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Author Topic: ALSA Sound recording problem  (Read 1634 times)

djrose

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ALSA Sound recording problem
« on: March 12, 2014, 04:09:46 PM »
I'm having trouble recording sound and selecting the source.

Admittedly, it doesn't help with me having precious little experience of ALSA.

I'm:

1 - Feeding a stereo signal into line in (on GPIO-4/13 and GPIO-4/15)
2 - Running alsamixer and selecting (what I think are) suitable parameters
3 - Running arecord -f S16_LE sample.wav
4 - Running aplay sample.wav

The best I can get from aplay here is a sound out of one channel. It could be an incorrect/bad connection for the other channel, but I don't think so.

I have tried to use a microphone instead of line in, but never get anything from this; even though I have selected microphone in alsamixer and wired up to MICIN1 and MICIN2.

But ... I'm not convinced that alsamixer is working correctly.

Reason #1 - If I:

1 - Go into alsamixer and set MicL to maximum
2 - Leave alsamixer
3 - Run arecord
4 - Go back into alsamixer and I find MicL always reverts to a level of 33%

Reason #2 - alsamixer doesn't seem to show any facility for selecting a capture device and toggling the enable of it via the 'space' key (which I can see if I run it on a PC with Ubuntu)

I've tried it with both the official "A10 OLinuXino LIME Debian image release-2" and with a self-built image from http://olimex.wordpress.com/2014/01/15/building-debian-linux-bootable-sd-card-with-hardware-accelerated-video-decoding-and-kernel-3-4-for-a10-olinuxino-lime/  - And both give the same result.

Can anyone provide any clues?




 

Robert Leacroft

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Re: ALSA Sound recording problem
« Reply #1 on: March 12, 2014, 08:16:19 PM »
Hi Djrose,

I have not yet played with the A10 Lime  but did do some work with the A10S which is very similar but does at least have audio jacks on it but has now unfortunately been made redundant. I spent a long time trying to get alsa set up using arecord etc. until I installed  Audacity audio editing program. This has visual monitoring as it records so you can actually see instantly any effects that changes to alsa settings have.  There is only 1 audio capture device built into the chip which is why alsa does not give you any option to select another one. You just have to turn on and off the multitude of inputs for this 1 device and this is where Audacity visual monitoring is very useful.

I am now trying to decide whether to use the Lime plus ribbon cables and adapters to decent pin spacings or whether to start using Beaglebone Black plus audio cape which cost more but is probably physically a lot less messy.

Robert