Related messages attached. Didn't see any from you, actually. Maybe
something you sent didn't reach me?
Capture works properly but playback has sync issues. The proper fix
(based on what the Windows driver does) would be to capture while
playing and to use the capture clock to synchronize playback, but no-one
had time to implement that.
Hopefully this helps.
--- Begin Message ---
Sorry about late reply.
> It appears to have most of the audio class descriptors, so it should be
> possible to tell the driver to just use it.
>
> Please try to add the following entry somewhere in sound/usb/usbquirks.h
> and to recompile the driver:
>
>
> {
> /* Edirol M-16DX */
> USB_DEVICE(0x0582, 0x00c4),
> .driver_info = (unsigned long) & (const struct snd_usb_audio_quirk) {
> .ifnum = QUIRK_ANY_INTERFACE,
> .type = QUIRK_COMPOSITE,
> .data = (const struct snd_usb_audio_quirk[]) {
> {
> .ifnum = 0,
> .type = QUIRK_AUDIO_STANDARD_INTERFACE
> },
> {
> .ifnum = 1,
> .type = QUIRK_AUDIO_STANDARD_INTERFACE
> },
> {
> .ifnum = 2,
> .type = QUIRK_MIDI_FIXED_ENDPOINT,
> .data = & (const struct snd_usb_midi_endpoint_info) {
> .out_cables = 0x0001,
> .in_cables = 0x0001
> }
> },
> {
> .ifnum = -1
> }
> }
> }
> },
This allows the device to be detected correctly and capture seems to be
working flawlessly. Playback also works, but there is a severe three
second distortion in audio once every 30 seconds, at 48 kHz. This seems
to be related to the device sampling rate, as the cycle is only 15
seconds when the device is running at 96 kHz.
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--- End Message ---
--- Begin Message ---
On Thu, 2008-11-13 at 20:12 +0200, Lasse Kärkkäinen wrote:
> Has anyone been able to solve the distortion problem yet?
>
> It seems like a broken ringbuffer implementation. The distortion itself
> seems to be just the signal itself in different phase. I tested this
> with a 441 Hz (100 samples) sine wave played thru the device and
> recorded back. The recording is here:
> http://zi.fi/debug/M16DX-bug.flac
I haven't solved it yet, though I exchanged emails with Tim Camp who
reported that he had this working when the device was set to 44.1khz (I
haven't had a chance to try this)
I had previously done something similar to Lasse in re-recording a test
signal and noticed the same interesting patterns. However, I also did
some usb-logging, and when I reassembled the data stream being sent to
the device it was as it should be, i.e. uncorrupted, suggesting that the
distortion is being caused in the device, and the driver isn't sending a
corrupted data stream (though obviously something in the way it is sent
is upsetting the device)
I also did some usb-logging under Windows (where it works) and
disappointingly couldn't see any obvious difference in the way the data
was sent. I played around with things like the size of the urbs in the
driver to try to make the raw usb data look the same, but it had no
effect.
However, what I did notice is that in all circumstances the windows
driver was capturing at the same time as playback, even when I was not
asking it to record. This suggests to me that the comment in the driver
source about synchronising playback to capture has some relevance ...
James
--- End Message ---
--- Begin Message ---
James Trevelyan wrote:
> ...
> However, what I did notice is that in all circumstances the windows
> driver was capturing at the same time as playback, even when I was not
> asking it to record. This suggests to me that the comment in the driver
> source about synchronising playback to capture has some relevance ...
Indeed. The driver would have to send the data at the exact speed of
the device's internal clock, and the only way to determine that clock's
speed is to capture data.
So far I haven't found the time to rewrite the driver to support this
synchronization mechanism.
Best regards,
Clemens
--- End Message ---
--- Begin Message ---
James,
Reading your email I was struck by something.
I also have a digital I/O connected to the mixer from the pc.
I wonder if this is allowing the clocks to sync?
Just a thought.
Tim
On Fri, 2008-11-14 at 00:55 +0000, James Trevelyan wrote:
> On Thu, 2008-11-13 at 20:12 +0200, Lasse Kärkkäinen wrote:
> > Has anyone been able to solve the distortion problem yet?
> >
> > It seems like a broken ringbuffer implementation. The distortion itself
> > seems to be just the signal itself in different phase. I tested this
> > with a 441 Hz (100 samples) sine wave played thru the device and
> > recorded back. The recording is here:
> > http://zi.fi/debug/M16DX-bug.flac
>
> I haven't solved it yet, though I exchanged emails with Tim Camp who
> reported that he had this working when the device was set to 44.1khz (I
> haven't had a chance to try this)
>
> I had previously done something similar to Lasse in re-recording a test
> signal and noticed the same interesting patterns. However, I also did
> some usb-logging, and when I reassembled the data stream being sent to
> the device it was as it should be, i.e. uncorrupted, suggesting that the
> distortion is being caused in the device, and the driver isn't sending a
> corrupted data stream (though obviously something in the way it is sent
> is upsetting the device)
>
> I also did some usb-logging under Windows (where it works) and
> disappointingly couldn't see any obvious difference in the way the data
> was sent. I played around with things like the size of the urbs in the
> driver to try to make the raw usb data look the same, but it had no
> effect.
>
> However, what I did notice is that in all circumstances the windows
> driver was capturing at the same time as playback, even when I was not
> asking it to record. This suggests to me that the comment in the driver
> source about synchronising playback to capture has some relevance ...
>
> James
>
--- End Message ---
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