Usb-audio

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Contents

The module options for usb-audio

please add to this section.

Setting up modprobe and kmod support

NB. Before you send a mail complaining that "I don't have /etc/modules.conf, where do I find it ....." ,The /etc/conf.modules has been deprecated with a few distro's so in your case, it may still be /etc/conf.modules. Basically they are both same, but recent version of modutils uses /etc/modules.conf instead. Nothing to worry about as such, optionally please update to latest version of modutils. This should solve your problem.

Here's the example for this module. Copy and paste this to the bottom of your /etc/modules.conf file.

# ALSA portion
alias char-major-116 snd
alias snd-card-0 snd-usb-audio

# OSS/Free portion
alias char-major-14 soundcore
alias sound-slot-0 snd-card-0

# card #1
alias sound-service-0-0 snd-mixer-oss
alias sound-service-0-1 snd-seq-oss
alias sound-service-0-3 snd-pcm-oss
alias sound-service-0-12 snd-pcm-oss

To copy and paste the above to your /etc/modules.conf file follow these instructions.

Here's a modules.conf file for the Emagic emi2|6.

alias usb-controller usb-uhci
# --- ALSA configuration
alias char-major-116 snd
alias char-major-14 soundcore
alias snd-card-0 snd-usb-audio
alias sound-slot-0 snd-card-0
# --- OSS compatibility
#alias sound-slot-0 audio
alias sound-service-0-0 snd-mixer-oss
alias sound-service-0-1 snd-seq-oss
alias sound-service-0-3 snd-pcm-oss
alias sound-service-0-8 snd-seq-oss
alias sound-service-0-12 snd-pcm-oss
# --- Options
options snd major=116 cards_limit=3
# --- ALSA configuration END
post-install sound-slot-0 /bin/aumix-minimal -f /etc/.aumixrc -L >/dev/null 2>&1 || :
pre-remove sound-slot-0 /bin/aumix-minimal -f /etc/.aumixrc -S >/dev/null 2>&1
|| :

Notes

Takashi Iwai is the maintainer of the code for this card.

First of all you need to have usb working correctly. There is much useful info available at http://www.linux-usb.org.

Optimally setting irq resources for usb is essential for good performance. If possible set pci/usb irq, from best to worst:

9,10,11,12,13,14,15,3,4,5,6,7

Request: could somebody please provide info on what needs to be done to set IRQ's properly?

Some jackd hints

Jack has changed so that -p must always be a power of two. This is because certain programs can have much more efficient algorithms if they can depend on that sort of buffer size. Someone will have to find a different period size that works well.

Using Linux Kernel 2.6.8.1 with Ingo Molnar's 2.6.8.1-VP patches, jackd 0.99.14 and alsa-lib 1.0.7, I'm able to get low latency audio with the emi 2|6::

echo 0 > /proc/irq/11/ehci_hcd/threaded
echo 0 > /proc/irq/11/uhci_hcd/threaded

jackd -R -d alsa -d hw:1 -p 64 -n 4 -P

USB-MIDI driver for Linux: http://member.nifty.ne.jp/Breeze/softwares/unix/usbmidi-e.html

USB MIDI sequencer support -- Clemens Ladisch

You should upgrade to kernel 2.4.19 or greater to get the correct infomation from lsusb -- Patrick Shirkey

Fernando's 2.4.19 low latency rpm is a useful resource. http://ccrma-www.stanford.edu/planetccrma/software/installkernelandsound.html

Midiman Quattro .asoundrc

One more note on configuring your kernel: there is an option for USB audio support in the USB section of the kernel config. You should _NOT_ enable it. It is intended for use with USB speakers. If you do enable it, your alsa usb audio module will load properly, but it will seriously confuse devfs if you have it. Device special files for your USB audio unit will not be made properly.

It seems that the newer USB Midi module is also unnecessary, even if your device has midi.

With the USB Audio Quattro, this results in very strange behaviour: apps that use the OSS compatibility layer can play sound on your device, but it becomes completely distorted once the loudness goed up. Apps that use ALSA directly will complain about device drivers not being found and such. You have been warned!

-- Denis de Leeuw Duarte

Tip: You can also add "usbmidi" and "usbaudio" to the file "/etc/hotplug/blacklist" to prevent hotplug from loading these OSS modules.

Tuning USB devices for minimal latencies

On linux-audio-user Christoph Eckert brought up the question about how to get better latencies out of USB audio devices, and USB guru Clemens Ladisch had a very good tip: The snd-usb-audio module accepts a module option called "nrpacks", which according to modinfo, sets the: Max. number of packets per URB. (int). Setting this to "nrpacks=1" should allow latencies in the area of 4-6 msecs.

Unfortunatly on some systems/kernels nrpacks=1 conflicts with a feature called "USB bandwidth allocation" in the kernel. Here's the way out:

:[   ] Enforce USB bandwidth allocation (EXPERIMENTAL)
:[   ] Dynamic USB minor allocation (EXPERIMENTAL)

modprobe snd-usb-audio nrpacks=1

options snd-usb-audio nrpacks=1

jackd -R -P89 -dalsa -dhw:2 -r48000 -p256 -n3 -S

You can omit the "-S" if your card supports 24bit or 32bit access as well and you want to use that.

