Ripping DVDs for the GP2X

So you're got your sexy handheld console and you've downloaded the games and put your MP3 collection onto SD card and all is well. . . But you've got this large, high-quality colour screen and you want to make more use of the multimedia. It's time to think about movies.

Before going any further, I should caution you that copying copyright media from disc to computer is illegal in some places, even when you own both. Copying (or downloading) copyright media that you don't own is illegal almost everywhere. This guide is intended for use solely by people who own the DVDs and are legally permitted to copy it for their own use. So don't sue me, please, you *AA bods! ;o)

Now then: To business. The GP2X is Linux based, and its movie player is based on the popular Mplayer software. Mplayer comes with a DVD-ripper, Mencoder. It's great, but it's CLI based. While I'm the first to agree CLI has many advantages over GUIs, mencoding for the GP2X consists of lines like

mencoder dvd://1 -dvd-device /dev/dvd -alang English -oac mp3lame -lameopts abr:br=10:mode=3:aq=0 -af volume=8:sc -ovc xvid -xvidencopts :bitrate=130:pass=1 -vf pp=de,eq2=1.0:1.5:0.1:1.4,crop=716:410:2:82,scale=320:-2 -ofps 10 -srate 11025 -o "/dev/null"
mencoder dvd://1 -dvd-device /dev/dvd -alang English -oac mp3lame -lameopts abr:br=10:mode=3:aq=0 -af volume=8:sc -ovc xvid -xvidencopts :bitrate=130:pass=2 -vf pp=de,eq2=1.0:1.5:0.1:1.4,crop=716:410:2:82,scale=320:-2 -ofps 10 -srate 11025 -o "/root/indy3.avi"

and if that doesn't scare you, then you probably know too much to benefit from this guide! ;o)

So I shall be explaining how to rip DVDs using another popular ripper, namely dvd::rip. If you're determined to use a different ripper, then just keep an eye out for the technical stuff & you should be able to transfer easily enough.

Installation of the software is beyond the scope of this guide: Consult your package manager documentation. Once you've got it installed, run it and you should see a screen like this:
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File -> New Project. You'll get asked for a name for the project. I've called mine GP2Xguide, and as you will see, it fills in the rest of the options for you:
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Your work here is done. Click the "Rip Title" tab, and read the DVD's table of contents. This can take a while, so wait until the status bar at the bottom reaches 100% and the DVD drive light goes out before you assume it's finished. You should get something looking vaguely like this at the end:
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Although usually you'll have rather less titles! This is a special features DVD with lots of goodies, so it's rather busier than a typical movie DVD. You get a lot of information. The bits that we care about are:

The rest we can mostly ignore.

Firstly, decide what you want to rip. Highlight multiple titles or chapters by holding down the CTRL key while mouse-clicking. Once you've got everything, click the "Rip selected titles" button. Take a break while it reads the disk: You'll get a status bar at the bottom telling you how long it's going to take.
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Once you've ripped, move to the next tab. You'll see a random thumbnailed frame from the movie you just ripped, in several stages of its life. Click the thumbnail for a full-sized image. In this example, you see the raw, mis-shapen image; the resized widescreen-aspect image; and the de-black-barred image. You might be starting to guess what movie you're dealing with here. . .
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At this point, you start to need the technical details of the GP2X, as you need to resize the image to fit the screen. So here's what you need to know:
Screen size: 320x240 actual size, but can play videos up to 720x480
Video formats: MPEG, DivX 3-5, Xvid
Frame Rate: up to 30fps
Video bitrate: up to 2500kbit/s
Audio bitrate: up to 284kbit/s
Captions: SMI

As you can see, the default screen size selected by dvd::rip is small enough, so we can move right along here.

Subtitles are not a subject I know much about, I fear. And on the GP2X you're just asking for eyestrain. Unless you really need them, I suggest skipping them completely and going straight to the really technical bit: Transcoding

This is where you need to know most of what's in the table above. Let's work through it, shall we?

Container: AVI.

Video Codec: Up to you. I personally like Xvid, but at the time of writing, it's not well supported, so I fall back on divx5

Framerate: Anything up to 30. This movie was only 25fps, so that's what I've left it at.

2-pass encoding: This doubles the transcoding time, but gives you a better quality movie at the end, for no extra space. Worth doing.

Deinterlace mode: TV screens work by drawing every odd line of an image, then every even line, then every odd line, and so on. As a simple example, consider a simple 3-frame animation showing a face moving across the square. What you want is something like this:


But what your TV shows you is something more like this:

TV animation

Every other line, you see. The awkward thing is, of course, that superimposing one image on the other doesn't give you the proper image, so your computer has to do some clever things behind the scenes, to turn this:

Interlaced image

into this:

Interlaced image

So watch the movie & see if you get lines when something moves fast across the screen. If so, you've got interlacing. Use "Zoom To Full Frame" for best results, but it'll take a lot longer to rip.

