Difference between revisions of "Snd-bt87x"

Revision as of 21:41, 18 October 2006

What Is It?

snd-bt87x is a Linux kernel driver for the Advanced Linux Sound Architecture (ALSA). It allows you to capture digitized sound directly from a bt87x capture card, without hooking it to your sound card.

For more information of bt87x capture cards, see bttv.

For a more generic overview of TV audio-over-PCI, including other (non-bttv) analog cards, see PCI TV audio.

Installing the Module

To use the snd-bt87x driver, the driver module needs to be installed. To see if your Linux distribution has already installed it, try

# find /lib/modules/`uname -r` -name 'snd[-_]bt87x*'

If it returns a filename, the module is installed. If it doesn't, you will have to get it installed. To do that, you will probably have to do one of the following:

• install it from a package included with your Linux distribution
• build it from the kernel source code included with your Linux distribution
• build it from the ALSA source code (available at http://www.alsa-project.org)

Loading the Module

Once the module is installed, it needs to be loaded. To see if your Linux distribution has already loaded it, try

# lsmod | grep 'snd[-_]bt87x'

If it returns one or more lines, the module is already loaded. If not, you will need to load it yourself. To do that, try

# modprobe snd-bt87x

If it doesn't give you any errors, use the lsmod command above to confirm that it's loaded.

Making Sure the Module Recognized Your bt87x Card

Sometimes the driver doesn't recognize a bt87x card. To make sure that your card was recognized, try

# cat /proc/asound/cards

The output should have one or more lines that look something like

1 [Bt878 ]: Bt87x - Brooktree Bt878

If it doesn't, you can reload the module using the load_all option, so it will recognize more cards. To do this, do

modprobe -r snd-bt87x; modprobe snd-bt87x load_all=1

Now, the 'cat' command above should show your card.

Making Your System Load the Module When it Boots

Different Linux distributions use different configuration files to load and configure modules. Here's what you need to do for some distributions.

• Mandriva
  • 2007
    • echo "snd-bt87x" >>/etc/modules # load the module on boot
    • echo "options snd-bt87x load_all=1" >>/etc/modprobe.conf # OPTIONAL - if required for your bt87x card

Using the Module

Once the module is loaded, it creates one or more ALSA sound card instances, one for each bt87x card it found. To see these, type

# cat /proc/asound/cards

The number preceding the card you are interested in, is the ALSA sound card number.

If your system uses udev, or devfs, a corresponding device file should be created automatically. It will probably be named /dev/dsp for ALSA sound card zero, or /dev/dsp<ALSA sound card number>.

If the device file has not been created, please refer to the documentation for your Linux distribution to determine how to create it.

Once you know the device

cat /dev/dsp1 >/dev/dsp

Card Specific Information

• ATI TV Wonder
  • I have a plain ATI TV Wonder and snd-bt87x was loading, but not seeing the card. To get it

Distribution Specific Information

• Mandriva Linux 2007