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View Full Version : Shrink DVD to 1 GB or less and retain 5.1 ???


CPYou
8th April 2008, 07:41
Greetings,

I am somewhat new to all this, but not a complete newbie. I have been backing up our DVD collection for the past year with no problems, but now that I am closing in on the 1TB mark or backups I would like to know how to shrink each one of these backups even more than the 4gb size they currently are. Now, I did have some success using AutoGK to shrink a few to a 1GB Xvid file that did in fact retain the 5.1 audio.

Now my question, is there a better way to be doing this? I just figured I would ask before backing up 1TB worth of movies only to find out that I had to start all over from scratch.

Thanks in advance for any and all help!

RememberTheFallen.com

Southstorm
8th April 2008, 11:30
For my needs, x264 is great. Try some of the GUI's listed here:
http://forum.doom9.org/showthread.php?t=129748

CPYou
9th April 2008, 03:38
You would consider that a better method of doing the conversions I take it?

Why so?

Just trying to learn more about the differences in formats, thanks =)

fibbingbear
9th April 2008, 14:14
You would consider that a better method of doing the conversions I take it?

Why so?

Just trying to learn more about the differences in formats, thanks =)

In general, H.264 (or the open source equivalent, x264) is a more advanced codec than Xvid. It generally gets better compression, especially at lower bitrates (at higher bitrates, xvid and h.264 look about the same).

There are several things to consider:

1.) Xvid and DivX are basically the same these days. A lot of people consider them equivalent. They are nice because they have fast encoding times and fast decoding times --- it doesn't take too long to encode a movie, and you don't need a fast machine to play them back. However, if you try to go to low bitrates, they tend to noticeably degrade.

2.) H.264 (or x264) is much more processor intensive. Encoding time is generally slower, and decoding time is as well --- you need a faster machine to watch those movies. However, it looks better at lower bitrates.

3.) What container format you're going to use. Almost everyone agrees that AVI is outdated. Popular replacements include mp4 and mkv (ogm seems to be more on the fringe). Both of those support AAC audio, which also supports 5.1 sound (I think...)

One thing I like about x264 is that it has a constant rate factor encoding (CRF), so you can have it encode all your movies at approximately the same quality --- if you encode based on bitrate or size (i.e., every movie will be 1 gigabyte in size, or every movie gets 1000kbps), you run the risk of some movies looking better than others (a movie with a lot of stuff in it may need more than 1000kbps to look good, and a movie with little movement or detail may need less than 1000kbps to look good). Popular CRF encodings are between the values 18 and 22.

Anyway, if you search the forum, you'll find a ton of stuff about this :)

The one last thing I'll say is: if you want to get extra compression and still retain quality, I highly recommend looking into Avisynth and a spatial/temporal noise filter, such as FFT3DFilter. Even if the movie looks very clean, there's probably some noise still in it. Using a noise filter with a very low strength (like sigma=0.5 for FFT3DFilter) will clean up noise that's practically invisible --- you can't tell the difference, and the encoder can squeeze a lot more bits out.

Ranguvar
9th April 2008, 16:54
Do note though, that unless you have an ancient machine, you can get x264 to encode in the same time as Xvid and still be more efficient. But it's even better if you give it time.

prOnorama
9th April 2008, 17:51
You have to keep in mind movies encoded with x264 do not play on standalone DVD players so if standalone compatibility is important to you stick with Xvid (though that will probably change in the future)

I'm sticking with Xvid for SD content for that reason (sure the movies need more bits but I can usually get 4 films in good quality on a DVD)