Section 9.6. Multimedia Applications

Once you have your hardware configured under Linux, you'll want to run some multimedia applications. So many are available for Linux that they can't possibly be listed here, so we instead describe some of the general categories of programs that are available and list some popular representative applications. You can look for applications using the references listed at the end of the chapter. Toward the end of the chapter, you will also find more in-depth descriptions of some popular or particularly useful applications.

These are the major categories of multimedia applications that are covered:

  • Mixer programs for setting record and playback gain levels

  • Multimedia players for audio and video files and discs

  • CD and DVD burning tools for authoring audio and video discs

  • Speech tools, supporting speech recognition and synthesis

  • Image, sound, and video editing tools for creating and manipulating multimedia files

  • Recording tools for generating and manipulating sound files

  • Music composition tools for creating traditional music scores or music in MIDI or MP3 format

  • Internet telephone and conferencing tools for audio communication over computer networks

  • Browser plug-ins for displaying multimedia data within a web browser

9.6.1. Sound Mixers

Sound mixers allow one to modify the hardware gain levels and input devices for your sound card. Most sound mixers are similar. If you are running KDE or GNOME you'll generally get the best results using the mixer provided with your desktop, which typically will appear as a speaker icon on your desktop's panel. Command line mixer programs such as aumix can be useful for use in scripts or startup files to set audio gains to desired levels during login, or when you are not running a graphical desktop, such as a remote login.

Figure 9-1 shows a screenshot of KMix, the mixer provided by KDE.

Figure 9-1. KMix

9.6.2. Multimedia Players

Media players are the area with the greatest selection of applications and widest range of features and user interfaces. No one application meets everyone's needssome aim to be lightweight and fast, whereas others strive to offer the most features. Even within the KDE desktop, for example, a half dozen different players are offered.

If you are running a desktop environment, such as KDE or GNOME, you likely already have at least one media player program. If so, it is recommended that you use this player, at least initially, since it should work correctly with the sound server used by these desktop environments and provide the best integration with the desktop.

When choosing a media player application, here are some of the features you can look for:

  • Support for different sound drivers (e.g., OSS and ALSA) or sound servers (KDE aRts and GNOME esd).

  • An attractive user interface. Many players are "skinnable," meaning that you can download and install alternative user interfaces.

  • Support for playlists, allowing you to define and save sequences of your favorite audio tracks.

  • Various audio effects, such as a graphical equalizer, stereo expansion, reverb, voice removal, and visual effects for representing the audio in graphical form.

  • Support for other file formats, such as audio CD, WAV, and video formats.

Here is a rundown of some of the popular media player applications:


Xmms is one popular media player, with a default user interface similar to Winamp. You can download it from if it is not included in your Linux distribution. A screenshot is shown in Figure 9-2.

Figure 9-2. Xmms


Xine is a full-featured audio and video media player that supports many file formats and streaming media protocols. The project is hosted at the following site: A screenshot is shown in Figure 9-3.

Figure 9-3. Xine


MPlayer is another popular video player that supports a wide range of file formats, including the ability to load codecs from Windows DLLs. It supports output to many devices, using X11, as well as directly to video cards. The project's home page is

Due to legal issues, MPlayer is not shipped by most Linux distributions and so must be downloaded separately.

9.6.3. CD and DVD Burning Tools

If you are running KDE or GNOME, basic CD data and audio burning support is available within the file manager. If you want to go beyond this, or need more help to step you through the process, specialized applications are available.

Note that many of the graphical CD burning applications use command-line tools such as cdrecord and cdrdao to perform the actual CD audio track extraction, ISO image creation, and CD recording. For maximum flexibility, some advanced users prefer to use these tools directly.


One of the first graphical CD burner applications was X-CD-Roast. Although newer applications may offer a more intuitive wizard interface, it is still a reliable and functional program. A screenshot is shown in Figure 9-4.

Figure 9-4. X-CD-Roast


K3b is a popular KDE CD burning tool. It presents a file manager interface similar to popular Windows CD burning utilities such as Easy CD Creator. A screenshot is shown in Figure 9-5. You can find an introduction to K3b in "Burning CDs with K3b," in Chapter 3.

