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Chapter 9. Editors, Text Tools, Graphics, and Printing 296 in outer space. A vacuum cleaner is a device used to clean a vacuum. See @xref{Invoking} for information on running @code{vacuum}. The next node for Overview is Invoking , which is the second "chapter" node and also the node to appear after Overview in the menu. Note that you can use just about any structure for your Texinfo documents; however, it is often useful to organize them so that nodes resemble chapters, sections, subsections, and so forth. It's up to you. The @chapter command begins a chapter, which has an effect only when formatting the source with T E X. Similarly, the @section and @subsection commands begin (you guessed it) sections and subsections in the resulting T E X document. The chapter (or section or subsection) name can be more descriptive than the brief name used for the node itself. You'll notice that the @code command is used in the chapter name. This is just one way to specify text to be emphasized in some way. @code should be used for the names of commands, as well as source code that appears in a program. This causes the text within the @code to be printed in constant-width type in the T E X output, and enclosed in single quotes (like 'this') in the Info file. Following this are three @cindex commands, which produce entries in the concept index at the end of the document. Next is the actual text of the node. Again, @code marks the name of the vacuum "command." The @xref command produces a cross-reference to another node, which the reader can follow with the f command in the Info reader. @xref can also make cross-references between other Texinfo documents. See the Texinfo documentation for a complete discussion. Our next node is Invoking: @node Invoking, Concept Index, Overview, Top @chapter Running @code{vacuum} @cindex Running @code{vacuum} @code{vacuum} is executed as follows: @example vacuum @var{options} @dots{ } @end example Here, @example @end example sets off an example. Within the example, @var denotes a metavariable, a placeholder for a string provided by the user (in this case, the options given to the vacuum command). @dots{ } produces ellipsis points. The example will appear as: vacuum options in the T E X-formatted document, and as: vacuum OPTIONS in the Info file. Commands, such as @code and @var, provide emphasis that can be represented in different ways in the T E X and Info outputs. Chapter 9. Editors, Text Tools, Graphics, and Printing 297 Continuing the Invoking node, we have: @cindex Options @cindex Arguments The following options are supported: @cindex Getting help @table @samp @item -help Print a summary of options. @item -version Print the version number for @code{vacuum}. @cindex Empty vacuums @item -empty Produce a particularly empty vacuum. This is the default. @end table Here, we have a table of the options that vacuum supposedly supports. The command @table @samp begins a two-column table (which ends up looking more like a tagged list), where each item is emphasized using the @samp command. @samp is similar to @code and @var, except that it's meant to be used for literal input, such as command-line options. A normal Texinfo document would contain nodes for examples, information on reporting bugs, and much more, but for brevity we're going to wrap up this example with the final node, Concept Index. This is an index of concepts presented in the document and is produced automatically with the @printindex command: @node Concept Index, , Invoking, Top @unnumbered Concept Index @printindex cp Here, @printindex cp tells the formatter to include the concept index at this point. There are other types of indices as well, such as a function index, command index, and so forth. All are generated with variants on the @cindex and @printindex commands. The final three lines of our Texinfo source are: @shortcontents @contents @bye This instructs the formatter to produce a "summary" table of contents ( @shortcontents ) and a full table of contents ( @contents), and to end formatting (@bye). @shortcontents produces a brief table of contents that lists only chapters and appendices. In reality, only long manuals would require @shortcontents in addition to @contents. 9.3.5.2 Formatting Texinfo To produce an Info file from the Texinfo source, use the makeinfo command. (This command, along with the other programs used to process Texinfo, are included in the Texinfo software distribution, which is sometimes bundled with Emacs.) The command: eggplant$ makeinfo vacuum.texi Chapter 9. Editors, Text Tools, Graphics, and Printing 298 produces vacuum.info from vacuum.texi. makeinfo uses the output filename specified by the @setfilename in the source; you can change this using the -o option. If the resulting Info file is large, makeinfo splits it into a series of files named vacuum.info-1, vacuum.info-2, and so on, where vacuum.info will be the top-level file that points to the various split files. As long as all the vacuum.info