Re: [LAD] Trying to fix the Edirol UA-101

Quoting Phil <p@email-addr-hidden>:

> Hi,
>
> I'm working toward getting the UA-101 to work on Linux. I've had a look
> at the Alsa drivers, and I after 23s of playback I hit the known glitch
> bug:

Hello,

You may want to get in touch with Ben who has been working on fixing this for
the past month (he has been busily learning innards of ALSA USB driver in the
process). Perhaps you guys can work together on this one? (I am cc-ing Ben)

Best wishes,

Ico

>
> http://lists.linuxaudio.org/pipermail/linux-audio-user/2009-April/059447.html
>
> I've tried fiddling with various alsa buffering settings to get a point
> solution that works, but with no luck.
>
> Comparing the USB traffic on Windows and Linux was interesting. The
> Linux trace has the sound samples being sent to USB Endpoint 2, but the
> Windows trace is weird.
>
> The both traces the sound sample was a long period of silence followed
> by a sine wave. There are several things 'odd' under windows:
>
> The data send to the sound card (on USB EP 2) started out as as string
> of '0x00 0x00...' as you would expect for a 'silence' sample. After
> about 2 seconds, 'silence' is send as lots blocks like
>
> 00000000: 00 00 ff ff 00 ff fe ff 00 ff ff ff 00 ff ff ff
> 00000010: 00 00 00 00 00 ff ff ff 00 00 00 00 00 ff ff ff
>
> in a pattern I haven't got to the bottom of yet.
>
> The second difference I've noticed is that on Windows the UA-101 is
> sending data to the PC (on USB EP 81). This is 'random' data (but it
> does have a lot of zeros in it), I haven't investigated it yet:
> 00000000: 00 a9 fb ff 00 e5 00 00 00 65 00 00 00 11 00 00
> 00000010: 00 5c 00 00 00 15 00 00 00 3f 00 00 00 f9 ff ff
>
> 5760 bytes are sent to the sound card, then 9120 bytes are sent back.
> This cycle repeats every ~4.6ms. That is about 26 bytes/sample out and
> 41 bytes/sample back. I'll take some more accurate measurements when I
> have a parser for the log format.
>
> On Linux there is no data being read back.
>
> My next move is going to construct some .wav files that differ in a few
> samples and compare the traces that they produce.
>
> I have a couple of questions:
>
> * Does anyone know the background behind "I think that's the mentioned
> synchronizing-problem in the UA-1000 quirk ('FIXME: playback must be
> synchronized to capture')"?
> * Any idea what could be causing the glitch?
> * Has anyone done any analysis on this problem before?
>
>
> Cheers,
>
> Phil
>
>
>
>
>
>
>
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>

Ivica Ico Bukvic, D.M.A.
Composition, Music Technology
Director, DISIS Interactive Sound and Intermedia Studio
Assistant Co-Director, CCTAD
CHCI, CS, and Art (by courtesy)
Virginia Tech
Department of Music
Blacksburg, VA 24061-0240
(540) 231-6139
(540) 231-5034 (fax)
ico.bukvic.net
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Received on Fri Jul 24 16:15:01 2009