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This chapter is from the book


Multimedia is playing an increasingly important role in modern desktops, and most people like to listen to music, watch movies, and watch videos on their desktops. Unfortunately, multimedia has had something of a checkered history in the Linux world due to the licensing problems with the all-important codecs required to view and hear media. This section explores some of the common problems faced with multimedia and your Ubuntu desktop.

I Downloaded a Particular Media File, and It Won’t Play

Included with Ubuntu are open source codecs such as Ogg Vorbis and Ogg Theora, but the vast majority of media on the Internet use restrictively licensed codecs such as MP3, Windows Media, QuickTime, and others.

Ubuntu does not ship these codecs for legal reasons. It’s legally questionable to freely distribute most multimedia codecs because either the codec is patented or the player is reverse engineered and, as such, may fall afoul of the Digital Millennium Copyright Act (DMCA) in the United States. For most codecs, when you attempt to play the multimedia file, the movie or audio player will attempt to install the codecs as they are needed.

Ubuntu 7.04 began shipping a new tool to help address this problem. If you try to play a file without a necessary codec, Ubuntu will prompt you and allow you to automatically install any available codecs that can decode the file in question.

My DVD Won’t Play

As with the previous problem, DVD playback is also a somewhat restricted process that requires special software to be installed. The software is available if needed. See http://help.ubuntu.com/community/RestrictedFormats/PlayingDVDs for more details.

DVD Playback Is Jittery and Jumpy

When you watch DVD movies on your computer, you may find that they are jittery and unstable. In most cases the problem is that the direct memory access (DMA) mode in your DVD drive is not enabled. When you enable this mode, your problems should disappear.

Check whether DMA mode is enabled by running this command:

foo@bar:~$ sudo /sbin/hdparm /dev/hdc | grep dma

Most DVD drives are /dev/hdc, but change the final letter if yours is different. If DMA mode is not enabled, you will see this:

using_dma   = 1 (on)

To turn on DMA mode, run this command:

foo@bar:~$ sudo /sbin/hdparm -d1 /dev/hdc

Now try to play your DVD.

If this solves your problems, you should edit /etc/hdparm.conf and add the following block:

/dev/hdc {
    dma = on

When I Start Some Applications, I Hear No Sound on Playback

There are literally hundreds of thousands of applications for the Linux system, and many of them have different requirements and dependencies. One area in which this can be a problem is audio software. Each audio application relies on one of many sound servers: pieces of software that manage communication with the sound card. These sound servers come in many forms, including pulseaudio, GStreamer, aRts, and JACK.

In Ubuntu, pulseaudio is the default sound server. Although the multimedia applications included with your desktop work fine, some other applications (such as Audacity) may fail to play with pulseaudio running. To solve this, go to Applications > System Tools > System Monitor. In the list of processes, click on pulseaudio, and click the End Process button. By stopping pulseaudio, you can now use the application.

My Microphone Doesn’t Work

Although it seems like an obvious first point to check, make sure that you have plugged your microphone into the right socket. Many computers include a number of audio inputs/outputs, and they can be easily confused. In recent years, a number of hardware manufacturers seem to have gone out of their way to poorly mark these sockets, so don’t worry if you get them mixed up. If in doubt, consult your manual.

With the microphone properly plugged in, load up the recording level monitor by clicking Applications > Sound & Video > Sound Recorder, press Record, and speak into your microphone. If you record nothing, you need to turn on and adjust the volume of your microphone. To do this, right-click the volume icon in the notification area, and select Open Volume Control. Inside the dialog that pops up, click the Capture tab, and make sure that the microphone sliders are near the top and that the small microphone icon does not have a red cross on it. Clicking this icon toggles whether devices are muted.

Now speak into the microphone, and you should see the recording level monitor flash.

My Sound Is Distorted

If you are experiencing distorted sound, one common cause is volume that is set too high. Open the Volume Control mixer by double-clicking on the Speaker in the upper right of your panel, beside the clock. Then set the PCM setting to around 70 percent. This might solve your problem.

How Do I Change the Visual Theme?

To change the way your Ubuntu desktop looks, click System > Control Center and choose Theme under the Look & Feel section. You will see a screen similar to that shown in Figure 6-4.

From there, you can select predefined themes or click Customize to create a custom theme. Changes are applied immediately. If you click Customize, you get a dialog box with three tabs. All themes are separated into three parts: the elements (buttons, text fields, and so on), the window frame (the title bar), and icons. If you have downloaded new themes, drag them into the theme details window, and click Install Theme. When you are done, click Close.

How Do I Find and Install New Desktop Themes and Backgrounds?

We all love tweaking our desktops so they look individual to our own tastes and preferences. Luckily, the desktop is very flexible in how it can be visually configured. To make this as simple as possible, the GNOME Art Web site was created to host a huge array of wallpapers and themes. You can use the site to spruce up your desktop.

To make this even easier, you can use the art manager tool to find new themes and backgrounds, but it is not installed by default. To install it, use Synaptic to install the gnomeart package. After it is installed, click System > Preferences > Art Manager.

To find desktop backgrounds, click Art > Backgrounds > All. If you don’t want to see GNOME backgrounds, click Art > Backgrounds > Other. Alternatively, if you want only GNOME backgrounds, click Art > Backgrounds > GNOME. The art manager downloads thumbnails and descriptions of all available backgrounds. The latest backgrounds are at the bottom of the list. Select one from the list. To show the background in detail, click Preview. To install it, click Install. The Change Background window then shows the installed background. From there you can optionally change its style. When you’re done, click Finish to get back to the art manager.

To find desktop theme elements, click Art > Desktop Themes > Application. The latest are at the bottom of the list. A sample window displaying the selected theme can be seen by clicking Preview. To install the theme, click Install. Then from the Theme window, choose the newly installed theme and then click the Close button to get back to the art manager.

Finding new window borders and icon themes works in a similar way. You can also install splash screens and login screens, but the former are not used by default in Ubuntu (though they can be enabled in the session manager), and the latter cannot be installed directly. GTK+ engines are seldom used. None of the applications installed by default use it.

How Do I Turn My Ubuntu Computer into a MythTV Box?

MythTV is a collection of applications that can convert a computer into a full-fledged media center with the ability to pause live TV, record shows, play music, play videos, play DVDs, access weather information, and more. More details about MythTV are available at www.mythtv.org. MythTV also goes to great lengths to look like a normal TV device and not like a computer plugged into a TV (see Figure 6-5 for an example).

To install a full MythTV system, install each of the mythtv packages available in Synaptic. You also need to install a few other packages:

  • xmltv: This is used to grab TV listings in XML formatting.
  • DVD support: To learn how to enable watching DVDs, you should refer to the Ubuntu wiki and install the relevant packages.
  • lirc: Install this if you want to use a remote control.

MythTV comes in two major parts: the front end and the back end. The back end is used to perform the grunt work such as recording and processing shows, and the front end provides an attractive user interface. With this architecture, you could run the back end on a bulky, noisy machine elsewhere in the house and run the front end on a fanless, attractive little machine in your living room.

Fortunately, a new Ubuntu derivation, Mythbuntu has been created and makes the installation of MythTV on Ubuntu a breeze. Take a look at the Mythbuntu Web site at http://mythbuntu.org.

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