Figure 9-5. K3B


Gcombust is a graphical burner application that uses the Gtk toolkit. The project's home page is A screenshot is shown in Figure 9-6.

9.6.4. Speech Tools

Speech synthesis and recognition have applications for accessibility and specialized applications, such as telephony, where only an audio path is available.

Speech synthesis devices fall into two major types. Dedicated hardware synthesizers are available that act as a peripheral to a computer and perform the text-to-speech function. These have the advantage of offloading the work of performing the speech conversion from the computer, and tend to offer good-quality output. Software synthesizers run on the PC itself. These are usually lower cost than hardware solutions but add CPU overhead and are sometimes of poor quality if free software is used.


The Rsynth package provides a simple command-line utility called say that converts text to speech. It is included with or available for most Linux distributions.

Figure 9-6. Gcombust


Emacspeak is a text-based audio desktop for visually impaired users. It offers a screen reader that can be used with a hardware or software text-to-speech synthesizer. More information can be found on the project's web site, available here:


Festival is a software framework for building speech synthesis systems. It supports multiple spoken languages and can be used to build systems programmed using the shell, C++, Java, and Scheme. The home page for the project is found at

IBM ViaVoice

IBM offers a Linux version of the ViaVoice speech SDK that provides both text-to-speech conversion as well as speech recognition. This is a commercial (nonfree) software product.

9.6.5. Image, Sound, and Video Editing and Management Tools

This section describes some of the popular tools for editing images , video, and sound files, as well as managing image collections:


The GIMP is the GNU Image Manipulation Program. It is intended for tasks such as photo retouching, image composition, and image authoring. It has been in active development for several years and is a very stable and powerful program. A screenshot is shown in Figure 9-7. The official web site for the GIMP is

Figure 9-7. GIMP


CinePaint, formerly called Film Gimp, is a painting and image retouching program designed for work with film and other high-resolution images. It is widely used in the motion picture industry for painting of background mattes and frame-by-frame retouching of movies. CinePaint is based on The GIMP but has added features for film editing, such as color depths up to 128 bits, easy navigation between frames, and support for motion picture file formats such as Kodak Cineon, ILM OpenEXR, Maya IFF, and 32-bit TIFF. A screenshot is shown in Figure 9-8. The CinePaint web site is

Figure 9-8. CinePaint


Gphoto2 is a set of digital camera applications for Linux and other Unix-like systems. It includes the libgphoto2 library, which supports nearly 400 models of digital cameras. The other major components are gphoto2, a command-line program for accessing digital cameras, and Gtkam, a graphical application. The project's home page is A screenshot of Gtkam is shown in Figure 9-9.


Digikam is the KDE digital camera application. It uses libgphoto2 to interface to cameras. A screenshot is shown in Figure 9-10.


Kooka is the KDE scanner program. It supports scanners using the SANE library. As well as basic image scanning, Kooka supports optical character recognition of text using several OCR modules. A screenshot is shown in Figure 9-11.

9.6.6. Imaging Tools

A variety of tools are available for acquiring, manipulating, and managing digital images on your computer. In this chapter, we look at some of them. Image management with KimDaBa

Many applications for viewing images exist, and in our experience, they can be grouped into two main categories: those which are good at generating HTML pages from your image sets, and those which are cool for showing fancy slide shows. The number of applications in both categories is counted in hundreds if not thousands, mostly differing in things that would be considered taste or even religion. You can browse the Linux application sites for your favorite application. Here we focus on an application with a slightly different set of design goals.

Figure 9-9. Gtkam

Figure 9-10. Digikam

Figure 9-11. Kooka

KimDaBa (KDE Image DataBase) is best explained by the following quote from its home page:

If you are like me you have hundreds or even thousands of images ever since you got your first camera, some taken with a normal camera, others with a digital camera. Through all the years you believed that until eternity you would be able to remember the story behind every single picture, you would be able to remember the names of all the persons on your images, and you would be able to remember the exact date of every single image.

I personally realized that this was not possible anymore, and especially for my digital imagesbut also for my paper imagesI needed a tool to help me describe my images, and to search in the pile of images. This is exactly what KimDaba is all about.

