Hi,

I have the configuration in the asound.conf above.

my_plug - - > my_route - - > my_multi - - > slave0 (forward) - - > slave1 (loopback)

I open the plug my_plug in the block mode:

writtenFrames = snd_pcm_writei(handle, bufferToWrite, bufferToWriteSize);

The issue I see is that there are several "writes" with 0 written frames. It seems like the snd_pcm_writei does not hold until data will be written. In general, 0 written frames sounds weird to me, because snd_pcm_writei should block itself if no space is available in the circular buffer right?

I have tried to fix the following method in pcm_multi.c, as Jaroslav Kysela suggests.

-static int snd_pcm_multi_may_wait_for_avail_min(snd_pcm_t *pcm, snd_pcm_uframes_t avail ATTRIBUTE_UNUSED) +static int snd_pcm_multi_may_wait_for_avail_min(snd_pcm_t *pcm, snd_pcm_uframes_t avail) { snd_pcm_multi_t *multi = pcm->private_data; - snd_pcm_t *slave = multi->slaves[multi->master_slave].pcm; - return snd_pcm_may_wait_for_avail_min(slave, snd_pcm_mmap_avail(slave)); + unsigned int i; + for (i = 0; i < multi->slaves_count; ++i) { + if (snd_pcm_may_wait_for_avail_min(multi->slaves[i].pcm, avail)) + return 1; + } + return 0; }

But unfortunately the issue has not been resolved.

#************************************************* # PLAYBACK #*************************************************

pcm.my_plug { type plug slave.pcm my_route slave.channels 2 }

pcm.my_route { type route slave.pcm my_multi slave.channels 4 ttable.0.0 1 ttable.0.1 1 ttable.1.2 1 ttable.1.3 1 }

pcm.my_multi { type multi slaves { slave0 { pcm my_dmix channels 2 } slave1 { pcm my_dmix_loop channels 2 } } bindings { 0 {slave slave0 channel 0} 1 {slave slave0 channel 1} 2 {slave slave1 channel 0} 3 {slave slave1 channel 1} } }

#-------------------- Slave 0 --------------------

pcm.my_dmix { type dmix ipc_key 1000 ipc_key_add_uid 1 ipc_perm 0600 slave.period_time 10000 slave.period_size 480 slave.buffer_size 3840 slave.rate 48000 slave.pcm "hw:0,0" }

#-------------------- Slave 1 --------------------

pcm.my_dmix_loop { type dmix ipc_key 1000 ipc_key_add_uid 1 ipc_perm 0600 slave.period_time 10000 slave.period_size 480 slave.buffer_size 3840 slave.rate 48000 slave.pcm my_loopback_out }

pcm.my_loopback_out { type hw card Loopback device 0 subdevice 0 }

#************************************************* # CAPTURE #*************************************************

pcm.my_dsnoop_loop { type dsnoop ipc_key 1000 ipc_key_add_uid 1 ipc_perm 0600 slave.period_time 10000 slave.period_size 480 slave.buffer_size 3840 slave.rate 48000 slave.pcm my_loopback_in }

pcm.my_loopback_in { type hw card Loopback device 1 subdevice 0 }