Date: Sun, 20 Jun 1999 22:45:22 +0200 (CEST) From: Oliver Fromme <olli@dorifer.heim3.tu-clausthal.de> To: freebsd-current@FreeBSD.ORG Subject: Re: audio-Device gone mute Message-ID: <199906202045.WAA07067@dorifer.heim3.tu-clausthal.de>
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Christian Weisgerber wrote in list.freebsd-current:
> Well, the blocking thing is peculiar.
>
> "buffer -S1024 </dev/zero >/dev/audio" writes 120kB into /dev/audio,
> then it blocks. (buffer was the first thing that came to mind that can
> output how much data it has copied.)
(dd can do it, too.)
> When I call it again, it blocks
> immediately. Now, if I start mpg123 and subsequently call buffer again,
> I can again write 120kB to /dev/audio before it blocks. So mpg123 seems
> to perform some kind of partial reset.
This sounds like a bug in the device driver.
If I'm not mistaken, it uses a pair of 64 Kb DMA buffers which
are used alternating ("double buffering" -- data is written to
one buffer while the other one performs audio playback).
So, in your case the playback isn't initiated for some reason,
so it is just filling those two buffers and then blocks because
the first buffer isn't available again.
Sorry, but I'm not that familiar with the sound driver code, so
someone else will have to look into this...
Regards
Oliver
--
Oliver Fromme, Leibnizstr. 18/61, 38678 Clausthal, Germany
(Info: finger userinfo:olli@dorifer.heim3.tu-clausthal.de)
"In jedem Stück Kohle wartet ein Diamant auf seine Geburt"
(Terry Pratchett)
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