The basic idea behind KimDaBa is that you categorize each image with who is in it, where it was taken, and a keyword (which might be anything you later want to use for a search). When looking at your images, you may use these categories to browse through them. Figure 9-12 shows the browser of KimDaBa.[*]

[*] You may add your own categories if the ones described do not fit your usage of KimDaBa.

Figure 9-12. Browsing images with KimDaBa

Browsing goes like this: at the top of the list shown in Figure 9-12 you see items for Keywords, Locations, Persons, and so on. To find an image of, say, Jesper, you simply press Persons and, from the list that appears, choose Jesper. Now you are back to the original view with Keywords, Locations, Persons, and so forth. Now, however, you are in the scope of Jesper, meaning that KimDaBa only displays information about images in which Jesper appears. If the number of images is low enough for you to find the image you have in mind, then you may simply choose View Images. Alternatively, repeat the process. If you want to find images with Jesper and Anne Helene in them, then simply choose Persons again, and this time choose Anne Helene. If you instead want images of Jesper in Las Vegas, then choose Locations and, from that view, Las Vegas.

There is no such thing as a free lunch. For KimDaBa this means that you need to categorize all your images, which might be a rather big task if you have thousands of images. KimDaBa is, however, up to this task after all, one of its main design criteria is to scale up to tens or even hundreds of thousands of images.

There are two ways of categorizing images in KimDaBa, depending on your current focus, but first and foremost let's point out that the categorizing tasks can be done step by step as you have time for them.

The first way of categorizing images is by selecting one or more images in the thumbnail view (which you get to when you press View Images), and then press the right mouse button to get to the context menu. From the context menu, either choose Configure Images One at a Time (bound to Ctrl-1) or Configure All Images Simultaneously (bound to Ctrl-2).

Configure All Images Simultaneously allows you to set the location of all images from, say, Las Vegas with just a few mouse clicks, whereas Configure Images One at a Time allows you to go through all the images one by one, specifying, say, who is in them.

Figure 9-13 shows the dialog used for setting properties for the images. In this dialog you may either select items from the list boxes or start typing the name in questionKimDaBa will offer you alternatives as you type. (In the screenshot, I only typed J, and KimDaBa thus found the first occurrence that matched.)

The alternative way of specifying properties is to do it while you view your images (e.g., as a full-screen slide show). In this mode, you simply set a letter token on the image by pressing the letter in question. This usage is intended for fixing annotations later onsay you are looking at your images and realize that you forgot to mark that Jesper is in a given image. Once you have set a number of tokens, you can use these for browsing, just as you use persons, locations, and keywords. What you typically would do is simply to browse to the images with a given token, and then use the first method specified previously to set the person missing in the images.

Once you have annotated all your images, you can drive down memory lane in multiple ways. As an appetizer, here is a not-so-uncommon scenario derived from personal use of KimDaBa: you sit with your girlfriend on the living-room sofa, discussing how much fun you had in Mallorca during your vacation in 2000, and agree to grab your laptop to look at the images. You choose Holiday Mallorca 2000 from the keyword category, and start a slide show with all the images. As you go on, you see an image from when you arrived home. On that image is an old friend who you haven't talked to in a long time. In the full-screen viewer, you press the link with his name (all the information you typed in is available during viewing in an info box). Pressing his name makes KimDaBa show the browser, with him in scope. Using the date bar, you now limit the view to only show images of him from 1990 to 2000. This leads you to some images from a party that you attended many years ago, and again the focus changes, and you are looking at images from that party. Often, you end up getting to bed late those evenings when you fetch the laptop.

Figure 9-13. Configuring KimDaBa Image manipulation with the GIMP

Introduction. The GIMP is the GNU Image Manipulation Program. It is intended for tasks such as photo retouching, image composition, and image authoring. It has been in active development for several years and is a very stable and powerful program.

The GIMP's home is, the online manual is available from, and additional plug-ins to expand GIMP's features can be found at

It is possible to use GIMP as a simple pixel-based drawing program, but its strength is really image manipulation. In this book we present a small selection of useful tools and techniques. A complete coverage of the GIMP would require a whole book, so read this only as a teaser and for inspiration to explore GIMP.

At the time of writing the current version of GIMP was 2.2. Minor details in the feature set and user interface will be different in other versions, but the overall idea of the application is the same.

