[LAU] DVD creator ?

[Florin Andrei]

Dave Phillips wrote:
> 
> Here's how I create an original AVI from the output of AVSynthesis:
> 
> First, I record a series of TGA images from AVS. Then I run:
> 
>    find *tga | sort -n > list
> 
> As I've mentioned, I can control FPS and video width & height in the AVS 
> config file. I currently set video to 720x480 and the frame rate to 30.

The source should be 640x480, if you want a 4:3 aspect ratio. This is a 
common source of confusion, the fact that DVD MPEG2 has non-square 
pixels. Just don't worry about the actual resolution of the DVD MPEG2 
stream, set the source to a "natural" size such as 640x480 and the 
resize will happen when you create the MPEG2 stream.

Remember: DVD MPEG2 has non-square pixels, while most sources are square.

Now the frame rate. I don't know what AVSynthesis is doing, whether it 
will interpret FPS="30" as true 30fps, or as the actual NTSC frame rate 
(30000/1001). The difference is small, about 0.1%, so you may actually 
ignore it if AVS actually does exactly 30 fps.
OTOH, it would be nice if AVSynthesis could do true NTSC frame rate.

The only issue if you choose to ignore the 0.1% is that audio and video 
may drift out of sync slowly. Or not. It depends on which part of the 
A/V chain becomes confused. :-)

> Audio sr is 48 kHz (which I can also set in the config file).

Yeah, that should be right. 192 kbps AC3 is at 48 kHz IIRC.

> Next I 
> process the list to create the master AVI:
> 
> mencoder -oac copy -audiofile render.wav -ovc lavc -lavcopts 
> vcodec=huffyuv:pred=2:format=422P:vstrict=-1 -noskip -mf fps=30 -o 
> master.avi mf://@list
> 
> This process creates a beautiful very high-resolution AVI, about 3GB

Yeah, no kidding, that's a lossless codec.

> large for a 4-minute animation. Obviously I'd like to keep as much of 
> that resolution throughout the DVD process. Is there any part of my 
> current encoding process I should change ?

Well, most MPEG2 encoding chains should accept huffyuv as a source, so 
that should be fine I guess.

What you create here is a progressive source, 30 fps. This will steer 
you towards 30p DVD, which is a bit of an odd format. I need to think 
about this, and perhaps do some experiments myself. Maybe try and create 
a 24p source, and do a "film-like" DVD (with 2:3 pulldown), just like 
all commercial DVDs made out of film sources (not digital).

Finally, if the DVD image quality is poor, given that this is an 
artificially generated source encoded with huffyuv (so there's no noise 
from natural sources such as film or CCD, and there's no loss due to the 
codec), it's definitely the fault of the MPEG2 encoder, or a less 
inspired choice of encoding parameters, or both, now I have no doubts.

Yeah, I think I may start playing a bit with AVS, you made me curious 
about this whole thing. There must be a way to create clean good NTSC 
DVDs out of it.

-- 
Florin Andrei

http://florin.myip.org/