using gem+linux for gigs (was Re: Gem segfault)

[Greg Rippin]

In my understanding, most of the usb audio problems come from the fact that usb is, by
default, asynchronous.  Latency becomes a huge issue, then, since there's no way to
ensure data is getting to its destination on time, especially if there are other devices
sharing the buss.  USB does, however, have an isosynchronous mode, which is, I think,
used with the "audio class" devices you mentioned.  This mode is designed to solve major
latency issues, but has not been used by many manufacturers and is, therefore, very
expensive.  That's my two cents.

Tschuss,
Greg

"Joseph A. Sarlo" wrote:

> I've been using the Swissonic Studio D USB audio interface under Linux
> with my laptop and after some initial difficulties it seems to work fine.
> The latency is nominal. I haven't done any hard-core testing, but the
> total latency (including audio buffer) is definately under 50 ms. It seems
> all the horror stories about usb are not true (well, most of them anyway).
> I can even use a usb joystick on the same port (with a hub) at the same
> time, which makes sense since full duplex 44.1k 16 bit stereo should only
> require about 350KByte/s of bandwidth and USB (ideally) offers 1.5MByte/s.
>
> The trick with linux is that the drivers only work with devices that are
> 100% usb audio class compliant.  I've only found two devices that can
> claim that, the Swissonic Studio D and Sound Technology's SoundBuster.
> The prolem is they're both kind of expensive and the Soundbuster is more
> of a data aquisition device for acoustic measurements.  You also are going
> to want to get the latest usb kernel modules.  I had some problems using a
> 2.2 backport that all went away when I moved to 2.4.1.  Also, I have an
> OHCI controller which everybody seems to say doesn't wor well, but it's
> been working fine for me. Some things are a little weird but nothing
> unworkable.
>
> --
>  __________________________
> |
> | Joseph A. Sarlo
> | Computer Music Dept.
> | Peabody Conservatory
> | Johns Hopkins University
> |
> | jsarlo at peabody.jhu.edu
> |__________________________
>
> On Fri, 30 Mar 2001 pix at test.at wrote:
>
> > I'm really interested in the 'remote gui' option rather than the
> > netsend/receive option, as it doesnt really require any functional changes
> > to existing patches. but at the moment im not in a oaition to test it,
> > only having the one pc. but real soon now i'll be getting a laptop
> > (curently in the 10-14 business days tease-zone), so i'll probably give it
> > a whirl then.
> >
> > another thing i hadn't thought about until today was looking into the
> > possibility of using multiple gfx cards under x4. it might not be
> > possible, but if it were possible to do multi-head using two different
> > kinds of cards (i know its possible with expensive cards that support
> > multihead) than you could just have the gem window appearing on whichever
> > one has video out. maybe i'm ascribing mythical superpowers to x4 here :)
> >
> > also, a friend forwarded me some mailing list exceprts about huge
> > latencies using usb-audio solutions on laptops under windows (using
> > audiomulch). has anyone on this list played with usb-audio (especially
> > under linux), and what kind of latencies have they got? i'm hoping the
> > latency isnt inherent in usbaudio, but i wouldnt be surprised if it was...
> >
> > (then again, my current patch has so much inherent latency, that this
> > wouldnt really be a problem for me anyhow, but i'm just curious).
> >
> > On Wed, 28 Mar 2001, Timmy B wrote:
> >
> > > HI Pix, Miller and others
> > >
> > > the way I have this running is to seperate the
> > > control to a laptop and the rendering to a linux box with a
> > > good graphics card. i use netsend/netreceive to send info from the
> > > laptop to
> > > a patch i have written on the box which opens the gem window
> > > at maximum size. i use pd -nogui on the box to get rid of the gui. i use
> > > twm as the window manager as it should be the simplest and fastest. i
> > > have
> > > added my own .twmrc to remove title bars and boundaries from
> > > the window, but i cannot get the positioning requests to be
> > > honoured, so i have to drag the top left corner of the gem window
> > > to the top left corner of the screen manually. suggestions
> > > welcome
> > >
> > > i chose netsend as the control mech because i believe it would
> > > be the simplest and fastest rather than using some remote
> > > control / X-window confusion.
> > >
> > > this is planned also to be very portable - for a workshop
> > > i need only take the video card and linux install CDs, all
> > > the extra code is on the laptop, so i can de-Bill a PC
> > > at the venue and make it do clever (well, half-clever)
> > > things [hopefully] quite quickly....
> > >
> > > haha
> > >
> > > tm
> > >
> > >
> > >
> > >
> > >
> > > Miller Puckette wrote:
> > > >
> > > > This should work... you can feed Pd a command line option "-guicmd" to
> > > > set how Pd will start the GUI up, which could use rsh to start up on another
> > > > machine, or even set the DISPLAY variable.  In either case Gem's window
> > > > should start up on the machine Pd is running on.
> > > >
> > > > I got this working once but I have another problem, which is that I don;t have
> > > > a good way of sizing and positioning the Gem window to cover all of the
> > > > display.  Should be easy, but it didn't just work instantly when I tried it.
> > > >
> > > > cheers
> > > > Miller
> > > >
> > > > >
> > > > > my current thought is to have the pd interface on another machine using
> > > > > the new gui options... i dont know if this is a possibility tho (i havent
> > > > > tried it yet)... also if it did work, would the gem window open up on the
> > > > > machine running pd or on the machine running pd-gui (i'm hoping it would
> > > > > open on the machine running pd).
> > > > >
> > > > > pix.
> > >
> > > --
> > > -------- ------------------------------------
> > >  \    /  Tim Boykett   mailto:tim at timesup.org
> > >   \  /   TIME'S UP
> > >    \/    Industriezeile 33 B
> > >    /\    A-4020 Linz
> > >   /xx\   ph/fax:+43/732-787804
> > >  /xxxx\  http://www.timesup.org
> > > -------- ------------------------------------
> > >
> >
> >