Re: [linux-audio-user] alsa rme96 jack - 186 msec latency?

On 9/6/05, Michael Rudolf <mich.rudolf@email-addr-hidden> wrote:
> I bought an RME Digi96/8 PST because it was said to have good Linux support
> and very low latency, therefore perfectly suitable for hd-recording and
> the like.
>
> It's driven by the alsa rme96 driver, and right now I'm configuring it for
> use with jack. Only to realize that it can only be set to either 1024
> frames and 8 periods or 256 frames and 32 periods, resulting in a
> calculated latency of 186 msec either way (displayed by qjackctl). Strikes
> me. Isn't that absolutely unacceptable for hd-recording use?
>
> This information is confirmed by the corresponding alsa documentation at
> http://alsa.opensrc.org/rme96 .
>
> There is a small note on that page that leaves some hope; it's
> basically saying that in jack versions > 0.99.0, I could "create" e.g. 32
> periods, but "use" much less, "resulting in much lower latency". Therefore
> I'm now using jack 0.100.1 with Kernel 2.6.12 and alsa 1.0.9b. Still the
> only two working configurations are 1024/8 and 256/32; when I try to
> reduce periods, I get lots of errors like this (detailed output attached
> at the end of the mail):
>
> delay of 139318.000 usecs exceeds estimated spare time of 5769.000;
> restart ...
>
> Any ideas about how to obtain a working low latency configuration? Or do I
> have to dump the card? Anyone here using that card in a hd-recording
> setup?
>
> Cheers
> Michael
>

Hi,

I'm the guy who tries to keep that page up-to-date. I use the Digi 96/8 PAD.

I've found the card to work quite well. While it may not have as many
bells and whistles as the Hammerfall series, I've not run into any
problems with it for quite some time. Most issues I had with it have
been fixed for almost 2 years now.

I've run jack with reduced number of periods without any problem.

You're output lookes like you have issues elsewhere though to fix
before worrying about the numer of periods you use. The xruns,
messages about interrupt delays, and driver messages suggest you have
problems that need fixed berfore jack will ever work well, reguardelss
of the number of periods you use.

Paul Davis wrote:
> where does it say this? the digi96/8 is an entirely different product
> (different h/w design, different chipset, different interactions with
> the host CPU) from the digi9652, HDSP and HDSP9652 systems. this latter
> range is well supported and works exceedingly well on almost all
> systems. the digi96/8 has support, but it does not work particularly
> well, especially not for low latency work (this is not because of the
> driver design (other than the overall way that ALSA works), but because
> of the h/w design

I don't know enough to comment on h/w design or driver design, I just
know I've been able to use JACK with this driver at very low latencies
without X-Runs.

If I can help in providing specific info, let me know. :)

-Reuben
Received on Fri Sep 9 04:15:09 2005