Subject: Re: Strange ESS1869 playback rate problem
To: Dave Huang <firstname.lastname@example.org>
From: David Brownlee <email@example.com>
Date: 07/21/2000 11:14:41
Random (probably unrelated) datapoint - on a thinkpad with
clcs0 at pci0 dev 6 function 0: Cirrus Logic CS4280 CrystalClear Audio Interface (rev. 0x01)
mp3 decoding works fine up to a sample rate of about 14700, but
above that it seems to set it to around half the desired playback
-- www.netbsd.org: A pmap for every occasion --
On Fri, 21 Jul 2000, Dave Huang wrote:
> I've got a Winbook XLi laptop that has a ESS1869 sound chip... the ess
> driver pretty much works with it, except that setting the playback rate
> <= 22050 actually sets the playback rate to twice the intended value.
> E.g. to get 22050Hz, I need to set the rate to 11025. However, to get
> 44100Hz, I can set the rate to 44100.
> I took a look at the driver's source, and thought ess_srtotc() looked
> rather strange, but I downloaded the 1869's data sheet, and I guess the
> code is correct. I don't understand the data sheet's emphasis on the
> time constant being a signed value though... "The sample rate is
> determined by the two's complement divider in bits 7:0" and later a
> seemingly contradictory "Bits: 6:0; Name: Sample rate divider;
> Description: Signed sample rate divider"
> If I change the code to use the "tc = 256 - 795500L / rate" regardless
> of the sample rate, it works fine... but that's not what the data sheet
> says to do :)
> NetBSD/i386 1.5_ALPHA, btw...
> Name: Dave Huang | Mammal, mammal / their names are called /
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