FIlrK1Gllw/dsbh2teR8p/0BULkLBpuBcA5sjI4eQD3cDNi lnrK82+tUnW2fZvTkaOxlHfB+9ha1scSKuqx9EqrNOuDVvPrLqYlbSgHMN4mQuc= =baUy -----END PGP SIGNATURE----- |