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Alighieri
Tux's lil' helper
Joined: 27 Jan 2005
Posts: 88
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 Posted: Tue Aug 30, 2005 4:00 am Post subject: Set default alsa card on usb speaker hotplug |
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I bought a pair of usb speakers and wanted alsa to automatically switch to the usb-audio card when the device is plugged into the usb port. First, make sure you have usb-audio configured. Plugin the speakers and cat /proc/asound/cards. You should see your usb-audio device. Then put the following
| Code: |
#!/bin/sh
CARDNUM=`sed -n 's/\(^[0-9]\).*/\1/p' < /proc/asound/cards | tail -n 1`
cat<<EOF > /etc/asound.conf
pcm.!default {
type hw
card $CARDNUM
}
ctl.!default {
type hw
card $CARDNUM
}
EOF
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in /etc/dev.d/sound/alsa-default.dev (name is unimportant, but must end in .dev). Make it executable. Whenever there is a sound hotplug event, the default alsa card will be the last one listed in /proc/asound/cards. This also works when the speakers are unplugged (returns to card 0). |
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BlueShadow
n00b
Joined: 30 Nov 2004
Posts: 24
Location: Switzerland
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| Posted: Mon Dec 05, 2005 4:08 pm Post subject: |
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Well that is exactly what I tried to do. I have an Creative Soundblaster MP3 USB-Card.
This works just great, I only had to adopt your script for my asound.conf.
Thx very much |
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henri
Apprentice
Joined: 15 Nov 2002
Posts: 182
Location: Germany
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| Posted: Fri Jun 30, 2006 9:31 am Post subject: |
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Hi Alighieri,
really: Great! It was also exactly what I was searching for 
It would be very nice if this hint could be added to the gentoo ALSA howto because laptops become more and more common and external USB speakers will probabely be the choice of many users.
But I had to change the CARDNUM fetching line from...
| Code: | | CARDNUM=`sed -n 's/\(^[0-9]\).*/\1/p' < /proc/asound/cards | tail -n 1` |
...to...
| Code: | | CARDNUM=`grep -o -e '[[:digit:]]' < /proc/asound/cards | tail -n 1` |
Many thanks for your posting,
yours Henri |
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