FreeBSD Handbook
Prev | Chapter 8 Multimedia | Next

# 8.2 Setting Up the Sound Card

Contributed by Moses Moore. Enhanced by Marc Fonvieille.

## 8.2.1 Configuring the System

Before you begin, you should know the model of the card you have, the chip it uses, and whether it is a PCI or ISA card. FreeBSD supports a wide variety of both PCI and ISA cards. Check the supported audio devices list of the Hardware Notes to see if your card is supported. The Hardware Notes will also mention which driver supports your card.

To use your sound device, you will need to load the proper device driver. This may be accomplished in one of two ways. The easiest way is to simply load a kernel module for your sound card with kldload(8) which can either be done from the command line:

    # kldload snd_emu10k1

or by adding the appropriate line to the file `/boot/loader.conf` like this:

    snd_emu10k1_load="YES"

These examples are for a Creative SoundBlaster® Live! sound card. Other available loadable sound modules are listed in `/boot/defaults/loader.conf`. If you are not sure which driver to use, you may try to load the `snd_driver` module:

    # kldload snd_driver

This is a metadriver loading the most common device drivers at once. This speeds up the search for the correct driver. It is also possible to load all sound drivers via the `/boot/loader.conf` facility.

If you wish to find out the driver selected for your soundcard after loading the `snd_driver` metadriver, you may check the `/dev/sndstat` file with the `cat /dev/sndstat` command.

A second method is to statically compile in support for your sound card in your kernel. The section below provides the information you need to add support for your hardware in this manner. For more information about recompiling your kernel, please see Chapter 9.

### 8.2.1.1 Configuring a Custom Kernel with Sound Support

The first thing to do is add the audio framework driver sound(4) to the kernel; for that you will need to add the following line to the kernel configuration file:

    device sound

Next, you have to add the support for your sound card. Therefore, you need to know which driver supports the card. Check the supported audio devices list of the Hardware Notes, to determine the correct driver for your sound card. For example, a Creative SoundBlaster Live! sound card is supported by the snd_emu10k1(4) driver. To add the support for this card, use the following:

    device snd_emu10k1

Be sure to read the manual page of the driver for the syntax to use. The explicit syntax for the kernel configuration of every supported sound driver can also be found in the `/usr/src/sys/conf/NOTES` file.

Non-PnP ISA sound cards may require you to provide the kernel with information on the card settings (IRQ, I/O port, etc), as is true of all non-PnP ISA cards. This is done via the `/boot/device.hints` file. During the boot process, the loader(8) will read this file and pass the settings to the kernel. For example, an old Creative SoundBlaster 16 ISA non-PnP card will use the snd_sbc(4) driver in conjunction with `snd_sb16`. For this card the following lines must be added to the kernel configuration file:

    device snd_sbc
    device snd_sb16

and these to `/boot/device.hints`:

    hint.sbc.0.at="isa"
    hint.sbc.0.port="0x220"
    hint.sbc.0.irq="5"
    hint.sbc.0.drq="1"
    hint.sbc.0.flags="0x15"

In this case, the card uses the `0x220` I/O port and the IRQ `5`.

The syntax used in the `/boot/device.hints` file is covered in the sound(4) driver manual page and the manual page for the driver in question.

The settings shown above are the defaults. In some cases, you may need to change the IRQ or the other settings to match your card. See the snd_sbc(4) manual page for more information about this card.

## 8.2.2 Testing the Sound Card

After rebooting with the modified kernel, or after loading the required module, the sound card should appear in your system message buffer (dmesg(8)) as something like:

    pcm0: <Intel ICH3 (82801CA)> port 0xdc80-0xdcbf,0xd800-0xd8ff irq 5 at device 31.5 on pci0
    pcm0: [GIANT-LOCKED]
    pcm0: <Cirrus Logic CS4205 AC97 Codec>

The status of the sound card may be checked via the `/dev/sndstat` file:

    # cat /dev/sndstat
    FreeBSD Audio Driver (newpcm)
    Installed devices:
    pcm0: <Intel ICH3 (82801CA)> at io 0xd800, 0xdc80 irq 5 bufsz 16384
    kld snd_ich (1p/2r/0v channels duplex default)

The output from your system may vary. If no `pcm` devices are listed, go back and review what was done earlier. Go through your kernel configuration file again and make sure the correct device driver was chosen. Common problems are listed in Section 8.2.2.1.

If all goes well, you should now have a functioning sound card. If your CD-ROM or DVD-ROM drive's audio-out pins are properly connected to your sound card, you can put a CD in the drive and play it with cdcontrol(1):

    % cdcontrol -f /dev/acd0 play 1

Various applications, such as `audio/workman` can provide a friendlier interface. You may want to install an application such as `audio/mpg123` to listen to MP3 audio files.

Another quick way to test the card is sending data to `/dev/dsp`, like this:

    % cat filename > /dev/dsp

where ``filename`` can be any file. This command line should produce some noise, confirming the sound card is actually working.

