[alsa-devel] problems about dummy alsa driver

longer longer.zhou at gmail.com
Mon Jul 26 11:44:24 CEST 2010

Hi all ,

I've written an ALSA driver(only support 8K sample rate), which register two 

dummy sound cards.The main function of this driver is to exchange audio data 

of that two dummy sound cards. In other words , the driver route audio data of 

dummy sound card (PLAYBACK) to the other (CAPTURE),and vice versa.   

And I've written some test programs based on my ALSA driver . When the sample 

rate in application is set to be 8K , the driver work well. But when requiring  

rate conversion , the driver can't get any data. And , when tracing the code of 

alsa-lib (1.0.23), I found that :

     In case of rate conversion, It mmap an address from my driver, but writing 

data to another address instead of that mmaped address.

I think this is why my driver don't get any audio data. But I don't know why it 

don't write audio data to that mmaped address.

I am looking forward to your reply. And any advices will help me a lot.

Thank you,
longer zhou

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