Date: Mon, 09 Dec 96 18:03 PST From: Denis DeLaRoca (310) 825-4580 <CSP1DWD@MVS.OAC.UCLA.EDU> To: dwhite@RESNET.UOREGON.EDU Cc: multimedia@FREEBSD.ORG Subject: Re: GUS & Mbone: more updates Message-ID: <199612100204.SAA24559@freefall.freebsd.org>
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On Mon, 9 Dec 1996 16:41:37 -0800 PST,
Doug White <dwhite@GDI.UOREGON.EDU> said:
> Hello again...
>
> After I replaced my VAT with a full duplex version from rah, the looping
> and popping and whatnot has stopped. I've been watching the IETF stuff
> for several hours now and it works like a charm. The only annoying thing
> is that the audio cuts out every so often, but I think this is from
> problems at the gateway or transmitter at ietf2.bbnplanet.com so I'm not
> worried about it.
Yes that gateway was dropping packets. Here at UCLA I was seeing a loss
not exceeding 8% -- not enough for significant audio cuts/dropouts,
only tiny dropouts here and there.
> I've noticed that the volume bars lag quite a bit behind the audio, such
> that I've just turned them off. Any ideas behind that?
Humm? I'll check that tomorrow.
> The thing that does worry me is the excessive debugging output from the
> kernel. I get lots of these:
>
> isa_dmastart: channel 1 busy
> isa_dmastart: channel 3 busy
It's in /sys/i386/isa/isa.c, I am not sure it these messages are
legacy diagnostic messages or legitimate error output...
> I know this is a silly stupid thing, but I can't remeber where this is at.
> Someone have the patch? (BTW: these pop up whenever I jump between vats
> (I'm watching both IETF channels currently), and just every so often. Any
> guesses why both the play and record DMAs bounce?
>
> Secondly, when I was using the half-duplex vat, I got a lot of these
> lines:
>
> Dec 8 23:55:26 gdi /kernel: write select 1
> Dec 8 23:55:27 gdi last message repeated 672 times
> Dec 8 23:55:27 gdi /kernel: isa_dmastart: channel 3 busy
> Dec 8 23:55:29 gdi /kernel: write select 0
> Dec 8 23:55:29 gdi last message repeated 4 times
> Dec 8 23:55:29 gdi /kernel: write select 1
> Dec 8 23:55:31 gdi /kernel: write select 0
> Dec 8 23:55:31 gdi last message repeated 4 times
I've never seen these with my PAS16 card. What I keep seeing very
freuqntly is
aud write: resource temporarily busy
which is a result of a pwrite("aud write") in vat's audio-voxware.cc
when its write() to the audio device fails. I haven't figured out what
activity on the system interferes with /dev/audio to trigger the above
failures.
> Here is the interesting part. The audio was clear until the 'channel 3
> busy' message came up. Then I got the write select 0's interspersing
> thoughout the write select 1 messages. (I got these write select's
> regularly.) At the same time, the looping, popping, and general poor
> audio started up.
>
> I'm guessing that these status messages may be related to the poor audio
> output from the half duplex vat (which must be used on SoundBlasters).
> Note that i got the exact same poor output until I bumped my vat to the
> full duplex version. I still have the half-duplex, so I'd be glad to do
> some testing. I'll only have my net until midday tomorrow or so, so get
> back to me soon if you want to deal with this before January.
>
> I'm not experienced enough programming to track down this stuff. I'm
> hoping someone will pick this up (bill?) and work with this. I'd really
> like to see the half-duplex vat's audio quality improve, as many of us are
> stuck with them and don't want to spend the $xxx on a gus when (IMHO) the
> awe32 has nicer MIDI audio :), and paid $200-300 for the AWE originally.
The sound quality I am getting in half-duplex mode with a ProAudio
Spectrum 16 card is quite good, not as splendid as with the GUS card
mind you, but quite acceptable -- the only minor problem is that
vat's clocking of audio output is slightly amiss and every so often
a couple of audio samples overlap on output as the playback buffer
is reset.
-- Denis
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