[alsa-devel] ALSA: Updating Sample Rates in sound/core/pcm_native.c

Jeremy Torres jeremy.torres at gmail.com
Thu Apr 19 01:51:18 CEST 2012


I have updated pcm.h in the linux kernel to allow for new sample
rates.  For example, I have added 128000 and 144000 sample rates.  Per
the documentation in pcm.h, I also updated pcm_native.c (the rates
table).  However when I try and use the "default" device for the
sample rates:

1.  For 128000: plug conversion occurs for 128K, but the slave is
configured to 96K;
2.  For 144000: plug conversion is attempted at the 176400 rate;

Note that:
a) I have snd_pcm_hw_resample set to FALSE in my application; however,
I've been using aplay/arecord to test as well with repeatable results.
b) I do not have an asoundrc setup for plug conversion, etc.  I only
have the default /usr/share/alsa/alsa.conf;
c) When I try the the device "hw:0,0", I get a (proper) warning that
the sample rate requested is not being honored (i.e., 96K instead of

I have placed debug in pcm_lib.c,  and pcm_native.c and my sample rate
constraints are set.  My understanding is if I define a specific rate
and it can be matched in the "rates" table, it should be honored.

Environment Info:
ALSA lib/driver version 1.0.20
SOC Driver

Any help would be greatly appreciated!


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