files are in the same directory, the Info reader should be able to find them. You can also use the Emacs commands M-x makeinfo-region and M-x makeinfo- buffer to generate Info from the Texinfo source. The Info file can now be viewed from within Emacs, using the C-h i command. Within the Emacs Info mode, you'll need to use the g command and specify the complete path to your Info file, as in: Goto node: (/home/loomer/mdw/info/vacuum.info)Top This is because Emacs usually looks for Info files only within its own Info directory (which may be /usr/local/emacs/info on your system). Another alternative is to use the Emacs-independent Info reader, info. The command: eggplant$ info -f vacuum.info invokes info, reading your new Info file. If you wish to install the new Info page for all users on your system, you must add a link to it in the dir file in the Emacs info directory. The Texinfo documentation describes how to do this in detail. To produce a printed document from the source, you need to have T E X installed on your system. The Texinfo software comes with a T E X macro file, texinfo.tex, which includes all the macros used by Texinfo for formatting. If installed correctly, texinfo.tex should be in the inputs directory on your system. If not, you can copy texinfo.tex to the directory where your Texinfo files reside. First, process the Texinfo file using: eggplant$ tex vacuum.texi This produces a slew of files in your directory, some of which pertain to processing and to the index. The texindex command (which is included in the Texinfo package) reformats the index into something the display systems can use. The next command to issue is therefore: eggplant$ texindex vacuum.?? Using the ?? wildcard runs texindex on all files in the directory with two-letter extensions; these are the files produced by Texinfo for generating the index. Finally, you need to reformat the Texinfo file using T E X, which clears up cross-references and includes the index: Chapter 9. Editors, Text Tools, Graphics, and Printing 299 eggplant$ tex vacuum.texi This should leave you with vacuum.dvi, a device-independent file you can now view with xdvi or convert into something printable. See Section 9.3.2 earlier in the chapter for a discussion of how to print .dvi files. As usual, there's much more to learn about this system. Texinfo has a complete set of Info pages of its own, which should be available in your Info reader. Or, now that you know the basics, you could format the Texinfo documentation sources yourself using T E X. The .texi sources for the Texinfo documentation are found in the Texinfo source distribution. 9.4 Graphics Many people are fascinated by computer graphics. Computers are being used to create photorealistic images of surreal scenes or fractally generated images of mountain ridges with lakes and valleys; to change images by bending, polishing, and aging them; or to make any other manipulations. Linux does not need to step shyly aside when it comes to graphics. It can do just about anything that other computing environments can do, and in some areas, such as dealing with many graphics files at the same time, it even excels. The X Window System, described in the next chapter, forms a very good base for bitmapped graphics. There is now also hardware support for 3D graphics conforming to the OpenGL standard. However, working with graphics on Linux is sometimes different from what you might be used to on other operating systems; the Unix model of small, interoperating tools is still alive and well here, too. This philosophy is illustrated most clearly with the ImageMagick suite of graphics manipulation programs, which we will describe here. ImageMagick is a collection of tools that operate on graphics files and are started from the command line or from shell scripts. Imagine that you have 2,000 files of one file format that you want to reduce to 256 colors, slant, and convert to another file format. On Linux, this requires only a few lines in a shell script. Now imagine doing this on Windows: click the File menu, click the Open menu entry, select a file, select an operation, specify the parameters for the operation in a dialog, click OK, choose Save from the menu, select a filename, and then click OK. Now repeat for next 1999 files. Can you say RSI? 1 Graphics can not only be drawn, but also programmed. Certain tools, such as the ray-tracer POVRAY presented in this chapter, enable you to specify the graphics to be generated by a suite of commands, often in a full-blown graphics programming language. While this is perhaps more difficult than drawing the desired graphics with a mouse, it is also infinitely more flexible once you have mastered how to use it. Now, not everybody wants to work with graphics from the command line. Part of the appeal of working with computer graphics is the immediate feedback you get when working with graphics programs, and Linux can provide this, too. The GIMP, which we will be covering shortly, is a fascinating package for interactive image manipulation that is superior to a lot of commercial graphics manipulation software on other systems. 