I write a asound.conf file in the /etc/ , the detail is as follows. pcm.hardware{ type hw:0 card 0 device 0 } pcm_slave.test { pcm "hardware" format S16_LE rate 44100 channels 2 period_time 20000 buffer_time 80000 } pcm.mix1{ type dmix ipc_key 1235675 ipc_key_add_uid true slave "test" }

pcm.mix2{ type dmix ipc_key 1235675 ipc_key_add_uid true slave { pcm "hw:0" format S16_LE rate 44100 channels 2 period_time 20000 buffer_time 80000 } } pcm.!default { type plug slave.pcm mix2 #slave.pcm mix1 }

when I use the slave.pcm mix2, the aplay works well. but if I select the slave.pcm mix1, the aplay gets the info: ALSA lib pcm_direct.c:1462:(_snd_pcm_direct_get_slave_ipc_offset) Invalid type 'dmix' for slave PCM

I compare the definition of mix1 with the definition of mix2, I feel they have the identical meaning. so why does the mix2 get the error? thank you!