UAC1/UAC2
Opened this issue · 4 comments
tried the usual configfs stuff in /opt/Bela/bela_gadget.sh:
mkdir -p functions/uac2.usb0
....
ln -s functions/uac2.usb0 configs/c.1/
so that the default values are loaded:
root@bela:/sys/kernel/config/usb_gadget/g# for a in functions/uac2.usb0/*; do echo $a:; cat $a; done
functions/uac2.usb0/c_chmask:
3
functions/uac2.usb0/c_srate:
64000
functions/uac2.usb0/c_ssize:
2
functions/uac2.usb0/p_chmask:
3
functions/uac2.usb0/p_srate:
48000
functions/uac2.usb0/p_ssize:
2
see here for some "documentation".
as a result, aplay -L gives:
default:CARD=UAC2Gadget
UAC2_Gadget, UAC2 PCM
Default Audio Device
sysdefault:CARD=UAC2Gadget
UAC2_Gadget, UAC2 PCM
Default Audio Device
dmix:CARD=UAC2Gadget,DEV=0
UAC2_Gadget, UAC2 PCM
Direct sample mixing device
dsnoop:CARD=UAC2Gadget,DEV=0
UAC2_Gadget, UAC2 PCM
Direct sample snooping device
hw:CARD=UAC2Gadget,DEV=0
UAC2_Gadget, UAC2 PCM
Direct hardware device without any conversions
plughw:CARD=UAC2Gadget,DEV=0
UAC2_Gadget, UAC2 PCM
Hardware device with all software conversions
but if I try to play a sound I get:
$ aplay -D hw:CARD=UAC2Gadget,DEV=0 /root/Bela/examples/terminal-only/samples/sample.wav
Playing WAVE '/root/Bela/examples/terminal-only/samples/sample.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Mono
aplay: set_params:1305: Channels count non available
Also, it does NOT show up on the host (tried Mac and Linux) as an audio device.
If I use uac1 instead, then the default parameters are:
root@bela:/sys/kernel/config/usb_gadget/g# for a in functions/uac1.usb0/*; do echo $a:; cat $a; done
functions/uac1.usb0/audio_buf_size:
48000
functions/uac1.usb0/fn_cap:
/dev/snd/pcmC0D0c
functions/uac1.usb0/fn_cntl:
/dev/snd/controlC0
functions/uac1.usb0/fn_play:
/dev/snd/pcmC0D0p
functions/uac1.usb0/req_buf_size:
200
functions/uac1.usb0/req_count:
256
then if I mknod the device files appropriately (see here):
mknod /dev/snd/pcmC0D0c c 116 24
mknod /dev/snd/pcmC0D0p c 116 16
mknod /dev/snd/controlC0 c 116 0
then I get this when running;
root@bela:/sys/kernel/config/usb_gadget/g# ls /sys/class/udc/ > UDC
ls: write error: No such device
which in turn dmesges this:
[ 214.519683] usb0: HOST MAC b6:e8:3f:ac:d9:86
[ 214.519819] usb0: MAC 16:09:d3:c0:73:89
[ 214.527247] configfs-gadget gadget: unable to open sound control device file: /dev/snd/controlC0
[ 214.536150] configfs-gadget gadget: we need at least one control device
[ 214.542844] configfs-gadget gadget: unbind function 'rndis'/dc7c4cc0
[ 214.549258] configfs-gadget gadget: unbind function 'Mass Storage Function'/dafb4880
[ 214.557072] configfs-gadget gadget: unbind function 'acm'/da867c00
[ 214.563307] configfs-gadget gadget: unbind function 'gmidi function'/daada400
[ 214.632260] configfs-gadget musb-hdrc.0.auto: failed to start g: -19
which is funny, because /dev/snd/controlC0 is actually there.
The above causes the unload of all the gadgets :(
Hi Guilio, did you ever figure this out? I'm trying to configure g_audio on a raspberry pi (aghast!). I have it playing stereo audio into my mac fine, but don't seem to be able to configure it for 4 channels. I can't quite get my head around the configfs stuff.
sorry didn't see this message before. Just found the email notification in the spam. No I never figured it out (I didn't spend any more time on it); I pointed a couple of people at this to give it a try and never heard back. So maybe it's not that straightforward? Do you have a link of your working config for the Pi?
probably a kernel version issue, plus I should have used plughw: instead of hw:, or at least specified the --channel count.