1 Repetitive Strain Injury — a malady that comes from typing too much. The better known carpal tunnel syndrome is one form of RSI. Chapter 9. Editors, Text Tools, Graphics, and Printing 300 Many more graphics programs are available for Linux, including 3D modelers and video players. Scouring some Linux archives will reveal a wealth of good software. Most of these programs require the X Window System, which we'll show you how to install and configure in later chapters. 9.4.1 ImageMagick ImageMagick is a suite of programs that convert and manipulate graphics files from the command line. It is also well suited for batch conversions — that is, converting many files at once. In addition, ImageMagick includes PerlMagick, a binding that lets you invoke the ImageMagick utilities from the Perl programming language. It comes with most Linux distributions; if yours does not have it, you can get it from ftp://ftp.x.org/contrib/applications/ImageMagick. ImageMagick consists of a library and a number of utilities: display display is a graphical frontend to many of the functions provided by ImageMagick. It is very useful if you want to experiment with the effects of a function before you go and batch-convert hundreds of images with these effects. display can load many different graphics file formats and display them on the X Window System. You can start display and pass it one or more filenames on the command line, or load a file from the menu provided. If you have started display and do not see a menu, click the image displayed with the left mouse button. display features a huge number of command-line switches. See the manual page for details. import import is a small program that captures either one window or the whole server into a file; that is, it allows you to make screenshots. For example, to make a screenshot of your whole screen and save it as myscreen.xpm in the graphics file format XPM, you would execute: tigger$ import -window root myscreen.xpm When you hear the first beep, the screen capture begins, and when the second one sounds, capturing is finished and the image data is in the process of being saved to the file you specified. If you want to capture the contents of only one window, the easiest way is to start import without the -window option: tigger$ import mywindow.xpm The cursor then turns into a crossbar, which prompts you to click any window. This window's contents are then captured and saved to the specified file. Like all ImageMagick programs, import has many command-line options; check the image(1) manual page. Chapter 9. Editors, Text Tools, Graphics, and Printing 301 montage montage is a very useful little tool with a functionality rarely found elsewhere. It takes a number of images and puts them together as one large image in a tiled manner. There are lots of options for changing how the images are exactly tiled and put together. In order to tile all your JPEG images in the current directory and create the image all.jpg out of it, you could call: tigger$ montage *.jpg all.jpg By default, there will be a label with the filename below each image. You can avoid this by entering: tigger$ montage +frame *.jpg all.jpg convert In a way, convert is the heart of the ImageMagick suite. It can convert between an amazing number of graphics formats. For example, let's assume that you want to port a GUI program from Windows to Linux. You have a large number of toolbar icons in Windows BMP format and want to convert those to XPM. You could do this with: for i in *.bmp do convert $i xpm:'basename $i .bmp'.xpm done convert will happily chug through all the images and convert them. If you want to do other things to the images, just add the necessary switches — e.g., -despeckle for removing speckles from the images. mogrify mogrify is like convert, but it overwrites the original images and is meant more for applying filter functions than for converting file formats (even though you can easily change the file format by using the switch -format ). identify identify outputs information about the images passed on the command line. For example: tigger$ identify tux.gif tux.gif 257x303+0+0 DirectClass 10968b GIF 1s This tells you, among other things, that tux.gif is a GIF file 257 pixels wide and 303 pixels high. If this is not enough information for you, try the -verbose switch! Chapter 9. Editors, Text Tools, Graphics, and Printing 302 combine As its name indicates, combine combines several images into one. You can, for example, put color-separated images together or put a logo on top of a larger image. xtp Like the ftp program, xtp downloads files from a remote site or uploads them to a remote site. But unlike ftp, it does not need interactive input (in order to get this with ftp, you would have to edit its configuration file). You can productively combine xtp with the other tools from the ImageMagick suite to automatically manipulate images on remote servers. To sum up, the programs from the ImageMagick suite are an extremely versatile means to manipulate graphics files. However, it takes some time to familiarize yourself with all the command-line options in order to know what is available. 