uaudio and Digigram UAX220

[Fabrice Grattier]

Dear Per Olof,

Indeed, the UAX220 feature you mention might have something to do with the problem that is encountered with FreeBSD.
By default, the UAX220 has a fixed internal clock, set at 48 KHz. 
Under Windows (XP), Microsoft DirectSound allows "on the fly" sampling rate conversion (processing being done on PC's CPU) if  playback and/or recording is performed at a different sampling frequency value. That ensures that Analog-To-Digital and Digital-To-Analog Converters provide the best possible quality with the UAX220, whatever actual playback/recording sampling frequency value.

Modifying this UAX220 feature requires a firmware change (to switch from fixed-48Khz-firmware to free-frequency-firmware).
Problem is that firmware updater program is not finalized yet, that is why you cannot find neither the firmware, not the firmware updater program on our site. 

Is this UAX220 feature definitely a problem to make it work under FreeBSD?

Please let me know.

With regards,

Fabrice


-----Original Message-----
From: Per olof Ljungmark [mailto:peo at intersonic.se] 
Sent: Sunday, October 23, 2005 10:50 AM
To: Ariff Abdullah
Cc: freebsd-multimedia at freebsd.org; Fabrice Grattier
Subject: Re: uaudio and Digigram UAX220


> http://people.freebsd.org/~ariff/snd_RELENG_5_20051009_054.tar.gz
> 
> tar -zxf snd_RELENG_5_20051009_054.tar.gz -C /usr/src/
> 
> Again, as I've stated in my previous post:
> 
> Your entire playback channel goes haywire by not returning appropriate
> sound format. Nothing can be done, even with this patch. Perhaps you
> can try replacing all your /usr/src/sys/dev/sound/usb/ sources from
> HEAD/CURRENT branch instead.

So I recompiled the kernel using
http://people.freebsd.org/~ariff/snd_RELENG_5_20051022_055.tar.gz
and as you foresaw, it changed nothing.
UAX220 works as a native USB Audio device under Win2k, XP, Linux and OS X.

I found this statement in the manual for the adapter, perhaps relevant 
to the problem?
I looked at digigram.com/drivers but saw nothing relevant contrary to 
the statement below, perhaps Fabrice could enlighten me?
The manual only refers to Windows XPsp2 as OS so I assume with all 
others the adapter will report that it supports 48kHz only?

###### From UAX manual:
UAX220 operates by default at an internal sample rate of 48 kHz. In case 
the files played back have a different sampling rate, the operating 
system performs a real-time frequency conversion.
Under Windows XP (≥SP2) only, it is possible to modify the embedded 
firmware version of the UAX220 so that it accepts other internal sample 
rates: 8 kHz, 11.025 kHz, 16 kHz, 22.05 kHz, 24 kHz, 32 kHz, 44.1 kHz, 
48 kHz. That makes it possible to work with files at e.g. 44.1 kHz 
without frequency conversion.
To use this feature, please download the corresponding firmware update 
application at www.digigram.com/drivers/index.htm. In the 'Firmware' 
section, select 'UAX220'. Read the instructions on how to use this 
application carefully.
Attention: When using this firmware, UAX220 notifies Windows that it is 
able to manage sample rates from 8 through 48 kHz. Nevertheless, UAX220 
uses internally the same sampling rate for recording and playback. This 
entails, that if an application plays a file at a given sample rate, and 
then another application is launched in parallel to record at another 
sampling rate, UAX220 will record at the sampling rate defined by the 
playback application, whereas the recording application assumes to work 
at another sampling rate. On the other hand, if a recording is already 
in hand at a certain frequency and a playback is launched at another 
frequency, the output will have the right frequency. To sum up, the 
audio stream being recorded or played back first imposes the sampling rate!
With the firmware delivered by default, Windows detects that UAX220 
supports only 48 kHz, and in consequence performs frequency conversions 
automatically when it detects that the frequency required by the 
application is different from 48 kHz.

Digigram, networking your sound