Selection tools. When GIMP is started, it shows the toolbox window, as seen in Figure 9-14. The upper part of the toolbox contains a number of buttons, each of which represents a tool. There is also a menubar with menus for creating new images, loading, saving, editing preferences, and so on. Below the buttons is a section showing the current foreground and background colors, selected pen, and so on. The lower part of the window shows the options for the current tool.

To create a new image, choose File New. This gives us a blank image to use for experimenting with the tools.

The first five tools are selection tools: rectangle, ellipse, freehand, magic wand, by color, and shape-based selection. A selection is an area of the image that almost any tool and filter in GIMP will work onso it is an important concept. The current selection is shown with "marching ants." You can show and hide the marching ants with Ctrl-Z.

The first three selection tools are, except for the shape of the selection made, quite similar. While dragging out a rectangular or elliptical selection, it is possible to keep a constant aspect ratio by holding down the Shift key. In the option window for each selection tool, it is possible to choose a selection mode to add to an existing selection, subtract from one, replace the current selection, and intersect with one.

All selection tools have a feather parameter that will control how soft the edges of the selection are. See Figure 9-15 for an example.

The magic wand allows you to click on a pixel in the image and thereby select a contiguous area around the pixel with similar color. Use the threshold slider to control how similar the colors must be. Selection by color works like the magic wand, but it selects all pixels with similar value contiguous or not. Finally, selection by shapes allows you to place points in the image and try to connect the points with curves that follow edges in the image. When you have selected enough points to contain an area, click in the middle of that area to convert the traced curve to a selection.

Figure 9-14. GIMP toolbox

Painting and erasing tools. To paint in an image, the Pencil, Paintbrush, Airbrush and Ink tools can be used. They differ in the way the shapes you draw look: Pencil paints with hard edges, and Paintbrush with soft edges, Airbrush paints semitransparently and Ink thickens the line when you paint slowly and thins the line when you paint quickly.

To fill in an area, make a selection and use the paintbucket or gradient fill tool to fill it with color. Selecting the pen style, color, and/or gradient can be done by clicking the controls in the middle of the toolbox window.

Some people have trouble drawing a straight line in GIMP, but since you have this clever book in your hands, you will know the secret: select one of the drawing tools, place the cursor where you want the line to start, press and hold Shift, and then move the mouse to where the line should end and click once with the left mouse button. Now either do the same again to draw another line segment or release the Shift key and enjoy your straight line.

Figure 9-15. GIMP selections

If you make a mistake, use the most often used keyboard shortcut in GIMP: Ctrl-Z to undo. Multiple levels of undo are available. There is also an eraser tool that allows you to selectively erase pixels.

Everything you do with the painting tools will be confined to the currently selected area if there is a selection.

Photo retouching tools . The tools in this section are mostly for modifying digital photos in subtle (and not so subtle) ways. The Clone tool is very useful to remove blemishes from a photo. It works by first Ctrl-clicking in an image to set the source point, and then painting somewhere in an image. You will now paint with "copies" of the source area. Figure 9-16 shows the upper-right corner of a landscape photo that got a bit of the roof from a house into the frame. The left image is the original, and the right one has the undesired feature removed by using the clone tool with some other part of the clouds as the source area.

The last tool in the toolbox is the Dodge and Burn tool. It is used to lighten (dodge) and darken (burn) parts of an image by drawing on it. This tool can be used to finetune areas with shadows or highlights.

Color adjustment. During postprocessing of digital photos, it can be very useful to adjust the overall appearance of the light, color, and contrast of a photo. GIMP supports quite a number of tools for this. They are available in the Layer/Colors context menu.

Figure 9-16. GIMP clone tool

One of the more useful tools is the Levels tool. It allows you to adjust the black and white points of an image. Figure 9-17 shows a photo shot in harsh lighting conditions. It has low contrast and looks hazy.

Figure 9-17. Original photo

Let's fix that problem using the Levels dialog! Open the dialog for the Levels tool by choosing Levels from the menu. The dialog can be seen in Figure 9-18.

