Most commercial DVDs are also encoded piece by piece. The producers will use different encode settings for each scene to get optimal results. Yes, money helps a lot, and so does time. I remember reading that over 8 months were spent on encoding "Star Wars Episode I" to get it just right.

What amazes me is that we home users are just getting to the point of being able to make DVDs at all. Hollywood was making them many years ago back when the best PC i had on my desk was a 16MHz 286 with 2MB of RAM and a 60MB (no, not GB) hard drive. What sort of equipment were they using???

If you look closely and hard at a commercial DVD playback, two things come to mind:

1. The contrast range is quite limited
2. The sharpness isn't *really* biting. Instead, it's got a beautiful filmic quality (yeah, yeah, I know it was film in the first place). Actually, it's got nothing to do with sharpness; it's the difference between a [stills] photograph being out of focus and being shot with a soft focus lens.

Another thing: if you look at the bitrates - either using your set top player or something like PowerDVD - you'll find them surprisingly low. This may be partly due to the 'softness' I mentioned before - there being less detail to encode.

It makes you wonder (it makes ME wonder, anyway) if the footage goes through some sort of pre-processing to make it more amenable to MPEG encoding.

Anyone know for sure?

-Pete

Hi
One thing also to consider is the source material.
A 35mm film telecined using a million dollar plus telecine chain
(film to video machine)!
Also professional video recorders have muck higher resolution than domestic cameras
(getting better though)
Plus proffessionals know how to use the gear to its max.
A lot of time and people go in to geting just one shot on a feature film.
I suspect the encoders we use are not to bad.
Cheers
Mike Slater
Micsound P/L

I worked at a high end post production house for many years and can tell you a few things about the way DVD are encoded in the professional world. The big quality difference comes from the source material being an uncompressed digital signal like D-1 or D-5 tape or a very high quality compressed format like Digital Betacam. Using DV as a source for MPEG-2 compression means using an already heavily compressed (and 4:1:1 sampled signal) for a source. Also, most of the video is encoded using a multi-pass (usually 2 or 3) encoding and film source almost always has IVTC applied to it. The one step that can make a BIG amount of difference in how the encoded MPEG-2 will look is the preprocessing involved. The facility where I worked used expensive noise/grain reducers before the encode. Their use is critical to getting the best quality at minimum bitrate and is more of an art than science. These are few things that I know of that distinguish the pro encoded DVDs from the consumer made DVD discs.

All the processes are important and doing it scene by scene. We have a hardware encoder at the office that turns out great quality encodes at 6 and 4 mb. It matches the 8 mb quality that I get from my software encoding from the same material.

What I was noticing though lately is a lot of the DVD's I have been buying are actually at 8 mb. They are using DVD9's for a 100 minute film and filling it.

For the benefit of we numbskulls, what is IVTC (alternatephase) and what are 4,6 and 8 mb encodes - are you referring to the bitrate?

What does '...using DVD9s for a 100 minute film and filling it...' mean?

I'd really like to learn as much about these things as I can. There's a whole host of settings in the Vegas encoder that I daren't touch in case they bite me. I could do with a tutorial - believe someone mentioned something like that was on the way...
A long time ago <g>

-Pete

< what are 4,6 and 8 mb encodes >, yes I am refferring to bitrate. :)

DVD9's are dual layer DVD's which hold 9 gig. The desktop writable are 4.7 gig single layer. (well sort off, but for this discussion that will do) They are filling up much more disc space than you have available.

Working with MPEG settings is an art in my opinion. I learned by reading papers on it and then I made hundreds of test encodes to figure out what each thing did to different types of material. I still think it is black magic, but I can pick some settings make my stuff look OK.

K