How to switch AV/TV's audio?

[zhongzhi.yang[?中志] <zhongzhi.yang@xxxxxxxxxx>]

   I am use a bt878 based TV card(Leadtek winfast TV2000xp),it has 3
channels and 1 audio.When I use a DVD Player as an input source( AV ),I can
get video correcttly,but I can't hear audio.the audio still plays the sounds
of TV.
     I think TV uses channel 0,AV uses channel 1,but they use the same
audio.Does this means I can only get TV's sound???