Figure 9-18. Levels dialog

The diagram seen under "Input Levels" is a histogram of the brightness values in the image. The left end of the histogram represents black, and the right end white. We see that that the lower 40% of the histogram is emptythis means that we are wasting useful dynamic range. Below the histogram are three triangular sliders. The black and the white ones are for setting the darkest and brightest point in the image, and the gray one is for adjusting how values are distributed within the two other ones. We can move the black point up as shown in Figure 9-19 to remove the haziness of the image. The result is shown in Figure 9-20.

Contrast enhancement can be done either with the Brightness-Contrast tool or with the Curves tool. The former is quite basic consisting of two sliders, one for brightness and one for contrast; the latter allows much more control. Figure 9-21 shows an original image and two modified versions with different curves applied. The middle image has the contrast-enhancing curve shown in Figure 9-22 applied, and the right image has the contrast-decreasing curve shown in Figure 9-23 applied. The curves describe a mapping from pixel values onto itself. A straight line at a 45-degree slope is the identity mapping; anything else will modify the image. Best results are obtained if you only deviate a little bit from the 45-degree straight line.

Figure 9-19. Levels dialog

Figure 9-20. Level adjusted

Figure 9-21. Curve adjusted

Colors can be changed with several tools, such as the Color Balance and Hue-Saturation tools. The Levels and Curves tools can also be set to operate on individual color channels to achieve various effects. But there is also another tool available: the Channel Mixer. Unlike the other tools this is located in the Filters/Colors/Channel Mixer context menu. The Channel Mixer can be used to create a weighted mix of each color channel (red, green, and blue) for each of the output channels. It is particularly useful for converting color images to monochrome, often giving better results than simply desaturating the image. Figure 9-24 shows the Channel Mixer, and Figure 9-25 shows two monochrome versions of the same color image. The upper one is simply desaturated, and the lower one is based only on the blue channel and seems to emphasize the bird rather than the background. When judging how to convert a color image to monochrome, it can be helpful to examine each color component individually. See the paragraph about channels for more about this.

Layers and channels. The most convenient way to access layers and channels is through the combined layers, channels, paths, and undo history window. It can be accessed by right-clicking in the image's windows and selecting the Dialogs Create New Dock Layers, Channels & Paths menu item. Layers and channels allow you to view and manipulate different aspects of your images in a structured way.

Figure 9-22. Contrast-enhancing curve


An image is made up from one or more channel(s). True color images have three color channels, one for each of the red, green, and blue components. Index-colored and grayscale images have only one color channel. All types can have an optional alpha channel that describes the opacity of the image (white is completely opaque; black is completely transparent). By toggling the eye button for each channel, you can selectively view only a subset of the channels in an image. Channels can be selected or deselected for manipulation. For normal operation, all color channels are selected, but if you only want to paint into the red channel, for example, deselect the other channels. All drawing operations will then only affect the red channel. This can, for example, be used to remove the red flash reflection in your subjects' eyes. You can add additional channels to an image using the buttons at the bottom of the dialog. A very useful feature is that you can save a selection as a channel and convert a channel to a selection. This allows you to "remember" multiple selections for later use, and it makes it easier to fine-tune a selection because you can paint into a channel to add or remove areas to a selection. Figure 9-26 shows the Channel tab in the combined Layers, Channels dialog. The green and blue channels are visible, and the green channel is selected for editing.


Layers are a very powerful feature of the GIMP. Think of layers as a way of stacking multiple images on top of each other, affecting each other in various ways. If a layer has an alpha channel, the layers beneath it will show through in transparent areas of the layer. You can control the overall opacity of a layer by using the opacity slider shown in the dialog. Use the buttons at the bottom of the dialog to create, duplicate, and delete layers and to move layers up and down the stacking order. You can assign a name to a layer by right-clicking it and choosing Edit Layer Attributes. Figure 9-27 shows the Layers tab in the Layers, Channels dialog with an image loaded and two duplicate layers created.

