Question / Help Audio input issue with M-Audio M-Track

M

Manite

Member
Not sure yet if it's a problem with OBS or something else yet but OBS is the only program I am having this problem in.

For some reason when I record mic audio through the m-track it only has my voice on the left channel. I've tested in audacity and teamspeak and both have the mic come through both channels. I'm really scratching my head on this one. The mic sounds great aside from only being on the left though. You can check what I mean on my twitch. http://www.twitch.tv/ovadex/b/583975588

The lack of game audio is something else. I forgot to remove and re-add the audio output. It sometimes doesn't actually record even though the input bars are jumping.

Only thing that jumped out at me was this in the log.

12:36:08 AM: pulse-input: Server name: 'pulseaudio 4.0'
12:36:08 AM: pulse-input: Audio format: s24le, 44100 Hz, 2 channels
12:36:08 AM: pulse-input: Sample format s24le not supported by OBS,using s16le instead for recording
12:36:08 AM: pulse-input: Started recording from 'alsa_input.usb-M-Audio_M-Track-00-MTrack.analog-stereo'
12:36:08 AM: source 'mic' (pulse_input_capture) created
Click to expand...

I have a feeling I need to get the m-track to do s16le rather than s24le but I'm unsure how to change that. I edited the daemon.conf to no avail.

I'm open to any suggestions.
 
L

leonhard

Developer
Having the mic only on one channel is kind of expected when you have a mono mic but use a stereo mixer. From what i could find "Mono/Stereo" Button on the M-Track will only have an effect on the Phones/Main Output, but not the USB connection. Whats interesting though, is the fact that both audacity and teamspeak work fine for you. They somehow seem to detect this situation and handle it accordingly.

It sometimes doesn't actually record even though the input bars are jumping.
Click to expand...
Is that the input bars in obs ? If so thats really strange, because the input levels are calculated from the same data that is going to be encoded. Can you reproduce that somehow ?

I have a feeling I need to get the m-track to do s16le rather than s24le but I'm unsure how to change that. I edited the daemon.conf to no avail.
Click to expand...
You can safely ignore this, both obs and pulseaudio are able to resample data into different formats. Since obs will in most cases resample the data anyways, we simply request the settings pulse has on that specific sink/source and use them if they are in a format obs understands. What happens here is that pulse is using s24le by default on the device but obs does not support that, so we ask pulse to resample that to s16le.
 
M

Manite

Member
Ok, this is weird. For some reason it is now working correctly. I just did a recording and it's coming across as stereo output properly.

I've never been able to reliably produce that other audio issue. It usually came up after a freeze on startup. I just switched to the experimental ppa and haven't had a startup freeze since that. (crosses fingers) If it happens again post the log?

Good to know that's not something to be concerned about.

One odd thing that happened when I started up this morning however is the mic output wasn't recording and when I opened the properties panel it was just a blank grey box. Had to remove completely and readd the input.
 
M

Manite

Member
Well, the m-audio is recording in obs in mono again. This time I have had no luck getting it to behave. Fell back on my blue yeti. Would REALLY rather use the m-audio though.

I just have no idea why the mic doesn't want to upmix in obs. It works fine in every other recording program I use.

Would it be possible to add a checkbox or somesuch to force a stereo upmix on it? Just a though.
Maybe someone knows how to get pulse to force upmix? I'm not too experienced with fudging with pulse settings.
 
ubuntuaddicted

ubuntuaddicted

Member
I just noticed on that same page is a specific reference to a m audio device. Look for:
Sound output is only mono on M-Audio Audiophile 2496 sound card
 
M

Manite

Member
Well, solved my mic problem. I ditched the m-audio and got a behringer mixer. Better in every way possible.
 
Ranko Kohime

Ranko Kohime

Member
I know it's not an issue for you anymore, but this post might help explain the issue to others who have the problem.

Most mic interfaces are designed to use two microphones, but since we generally only use one in streaming/podcasting, it's putting out audio only to the left channel. One easy fix is to use a null sink in Pulseaudio, and a monaural loopback from the mic source to the null sink, and then record the null sink instead of the microphone directly.

Some mixers, and probably the mixer you are using, are designed for just such a setup as we have, and have an input that is by default spanned across both channels when it is sent to the computer.
 
M

Manite

Member
Yea, I think it was just that the M-audio was a cheapy. Didn't properly mix mono sources to the stereo output. Prolly would have gotten this mixer eventually anyway. Now I have 10 channels that I can use to pipe all audio through to better and more easily control the levels. Already have hooked up to my tablet for sound fx.
 
ubuntuaddicted

ubuntuaddicted

Member
Manite said:
Yea, I think it was just that the M-audio was a cheapy. Didn't properly mix mono sources to the stereo output. Prolly would have gotten this mixer eventually anyway. Now I have 10 channels that I can use to pipe all audio through to better and more easily control the levels. Already have hooked up to my tablet for sound fx.
Click to expand...
i don't think you're understanding what ranko stated, it's not that it didn't properly mix mono sources to the stereo output, it's that the m-audio is designed to use two microphones but you only had 1 connected. I provided the fix in a link above which is to first find out the source for your m-audio device with
Code: 
pacmd list-sources
then with something like name: <alsa_input.pci-0000_00_14.2.analog-stereo>
you need to add a remap to pulseaudio /etc/pulse/default.pa file which would look like
Code: 
load-module module-remap-source master=alsa_input.pci-0000_00_14.2.analog-stereo master_channel_map=front-left,front-right channels=2 channel_map=mono,mono
after you add that remap rule, you need to restart pulseaudio, it should auto-respawn so issuing should work
Code: 
pulseaudio -k
NOTE: you must change the "source" to be whatever your system returned for the pacmd list-sources command returned for your m-audio device. you may have multiple sources due to motherboard onboard microphone. Good luck
 
M

Manite

Member
Thanks Ubu, It's a non-issue though. As mentioned I got a proper mixer from Behringer which worked right out of the box and gives me more options anyway.
 
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