> Note: The device nodes `/dev/dsp*` will be created automatically when needed. If they are not used, they do not exist and will not appear in the output of ls(1).

Sound card mixer levels can be changed via the mixer(8) command. More details can be found in the mixer(8) manual page.

### 8.2.2.1 Common Problems

Error | Solution
--- | ---
`sb_dspwr(XX) timed out` | The I/O port is not set correctly.
`bad irq XX` | The IRQ is set incorrectly. Make sure that the set IRQ and the sound IRQ are the same.
`xxx: gus pcm not attached, out of memory` | There is not enough available memory to use the device.
`xxx: can't open /dev/dsp!` | Check with `fstat | grep dsp` if another application is holding the device open. Noteworthy troublemakers are esound and KDE's sound support.

Another issue is that modern graphics cards often come with their own sound driver, for use with HDMI and similar. This sound device will sometimes be enumerated before the actual soundcard and the soundcard will subsequently not be used as the default playback device. To check if this is the case, run dmesg and look for `pcm`. The output looks something like this:

    ...
    hdac0: HDA Driver Revision: 20100226_0142
    hdac1: HDA Driver Revision: 20100226_0142
    hdac0: HDA Codec #0: NVidia (Unknown)
    hdac0: HDA Codec #1: NVidia (Unknown)
    hdac0: HDA Codec #2: NVidia (Unknown)
    hdac0: HDA Codec #3: NVidia (Unknown)
    pcm0: <HDA NVidia (Unknown) PCM #0 DisplayPort> at cad 0 nid 1 on hdac0
    pcm1: <HDA NVidia (Unknown) PCM #0 DisplayPort> at cad 1 nid 1 on hdac0
    pcm2: <HDA NVidia (Unknown) PCM #0 DisplayPort> at cad 2 nid 1 on hdac0
    pcm3: <HDA NVidia (Unknown) PCM #0 DisplayPort> at cad 3 nid 1 on hdac0
    hdac1: HDA Codec #2: Realtek ALC889
    pcm4: <HDA Realtek ALC889 PCM #0 Analog> at cad 2 nid 1 on hdac1
    pcm5: <HDA Realtek ALC889 PCM #1 Analog> at cad 2 nid 1 on hdac1
    pcm6: <HDA Realtek ALC889 PCM #2 Digital> at cad 2 nid 1 on hdac1
    pcm7: <HDA Realtek ALC889 PCM #3 Digital> at cad 2 nid 1 on hdac1
    ...

Here the graphics card (`NVidia`) has been enumerated before the sound card (`Realtek ALC889`). To use the sound card as default playback device, change `hw.snd.default_unit` to the unit that should be used for playback, enter the following:

    # sysctl hw.snd.default_unit=n

Here, `n` is the number of the sound device to use, in this example `4`. You can make this change permanent by adding the following line to `/etc/sysctl.conf`:

    hw.snd.default_unit=4

## 8.2.3 Utilizing Multiple Sound Sources

Contributed by Munish Chopra.

It is often desirable to have multiple sources of sound that are able to play simultaneously, such as when esound or artsd do not support sharing of the sound device with a certain application.

FreeBSD lets you do this through Virtual Sound Channels, which can be enabled with the sysctl(8) facility. Virtual channels allow you to multiplex your sound card's playback by mixing sound in the kernel.

To set the number of virtual channels, there are three sysctl knobs which, if you are the `root` user, can be set like this:

    # sysctl dev.pcm.0.play.vchans=4
    # sysctl dev.pcm.0.rec.vchans=4
    # sysctl hw.snd.maxautovchans=4

The above example allocates four virtual channels, which is a practical number for everyday use. Both `dev.pcm.0.play.vchans=4` and `dev.pcm.0.rec.vchans=4` are the number of virtual channels `pcm0` has for playback and recording, and are configurable once a device has been attached. `hw.snd.maxautovchans` is the number of virtual channels a new audio device is given when it is attached using kldload(8). Since the `pcm` module can be loaded independently of the hardware drivers, `hw.snd.maxautovchans` can store how many virtual channels any devices which are attached later will be given. Refer to pcm(4) manual page for more information.

> Note: You cannot change the number of virtual channels for a device while it is in use. First close any programs using the device, such as music players or sound daemons.

The correct `pcm` device will automatically be allocated transparently to a program that requests `/dev/dsp0`.

## 8.2.4 Setting Default Values for Mixer Channels

Contributed by Josef El-Rayes.

The default values for the different mixer channels are hardcoded in the sourcecode of the pcm(4) driver. There are many different applications and daemons that allow you to set values for the mixer that are remembered between invocations, but this is not a clean solution. It is possible to set default mixer values at the driver level -- this is accomplished by defining the appropriate values in `/boot/device.hints`, e.g.:

    hint.pcm.0.vol="50"

This will set the volume channel to a default value of 50 when the pcm(4) module is loaded.

Prev | Home | Next
Multimedia | Up | MP3 Audio