9.4.2 The GIMP The GIMP (which expands to either GNU Image Manipulation Program or General Image Manipulation Program and is often written with the definite article) specializes in image manipulation like the ImageMagick package described in the last section. But while ImageMagick's strength is batch processing, GIMP does everything via its GUI. The GIMP is often cited as one of the most impressive and successful products for Linux (and other Unix versions). People who use image manipulation programs professionally have said that while GIMP can feel a little bit awkward to use, it is functionally comparable to its commercial competitor from the Windows and Macintosh world, Adobe Photoshop. Some people even have called it "the free alternative to Photoshop." GIMP draws its power from an amazing number of plug-ins that are available for it. Thus, in order to be able to use a newly written image manipulation filter or file format import filter, you only need to install the plug-in and restart GIMP, and you are ready to go. In addition, GIMP uses a clever tiling mechanism that allows you to load arbitrarily large images into it; GIMP will keep in memory only the part that is currently being used or visible. And if these features are not enough, GIMP also has its own scripting language called script- fu, and can be scripted with Perl as well. GIMP comes with most Linux distributions on the market today and can be run simply by entering the command gimp in a shell after starting X. If your distribution does not have GIMP, you can get the source code from www.gimp.org. If you plan to do more work with GIMP, you should check this web site anyway because it also contains the documentation and sample images that show off what you can do with it. A screenshot showing the toolbar, dialog boxes, and a work area is shown in Figure 9-5. Chapter 9. Editors, Text Tools, Graphics, and Printing 303 Figure 9-5. The Gimp 9.4.3 POVRAY While ImageMagick and GIMP are mainly for manipulating existing images, POVRAY (the first three letters stand for Persistence Of Vision) is a program for automatically creating new images. It is a so-called ray-tracer; a program that computes a scene from some information about which objects should be in the scene, what their physical and optical properties are, where the light is coming from, and where the spectator is standing. You describe this to POVRAY in a programming language of its own. This brief description should already indicate that using POVRAY is not something you learn in one afternoon. If you are interested in this program, you can download it from http://www.povray.org, which is also the first source for all kinds of POVRAY resources like sample files, documentation, and so on. Since we cannot give you even a crash course into using POVRAY here, we'll refrain from attempting this futile task. If you are interested in POVRAY, though, but find the task of describing your scenes in a programming language daunting, it might interest you to know that certain graphic modeling programs can be used with ray-tracers like POVRAY, so you do not have to create the 3D models completely by hand. One of these programs is Blender, about which you can find more information at http://www.blender3d.com. 9.5 Configuring and Using Linux Audio This section covers the configuration of sound cards under Linux and other issues related to Linux sound support. Chapter 9. Editors, Text Tools, Graphics, and Printing 304 Sound has historically been one of the most challenging aspects of Linux, and one that did not receive as much attention from Linux distributions as it should have, perhaps because Linux was initially embraced by so many as a server operating system. On the desktop, users have come to take multimedia support and sound for granted. Once you're armed with a little knowledge, the good news is it's not too hard to get a sound card up and running, and in fact Linux is well suited to audio and other multimedia applications for a number of reasons. We start off this section with a quick overview of digital audio concepts and terminology. Those familiar with the technology may wish to skip over this section. If you don't really care about how it all works or get lost in the first sentence of this section, don't worry, you can get sound on your system without understanding the difference between an MP3 and a WAV file. We'll then look specifically at how sound is supported under Linux, what hardware is supported, the different device drivers available, and the different approaches to configuring sound taken by Linux distributions. Next we'll step through the process of configuring sound support, building or locating the necessary kernel drivers and testing and debugging the sound devices. We'll provide some hints for