Question - Expanding Audio Driver support

[mungewell]

Hi, With MPC v2.10 class compliant audio interfaces are supported, I assume (have MPC Touch myself) that the hardware actually relies on the Linux driver system (ALSA??) to implement this.

There are a few project which go beyond the hardware supported by the kernel. How realistic is the dream that these could be built for the MPC line?

If you wanted a request/suggestion/target, how about this one?? Self contained, but limited driver: https://github.com/Drumfix/motu-avb-usb

Cheers, Simon.

[TheKikGen]

This implies to Install the kernel source of your running kernel...but we don't have it....

[mungewell]

Does the inbuilt kernel support loading modules (insmod, lsmod, modinfo commands)?

If so it may be possible to build a new module based on the kernel's setup and then load that into it - ie without needing to rebuild the kernel itself.

[TheKikGen]

Some modules can or can't be loaded as Akai customized the kernel for the MPC, and some are linked statically... I tried 2 years ago to build a Kernel from scratch, but I missed a lot of specific drivers (like touch screen for example, or SoC board..). I was successfull in launching a kernel at boot time, but only in command line mode !

Concerning Alsa, it is theoritecally possible to make a config file for the MOTU AVB, as the new 2.10 version support Alsa audio compliant sound cards. Did you tried to plug the board in your MPC ?

A fast track is probably to make it works on a Raspberry Pi, and then to make it works on the MPC.

[henning]

This discussion goes down to something I already wondered recently since becoming aware that MPC is Linux based:

Where are the sources that akai/inmusic is obliged to publish as result of using GPL code? Did anyone every ask them to provide it? I found some GPL Notes on other inmusic Brand products (I think denonDJ if i remember correctly) bnut no info at all from akai and about MPC's.

Not sure if the GPL can enforce getting the kernel config used, but it might...

[nicola-lunghi]

THis is an old thread but there's any possibility to change the sample rate of the usb interface to 48khz? anyone has investigated how the usb sound card support works?

[nicola-lunghi]

I don't think the issue is the kernel there's a dbus service az01-unsupp-dev that is handling this I think.

here's the log from my allen heath cq18 (that is class compliant but works at 48khz) with 32ch in disabled

