[alsa-devel] Audio capture on embedded system (via USB port)

[Israel Alejandro Arriaga Trejo]

Hello,
 
I am writing to kindly ask for assistance with ALSA on an embedded platform, in particular to record audio via a USB headset. The embedded platform I am currently using has analog inputs and outputs for audio (mic and headphone). So far I have been able to play and capture audio using the analog audio inputs/outputs with the commands aplay and arecord respectively from ALSA without any problems. However this is not the case when I am trying to use a USB headset via the USB port, at least while trying to record audio (playing audio is not a problem, it works perfectly fine for different rates and formats and the devices are recognized when I type aplay –l or arecord -l).  However, when I try to capture audio, using the ALSA command line arecord as in:
 
$ arecord –d 10 –r 16000 –f S16_LE –t wav  –Dhw:1,0  test.wav
 
even though the following message appears:
 
$ Recording WAVE  ‘test.wav’ : Signed 16 bit Little Endian, Rate 16000 Hz, Mono
 
the application seems “to freeze”.  In fact, the recording does not stop in the indicated 10 seconds, instead it continues “working” for a long period of time and creates the file test.wav which after is played it contains fragments of what actually was recorded via the microphone nonetheless, its content is unintelligible. In some cases the following error also appears:
 
$ arecord: pcm_read:1617: read error: Input/Output error  
 
As mentioned previously this behavior is only observed during capture mode (while attempting to record using the microphone) since the playback mode using the USB headphone works properly. After browsing for a while I have found similar situations reported, however I have not been able to find a solution to my problem.
I would highly appreciate for any hint that could help me to solve this issue.
 
Best regards,
 
Alejandro