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Old 08-12-2010, 02:01 PM   #1
Registered: Apr 2002
Location: OK, USA
Distribution: Slackware64
Posts: 195

Rep: Reputation: 37
/dev/dsp|video - clone, fork, sharing of the device

I'm looking for a way to take one device like /dev/dsp or /dev/video and pipe it to another, new device...

source: /dev/dsp
destination1: /dev/dsp1
destination2: /dev/dsp2

The same with the video device...

1. Be able to stream audio only on one device
2. Be able to stream video and audio on the other device
3. Be able to stream audio/video to DISK w/ 1 app and to the LAN with another app...

Right now, once one application uses the device, it locks it so other applications can't use that device...

I did find that my /dev/audio1 is the same device as /dev/dsp1 so when one is used the other gets locked too =/

I've looked at JACK! but it doesn't seem to work for me, yet... mencoder doesn't have an option to record with jack.

Another option which i'd like to avoid is to get a second sound card and just pipe /dev/dsp1 to /dev/dsp2 with a phisical cable... It would let me work with audio, but not the video... (I suppose I could grab another TV card but there should be a simpler route...)

Old 08-13-2010, 06:55 AM   #2
Registered: Apr 2002
Location: OK, USA
Distribution: Slackware64
Posts: 195

Original Poster
Rep: Reputation: 37
I've been messing with JACK Audio Connection Kit... This is what I have found:

# start jack
jackd -R -d oss -r 32000 -C /dev/dsp1 &
# start darkice
darkice -c darkice.cfg

# at this point, I stream the /dev/dsp1 over the LAN... all works

# start mencoder
mencoder tv:// ...:adevice="plug:SLAVE=jack":alsa:...

# at this point mencoder begins recording...
# once mencoder stops, the darkice stream stops... darkice and jackd is still running but I no longer recieve sound...
# If i start mencoder again then I get sound from darkice -- until mencoder stops...
# The other thing is that the mencoder audio doesn't exist - its quiet...

Edit: I think I may just be fighting an old tv card (saa7134 - KWorld Global TV Terminator)

Is there anything out there to create more devices or something?
I've tried dd if=/dev/video0 of=/dev/video1 and even cat /dev/video0 | tee /dev/video1 - no worky...

Can you build a circular buffer that I can pass /dev/video0 to and have other apps read it? (multiple apps)

Last edited by Micah; 08-13-2010 at 06:59 AM.
Old 07-14-2012, 04:29 PM   #3
LQ Newbie
Registered: Jul 2012
Posts: 1

Rep: Reputation: Disabled
I found vloopback kernel module, but it does not work on new kernel.



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