Request: could somebody please provide info on what needs to be done to set IRQs properly?

Devices using snd-usb-audio driver

Roland/Edirol EXR-3s with Linux 2.6

I've put some instructions for getting EXR-3s working with snd-usb-audio: [1]. It requires a minor kernel patch.

Roland Juno-G synthesizer USB MIDI patch

I made a patch for the USB MIDI function of the Roland Juno-G synthesizer to work. Basically it is a missing entry in alsa-driver-1.0.14rc2.orig/sound/usb/usbquirks.h. The patch is here.

DSP-400 under Linux 2.6

If you are trying to get USB headphones working under the 2.6 kernel (such as the Plantronics DSP series), there is some information to be found at http://www.xantius.com/articles/dsp-400.php, however it's not being updated...

SB Audigy2 NX USB

I was fooling around with this for a while and finally came to a solution thanks to banshee in #creative and some tinkering. Some might notice that the NX is detected but the sound is garbled, simply lower from 44khz to 22khz in xmms, it might not be a complete fix, but it makes it possable to listen to more than sytem sounds. AIM - Ryox82 for questions

With ALSA 1.0.2c from the 2.6.9 kernel, the following (found elsewhere here) did the trick (and is mandatory for getting the EMI 6|2 recording!):

modprobe snd-usb-audio nrpacks=1

Then I ran Jack with 48kHz, 16 or 24 bit samples, 512 or 1024 sample blocks and 2 buffers.

With this configuration, my Audigy 2 NX works perfectly on my USB 2.0 bus on my HP/Compaq NX 7010 notebook.

ALSA 1.0.9 did not allow me to un-mute the card at all. Sample rates other than 48kHz fail miserably.

M-audio Audiophile USB

This is a strange one at the moment - since it isn't completely compliant with the USB audio spec and nobody in the dev team has one of these devices, support is limited. (I do have one and am happy to aid the developers in improving support for the device by the way)

Anyway, issues I've fond to date: (ALSA 0.9.7 with Linux 2.4.22, premptable kernel, low latency)

Playback only possible at 48khz 2-channel 16-bit (S16_LE) (see below) Record: as playback, but I haven't managed to get any audio from the device (it returns all zeros - not even any codec noise)

Although I'm telling the device the data is little endian, the data should be sent as *Big endian*!

-- David Hughes

Turtle Beach Audio Advantage Roadie

I have one of these and am interested in getting surround sound working on it. If anyone knowledgeable would like to help, it would be appreciated.

Creative USB X-Fi Surround 5.1

The card works fine with the snd-usb-audio module. I've only tested the stereo output though. The X-Fi USB doesn't have a hardware mixer. So you have to use the softvol plugin along with dmix. Here is a simple \~/.asoundrc file that will give you a 'Master' Volume control.

``

pcm.!default {
    type            plug
    slave.pcm       "softvol"   #make use of softvol
}

pcm.softvol {
    type            softvol
    slave {
        pcm        "dmix"      #redirect the output to dmix (instead of "hw:0,0")
    }
    control {
        name        "Master"       #override the PCM slider to set the softvol volume level globally
        card        0
    }
}

One important thing to note about softvol is that the Master control won't appear until the device is used for playback.

The device has a volume knob, the behavior of which is identical to that of IR remotes bundled with some Creative USB Audio devices. It also has a LED which can be set to On or can be set to Blink continuously. There doesn't seem to be a way to switch it off.

The latest stable kernel release (2.6.37) has support for this. alsa-driver-1.0.24 too has these changes but I haven't tested it yet.

~~Support for this is now in the git repo. Ref: 1 2 Here is the patch for alsa-driver-1.0.23~~

Once the snd-usb-audio module is loaded, you'll see the 'Power LED' control in alsamixer. Muting it will set the LED to Blink and unmuting it will set it to On. For the volume knob, you need to use the alsa_usb driver with lirc. Lirc will receive events whenever the volume knob is turned or pressed.

There is a remote bundled with this device sometimes. Its possible the remote will work with the same patch but unfortunately I don't have one with me.

The default alsa_usb config can be used as the codes are 0x0d for Mute, 0x0f for Vol- and 0x10 for Vol+. These are identical to the remote identified by name RM-1500 (Not Creative_RM-1500)

cp /usr/share/lirc/remotes/creative/lircd.conf.alsa_usb /etc/lircd.conf

Lirc needs to be started with these options. You can set your distro's config file accordingly

lircd --driver=alsa_usb --device=hw:S51

Run irw and you'll be able to see the received code when you turn or press the volume knob. If you need to execute commands for Vol-,Vol+ and Mute, setup \~/.lircrc . You need to have "irexec -d" running in the background for these commands to be executed. Everytime you change \~/.lircrc you need to restart irexec

``

# $HOME/.lircrc
#S51 Volume Knob
begin
 prog = irexec
 remote = RM-1500
 button = vol-
 repeat = 1
 config = amixer sset Master 1- 
end

begin
 prog = irexec
 remote = RM-1500
 button = mute
 repeat = 1
 config = if [ `amixer sget Master|grep "Front Left:"|awk '{print $3}'` -gt 0 ]; then alsactl store -f ~/.asound.state; amixer sset Master 0; amixer sset 'Power LED' off; else alsactl restore -f ~/.asound.state; amixer sset 'Power LED' on;  fi 
end

begin
 prog = irexeca
 remote = RM-1500
 button = vol+
 repeat = 1
 config = amixer sset Master 1+ 
end

The Mute part is messy because softvol plugin doesn't have the Mute feature. This lircrc allows you to mimic the behaviour under Windows i.e. LED blinking on Mute.

