[alsa-devel] PulseAudio and SNDRV_PCM_INFO_BATCH

[Raymond Yau]

> > Hmm...I was trying to understand this power save argument. I tried to
> > figure out a "typical" URB size by just plugging my headset in, and I
> > saw wMaxPacketSize being 96 and/or 192 bytes.
> > Then, MAX_PACKS is set to either 6 (or 48 for USB 2.0 devices, but this
> > is just a headset).
> >
> > Can this be correct? Does it mean that we are getting interrupts every
> > 192 * 6 bytes (i e, every 6 ms for a 48kHz/stereo/16bit stream)?
>
> The driver can build up a URB containing multiple packets, so the
> wakeups can be reduced in some level.  But, then the hwptr update also
> suffers, and more badly, the in-flight size also increases -- both are
> bad for sample mixing, obviously.
>
>
>

Do it mean that period_bytes_max is wMaxPacketSize * MAX_PACKS, driver only
support small period sizes ?