[LAU] Using the Zoom H5 as a audio interface under Linux

[Faheem Mitha]

Hello everyone,

I've posted a question about using the Zoom H5 as an audio interface
to sound.stackexchange.com, see
https://sound.stackexchange.com/q/44364/24842

I've found scattered references to H5 working on Linux. One is on this
mailing list -
http://linux-audio.4202.n7.nabble.com/checking-passive-input-frequencies-on-non-Hi-Z-connection-td103669.html

But I can't get it to work.

I've posted the contents of that question below. Any help would be
appreciated. Please copy me on any reply. Thank you.

Regards, Faheem Mitha

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I just purchased the Zoom H5 sound recorder, with the intention of
using it both as a sound recorder, and also as a audio interface under
Linux. My OS is Debian stable. Currently 9/stretch.

Unfortunately, there is hardly any documentation on how to use it
under Linux. I managed, by looking at the manual, to get my OS (Debian
stable/stretch) to at least recognize the device.

However, right now I'm not sure how to go with either Stereo or 4
Track. In both cases I end up with a screen that shows `USB AUDIO I/F
XY5`, along with L, R, 1, and 2. But I see no motion in any of these.

However, right now I'm not sure how to go with either `Stereo` or
`Multitrack`. In both cases, it is clear that I need to go with the
`Bus Powered` option. As mentioned in various places, if I choose
`Stereo`, Debian thinks it is the H4, but with `Multitrack` correctly
identifies it as the H5.

In both cases I end up with a screen that shows `USB AUDIO I/F`, along
with L, R, 1, and 2. But I see no motion in any of these.

`lsusb` is showing the following:

     Bus 006 Device 006: ID 1686:01c5 ZOOM Corporation

The syslog is printing a bunch of complaints:

     May 28 21:38:01 orwell kernel: [1505026.660071] usb 11-1: Warning! Unlikely big volume range (=4294967295), cval->res is probably wrong.
     May 28 21:38:01 orwell kernel: [1505026.660076] usb 11-1: [2] FU [Mic Capture Volume] ch = 2, val = 1/0/1
     May 28 21:38:01 orwell mtp-probe: checking bus 11, device 3: "/sys/devices/pci0000:00/0000:00:13.0/usb11/11-1"
     May 28 21:38:01 orwell mtp-probe: bus: 11, device: 3 was not an MTP device
     May 28 21:38:01 orwell systemd-udevd[28202]: Process '/usr/sbin/alsactl -E HOME=/run/alsa restore 2' failed with exit code 99.
     May 28 21:38:02 orwell pulseaudio[6363]: [pulseaudio] alsa-mixer.c: Your kernel driver is broken: it reports a volume range from 0 to -1 which makes no sense.

The H5 is also showing up in `pavucontrol`. The configuration section
offers various options. I'm not sure which one to choose - the options
are:

Analog Stereo Output + Multichannel Input
Analog Stereo Output
Digital Stereo (IEC958) Output + Multichannel Input
Digital Stereo (IEC958) Output
Multichannel Input
Off

If I choose `Multichannel Input`, then it shows up in `pavucontrol`
under `Input Devices`, but the volume level (or whatever it is called)
for that device stays at zero. As it happens, I have another, regular
mic plugged into my main (PCI Express) sound card (Xonar DX) right
now, and that is responding fine. Also, I assume a working mic makes
some noise, and the mics on the H5 are completely silemt.

I'm sure I'm missing something obvious, so help would be much
appreciated, bearing in mind my knowledge of things sound-related is
very limited.

And finally, can someone exactly what an "audio interface" means,
exactly?