USB uaudio soundcards question

[Barry Bouwsma]

On Wed, 1 Dec 2004 10:29:22 +0100 (CET) I wrote to freebsd-multimedia
something about one external USB-attached sound device (sound card
they call it, but it sure doesn't look like a card, though it has
the functions of one)

I thought I'd clarify/update my post, should anyone be interested.
The original can be found in multimedia@ around the above time.
See my References: header.  (oops, this isn't usenet, sorry)


> > in shops too, as well as a Hercules Muse knob that supposedly
> > also works on a Mac as only 2-channel, so may well work on BSD...

> There are issues with my OHCI source code that cause playback to
> stop after 10 to 13 minutes; this is not an issue with UHCI and
> playback for several hours -- nor did I notice this problem with
> OHCI when booted into NetBSD.

This still happens with the latest 4.x OHCI code downloaded this
morning, with negligible hacks (probably due to having leftovers
from Ian Dowse's patchsets somewhere else).  My USB stack at present
is rather close to 4-stable.

When I did the test this time, I was in single-user, no swap active.
I noted the following from the kernel after about 11 minutes of playback:
  swap_pager_getswapspace: failed
Playing a file (waveplay) was the only thing I was doing.
Then something like half a minute later, the usual
  usb0: isoc TD alloc failed
(x2)
  pcm1:play:0: play interrupt timeout, channel dead

And that was that.  Interesting?


> I didn't think to check this with NetBSD, as all my audio samples
> are at 48kHz samplerate, but attempts to use a lower rate for
> playback with FreeBSD did not work well at all:  the pitch tries
> to remain the same as the samples are stretched to an extended

Argh, forgot to check this when booted into netbsd

> I noticed that when playing over UHCI, the first fraction of a
> second would be repeated at the beginning of playback.  Ah, this
> also affects OHCI.  I'll need to try NetBSD again.  Perhaps this

This is *NOT* a problem with NetBSD.  The audio starts and stops
cleanly, with no stuttering or repeated bits.  I suspect this is
not USB-related, but has to do with FreeBSD 4.x audio.  (hmmm, can
I build uaudio into 3.x, which if I remember, plays audio much more
cleanly than 4.x ?  hmmm)


thanks
barry bouwsma