A Multimedia Tutorial For FreeBSD

As I have spent more and more time checking out the Linux and Unix forums on this site, I have realized the volume of dedicated Unix enthusiasts. Realizing not many articles on Exam Notes apply directly to them, I have decided to dedicate an entire article to FreeBSD, which is a Unix derivative developed at the Berkley Campus of the University of California.

In the old days, FreeBSD didn’t offer much along the lines of Sound support but that has all changed. FreeBSD now can provide sound and multimedia support as good as, or better than, and Windows system. In this article, I’m going to explain how you can:

· Set up the kernel for multimedia support

· Set device nodes

· Learn to use multimedia applications

· Rip CD’s using FreeBSD

Sound Card Support

Chances are really good that if you have a common sound card, FreeBSD will support it. In order to check to see if your sound card is supported and if there is a PCM driver loaded you need to search through your Kernel configuration file to find a line that says:

device pcm

If you are able to find that line it means that sound support is already configured in your FreeBSD kernel. If you don’t see the line, don’t panic! If you were to see this line it would mean that you have been working ahead and had already configured your own custom FreeBSD kernel. I didn’t expect you to be able to find the line at this time – but I wanted to save those who had been working ahead a few steps.

In order to add sound to your FreeBSD kernel, you will need to type the following at the command prompt:

$ cd /usr/src/sys/i386/conf

By typing that entry at the command prompt you are telling FreeBSD that you want to change to the directory where the Kernel Configuration files are kept.

After arriving in this directory, logout and log back in as Root. After logging back in as Root, you need to copy the GENERIC file in this directory to a new file that you have named. In this instance, we are going to copy the GENERIC File to a file called SOUNDKERN. In order to copy GENERIC to SOUNDKERN, you need to type the following at the command prompt:

# cp GENERIC SOUNDKERN

If you are familiar with copying files through Windows or DOS, you will know that when you copy a file it appears in the new location, and also in the old location. Therefore, your new file called SOUNDKERN will be a carbon copy of GENERIC. You will want to look in your new SOUNDKERN file, for a file named LINT. LINT contains drivers for sound cards, along with other files that we won’t be discussing at this time.

When you locate the LINT file, you will find two different sets of drivers for soundcards:

· Voxware

· PCM

Voxware drivers – These drivers are very old, and work better with older sound cards that may not be supported by PCM. Beginning in FreeBSD 5.0, Voxware drivers will no longer be supported by FreeBSD.

PCM drivers – These drivers are newer drivers for use with FreeBSD and support most newer sound cards.

PCM Sound Card Drivers

As we have discussed, PCM sound card drivers support most newer sound cards. In order to install the PCM sound card drivers and set up your new SOUNDKERN file, you need to type the following command at the command prompt:

# device PCM

You will now need to copy the sound files from the LINT file to the very end of your new SOUNDKERN file, and save. Then, in order to build and install your new kernel, you will need to enter a series of commands at the command prompt. Since you have already logged on as Root while in the /usr/src/sys/i386/conf directory, you should have no problems with this.

At the command prompt in this directory you need to type config SOUNDKERN, for example:

/usr/src/sys/i386/conf # config SOUNDKERN

After typing this command, you are going to want to change to the SOUNDKERN directory in order to compile it. To do this, you need to type cd ../..compile/SOUNDKERN at the command prompt. For example:

/usr/src/sys/i386/conf # cd…/…/compile/SOUNDKERN

You should now find yourself in the /usr/src/sys/compile/SOUNDKERN directory. At this point, it is time to build the new kernel. In order to create the new kernel, you need to tell FreeBSD that you want to make and install the new Kernel. In order to do this, you need to type the following commands at the command line:

/usr/src/sys/i386/compile/SOUNDKERN # make depend

/usr/src/sys/compile/SOUNDKERN # make

/usr/src/sys/compile/SOUNDKERN # make install

Now, for those of you who are used to Windows, you know that whenever you install a new program or make big changes to the system, in order for them to take effect you have to reboot your machine. FreeBSD is the same way when compiling a new kernel. In order to tell FreeBSD to reboot, you need to type the following line at the command prompt:

/usr/src/sys/compile/SOUNDKERN # /sbin/reboot

FreeBSD will now begin the process of creating the new kernel that you have just configured! This can take anywhere from 10-30 minutes, depending upon the speed of your system. After the kernel has been created, you system will reboot. Upon rebooting, you will need to set up device nodes.

