[alsa-devel] [RESENT] [PATCH - Fix Fast Track Ultra series: 44.1/88.1 kHz 1/Fix playback/capture issues and related chrashes at 44100 Hz and 88200 Hz for M-Audio Fast Track Ultra series.

[Felix Homann]

Hi,

This is my second try to get support for all supported sample rates for 
the Fast Track Ultra (FTU) series into mainline alsa.

For clarification: Current Alsa already recognizes the supported sample 
rates. But it will sound very corrupted at 44.1000 Hz and 88.200 Hz. 
Without this patch your system will even probably freeze eventually when 
using the FTU at 44.100/88.200 Hz too long.

So the key idea in this patch is not to get 44.1 kHz and 88.2 kHz listed 
as supported sample rates (as they already are recognized) but to change 
the endpoint attributes.

Citing dhubsith on the M-Audio forum:

" The problem with using QUIRK_AUDIO_STANDARD_INTERFACE rather than 
QUIRK_AUDIO_FIXED_ENDPOINT is that ep_attr does not get set correctly. 
The device default for synchronization is async (0x05) for both capture 
and playback, but in fact it should be set to adaptive (0x09) on 
playback, so that playback follows capture, this way you don't get 
capture and playback using different sample rates.

Also, the Interface Class protocol for the device defaults to Vendor 
Specific Class, but the driver only recognizes Class 1 or 2. The device 
is really Class 1, so we have to force it to reflect this. There are 4 
places that we need to set this."



The patch has been discussed starting here:

http://forums.m-audio.com/showthread.php?714-Not-a-problem.-FastTrack-on-linux/page8

The "key" has been found by dhubsith. Please read posts #79, #81, #84, 
#87, #97.


In post #102 of that forum you can even find an alternate patch by 
dhubsith which doesn't use a fixed endpoint quirk but sets

      protocol = UAC_VERSION_1;

for the FTU devices in sound/usb/format .c. You might even consider that 
patch. (I've resend it to alsa-devel yesterday).

After all, either one of the above mentioned patches should go into 
alsa, as right now we can't use the FTU devices at 44.1 and 88.2 kHz.

Kind regards,

Felix

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