Hiho,
On Thursday 09 July 2009 23:11:09 Jonathan Woithe wrote:
> > Woithe<jwoithe@email-addr-hidden> wrote:
> > > AFAIK FFADO got started through the cooperation of one or two vendors
> > > and as momentum has built additional vendors have come on board to a
> > > greater or lesser extent. I expect something similar will have to
> > > happen for professional USB2 audio devices to be generally supported
> > > under Linux.
> >
> > This misses out on the most important step in the evolution of FFADO.
> >
> > Before FFADO was Freebob, an open source implementation of software to
> > support the BeBob API. Freebob was a project that was started by
> > someone who worked for the company that developed the Bebob chipsets
> > (Bridge Co.) ...
>
> Ok, I should have included a little more detail. By "FFADO" in the above
> paragraph I was referring to the FFADO/FreeBoB combination. BridgeCo was
> indeed one of the cooperative companies I was referring to. I gave the
> brief three line version whereas Paul has filled in a few more details.
> :-) It wasn't that I missed the most important step but rather glossed over
> the details in the name of brevity. Perhaps I was too brief.
>
> > TC Electronic ... the existence of Freebob convinced them to seek out the
> > two people involved in that project and pursue drivers for their new
> > chipsets. I was happy to play a tiny role in helping this meeting to take
> > place (very tiny).
>
> Ah - I didn't know that.
>
> > The problem with USB2 is that it doesn't seem as though there is any
> > similar embedded systems interest in linux support for audio over
> > USB2, and nor is there a single company (or 2 companies) with a choke
> > hold on the chipsets used for this. This makes the problem a lot
> > harder to solve. Maybe the companies that were thinking about firewire
> > audio are now thinking about USB2 audio, but if they are I don't have
> > my ear close enough to the ground to hear.
>
> For devices with higher channel counts USB2 hasn't really been the
> interface of choice thus far. This is mainly due to the limitations of the
> USB bus and the fact that it makes it hard to do low latency audio well.
> Things like it being a half-duplex bus with a host-slave architecture, and
> the fact that the real-world throughput is *much* less than the 480 Mbps
> *signalling* rate. The picture is a little different with USB3 since this
> version adds full duplex capability along with a number of other
> enhancements (beyond the obvious speed increase). How well it will go with
> audio given the latency requirements remains to be seen.
>
> As a side note, it seems RME are posed to release a USB2 version of the
> Fireface. I don't know much about it except that the device runs different
> firmware based on the operating system it's being used with. This suggests
> to me that RME work at a very low level both in the operating system driver
> stack and at the bus hardware levels in an attempt to circumvent the
> biggest audio-related USB showstopper issues.
Maybe one of the things to note as well is that some of the USB2 audio
interfaces are not even really keeping to the USB standard, and certainly not
to the the USB audio standard. I believe some of them aren't even allowed to
carry the logos for these protocols on the boxes.
sincerely,
Marije
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Received on Sat Jul 11 00:15:02 2009
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