Re: [LAU] multi-channel recording

On Mon, Dec 28, 2009 at 2:58 AM, Patrick Shirkey <pshirkey@email-addr-hidden
> wrote:

>
> On 12/28/2009 08:18 AM, Ken Restivo wrote:
> > On Sat, Dec 26, 2009 at 11:07:05PM +0000, Edward Barrow wrote:
> >
> >> I've been getting by so far with an amd64 box running debian, jack,
> ardour
> >> etc through Terratec DMX-6fire (Envy24 based) card, but now find that I
> need
> >> to record more channels simultaneously.
> >>
> >>
> >> I would like (and can just about afford) the M-Audio FastTrack Ultra,
> but it
> >> doesn't look as though it is going to be easy to get it to work under
> Linux.
> >> It's a USB 2.0 device - it needs those 480Mb/s to record 8 channels
> >> simultaneously - so it isn't class-compliant.
> >>
> >> Has anyone succeeded in getting this interface to work properly in
> Linux?
> >>
> >> If not, can anyone suggest alternatives in the same sort of price range?
> >>
> >>
> > This is probably the most FAQ on LAU these days (well, maybe thirdmost,
> after questions about PulseAudio and Xruns, and slightly ahead of questions
> about RT kernels).
> >
> > Being shut out of the USB 2.0 market is an upcoming and serious threat to
> the continued viability of Linux audio, IMHO.
> >
> > USB 2.0 devices are affordable and great-- for everyone except Linux
> users. We have to pay more and get Firewire-- iff we have, or can get, a
> laptop that has Firewire, which seems to be on the way out.
> >
> > I sure hope someone can either get a manufacturer of USB 2.0 cards to
> open up the specs enough to write a driver for it, or, alternately, that the
> Ethernet-based Open Source multichannel audio interface project bears fruit
> soon enough. I'm personally more excited about the Ethernet interface
> because it'll be open and hackable, but for cheapness and convenience, the
> USB2.0's are going to be hard to beat.
> >
> > Someone posted a link to a USB 2.0 maufacturer that, IIRC, said they'd be
> willing to help someone write a Linux driver. Did any USB developers take
> them up on that?
> >
> >
>
>
>
> The other way is for people to buy a device and work with the various
> developers interested in usb-audio to get it to figure out the quirks.
>

In principle, I'm happy to help with this, but I don't really want to help
an obstructive manufacturer. If m-audio/avid are being
particularly uncooperative, then even though their kit is good and good
value, I'd rather not give them my shilling and spend
a disproportionate amount of time hacking at it to get it to work. On the
other hand, if there's a USB 2.0 device from a manufacturer
who's just a little bit more cooperative, even if there is no driver
available at present, I'd be prepared to give it a try.

I certainly don't have years to wait though; I've got a bunch of creative
musicians ready to go now.

There is a linux driver for the M-audio FastTrack Pro, which uses USB 1.1;
use of the driver permits 24-bit recording as against 16-bit only in
class-compliant mode. It occurred to me that this driver might work with
USB 2.0 and the FastTrack Ultra - but I don't know enough about the innards
of
USB to know whether this is remotely realistic.

> This is how most of the usb-1.0 devices were made to work anyway. If you
> look at the quirks list for the snd-usb-audio driver a considerable
> number of usb-1.0 devices are on that list. The thing is that many of
> those devices have been bought, tested and triaged years back so for
> anyone buying a device recently it would seem like there were no hassles
> associated with the usb-1.0 driver.
>
> In reality it took nearly 5 years for it to get to a point where most
> popular cards were supported ootb or with minimal driver tweaking. It
> took almost two years to get my device working properly and it had
> plenty of non standard quirks that had to be understood without any
> assistance from maudio in the slightest. We did it in the end though.
> The final nail was figuring out that the inputs are little endian and
> the outputs are big endian. That one took a while as it mostly just
> sounded like the driver was broken when it was actually just a case of
> specifying the correct endianess when testing with arecord.
>
> It turns out that there are a couple more manufacturers that chose that
> approach too. But at the time of testing it was a very strange "quirk"
> that got a few laughs round here when it was realised what they had done
> and reinforced the idea in many peoples minds that usb-audio is a
> crapfest of interstella proportions.
>
>
>
>
> Patrick Shirkey
> Boost Hardware Ltd
>
>
>
>
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>

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Received on Wed Jan 6 16:15:02 2010