Figure 9-23. Contrast-decreasing curve

Recall the image of the car from the curves example. The ground and car looked most interesting with the high-contrast curve, but the sky lost detail with this curveit looked better with the low-contrast curve because it pulled out detail from the bright sky. Let us try to combine those two approaches. We'll leave the lowest layer alone it will serve as a reference. Rename the middle layer "Ground" and the topmost one "Sky." Now make only the Ground layer visible, select it, and use the Curves tool to enhance contrast. Then make the topmost layer visible, select it, and apply a low-contrast curve to it. Now we need to blend the two layers together. To do this, we add a layer mask to the topmost layer, but before we do that, we want to get a good starting point for the mask. Use the magic wand selection tool to select as much of the sky as possible without selecting any of the trees, cars, or the ground. Remember that Shift-clicking adds to a selection. When most of the sky is selected, right-click on the topmost layer and choose Add Layer Mask and then choose Selection in the dialog that pops up. Don't worry if the selection doesn't align perfectly at the pixel level with the horizon we can fix that later. Press Ctrl-Shift-A to discard the current selectionwe don't need it any more. Now the Layers dialog should look like Figure 9-28.

Figure 9-24. Channel Mixer

By clicking on either the layer thumbnail or the layer mask thumbnail, you can choose which one of them you want to edit. Choose the layer mask and zoom in on the boundary between the trees and the sky. Now the mask can be adjusted by simply painting on the image with a black or white pen. White makes the sky show through and black makes the trees show through. To see the mask itself instead of the image, right-click the mask in the Layers dialog and choose Show Mask. The result should look something like Figure 9-29.

Figure 9-25. Channel Mixer example

So far we've only been using layers in Normal mode, but there are other modes as well. The other modes make a layer interact with the layers below it in interesting ways. It is possible to make the pixel values in a layer burn, dodge, multiply, and so forth, with the pixel values of the layer below it. This can be very powerful when used properly. Figure 9-30 shows the image from before with a new transparent layer added on top of it. This new layer contains the result of selecting a rectangle slightly smaller than the whole image, feathering the selection with a large radius (10% of the image height), inverting it, and filling out the selection with black paint. The mode of the layer is set to Overlay, which causes a slight darkening of the layers below it around the black areas near the borders. The effect looks as if the photo were taken with an old or cheap camera and adds to the mood of the scene. If we had used the Normal mode instead of Overlay, the effect would have been too much and looked unnatural. Try experimenting with the different modes yourself!

Figure 9-26. Channels dialog

Figure 9-27. Layers dialog

Figure 9-28. Layers and mask

Filters. The final major aspect of GIMP we cover here is its filters. Filters are effects that can be applied to an entire image or a selection. GIMP is shipped with a large number of different filters, and it is possible to plug in new filters to extend the capabilities of GIMP. Filters are located in the right mouse button Filters menu. The Channel Mixer is an example of such a filter. We discuss two useful filters, Gaussian Blur and Unsharp Mask, and apply them to the image from the previous example.

Gaussian Blur

This filter provides a nice smooth blurring effect. Try it with different blur radius settings. The IIR-type Gaussian blur seems to look better than RLE with most images.

For our example we are not going to blur the actual image. Instead, we are going to smooth out the transition between the high- and low-contrast layers. Do this by selecting the layer mask in the sky layer and applying Gaussian Blur. A radius of 8 seems to work well here. Zoom in on the border between the trees and the sky, and don't be afraid to experiment you can always press Ctrl-Z to undo and try again. Figure 9-31 shows a closeup of before and after applying Gaussian Blur to the mask. The effect is subtle, but important for making the two layers blend seamlessly.

Unsharp Mask

Despite its name, Unsharp Mask is a filter for enhancing the perceived sharpness of images. It offers more control and often provides more pleasing results than the simple Sharpen filter. Unsharp Mask works like this: first it makes an internal copy of your image and applies a Gaussian blur to it. Then it calculates the difference between the original and the blurred image for each pixel, multiplies that difference by a factor, and finally adds it to the original image. The idea is that blurring affects sharp edges much more than even surfaces, so the difference is large close to the sharp edges in the image. Adding the difference back further emphasizes those sharp edges. The Radius setting for Unsharp Mask is the radius for the Gaussian blur step, the Amount is the factor that the differences are multipled by, and the Threshold setting is for ignoring differences smaller than the chosen value. Setting a higher threshold can help when working with images with digital noise in them so we don't sharpen the noise.

