Hack72.Create Self-Booting Movies

Hack 72. Create Self-Booting Movies

Make a video that will boot and play directly from CD.

I love my son and try to give him what he needs in life. Sometimes I even give him what he wants, too. He has a nice bike that he uses quite a lot, and he is always out and about. Of course he has his own PC, which is online 24/7 while he constantly surfs for sports car images. (For some strange reason, the teachers at his primary school think he's some sort of genius, as he's always telling them that Windows sucks and the TCO is much less when using Linux.) At times I think I let him have too much: I have let him play games on a Windows machine. Then, of course, at age 11 he broke my collarbone, and all I did was lecture him on his propensity for causing "incidents."

However, sometimes I put my foot down. One example involves my DVD collection. I don't trust him with those little discs of plastic and dreams. We sometimes have debates about what he's allowed to watch, and often he wants to take my DVDs to a friend's house, which I absolutely forbid. What's a father to do?

The answer is to make a self-booting CD copy of the DVD that he can watch on any PC. And that is where this hack comes in. It shows you how to reduce a DVD-length movie so it fits on a single CDand to top it all off, it makes the CD bootable, so when you start a computer with the CD in the drive, it loads a very lightweight Linux OS with just enough software to play the movie on the CD.

Before diving into the guts of the hack, please keep in mind that I'm not suggesting you do anything illegal. I shudder to think that some evil person will impoverish an unassuming multinational corporation by depriving it of the opportunity to make a small profit off a piece of entertainment geared for the unwashed masses. That's why the United States has such wonderful laws protecting companies' rights. (Did I tell you that I live in Canada?) Instead, I implore you to use the following approach only for DVDs unencumbered by licensing issues.

3.27.1. The Tools

Creating a movie involves a few software and hardware considerations:

  • The PC that plays the movie must have a CD reader as its primary bootup device. To play the video without jitters it should have a Pentium III or better CPU.

  • The PC used to create the movie must have a DVD reader, a CD burner, and at least 2 GB of free space.

Making these movie backup copies requires several distinct, free utilities, including:

  • LAME, the MP3 encoder

  • MPlayer, the premier movie player, which can also translate the DVD's native encoding to AVI

  • transcode, a Linux text-console utility for video streams that includes a utility to break a large AVI file into smaller ones

  • eMoviX, a mini live Linux OS burned onto a CD, which permits the CD to boot and auto-magically play its files with MPlayer

  • mkisofs, which of course creates the ISO image

  • cdrecord, the ubiquitous CD-burning software

  • growisofs, for those people who have a DVD burner

This list looks pretty daunting, doesn't it? Just look at all those utilities that you need to create your movie.

Actually, you can make things work with very little knowledge by using one more utility that ties all the above together: K3b [Hack #62]. K3b is a CD- and DVD-burning application for Linux systems. It is optimized for KDE, but it will run with other desktop environments and provides a comfortable user interface for performing most disc-burning tasks.

3.27.2. The Moviemaking Routine

The basic process for creating this self-booting and playing miracle is:

  1. Read the DVD and convert it into an AVI.

  2. Break the completed AVI into files small enough to fit onto a CD.

  3. Use K3b to create a new eMoviX project/CD for each AVI file.

  4. Burn away.

Now let's start putting the pieces together. Ripping the DVD Using MPlayer.

Of all the utilities, MPlayer is not only the most critical but also the trickiest to set up and use correctly. For more information on how to get and use MPlayer, check out [Hack #48].

Ironically, for all MPlayer's complication, you can create your AVI with this simple incantation from the command line:

 $ mencoder dvd:// -o  temp.avi  -ovc lavc -lavcopts \ vcodec=mpeg4:vhq:vbitrate=1800 -oac mp3lame -lameopts \ cbr:vol=3 -aid 128  

Let's break down the above command:

  • mencoder specifies the MPlayer command utility used to extract the video information from the DVD.

  • dvd:// identifies the device from which the utility reads. You can also add a track number to use a track other than the default, at dvd://1.

  • -o temp.avi is the name of the AVI file to create.

  • -ovc lavc will use the libavcodec codec to compress the video data.

  • -lavcopts vcodec=mpeg4:vhq:vbitrate=1800 provides further information to the libavcodec codec on constructing the resulting file.

    For the most part, you don't have to worry about this option. However, vbitrate=1800 is crucial to the screen size of the movie. This particular setting, for example, sets the whole screen for a 17-inch monitor. Reducing the number reduces not only the screen size but also the file size! Halving the number means you can fit 2 hours on one CD, rather than 1 hour. [Hack #60] explains mencoder's bitrate settings.

  • -oac mp3lame encodes the audio track to the MP3 format.

  • -lameopts cbr:vol=3 sets the bitrate method and the volume input for LAME's sound encoding.

  • -aid 128 chooses the audio stream (language) to use. DVDs often have more than one language sound track for a given recording. The number 128, for example, is the industry's identification number for the English language.

Normally, you don't need to worry about setting the audio stream because it defaults to English. However, I personally often use 129 for the French language sound track. I add the -alang fr country identification switch, too.

