i am working in Linux 9, and write a voip application

soundcard chip: C-Media CMI8738

my problem is

when i recording voice from mic, the signal will be hear from my earphone.

but i do not want hear the echo from the earphone, because my earphone

need to play the RTP packet data.

in C-Media CMI8738 device driver the mixer seem only support

volume,line,mic,pcm,synth,speaker,cd

what i need to do from the "ioctl" function(i need to write the problem,and

can not use the toolkit to change the mixer setting), that i will not hear the

echo vocie from my mic. Likely in WinXP turn the mic to mute.


thank for your help.