Re: Delay channel X by one sample

[James Courtier-Dutton <James@superbug.co.uk>]

Edson Pereira wrote:
> 
> Greetings,
> 
> I am in the process of implementing a small software defined radio 
> receiver using the PCM2903 codec and have a question for the 
> alsa-developers.
> 
> The ALSA USB-Audio interface is working very well. The audio quality of 
> the chip is quite good, but the chip has a bug! The audio stream of one 
> channel is delayed by one sample in respect to the other channel. This 
> is drastic for the mentioned application since the phase correlation 
> between channels is critical. I have contacted Burr Brown technical 
> support and they have acknowledged the problem. The error is in the FIFO 
> addressing hardware and is present in the ADC as well in the DAC (but in 
> reversed channels).
> 
> The problem is quite easy to get around in the application, but this 
> prevents the hardware interface being used with other programs (testing 
> software for example). My question is: Where in the system software 
> chain could a work around be implemented? In the ALSA snd-usb-audio? Or 
> is there any other more appropriate place?
> 
> Thanks and best regards,
> 
> -- Edson
> 

I think adding this "delay channel X by one sample" feature would be a 
nice feature to add to alsa-lib. We are going to need it in order to 
support 96khz SPDIF out on the Audigy 2 cards via the P16V chip.
So, if other cards also need it, it would be good to add.

James



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