Greetings, Someone has proposed a great idea recently: what if it were possible to play two audio tracks of a video file simultaneously, for example, when several people want to watch a film, but some want it translated and someone understands the film’s original language and prefers that track? To implement that, one needs ALSA to have distinct devices for headphones and speakers, and one has to configure the media player accordingly. Could you please tell me how does one perform the first part of the task? I’ve done a lot of research/RTFM, but none of my solutions were satisfactory. (The second part: http://rsdn.ru/forum/message/3283171.1.aspx (in Russian). If someone’s interested, I can elaborate.) I have an Intel HDA physical device (the one built into Asus P5GD1 motherboard), which has eight channels (7.1), to which six (5.1) speakers are connected and also the headphones. ALSA thinks the headphones and the front channel of the speakers are the same, and I failed to configure it otherwise. However, because a pair of outputs (namely, the side channel) is free, an obvious solution would be to plug the front speakers there and have ALSA redirect the channels 0/1 to 6/7. I’m stuck with this seemingly trivial task though. If I use the route plugin, then two programs can’t output sound simultaneously, even if they use different channels. If I choose dshare, then it works, but mixing is gone: only one program can use a given channel, and Amarok won’t even start. If I use dmix, then I get annoying clicks every second or even more often. Each of the asoundrc snippets below works in the sense aplay -D headphones, mplayer -ao alsa:device=speakers produce sound as intended, but each suffers from one of the above drawbacks. With the default settings mixing is completely OK; how do I just rearrange audio channels? http://qwertty.com/tmp/alsa-info.txt is available, though I don’t think it’s needed. My attempts: #################### route #################### pcm.hda71 { type plug slave.pcm "surround71" } pcm.headphones { type route slave.pcm "hda71" slave.channels 8 ttable.0.0 1 ttable.1.1 1 } pcm.speakers { type route slave.pcm "hda71" slave.channels 8 ttable.0.6 1 ttable.1.7 1 ttable.2.2 1 ttable.3.3 1 ttable.4.4 1 ttable.5.5 1 } #################### dshare #################### pcm.headphones { type dshare ipc_key 3071 slave.pcm "hw:0" slave.channels 8 bindings { 0 0 1 1 } } pcm.speakers { type dshare ipc_key 3071 slave.pcm "hw:0" slave.channels 8 bindings { 0 6 1 7 2 2 3 3 4 4 5 5 } } pcm.!default { type dshare ipc_key 3071 slave.pcm "hw:0" slave.channels 8 channels 6 bindings { 0 0 1 1 0 6 1 7 2 2 3 3 4 4 5 5 } } #################### dmix #################### pcm.hda71 { type dmix ipc_key 2071 slave { pcm "hw:0,0" channels 8 rate 48000 periods 128 period_time 0 period_size 2048 buffer_time 0 buffer_size 4096 # Experimented with settings a lot, clicks persist... } } pcm.headphones { type route slave.pcm "hda71" slave.channels 8 ttable.0.0 1 ttable.1.1 1 } pcm.speakers { type route slave.pcm "hda71" slave.channels 8 ttable.0.6 1 ttable.1.7 1 ttable.2.2 1 ttable.3.3 1 ttable.4.4 1 ttable.5.5 1 } pcm.!default { type route slave.pcm "hda71" slave.channels 8 ttable.0.0 1 ttable.1.1 1 ttable.0.6 1 ttable.1.7 1 ttable.2.2 1 ttable.3.3 1 ttable.4.4 1 ttable.5.5 1 } -- TIA Roman.
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