Figure 9-29. Two layers

Figure 9-30. Two layers

Looking at our example with the sky and car again, we notice that the high-contrast part lost some details in the shadows when we pulled up the contrast. This can also be remedied with Unsharp Mask. To do this, we apply Unsharp Mask with a high radius and low amount. This technique is called "local contrast enhancement." Start out by making a copy of the whole image by pressing Ctrl-D and merging all layers in the copy. This is done by choosing Image Flatten Image from the context menu. Then we want to scale the image for screen viewing. Open the scaling dialog by choosing Image Scale Image from the context menu and choosing a suitable size and the bicubic (best) scaling algorithm. Now we are ready to apply Unsharp Mask for local contrast enhancement. A radius of 25, an amount of 0.15, and threshold of 0 seems to look good.

Figure 9-31. Blurring the mask before and after

Finally, we want to sharpen up the edges a bit. To do this, we apply Unsharp Mask with a small radius (0.5) and higher amount (0.5) and with a threshold of 6. Figure 9-32 shows the unsharpened image on the left, the image with local contrast enhancement applied in the middle, and the image with the final sharpening pass applied on the right.

9.6.7. Recording Tools

If you want to create your own MP3 files, you will need an encoder program. There are also programs that allow you to extract tracks for audio CDs.

Although you can perform MP3 encoding with open source tools, certain patent claims have made the legality of doing so questionable. Ogg Vorbis is an alternative file format and encoder that claims to be free of patent issues. To use it, your player program needs to support Ogg Vorbis files because they are not directly compatible with MP3. However, many MP3 players, such as Xmms, support Ogg Vorbis already; in other cases, there are direct equivalents (such as ogg123 for mpg123). For video, Ogg has developed the Ogg Theoris codec, which is free and not encumbered by any patents.

This section lists some popular graphical tools for recording and manipulating multimedia.

Figure 9-32. Two passes of Unsharp Mask


KDE includes Krec as the standard sound recorder applications. You can record from any mixer source, such as a microphone or CD, and save to a sound file. Although it offers some audio effects, it is intended as a simple sound recorder application. A screenshot is shown in Figure 9-33.

Figure 9-33. Krec


Audacity is an audio editor that can record and play back sounds and read and write common sound file formats. You can edit sounds using cut, copy, and paste; mix tracks; and apply effects. It can graphically display waveforms in different formats.

A screenshot is shown in Figure 9-34. The project home page is

Figure 9-34. Audacity


Ardour is a full-featured digital audio workstation designed to replace analog or digital tape systems. It provides multitrack and multichannel audio recording capability, mixing, editing, and effects. A screenshot is shown in Figure 9-35. The project home page is

Figure 9-35. Ardour


Freevo is an open source home theater platform based on Linux and open source audio and video tools. It can play audio and video files in most popular formats. Freevo can be used as a standalone personal video recorder controlled using a television and remote, or as a regular desktop computer using the monitor and keyboard.

A screenshot is shown in Figure 9-36. The project home page is

Figure 9-36. Freevo


MythTV is a personal video recorder (PVR ) application that supports a number of features, including

  • Watching and recording television

  • Viewing images

  • Viewing and ripping videos from DVDs

  • Playing music files

  • Displaying weather and news and browsing the Internet

  • Internet telephony and video conferencing

A screenshot is shown in Figure 9-37. The MythTV home page is

Figure 9-37. MythTV

9.6.8. Music Composition Tools

Many applications are available that help music composers.

MIDI sequencers allow a composer to edit and play music in MIDI format. Because MIDI is based on note events, tracks, and instruments, it is often a more natural way to work when composing music than directly editing digital sound files.

Scoring programs allow composers to work with traditional music notation and produce typeset sheet music. Some support other notation formats such as tablature for guitar and other instruments.

Some programs combine both MIDI sequencing and scoring, or can work with various standardized file formats for musical notation.


Brahms is a KDE-based MIDI sequencer application that allows a composer to edit tracks and play them back. You can work with MIDI events or a traditional music score using different editor windows. A screenshot is shown in Figure 9-38. The project home page is


Rosegarden is an audio and MIDI sequencer, score editor, and general-purpose music composition and editing environment. It allows you to work with MIDI events or music notation. It is integrated with other KDE applications and has been localized into about 10 languages.