Filters: You can usually ignore this

Bitrate calculations: dvd::rip uses two ways to set this. Either tell it how much space you have, and it'll give you the highest quality; or tell it what quality you want by checking the "manual" button and filling in a bitrate of no more than 2500

Audio options: The audio track is usually right, but not always. The only other thing you may want to change is the quality: Setting it to two is much quicker & doesn't give any real loss of quality.

General options: This is where we will generate a quick preview to make sure all is well, and also make sure the transcoding doesn't lock up our PC.

Set the frame range to something small, like ten seconds. You'll probably want it a reasonable way into the movie to make sure there's something worth watching, such as 1000 to 1250. Lastly, set the nice level to fifteen or so. This will ensure that your ripper only uses free resources, so your PC will remain perfectly useable.
Click to enlarge

We're now ready to take a look at our video clip. Click Transcode. My machine takes 13 seconds on this particular task, so we're not expecting much of a wait here.

Once the coding is finished, click "View AVI" and check that it looks okay. If it doesn't, there are two likely culprits: Improper image quality, which is solved by fiddling with the bitrate; and sound is out of sync with the video. Don't meddle with sound until you've sorted the bitrate: Changing the bitrate can create or remove synch issues.

Clip 1 (2.5MB, right-click to save to your machine)

Once you're satisfied, clear the frame range. It's time to transcode this puppy. It'll be a 44.37MB file, so it might take a while.
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Since we're waiting, I'll tell you about what I'm ripping. It's the first trailer I ever downloaded off the Net, back in the days before broadband. But it was worth it: The film had been hyped so much, after all, everybody wanted to see the trailer. Remember the news stories about people going to see a film at the cinema just so they could watch the trailer?

Star Wars episode one: The Phantom Menace. How cool did the idea of a double-bladed saber seem back then? :o)

I chose this one partly for the nostalgia, and partly because it has both fast-paced action shots and slower scenes that wil help to emphasize the difference bitrates can make in such matters.

So, the trailer is transcoded, and here it is, in all it's 44MB, 640x272, 2500kbit/s glory. Looks good on the GP2X. Heck, looks good on my 1280x1024 monitor!

Clip 2 (45MB)

But more than 20MB per minute is. . . well, it's going to need a lot of SD cards to get the whole film on at this rate! SW1 is 131 minutes long: 2.6 gigs at our current rate. Ouch.

So let's look at cropping out some deadwood. Firstly, let's go back to the screen size in "Clip & Zoom". 640x272 is all well and good, but the GP2X screen is only 320x240. Unless we're going to hook it up to a high-def TV, it's overkill. Let's halve the screen size. Go down to the Zoom options, replace 640 with 320, and then click the "Calc height" button. Then a top&bottom clip of 22 to trim the black bars. This gives us a final size of 320x176.

Back to the transcode tab. The calculated size of the movie is still the same, because the bitrate is still the same. 2500 was good enough for the big movie. Halving in size quarters the screen area, so 625 would presumably give a pretty good quality image, right?

Let's see how this movie looks now it's only 12.86MB

Clip 3 (13MB)

Pretty good, I think. Okay, it's no longer looking that wonderful at fullscreen on my monitor, but on a GP2X, it's fine. 6MB a minute is pretty reasonable: The whole film will be 786MB now, which'll easily fit on a 1GB card.

(You may notice that the audio & video are slightly out of synch on this version - a perfect example of why you shouldn't play around with the synching until you're happy with the video settings you're using!)

But can we go any lower. . ?

Well, that depends on the type of film. For a less action-packed film, a bitrate of 300 will actually do pretty well. Observe:

Clip 4 (7.3MB)

For a file under 8MB, that's not all that bad, for the most part, is it? It's not great, of course, but for the easier scenes it renders pretty well. The 'busier' scenes are less wonderful, of course. Depending on the movie you're ripping, this could be good enough - A bitrate of 300 worked great for Wallace & Gromit films on the Gp2X!

And if you're not quite sure what a movie looks like with a too-low bitrate, let's give you a 100kbit/s example to clear it up ;o) Even here, a few scenes are pretty good, but it's mostly lousy. This illustrates the need to look at more than just one scene when sampling your bitrate: A scene that's too easy to transcode will give a falsely low bitrate requirement for the rest of the film.

Clip 5 (4MB)

That pretty much covers everything. You should now know everything you need to get a DVD movie onto your GP2X at an acceptable quality level with minimal tinkering. If you want even more information, I recommend the guide to ripping by Moritz Bunkus and/or the GP2X forums.

Creative Commons LicenseThis work is copyright and belongs to Dominic Humphries. It may be redistributed under a Creative Commons License. This page's URL must be supplied in attribution.

The trailer used as illustration is copyright Lucasfilm Ltd.

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