Anyway, you should change the commands based on your configuration. Eg. If you are using Pulseaudio you probably don't even need to use dmix & softvol. You could just use dbus-send or qdbus to change volume in Pulseaudio or use Pulseaudio's Lirc config in which case you don't need irexec running at all . I don't use Pulseaudio. Someone who is using it can probably explain it.

Creative USB X-Fi HD

This card works fine with snd-usb-audio.

The analog and the SPDIF parts are separated, they show up as different devices - just like under MS Windows. The analog part offers 48 kHz and 96 kHz as output frequency, while the SPDIF output is capable of 44.1 kHz and 48 kHz. Both outputs can handle 24 bit mode (though on SPDIF the X-Fi will emit only 16 bits). They are independent of each other, you can e.g. play a sound in 44.1 kHz/16 bit mode on the SPDIF output while playing a different, 48 kHz/24 bit sound on the analog output.

The analog recording capability seems to be fixed at 48 kHz / 16 bit while the SPDIF can handle 44.1 kHz or 48 kHz, depending on the input.

The X-Fi HD's volume knob is just a knob that does not do anything directly with the volume - by default it does not do anything in Linux. It shows up as a USB HID device and you need LIRC to use it.

After installing LIRC you have to set up three files:

/etc/lirc/hardware.conf should contain the following lines:

DRIVER="devinput"
DEVICE="/dev/input/by-id/usb-Creative_Technology_USB_Sound_Blaster_HD_000004Jt-event-if05"

Note1: Check the device file name in /dev/input/by-id/ as it contains the X-Fi's serial number so it's slightly different for everyone.

Note2: Some distributions (like Ubuntu) use REMOTE_DRIVER and REMOTE_DEVICE instead of DRIVER and DEVICE - check your default hardware.conf.

/etc/lirc/lirdc.conf can be replaced with lircd.conf.devinput.

The actual code to change the volume is in /etc/lirc/lircrc, insert the following:

# X-Fi HD Volume Knob
begin
    prog = irexec
    remote = devinput
    button = KEY_VOLUMEDOWN
    repeat = 1
    config = amixer -c HD sset 'PCM' 2- 
end

begin
    prog = irexec
    remote = devinput
    button = KEY_MUTE
    repeat = 1
    config = if [ -n "$(amixer -c HD cget name='PCM Playback Switch' |grep 'values=on')" ] ; then amixer -c HD cset name='PCM Playback Switch' off ; else amixer -c HD cset name='PCM Playback Switch' on ; fi
end

begin
    prog = irexec
    remote = devinput
    button = KEY_VOLUMEUP
    repeat = 1
    config = amixer -c HD sset 'PCM' 2+
end

Restart LIRC (make sure that irexec is also (re)started) and you should have a working volume knob.

2002-06-03 - The original release notes usb-audio

Takashi Iwai wrote: right now you can find a driver for USB audio on cvs. It's in alsa-driver not in alsa-kernel. The driver will be built automatically when CONFIG_USB is specified in kernel config. Please note that this driver is EXPERIMENTAL and TENTATIVE. My first plan was to implement a USB library layer on alsa-lib, but it was found out that implementation of isochronous transfer via usbdevfs will bring some difficulty. So I started coding of a normal kernel driver at first. If any feasible solution to port such a stuff into user space, we should do that. But anyway, it's good to have a working code. We can move it to other place later.

The current code is partly based on OSS/USB audio.c code, but apart from the parsing routine of audio-streaming, the resultant codes became fairly different from the oss code. Almost all mixer controls are supported except for graphic equalizer. The mapping of topology might not be perfect, since alsa has a plain control structure.

So far, I've tested only audio playback on my speaker, which is adaptive out without pitch/freq setting. xmms is working. The driver accepts the period size up to 1ms. A courageous user can try such a heavy condition. (me? did not yet :) 24bit/96kHz should work, too, but I have no such a hardware. Besides, capture is not tested at all.

If you have a usb audio device, please test once. (oh, I forgot to mention the driver name - it's "snd-usb-audio" quite easy, isn't it?) If you find somewhat strange behavior (especially in mixer controls), please send me the output of lsusb. BTW, when you use snd-usb-audio module, please make sure that you don't load OSS audio.o together. Hotplug likely loads both modules at the same time.

See also

Retrieved from "http://alsa.opensrc.org/Usb-audio"

Category: ALSA modules

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