[alsa-devel] About Alsa arecord

Hello! There have 2 stereo ADCs support one stereo microphone and one legacy mixer recording simultaneously, said in the document of ALC888 Datasheet .I inputed 1KHz sine wave into every pins (Line1-R,Line1-L,MIC1-R,MIC1_L,MIC2-R,MIC2-L,LINE2-R,LINE2-L) of ALC888 by signal genrator,and used command 'arecord -c 4 -f S16_LE -r 44100 >test.wav' recording in fedora14.but ALL audio data are recorded in channel 1,2.No any data in channel 3,4.Why?How can I record every pins audio data in each channel? Thank you!Best regards.