[linux-audio-user] Re: es1370 latency and jackd, late driver wakeup

[R Parker]

Hi Louis,

--- Louis Lam <lshoujun at yahoo.com> wrote:

> Hi Ron,
> 
> Thanks for the reply...
> 
>  --- R Parker <rtp405 at yahoo.com> wrote: 
> 
> > If the card is capable and assuming you're not
> using
> > an external hardware mixer, you need Hardware
> monitor;
> > Options, Misc, Hardware monitor.
> 
> I'm not sure whether my card supports this or not,
> is there a way to find out? But I was able to
> start jack with HW monitoring and I can also hear
> what I play on the line in even when I'm not
> recording.

I think what's required is called "full duplexing."
The card is capable of simultaneous input and output.
I use a hardware mixer so I'm not real on the ball
about this. In a sense, what you want to do with an
audio card and what I do with the mixer are identical.
I achieve zero latency monitoring by routing the
hardware mixer inputs to aux1,2. You accomplish this
by returning an input to its counterpart output at the
audio card. So I think the only difference is that I
can route the input in a mixer but you can't in a pci
audio card. Or maybe you can route the signals which
would be very useful. Hmmm, it only makes sense that
you can route input signals with cards that have
hardware mixers. This is something that you should
study up on.

If pci card hardware mixers follow mixing consol
paradigms then you might be able to create scenarios
where you route input N to the equivalent of an Aux
bus. If this paradigm is followed, you might be able
to configure a port's send source as post or pre
fader. If that's the case, then you can run multiple
monitoring mixes; control room, head phone, etc. This
is interesting because the drummer needs a very loud
click track but you (control room) don't want that
loud click.

My audio card has one to one mapings for inputs and
outputs and doesn't have a hardware mixer. I imagine
cards like the newer RME HDSP that have hardware
mixers can do the things I'm describing. It's hard for
me to imagine that they can't but I have no experience
with hardware card mixers.

> I tried to set Options->Misc->HW monitor in Ardour
> too... but didn't notice any difference.
> Still i see "late driver wakeups" and such. I guess
> running it with n=4 and p=128 is quite 

I've never understood why the same option exists in
both Ardour and Jackd. And I've never cared.

Because you're not monitoring the Ardour track
outputs, you should be able to record enable and mute
them but still monitor a signal. I suppose that's a
little test.

> > Normal, I don't know. Common, is another story.
> The
> > key is that you have monitoring options that
> eliminate
> > the need for low latency. Make sense?
> 
> Kind of... but how about actual recording itself
> from the capture? Please correct me if my concept
> is wrong. I'm quite new to this computer recording
> stuff. HW Monitoring makes the line input
> audible on the output.

Yes, it routes the hardware audio card input to its
output. What you monitor has never reached Ardour.

 Capture puts the recorded
> samples to the application buffer then to the
> disk. I agree with the "monitoring" latency but how
> about the "recording" latency?

Ardour recieves an incoming audio signal, builds a
playlist that says start position equals N, volume N,
pan X/Y, etc. Within Ardour, there's nothing we can do
to adjust latency of recording. That isn't the users
problem. Besides, any latency within the Ardour record
realm will be relative across all tracks. Am I
understanding your concern?

ron

> Thanks,
> Louis
>  
> 
> 
>
________________________________________________________________________
> Yahoo! Messenger - Communicate instantly..."Ping" 
> your friends today! Download Messenger Now 
> http://uk.messenger.yahoo.com/download/index.html
> 



		
__________________________________
Do you Yahoo!?
Yahoo! Mail - 50x more storage than other providers!
http://promotions.yahoo.com/new_mail