On a 4.14 kernel, this works :
In /opt/Bela/bela_gadget.sh (https://github.com/BelaPlatform/bela-image-builder/blob/master/misc/rootfs/opt/Bela/bela_gadget.sh):
cd /sys/kernel/config/usb_gadget/
mkdir -p g && cd g
mkdir -p functions/uac2.usb0 # Audio
echo 44100 > functions/uac2.usb0/c_srate
echo 44100 > functions/uac2.usb0/p_srate
...
ln -s functions/uac2.usb0 configs/c.1/
[You can also set the number of channels by setting c_chmask and p_chmask. This is a mask, so you should set it to ((2^(nCh)) - 1) (e.g.: 3 means 2 channels, 63 means 6 channels)]
then reboot and ...
playback:
aplay -D plughw:CARD=UAC2Gadget,DEV=0 /root/Bela/examples/terminal-only/samples/sample.wav --channels 2
(it would probably work without plug if the audio file was stereo)
record:
arecord -D hw:CARD=UAC2Gadget,DEV=0 --rate 48000 --format S16_LE
loopback:
BUFFER=128; PERIOD=128
arecord -D hw:CARD=UAC2Gadget,DEV=0 --disable-resample --disable-format --disable-softvol --format S16_LE --rate 44100 --channels 2 --buffer-size $BUFFER --period-size $PERIOD | aplay -D hw:CARD=UAC2Gadget,DEV=0 --disable-resample --disable-format --disable-softvol --format S16_LE --rate 44100 --channels 2 --buffer-size $BUFFER --period-size $PERIOD
These are the relevant endpoints created by this operation:
Interface #10 - Audio/Streaming .............................................. "Playback Inactive"
Alternate Setting 0
Number of Endpoints 0
Interface Class: 1 (Audio)
Interface Subclass; 2 (Streaming)
Interface Protocol: 32
Interface #10 - Audio/Streaming (#1) .............................................. "Playback Active"
Alternate Setting 1
Number of Endpoints 1
Interface Class: 1 (Audio)
Interface Subclass; 2 (Streaming)
Interface Protocol: 32
Audio Control Class Specific Header
Audio Stream General
Endpoint Terminal ID: 1
Format Type: 1
Formats PCM
Number of Channels 2
Channel Configuration 3
Dump Contents (hex): 10 24 01 01 00 01 01 00 00 00 02 03 00 00 00 00
Audio Class Specific Audio Data Format
Audio Stream Format Type Desc.
Format Type: 1
Slot Size: 2
Bit Resolution: 16
Dump Contents (hex): 06 24 02 01 02 10
Endpoint 0x06 - Isochronous Output
Address: 0x06 (OUT)
Attributes: 0x05 (Isochronous asynchronous data endpoint)
Max Packet Size: 0x00b4 (180 x 1 transactions opportunities per microframe)
Polling Interval: 4 (8 microframes (1 msecs) )
Class-Specific AS Audio EndPoint
Attributes: 0x00
bmControls: 0x00
bLockDelayUnits: 0x00 (UNDEFINED)
wLockDelay: 0
Interface #11 - Audio/Streaming .............................................. "Capture Inactive"
Alternate Setting 0
Number of Endpoints 0
Interface Class: 1 (Audio)
Interface Subclass; 2 (Streaming)
Interface Protocol: 32
Interface #11 - Audio/Streaming (#1) .............................................. "Capture Active"
Alternate Setting 1
Number of Endpoints 1
Interface Class: 1 (Audio)
Interface Subclass; 2 (Streaming)
Interface Protocol: 32
Audio Control Class Specific Header
Audio Stream General
Endpoint Terminal ID: 4
Format Type: 1
Formats PCM
Number of Channels 2
Channel Configuration 3
Dump Contents (hex): 10 24 01 04 00 01 01 00 00 00 02 03 00 00 00 00
Audio Class Specific Audio Data Format
Audio Stream Format Type Desc.
Format Type: 1
Slot Size: 2
Bit Resolution: 16
Dump Contents (hex): 06 24 02 01 02 10
Endpoint 0x89 - Isochronous Input
Address: 0x89 (IN)
Attributes: 0x05 (Isochronous asynchronous data endpoint)
Max Packet Size: 0x00b4 (180 x 1 transactions opportunities per microframe)
Polling Interval: 4 (8 microframes (1 msecs) )
Class-Specific AS Audio EndPoint
Attributes: 0x00
bmControls: 0x00
bLockDelayUnits: 0x00 (UNDEFINED)
wLockDelay: 0
Device Qualifier Descriptor
Descriptor Version Number: 0x0200
Device Class 0 (Composite)
Device Subclass 0
Device Protocol 0
Device MaxPacketSize: 64
Number of Configurations: 1
bReserved: 0