Device Nodes

Now that you have created your new kernel, and rebooted your computer you need to login as Root. You should now use the dmesg command in order to see if your sound card has been detected. For example:

# dmesg | grep pcm

After pressing enter, all PCM devices should be listed on your screen. If you do not see any PCM devices listed, you need to reconfigure SOUNDKERN so that the right device shows up.

If your listed PCM device ends in 0, you need to enter the following commands at the command prompt:

# cd /dev

# sh MAKEDEV snd 0

If your listed PCM device ends in 1, you need to type the following commands at the command prompt:

# cd /dev

# sh MAKEDEV snd1

These commands will not create a PCM device, but they do create device nodes! The MAKEDEV device nodes are explained in Table 1.1.

Table 1.1

MAKEDEV Device Nodes and Related Devices

When FreeBSD 5.0 stable is released, it will use a new file system called DEVFS. DEVFS will create and build device nodes every time your system boots, and therefore you will not have to use the MAKEDEV command.

The Control Port Mixer

Out of all of the Device Nodes mentioned in Table 1.1, the most important is the Control Port Mixer. The FreeBSD mixer shows you the percentages that each of your sound devices are set to for both the left and right audio channels. In order to access the FreeBSD mixer you need to type mixer at the command prompt. For example:

# mixer

After pressing Enter, information similar to the following should appear on your screen:

Mixer vol is currently set to 80:80

Mixer bass is currently set to 75:75

Mixer treble is currently set to 75:75

Mixer synth is currently set to 60:60

Mixer pcm is currently set to 80:80

Mixer speaker is currently set to 90:90

Mixer line is currently set to 75:75

Mixer mic is currently set to 0:0

Mixer cd is currently set to 85:85

Mixer igain is currently set to 0:0

Mixer ogain is currently set to 60:60

If you have ever run a stereo or an audio program before, you know what bass, treble are. It’s also not to difficult to figure out that PCM controls the sound for the PCM devices, Speaker controls the sound for the speakers, that CD controls the volume for the CD-ROM drive, and that MIC controls the volume for any microphones on your system. The other mixer items are a little bit more difficult to decipher. These items are explained in Table 1.2.

Table 1.2

Mixer Items and Their Primary Functions

MP3 Players For Your FreeBSD System

I would imagine that you are probably ready to strangle me by now, because I promised that this would be fun. Now that you have completed the more difficult tasks, its time to set up and install an MP3 player for your FreeBSD system. Let’s Rock!

XMMS

The MP3 player you will hear most about for Unix and BSD, as well as for Linux systems is XMMS. Fortunately, XMMS is also very easy for Windows users to learn, and to use. The reason Windows users find XMMS so easy to master is that it resembles one of their trusty sidekicks – Winamp. XMMS is as close to a twin to Winamp as you can get. The both look very much the same, the controls are in the same places, and the controls also work the same. Winamp skins even work with XMMS!

In order to install XMMS, login to your computer as Root. After logging in as Root, connect to the Internet and enter the following command at the command prompt:

# cd/usr/ports/audio/xmms

# make install

After XMMS has finished installing, simply type the following command at the command prompt in order to begin using XMMS:

# xmms &

NOTE: You can type the command to start XMMS as a regular user, or as Root. Since you are already logged in as Root, I used the Root command prompt in my example.

Decoding and Burning MP3’s

Now that you have set up your device nodes, and installed an MP3 player, we are going to talk about decoding and burning MP3’s. In order to burn your favorite MP3’s onto a CD-R or CD-RW, the MP3 has to be converted into a non-compressed file format.

While this sounds complicated, its really not, and can be done through XMMS. In order to decode and burn an MP3 to a CD, you need to have XMMS open, and follow these steps:

1. Right-click the XMMS window

2. The XMMS menu should now appear on your screen

3. Select the Options menu

4. Select Preference

5. Find Output Plugin, and change it to Disk Writer Plugin

6. Click the Configure button

7. Select the directory you want to place the files in once they are uncompressed

8. Put the MP3 file into XMMS

9. Turn the volume for the MP3 file up to 100%

10. Turn of the EQ settings for XMMS off

11. Click Play

12. XMMS will now appear to be playing an MP3, but you won’t be able to hear it. If the volume is 100%, it seems a little strange that you won’t be able to hear it. The reason is that XMMS is playing the MP3 to a WAV file that can be burned to a CD.

By: Tracey J. Rosenblath

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