It's a good idea to test the command first, because the encoding process will take several hours. The most common encoding mistake involves recording the sound improperly, and you'll hate to find out you'll have to repeat the wait. Doing a test recording is pretty simple. Add the following switches to the earlier command invocation:

 -endpos 30 -ss 00:10:00 

This will cause MPlayer to record for a period of 30 seconds at about 10 minutes into the DVD recording.

There's often more than one track on a DVD. You might want to record something other than the first track. The easiest solution is to simply play the tracks until you find the one you're interested in. For example, mplayer dvd:// plays the first track by default; mplayer dvd://1 plays the first track explicitly; and mplayer dvd://2 plays the second track explicitly.

There's more than one command incantation to create an AVI. It's all a question of experimenting with the different video and audio codecs. For example, you can restate the audio command so the audio stream is directly copied into the AVI without converting it to MP3:

 $ mencoder dvd://1 -endpos 30 -ss 00:10:00 -o  temp.avi  -ovc lavc -lavcopts \  vcodec=mpeg4:vhq:vbitrate=1800 -oac copy -aid 128  

This incantation will normally result in a 1.4 GB AVI.

Play back the ripped recording by running mplayer:

 $ mplayer  temp.avi Breaking Up the AVI.

The transcode suite of utilities is ideal for video-stream processing. That's exactly what we want to use here. For more information on how to install and configure transcode check out [Hack #63]. Once you have installed transcode, you can run the tcprobe utility on your newly created temp.avi:

 $ tcprobe -i  temp.avi  [tcprobe] RIFF data, AVI video [avilib] V: 29.970 fps, codec=DIVX, frames=135989, width=720, height=480 [avilib] A: 48000 Hz, format=0x2000, bits=16, channels=2, bitrate=448 kbps, [avilib] 9076 chunks, 254128000 bytes, CBR [tcprobe] summary for temp.avi, (*) = not default, 0 = not detected import frame size: -g 720x480 [720x576] (*) frame rate: -f 29.970 [25.000] frc=4 (*) audio track: -a 0 [0] -e 48000,16,2 [48000,16,2] -n 0x2000 [0x2000] bitrate=448 kbps length: 135989 frames, frame_time=33 msec, duration=1:15:37.504 

transcode includes a utility called avisplit for splitting AVI files into chunks of a specified maximum size. This example command breaks temp.avi into chunks no larger than 640 MB apiece (a perfect size for CDs):

 $ avisplit -s 640 -i  temp.avi  

In this case, it creates two files, temp.avi-0000 and temp.avi-0001. Remember to check them out by playing little snippets at different points in the movie, say at the beginning and end of each file. Creating the ISO.

At this point you're ready to create the self-booting movie ISO. It'll take several utilities to do this, but using K3b makes it simple.

The first thing to do is to ensure that K3b sees all the requisite utilities, as seen in Figure 3-10. Launch the program, go to the Settings menu item, and click on the Configure option. You won't need all the utilities listed here, but you'll certainly require those listed at the beginning of this hack.

Figure 3-10. K3b external programs window missing eMovix!

Figure 3-11 shows a snapshot of a new eMoviX project. Choose the eMoviX project that suits the medium to which you are burning. You may have a DVD burner, but be sure to select a CD project if the recording medium is a CD-R.

Figure 3-11. Creating a new eMovix project

Using K3b is a fairly intuitive process. When you run the program, you'll first see three panes. The top right one shows the files, defaulting to your home directory. From this pane you can navigate to the AVI files. Now drag and drop the first ISO image into the bottom pane. You can bring up the Burn window by clicking on the Burn icon, selecting Project Burn from the menu, or pressing Ctrl-B to start the burn process. The Burn window, as shown in Figure 3-12, provides the opportunity to provide the information to include on your CD, as well as indicate how the movie should start and what should happen when it finishes. Take a minute to tab through the options: its pretty cool what eMoviX can do.

I don't change much of anything except for the volume description and whether I want the system to eject the CD or shut down the system after the movie ends. When you're satisfied with your options, click on the Burn button to begin the burn process.

That's it, folks! Repeat the process for the next images until you have completed burning your CD movie.

Figure 3-12. The K3b burn window

3.27.3. Using the CDs

Put the first CD in CD drive of any PC and boot the machine. The CD uses ISOLinux to boot a small Linux kernel, run MPlayer, and start up the movie file you have on the CD. When the movie ends on one CD of a multi-CD video, replace it with the next CD, and type movix in the console to start the next movie.

3.27.4. One More Trick

I like using an image from the movie as my label for the CD jewel case. I use MPlayer to screen capture an image:

 $ mplayer dvd:// -ss 00:10:00 -vo jpeg 

This example command will begin screen capturing several frames per second, beginning 10 minutes into the movie. You will end up with a collection of numbered JPEG images in the directory where you invoked mplayer. Press Ctrl-C as soon as you've collected enough images to choose from.

Now load them into your favorite graphics package. I use display from the ImageMagick graphics suite because I can load them all with one command:

 $ display *.jpg 

Select the one you would like to use, print it, fold the paper, and you're done.

Robert Bernier

Linux Multimedia Hacks
Linux Multimedia Hacks
ISBN: 596100760
Year: 2005
Pages: 156

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