troubleshooting and point out some common pitfalls. Once you have sound support up and running, you'll want to run some multimedia applications. We'll take a quick look at the types of sound programs available for Linux. Last, we'll round out this section with some references to more information on Linux audio that will help you get to the next level. A word of advice: there are minor differences between Linux distributions. The Linux kernel and applications are also undergoing constant change and enhancement. We've made every effort to make the information in this chapter applicable to all Linux systems, and to point out areas where they are likely to differ, but for details you should consult the documentation for your distribution and consult fellow users. 9.5.1 A Whirlwind Tour of Digital Audio In this section we will give a very quick overview of some concepts relevant to digital audio and sound cards. Sound is produced when waves of varying pressure travel through a medium, usually air. It is inherently an analog phenomenon, meaning that the changes in air pressure can vary continuously over a range of values. Modern computers are digital, meaning they operate on discrete values, essentially the binary ones and zeroes that are manipulated by the computer's CPU. In order for a computer to manipulate sound, it converts the analog sound information into digital format. A hardware device called an analog-to-digital converter converts analog signals, such as the continuously varying electrical signals from a microphone, to digital format for manipulation by the computer. Similarly, a digital-to-analog converter converts digital values into analog form so that they can be sent to an analog output device such as a speaker. Sound cards typically contain several analog-to-digital and digital-to-analog converters. Chapter 9. Editors, Text Tools, Graphics, and Printing 305 The process of converting analog signals to digital form consists of taking measurements or samples of the values at regular periods of time, and storing these samples as numbers. The process of analog-to-digital conversion is not perfect, however, and introduces some loss or distortion. Two important factors that affect how accurately the analog signal is represented in digital form are the sample size and sampling rate. The sample size is the range of values of numbers that are used to represent the digital samples, usually expressed in bits. For example, an 8-bit sample would convert the analog sound values into one of 2 8 or 256 discrete values. A 16-bit sample size would represent the sound using 2 16 or 65,535 different values. A larger sample size allows the sound to be represented more accurately, reducing the sampling error that occurs when the analog signal is represented as discrete values. The tradeoff with using a larger sample size is that the samples require more storage (and the hardware is typically more complex and therefore expensive). The sample rate is the speed at which the analog signals are periodically measured over time. It is properly expressed as samples per second, although sometimes informally but less accurately expressed in Hertz. A lower sample rate will lose more information about the original analog signal, while a higher sample rate will more accurately represent it. The sampling theorem states that to accurately represent an analog signal it must be sampled at least twice the rate of the highest frequency present in the original signal. The range of human hearing is from approximately 20 to 20,000 Hertz under ideal situations. To accurately represent sound for human listening, then, a sample rate of twice 20,000 Hertz should be adequate. CD player technology uses 44,100 samples per second, which is in agreement with this simple calculation. Human speech has little frequency activity above 4,000 Hertz. Digital telephone systems typically use a sample rate of 8,000 samples per second, which is perfectly adequate for conveying speech. The tradeoff involved with using different sample rates is the additional storage requirement and more complex hardware needed as the sample rate increases. Other issues that arise when storing sound in digital format are the number of channels and the sample encoding format. To support stereo sound, two channels are required. Some audio systems use four or more channels. The samples themselves can be encoded in different formats. We've already mentioned sample size, with 8-bit and 16-bit samples being the most common. For a given sample size the samples might be encoded using signed or unsigned representation, and when the storage takes more than one byte, the ordering convention must be specified. These issues are important when transferring digital audio between programs or computers to ensure they agree on a common format. File formats, such as WAV, standardize how to represent sound information in a way that can be transferred between different computers and operating systems. Often, sounds need to be combined or changed in volume. This is the process of mixing, and can be done in analog form (e.g., a volume control) or in digital form by the computer. Conceptually, you can mix two digital samples together simply by adding them, and you can change volume by multiplying the digital samples by a constant value. [...]