Re: [Alsa-user] Basic S/PDIF Recording

[Paul B. <bra...@gm...>]

Clemens Ladish wrote:
>
> Almost all sound cards decode the S/PDIF stream; what you get are
> plain samples (or compressed data pretending to be samples in case
> of AC-3 or DTS).  The information in the other bits is usually
> available with the control "IEC958 Capture Default".

Hrmmm ... well, the reality of the hardware application to which I am
programming is quite a bit more disturbing. S/PDIF data is being
captured by a Wolfson WM8804 S/PDIF Digital Interface Transceiver (or
similar) and streamed over USB by a Texas Instruments TAS1020B USB
Streaming Controller. There are more complicated issues regarding
exactly what data is transmitted but perhaps my biggest concern is how
to make sure I take into account the possibility of changing bitrates.

That is, the S/PDIF bitrate may change based on content and I don't
want a period/buffer too large lest I get high latency nor do I want a
period/buffer too small lest I run into the dreaded overrun (xrun).
There's no way to change things on the fly so I figured if someone
knew of some intelligent defaults that seemed to work I wouldn't have
to spend all my time trying to figure it out for my particular
application.

It seems like, sometimes, the stuff that is trying to make things
simple just makes it more complicated to deal with in the end. Bleh.


Paul Braman