Jun 29 22:17:13 mpc-one-mk2 kernel: usb 2-1: new high-speed USB device number 6 using ehci-platform
Jun 29 22:17:14 mpc-one-mk2 kernel: usb 2-1: New USB device found, idVendor=22f0, idProduct=0023, bcdDevice= 0.01
Jun 29 22:17:14 mpc-one-mk2 kernel: usb 2-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
Jun 29 22:17:14 mpc-one-mk2 kernel: usb 2-1: Product: CQ18T
Jun 29 22:17:14 mpc-one-mk2 kernel: usb 2-1: Manufacturer: Allen&Heath Ltd
Jun 29 22:17:14 mpc-one-mk2 az01-unsupp-dev[288]: device add: 2-1 (driver 'usb'; syspath '/sys/devices/platform/ff500000.usb/usb2/2-1')
Jun 29 22:17:14 mpc-one-mk2 az01-unsupp-dev[288]: waiting for queue to empty before signalling (1 pending)
Jun 29 22:17:14 mpc-one-mk2 az01-unsupp-dev[288]: device add: 2-1:1.0 (driver 'snd-usb-audio'; syspath '/sys/devices/platform/ff500000.usb/usb2/2-1/2-1:1.0')
Jun 29 22:17:14 mpc-one-mk2 az01-unsupp-dev[288]: waiting for queue to empty before signalling (1 pending)
Jun 29 22:17:14 mpc-one-mk2 az01-unsupp-dev[288]: device bind: 2-1:1.0 (driver 'snd-usb-audio'; syspath '/sys/devices/platform/ff500000.usb/usb2/2-1/2-1:1.0')
Jun 29 22:17:14 mpc-one-mk2 az01-unsupp-dev[288]: waiting for queue to empty before signalling (1 pending)
Jun 29 22:17:14 mpc-one-mk2 az01-unsupp-dev[288]: device add: 2-1:1.3 (driver 'snd-usb-audio'; syspath '/sys/devices/platform/ff500000.usb/usb2/2-1/2-1:1.3')
Jun 29 22:17:14 mpc-one-mk2 az01-unsupp-dev[288]: device add: 2-1:1.4 (driver 'snd-usb-audio'; syspath '/sys/devices/platform/ff500000.usb/usb2/2-1/2-1:1.4')
Jun 29 22:17:14 mpc-one-mk2 az01-unsupp-dev[288]: waiting for queue to empty before signalling (1 pending)
Jun 29 22:17:14 mpc-one-mk2 az01-unsupp-dev[288]: device bind: 2-1:1.3 (driver 'snd-usb-audio'; syspath '/sys/devices/platform/ff500000.usb/usb2/2-1/2-1:1.3')
Jun 29 22:17:14 mpc-one-mk2 az01-unsupp-dev[288]: waiting for queue to empty before signalling (1 pending)
Jun 29 22:17:14 mpc-one-mk2 az01-unsupp-dev[288]: device add: 2-1:1.2 (driver 'snd-usb-audio'; syspath '/sys/devices/platform/ff500000.usb/usb2/2-1/2-1:1.2')
Jun 29 22:17:14 mpc-one-mk2 az01-unsupp-dev[288]: waiting for queue to empty before signalling (1 pending)
Jun 29 22:17:14 mpc-one-mk2 az01-unsupp-dev[288]: device bind: 2-1:1.4 (driver 'snd-usb-audio'; syspath '/sys/devices/platform/ff500000.usb/usb2/2-1/2-1:1.4')
Jun 29 22:17:14 mpc-one-mk2 az01-unsupp-dev[288]: device bind: 2-1:1.2 (driver 'snd-usb-audio'; syspath '/sys/devices/platform/ff500000.usb/usb2/2-1/2-1:1.2')
Jun 29 22:17:14 mpc-one-mk2 az01-unsupp-dev[288]: waiting for queue to empty before signalling (1 pending)
Jun 29 22:17:14 mpc-one-mk2 az01-unsupp-dev[288]: device add: 2-1:1.1 (driver 'snd-usb-audio'; syspath '/sys/devices/platform/ff500000.usb/usb2/2-1/2-1:1.1')
Jun 29 22:17:14 mpc-one-mk2 az01-unsupp-dev[288]: waiting for queue to empty before signalling (1 pending)
Jun 29 22:17:14 mpc-one-mk2 az01-unsupp-dev[288]: device bind: 2-1:1.1 (driver 'snd-usb-audio'; syspath '/sys/devices/platform/ff500000.usb/usb2/2-1/2-1:1.1')
Jun 29 22:17:14 mpc-one-mk2 az01-unsupp-dev[288]: waiting for queue to empty before signalling (1 pending)
Jun 29 22:17:14 mpc-one-mk2 az01-unsupp-dev[288]: device bind: 2-1 (driver 'usb'; syspath '/sys/devices/platform/ff500000.usb/usb2/2-1')
Jun 29 22:17:14 mpc-one-mk2 az01-unsupp-dev[288]: waiting for queue to empty before signalling (1 pending)
Jun 29 22:17:14 mpc-one-mk2 az01-unsupp-dev[288]: signalling unsupported devices (1 pending)
Jun 29 22:17:14 mpc-one-mk2 az01-unsupp-dev[288]: delaying 190ms before signalling unsupported
Jun 29 22:17:14 mpc-one-mk2 az01-unsupp-dev[288]: signalling unsupported devices (1 pending)
Jun 29 22:17:14 mpc-one-mk2 az01-unsupp-dev[288]: skipping supported device 2-1:1.1 (driver snd-usb-audio)
Jun 29 22:17:14 mpc-one-mk2 az01-launch-MPC[323]: Reducing RLIMIT_DATA from 1913356288 -> 1913331712
Jun 29 22:17:29 mpc-one-mk2 az01-launch-MPC[323]: Error: 44100 may not be a supported sample rate on the external device.
Jun 29 22:17:29 mpc-one-mk2 az01-launch-MPC[323]:  Code: -22
Jun 29 22:17:29 mpc-one-mk2 az01-launch-MPC[323]: Error: 44100 may not be a supported sample rate on the external device.
Jun 29 22:17:29 mpc-one-mk2 az01-launch-MPC[323]:  Code: -22
Jun 29 22:17:29 mpc-one-mk2 az01-launch-MPC[323]: **** Failed to open ALSA device for capture hw:2
Jun 29 22:17:29 mpc-one-mk2 az01-launch-MPC[323]: **** Audio 44100Hz; 2-in; 2-out; 192sample buffer
Jun 29 22:17:29 mpc-one-mk2 az01-launch-MPC[323]: **** Warning: inefficient input path: hardware=2 filter=32
Jun 29 22:17:29 mpc-one-mk2 az01-launch-MPC[323]: **** Warning: inefficient output path: hardware=2 filter=32
Jun 29 22:17:45 mpc-one-mk2 az01-launch-MPC[323]: Error: 44100 may not be a supported sample rate on the external device.
Jun 29 22:17:45 mpc-one-mk2 az01-launch-MPC[323]:  Code: -22
Jun 29 22:17:45 mpc-one-mk2 az01-launch-MPC[323]: Error: 44100 may not be a supported sample rate on the external device.
Jun 29 22:17:45 mpc-one-mk2 az01-launch-MPC[323]:  Code: -22
Jun 29 22:17:45 mpc-one-mk2 az01-launch-MPC[323]: **** Failed to open ALSA device for capture hw:2
Jun 29 22:17:45 mpc-one-mk2 az01-launch-MPC[323]: **** Audio 44100Hz; 2-in; 2-out; 192sample buffer
Jun 29 22:17:45 mpc-one-mk2 az01-launch-MPC[323]: **** Warning: inefficient input path: hardware=2 filter=32
Jun 29 22:17:45 mpc-one-mk2 az01-launch-MPC[323]: **** Warning: inefficient output path: hardware=2 filter=32