... 65 525, 65 530, 65 535, 65 540, 65 545, 65 5 46, 65 548, 65 550, 65 554, 65 555, 68 554, 69 000, 64 200, 64 300 Cirrus Logic Alpine (5430, 5434, 54 36, 54 46, 5480, 7548), Laguna (5 462 , 5 464 , 5 465 ) Compaq/Digital DEC 21030 TGA 8-plane, 24-plane, 24-plane 3D chips Cyrix Cyrix MediaGX IBM Standard IBM VGA Integrated Micro Solutions (IMS) IMS Twin Turbo 128, Twin Turbo 3D Intel i740, i810, i815, i830 Matrox MGA2 064 W (Millenium... Silicon Integrated Systems (SIS) 300, 530, 540, 62 0, 63 0, 63 26 Silicon Motion, Inc Lynx, LynxE, Lynx3D, LynxEM, LynxEM+, Lynx3DM Sun Microsystems BW2, CG3, CG6, CG14, FFB, LEO, TCX framebuffers Trident Microsystems TVGA8900B, TVGA8900C, TVGA8900CL, TVGA9000, TVGA9000i, TVGA9100B, TVGA9200CXr, TVGA8900D, TGUI9440AGi, TGUI 966 0, TGUI 968 0, ProVidia 968 2, ProVidia 968 5, 3DImage975, 3DImage985, Blade3D, Cyber9320,... Number Nine Imagine 128, Ticket 2 Ride, Revolution 3D, Revolution IV 3 26 Chapter 10 Installing the X Window System Rendition/Micro Verite 1000, 2100, 2200 S3 964 (revisions 0 and 1), 968 , Trio32, Trio64, Trio64, Trio64V+, Trio64UV+, Aurora64V+, Trio64V2, and PLATO/PX (only models using the IBM RGB 524, Texas Instruments 3025, or an internal TrioDAC RAMDAC chip are supported); ViRGE, ViRGE/VX, ViRGE/DX,... this: % cat /dev/sndstat OSS/Free:3.8s2++-971130 Load type: Driver loaded as a module Kernel: Linux curly 2.2. 16 #4 Sat Aug 26 19:04: 06 PDT 2000 i6 86 Config options: 0 Installed drivers: Card config: Audio devices: 0: Sound Blaster 16 (4.13) (DUPLEX) Synth devices: 0: Yamaha OPL3 MIDI devices: 0: Sound Blaster 16 Timers: 0: System clock Mixers: 0: Sound Blaster 311 Chapter 9 Editors, Text Tools, Graphics,... (Millenium I), MGA1 064 SG (Mystique), MGA2 164 W (Millenium II) PCI and AGP, G100, G200, G400, G450, G550 NeoMagic NM2070, NM2090, NM2093, NM2097, NM2 160 , NM2200, NM2230, NM2 360 , NM2380 NVIDIA Riva 128, 128ZX, TNT, TNT2 (Ultra, Vanta, M64), GeForce (DDR, 2 56) , Quadro, GeForce2 (GTS, Ultra, MX), GeForce3, Quadro2 Number Nine Imagine 128, Ticket 2 Ride, Revolution 3D, Revolution IV 3 26 Chapter 10 Installing... many other operating systems (including Linux) has been added — and XFree 86 implements the latest version, X11R6.3 We should mention here that commercial X Window System servers are available for Linux that may have advantages over XFree 86 (like support for certain video cards) Most people use XFree 86 happily, though, so this should certainly be your first stop Linux distributions usually automatically... others, is loaded: % /sbin/lsmod Module parport_pc lp parport 3c574_cs serial cs46xx soundcore ac97_codec rtc Size 212 56 6080 24512 8324 43520 54472 3492 9 568 5528 Used by 1 (autoclean) 0 (autoclean) 1 (autoclean) [parport_pc lp] 1 0 (autoclean) 4 3 [cs46xx] 0 [cs46xx] 0 (autoclean) Here the drivers of interest are cs46xx, soundcore, and ac97_codec When the driver detected the card the kernel should... cards under XFree 86 are posted to the Usenet newsgroups comp.windows.x.i386unix and comp.os .linux. misc regularly As a side note, one author's (Kalle's) secondary personal Linux system is an AMD K6-2 with 128 MB of RAM and is equipped with a PCI Permedia II chipset card with 8 MB of DRAM This setup is already a lot faster with respect to display speed than many workstations XFree 86 on a Linux system with... to sound under Linux: • • • • • • The Linux Sound HOWTO, available from the Linux Documentation Project at http://www.tlpd.org The ALSA Project web site at http://www.alsa-project.org The 4Front Technologies web site at http://www.opensound.com The Sound and MIDI Software for Linux web site at http://sound.condorow.net The book Linux Multimedia Guide, published by O'Reilly The book Linux Music and... printing to your trusty tractor-feed printer (named dino here): nenscript -B -L 66 -N -Pdino myprogram.c The nenscript filter numbers each line of the file passed through it when you specify the -N option The -B option suppresses the usual header information from being printed on each page, and the -L 66 option specifies formatting at 66 lines per page The nenscript filter just passes the -Pdino option through . as a module Kernel: Linux curly 2.2. 16 #4 Sat Aug 26 19:04: 06 PDT 2000 i6 86 Config options: 0 Installed drivers: Card config: Audio devices: 0: Sound Blaster 16 (4.13) (DUPLEX) Synth. 212 56 1 (autoclean) lp 60 80 0 (autoclean) parport 24512 1 (autoclean) [parport_pc lp] 3c574_cs 8324 1 serial 43520 0 (autoclean) cs46xx 54472 4 soundcore 3492 3 [cs46xx] ac97_codec 9 568 . 11 with 01:00.0 Crystal 4280/46xx + AC97 Audio, version 1.28.32, 19:55:54 Dec 29 2001 cs46xx: Card found at 0xf4100000 and 0xf4000000, IRQ 11 cs46xx: Thinkpad 60 0X/A20/T20 (1014:0153) at 0xf4100000/0xf4000000,