Fwd: Re: [linux-audio-user] Sampling rate problems on a VXPocket v2
pshirkey at boosthardware.com
Thu Dec 11 04:25:05 EST 2003
Fwd'd to alsa-devel.
Geoffrey Martin wrote:
> I'm using the following:
> IBM T40 laptop
> Digigram VXPocket v2
> RedHat 9
> Kernel 2.4.22-ac4
> ALSA drivers 0.9.8
> vxloader 0.9.7-i686
> Measurement gear
> Audio Precision System Two Cascade
> PrismSound DSA-1
> Some of my other gear is having difficulties locking to the S/PDIF output
> of the card at 44.1 kHz and I have a suspicion as to why this is
> I have control over the sampling rate of the S/PDIF output of the card as I
> would expect, however...
> In the S/PDIF Channel Status Block information there is a portion of Byte 3
> that is used to send the intended sampling rate (selectable between three
> values, 32 kHz, 44.1 kHz and 48 kHz, depending on the arrangement of bits
> 0-3 in Byte 3. For specific information on this, please see Application
> Note AN22REV2 from www.crystal.com). It is also possible, using bit 0 of
> Byte 0, to indicate whether the signal is Professional or Consumer format.
> Using my present configuration, I do not appear to have control over either
> of these two variables. For example, even when I am sending a 44.1 kHz
> signal at a rate of 44.1 kHz (or close enough... it's actually 44.0993, -17
> ppm) Byte 3 of the Channel Status Block is saying that the signal is a 48
> kHz transmission.
> Are the VXPocket drivers in ALSA capable of changing these values in the
> card? The official drivers for Mac OSX allow me to change the Pro/Consumer
> flag using an application, and the sampling rate indicator changes
> automatically with the actual sampling rate of the card's output.
> Geoff Martin Ph.D.
> Tonmeister, Bang & Olufsen a/s
> email: ggm at bang-olufsen.dk
> web: www.bang-olufsen.com
> web: www.tonmeister.ca
> phone: +45 96 84 49 54
Patrick Shirkey - Boost Hardware Ltd.
Http://www.djcj.org - The Linux Audio Users guide
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