[linux-audio-user] open source firewire

[Ryan Gallagher]

On Sun, 2004-11-28 at 10:14 -0800, Mark Knecht wrote:
> On Sun, 28 Nov 2004 10:55:46 -0600, Ryan Gallagher
> <ruinaudio at comcast.net> wrote:
> > Guys,

<snip>

> > Anyway, to get to the point... isn't it true that firewire by virtue of
> > it's similar-to-USB-nature suffers from the same limitations as USB?
> > Iirc I was told that whatever limitations causing the (IMO) extreme
> > suckage of USB audio on linux will be present in a firewire interface.
> > 
> > I'm speaking from distant memory here as I've given up on my ~$400 USB
> > investment, which now collects dust.
> > 
> > What a shame it would be to expend effort and $$$ to find there's some
> > <cat /dev/random> issue that prevents firewire audio from working
> > acceptably.
> > 
> > -ry
> > 
> > 
> 
> Ryan,
>    Good points to keep in mind. However, I can say that I use
> DigiDesign/Pro Tools 1394 under Windows with latencies that you would
> term acceptable so I know it *can* be done. Whether is can be done
> under Linux is another question.

True, USB audio works wonderfully under windows and OS X.  Sub 6ms
glitch free latency.  But... Mark googling around I found discussions
you and I have had about USB/Firewire audio more than a year ago, then
resumed next year and now again for the third year:

http://ccrma-mail.stanford.edu/pipermail/planetccrma/2002-December/000836.html

http://www.eca.cx/lau/2003/12/0442.html

Here's why I'm sadly of the opinion something like a custom 1394 card
wont work;

More than two years pass and USB is still useless for low latency work
under linux.  Anyone out there have a different experience?

USB audio is ubiquitous in the windows/mac world and is pretty damn
common umong linux users I'm guessing.  (How many laptop users out
there?)  USB audio is a perfectly reasonable technology despite whatever
predjudices people may have.

I'm left to believe that there is 1) not enough developer/user interest
to make USB audio work well or 2) linux is not up to the task of running
USB audio interfaces 3) (less likely) a strong bias against USB by
developers.

Now if 1 or 2 are true for USB, I'm guessing they'll be true for
FireWire, if 3 is the reason for USB audio err... "not working so good"
on linux well... there may be hope for FireWire.

Either way, I'm sorry but if we can't even have functional low-latency
USB audio, how could it possibly be that FireWire will be supported, now
add to it the task of developing the hardware?

Even were it to be supported, the USB user base must be absolutely HUGE
compared to any potential FireWire base.

>    *Most* 1394 devices under Windows use the normal Windows 1394
> driver. QUESTION: Are the Linux 1394 drivers up to the task? I'm not
> sure.

I'm sure the generic 1394 drivers are approaching the performance of
windows now.  But I'm operating under the assumption the audio end of
things are going to require a bit more coding.

> I own 6 1394 peripherals. (3 hard drives, an external CDROM, an
> external DVD and a video conferencing camera.) All work perfectly
> under Windows. Under Linux 3 work, 3 do not. There are only about 5
> people developing the 1394 stack under Linux. The stack has been in
> development since 1999. This does not make me confident about Linux
> and 1394 unless this hardware project was to undertake ensuring that
> the 1394 stack gets attention from our hardware/software developers
> should it need it.

I can't see how it could possibly gain that needed attention.

>    I will also raise the question 'why can't USB attain the latencies
> you want under Linux?' I *think* they can be attained under Windows,
> so why not Linux? Does this say something about the USB stack? USB
> support under Alsa? I don't know and I'm not capable of finding out.

Ah, Mark but we've tried for years haven't we ;-)

>    Unfortunately, Alsa (as I see it, and which is probably an
> uninformed view) is really only a few people. I think that there are
> not enough people developing Alsa, and then developing Alsa drivers,
> to ensure it works as well as the hardware specs can support.
> 
>    As background, I helped write the 1394-2000. (Small contributions
> only, but I was part of the committee.) I can say with certainty that
> hardware like we are talking about was contemplated in the committee
> meetings. I firmly believe that this project is completely within the
> capabilities of 1394. Whether we are good enough hardware and software
> designers would have to be shown. On this point I am confident.

Mark it's a knoble cause and I support your efforts, but... well I just
can't believe we could develop a FireWire Audio interface and
software/drivers to run it when exponentially more popular USB audio is
still languishing if not completely ignored.

It's a horse before the carriage issue, the support will need to be
there before $$$ is invested in hardware, it's like designing and
building a car from scratch with no road to drive it on.

> Cheers,
> Mark
-- 
Ryan Gallagher <ruinaudio at comcast.net>