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nasask8r
n00b
Joined: 16 Jul 2007
Posts: 32
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 Posted: Sat Nov 02, 2013 4:16 am Post subject: JACK upmixing + IEC958 Output in ALSA |
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Calling all ALSA configuration experts! I've been struggling with this for the past couple days and I can't seem to figure out the correct configuration. Any and all help would be greatly appreciated.
My setup:
I have an Audigy 2 ZS Platinum and I use the IEC958 optical output for digitally encoded 5.1 surround out to my receiver.
What I want:
I want to automatically upmix the output of applications using the ALSA 'default' device as well as my playback_1 and playback_2 outputs from JACK to 5.1 and digitally encode the resulting signal to send to my receiver. Alternatively, if the above isn't possible, I'd be okay with having 6 outputs in JACK, as long as they could be digitally encoded and sent out over IEC958.
What I have working:
- Using the following in my /etc/asound.conf, I can upmix output of applications using the ALSA 'default' device to 5.1:
| Code: | pcm.Filter_A52Encode {
type a52
bitrate 448
card 0
}
pcm.Filter_SimpleUpmix {
type upmix
slave.pcm "Filter_A52Encode"
channels 6
}
pcm.!default{
type plug
slave.pcm "Filter_SimpleUpmix" |
- I can send JACK outputs to the IEC958 optical output of my soundcard by adding the following configuration to /etc/asound.conf (and using the device 'jack51' when starting jackdbus), but it only sends two channels (so I only get L+R):
| Code: | ctl.jack51 {
type hw
card 0
}
pcm.jack51 {
type asym
playback.pcm {
type plug
slave.pcm "iec958"
route_policy duplcate
}
}
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- I can get analog 5.1 out of JACK by using the following instead:
| Code: | ctl.jack51 {
type hw
card 0
}
pcm.jack51 {
type asym
playback.pcm {
type plug
slave.pcm "surround51"
slave.channels 6
route_policy duplcate
}
capture.pcm {
type hw
card 0
}
} |
What doesn't work:
- My JACK outputs won't be upmixed or sent over IEC958, even if I set the JACK device to 'default'.
- Adding the channels parameter when using the slave.pcm 'iec958'. JACK won't start, so I suspect 'iec958' doesn't support a 'channels' parameter (although I'm having a hard time finding documentation).
- Changing ctl.jack51 to plug into the Filter_SimpleUpmix instead of going directly to the hardware. |
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PaulBredbury
Watchman
Joined: 14 Jul 2005
Posts: 7310
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| Posted: Sat Nov 02, 2013 1:18 pm Post subject: |
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See my sig, for an example.
Note that the output should always be via "dmixed", to e.g. ensure that the soundcard is opened for output to 6 speakers rather than only 2.
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