DivX encoding and random thoughts...

[lonny]

First of all...
today I ripped my first DVD to DivX. It feels great, and I love my humble Mac (see sig) for coping with it!

It worked almost flawlessly.. I just had to split up the DVD into 3 VOB files, because otherwise I got an error message.
Then just a little validating, and re-syncing in QT Pro. Perfect!

There are still a few things that look obscure to me though, and I wonder if anyone can enlighten me.

What is actually an .avi?
I mean, I ripped the movie using the DivX5-mpg4 encoder in MacDivX, and the output file is in avi. Why do files have to be embedded into avi? If I convert this avi into mp4 into QT, what difference am I gonna see?
And.. is the mp4 coded in DivX5 a standard mp4 codec?


Ok, I don't know if I made myself clear, I'm a bit confused... but I hope someone can give me a brief lesson on codecs.

Thanks!

[lonny]

Hmmm... no replies yet.
Weel, my DivX plays fine. I still have to understand what is the difference between an avi embedded divx and a mov embedded one.

[voice-]

How'd you do it? I REALLY wanna know how (step-by-step) to rip a DVD so I can watch them on my PowerMac(see sig)

[Jason]

i would like to know how to play divx in quicktime without having to convert it to all sorts of different files

[Krevinek]

My best experience with DivX viewing is actually with the official codec. Run DivX Validator on the file (since VBR MP3s in AVIs aren't standard, and don't work well except with the hacks done on PCs) and the resulting file will go from PC to Mac and back without ANY CHANGE and play just fine. QT 5/6 can then play DivX using the ffmpeg or official DivX component and get decent performance.

For encoding, I have seen many recommend OSEx to grab the actual VOB files, and to split them... you can then use ffmpegX to do the actual encode. It is actually pretty fast, as I have done encoding from DivX to MPEG-1 for VCD use within 2 hours (for 30 minutes of footage) on my STOCK 300Mhz 604e!

The difference between DivX in AVI and DivX in MOV is nearly nothing, except the format of the file they are in. The DivX QT components are fairly nice in that embedding DivX in a MOV is straight=forward, and any QT-compatible movie editor can decode em for use in editing (great for us AMV peoples). However, MP4 (MPEG-4) is not DivX, nor is DivX compliant with it. In fact, DivX now says that their codec is MPEG-4 /BASED/, not MPEG-4 or MPEG-4 /COMPATIBLE/. While they are based upon the similar routines for compression and similar format for video, DivX is only video, (I have seen DivX embedded in ogg files, vorbis is the music format, ogg is just a container format), and usually uses MP3, WMA or Ogg for the audio. MPEG-4 uses AAC for the audio. Big difference there.


Any more questions?

[lonny]

How'd you do it? I REALLY wanna know how (step-by-step) to rip a DVD so I can watch them on my PowerMac(see sig)

Ok, here we go!
It's all pretty simple and works well on my B&W G3 (see sig).

First of all you'll need:
OSEx (www.cs.buffalo.edu/~afaversa/)
MacDivX (http://thegoods.ath.cx/~hmason/mdc/)
You can find a guide on this website too.

Use OSEx to copy the VOB file from DVD to HD. You can select chapters, language and audio specs. Then start extracting. This process took about 1 hour on my machine.

You'll have now a big (around 4Gb) VOB file on the HD, you can actually play this in full DVD quality with something like VLC, but you might want to compress it in DivX.

Enter MacDivX, which is essentially a fron end for ffmpeg. Start the app and open the VOB file. You can set a few parameters, like screen size, motion prediction algorythm, etc. Start encoding and go out for a walk. This process took about 3-4 hours on my Mac.

You have now a nice and small (600Mb) avi file you can play in QT with the official DivX plug-in (http://www.divx.com/divx/mac/).
The video will play nice, but a bug in QT prevents the audio from playing, so you'll nedd to "validate" the file with DivX Validator, part of the official DivX package. Validating only takes a few seconds.

Now everything plays, but audio and video will likely be out of sync. Open the avi file (A) in QT Pro. Extract the audio. You'll end up with a second file (B) with only the audio track. Go back to (A), select all and copy. Then "Add scaled" to (B), this will sync audio and video. "Add scaled" will also add a second audio track wich you'll need to delete. Save (B).
Final result: (B) will have same video and audio from (A), but in sync.

It sounds a bit confusing, but it becomes very clear once you actually do it.
Enjoy!

[voice-]

I'll try that when I get home...I just hope OSEx is better than the last time I tried it...it quit itself after 1.92 Gb...tried it on 2 different Macs with 2 different movies and same result...but I'll cross my fingers again and hope for the best.

[lonny]

Thx Krevinek for your answers!
I have some more questions though:

1) will a .mov embedded divx file play in any QT without divx plugins?
2) will converting and avi divx to mpeg4 make it smaller thanks to AAC audio?

You seem to be quite in the know!