A screenshot is shown in Figure 9-39. The project home page is


LilyPond is a music typesetter that produces traditional sheet music using a high-level description file as input. It supports many forms of music notation constructs, including chord names, drum notation, figured bass, grace notes, guitar tablature, modern notation (cluster notation and rhythmic grouping), tremolos, (nested) tuplets in arbitrary ratios, and more.

LilyPond's text-based music input language support can integrate into LATEX, HTML, and Texinfo, allowing documents containing sheet music and traditional text to be written from a single source. It produces PostScript and PDF output (via TEX), as well as MIDI.

The project home page is There is a graphical front end to LilyPond called Denemo.

9.6.9. Internet Telephony and Conferencing Tools

Telephony over the Internet has recently become popular and mainstream. Using VOIP (Voice Over IP) technology, audio is streamed over a LAN or Internet connection. SIP (Session Initiation Protocol) is a standard for setting up multimedia sessions (not just audio). Either a sound card and microphone or dedicated hardware resembling a traditional telephone can be used. Internet telephony has a number of advantages, but the main one is costmany users today have a full-time high-speed Internet connection that can be used to connect to anyone else in the world with compatible software. With a suitable gateway, you can make a call between a VOIP phone and the public telephone network.

There are many VOIP applications for Linux. KPhone is one popular KDE-based one. As well as audio, it supports instant messaging and has some support for video. The project's home page is

There are also commercial applications that use proprietary protocols or extensions to protocols. One example is Skype, which offers a free client but requires subscription to a service to make calls to regular phones through a gateway. Skype can be found at

H.323 is a standard for video conferencing over LANs. It is supported by Microsoft NetMeeting, which is included with Microsoft Windows. H.323-compliant applications are available on Linux, the most notable being GnomeMeeting. The project's home page is

Figure 9-38. Brahms

9.6.10. Browser Plug-ins

Browser plug-ins allow data types other than HTML to be presented in your web browser. Some of these qualify as multimedia. They can be divided into three categories:

  • Plug-ins that come with the browser or are available from the same source as the browser (e.g., Mozilla or Firefox).

  • Native plug-ins from third parties, such as Adobe Acrobat, usually available at no cost although they may be closed source.

  • Windows plug-ins that can run inside some Linux browsers using CodeWeaver's CrossOver (Wine) technology. This category includes plug-ins such as Apple QuickTime, Windows Media Player, and Adobe Shockwave. Many of these are not available as native Linux plug-ins.

Figure 9-39. Rosegarden

The Netscape plug-in format is supported by Netscape, Mozilla, and some other browsers derived from Mozilla, such as FireFox. Netscape plug-ins are also supported by the KDE project's Konqueror browser.

9.6.11. Putting It All Together

This chapter has talked about a lot of different multimedia tools. Although most of these tools are straightforward to use and perform a well-defined function on their own, more powerful tasks can be performed by combining tools. Let's look at a real-life example.

I like to collect and restore old vacuum tube radios from the 1930s through 1950s. After I have restored a radio to working condition I like to display it. But when I turn it on, hearing the local sports or talk radio station doesn't seem appropriate. Wouldn't it be fun to hear some old radio shows from the era in which the radio was made coming out of the radio?

Lots of old-time radio broadcasts are available as free downloads on the Internet. I can download a number of these to my computer. It is also possible to buy CDs of old radio programs. I might even have an old vinyl record or cassette tape of old radio shows. Using Audacity and connecting a turntable or tape player to my sound card's audio input, I can convert them to sound files. The files can have some simple editing and processing done to clean them up, and they can be converted to MP3 format.

If I want to listen to them on my computer, I can use Juk to arrange them in playlists of my favorite programs arranged by type and have hours of continuous music or radio shows. I can save the MP3 files to my portable MP3 player to listen to when I am away from the computer, or burn them to a CD to listen to with a portable CD player.

Using a low-power AM transmitter, I can legally broadcast programming throughout my home. An inexpensive AM transmitter is available from a number of sources and connects either to the sound card output of my computer or a CD player, and can broadcast vintage radio programs on the AM band to radios within the house. Now when I turn on that old radio, I can hear Burns and Allen, The Shadow, or some swing music from the 1940s. I might even be able to convince the more gullible visitors to my radio room that old radios can still pick up old radio programs.

Part I: Enjoying and Being Productive on Linux
Part II: System Administration