[alsa-devel] new driver: channel alignment (was: 30mS interval problem)

William Juul william at juul.no
Wed Feb 27 13:56:16 CET 2008


I am new to ALSA and trying to write a new driver for a ADC connected
with PCM to an AVR32 on a NGW100 reference card provided by Atmel.

I have the problem that different channels from the PCM stream comes
in different positions in the WAV file. For example when I disable all
but the first PCM channel on the ADC, I can see with an oscilloscope
that there is only data in the first timeslot on the PCM data stream.
But the data from this channel can occur in any of the 4 channels in
the WAV file. This is consistent throughout the one capture/file, but
in the next capture the data will occur in another channel in the

How can I make sure that the data from one particular channel always
occur in a fixed position in the WAV file?

Best regards
William Juul

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