Fwd: Re: [linux-audio-user] Sampling rate problems on a VXPocket v2

[Patrick Shirkey]

Fwd'd to alsa-devel.


Geoffrey Martin wrote:
> 
> 
> 
> Hi,
> 
> 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
> happening...
> 
> 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.
> 
> Cheers
> -geoff
> 
> 
> 
> 
> ____________________________________________________
> 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.boosthardware.com
Http://www.djcj.org - The Linux Audio Users guide
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