[alsa-devel] Using snd-aloop as default soundcard (need urgent help T.T)

[Santo Chow]

Hi every one..

I'm currently on a project that requires me to capture a raw audio data from a dummy soundcard. I've so far manage to do that, by using snd-aloop. Now the problem i have is.. when i'm running several audio program at the same time, i can only hear the sound from the first program that i ran. i've followed the example os dmix, but this doesn't help either.

So, right now, i have a Loopback soundcard as my default. My .asoundrc looks like this:

pcm.!default{
   type hw
   card 1
}

Card 0 is my actual soundcard (that can actually produce sound). Card 1, when i checked on the /proc/asound/cards actually pointing to Loopback card. So right now, the way i test the card 1, is to call arecord from card 1, and play it to card 0. Right now, i'm still developing this in my ubuntu PC.

so i ran this
arecord -f cd -D hw:1,1 | aplay -f cd -D hw:0

in one terminal, and in the other terminal i can play mplayer, watching youtube, etc.. and the sound would come out nicely. (Thanks to all of your efforts, nevertheless)

But I notice that, when i play mplayer, then i open a web-browser, and surf youtube, the sound from youtube is gone. But if i close the browser, close the mplayer, then reopen the browser, go to youtube and play a video, i can hear the sound nicely. but then, if during the time i start mplayer, it will complain about 'no sound'. Turns out, I have to use dmix. So, i modify my .asoundrc like this:

pcm.!default {
   type plug
   slave.pcm "dmixer"
}

pcm.dmixer  {
   type dmix
   ipc_key 1025
   slave {
      pcm "hw:0,0"
      rate 44100
   }
   bindings {
      0 0
      1 1
   }
}
i put 'pcm "hw:0,0" ' over there, because i want to make sure that this setting works with my actual sound card first. If it works with my card 0, it should work with my card 1. with the above .asoundrc file, i can play multiple sound from different application at the same time. I even tried to remove the "bindings" tag, and it still able to play multiple sound very well. so i guess, this should work on my card 1.

then i change the .asoundrc become like this again:


pcm.!default {
   type plug
   slave.pcm "dmixer"
}

pcm.dmixer  {
   type dmix
   ipc_key 1025
   slave {
      pcm "hw:1,1"
      period_time 0
      period_size 881
      buffer_size 3524
      rate 44100
   }
}the value for perio_time, period_size, and buffer_size have been adjusted by me to suits my hardware requirement. This is the setting that works on my machine. It's just that, in the end, I'm still ended up with one sound at a time. I can't run mplayer + youtube at the same time. I can only run one of them. And furthermore, if i just paused the mplayer, the audio device is still locks. It will be good enough if someone can hint me a way to unlock the audio device.

So, what i want to ask is.. can this Loopback card handle more than 1 sound at a time? Have anyone tried this before? I have tried changing the value of .asoundrc, switching the slave pcm to pcm "hw:1,0" (not working) pcm "hw:1" (works, but only 1 sound too). Any idea guys?


-santo-