How do professional studios create DVDs?

[Phire]

I've been wondering how professional studios create DVDs (The video). Correct me if im wrong, but i've heard that film isn't measured by resoultion, but if it had to be then it would be something in the 3000x#### resoultion? So then studios would transfer that almost lossless high resoultion film onto a PC and compress that to MPEG-2. But what about things that are TV series? such as The Sopranos or X-Files (I believe these 2 are on DVD), aren't their sources a digital tape? which are already compressed correct?

[KRSESQ]

Phire:

Usually television programs are shot on 35 mm film (or, occasionally, Super-16), then the negative is transferred to high-quality videotape for all post-production work, including VHS and DVD distribution. Film is the preferred medium because a) it has a wider exposure latitude than video (though the gap is closing) and b) because film is so well entrenched in Hollywood it takes "mavericks" like George Lucas and Spike Lee to demonstrate what video can do.

As the quality of DV goes up and the cost comes down and more independent producers enter the ranks, eventually film will fall by the wayside, though not without its mourners.

Kevin

[Frankie G]

Which brings up a question for our UK friends:
Why, in British TV shows, mainly older ones like Monty Python,
Fawlty Towers, etc., are interior scenes shot on video, while
anything outdoors is on film? The effect is kind of
jarring when they go from one to another. I have never
seen this on US TV; it's either all film or video.
(This doesn't count the old kinescopes).

[Maggi]

Hey Kevin, it's all a matter of cost ...

if the production company is willing to afford the higher quality, they will go for real filming onto celluloid, but most of the time TV productions are filmed on digital video equipment nowadays.

...

about DVDs:

Usually they just take the TV version of a big screen movies which was scanned in a telecine and already converted down to match the according TV standard (PAL, NTSC to name two).
Professional digital video tapes and machines use a totally different technique than the one used in DVDs, thus you'd always have to take the contents into an authoring system, which let's you arrange the movie (split into chapters), build some fancy menus, compress the video and sound streams into MPEG-2 and generate the DVD master which then can be copied in masses.

I think one of the rare exceptions to this procedure was "A Bug's Life" (and probably all movies that consist solely of CG), where they simply used their rendering/compositing results on a filesystem transfer base, rather than rescanning the printed movie.

Hope that helps a bit ...

Cheers,
Maggi

PS: celluloid is also used for it's natural look, but that's just because we (humans) are so f*cking used to that look ...

[Maggi]

forgot one thing ...

Frankie,

my guess is that the Monty Python troup just didn't have the money to afford 'out door' TV equipment and went the cheaper route (back then when electronical cameras were something called Hi-Tech and thus much more expensive than conventional film equipment)

Just keep in mind that one of these modern DV cams with built in filters etc. is comparable (maybe even better) to a whole TV studio from the 60s ... but it fits into your pocket.

[KRSESQ]

My understanding of the whole British indoor / outdoor thing (apart from the expense and prohibitive nature of lugging videotape equipment outdoors) was that different trade unions demanded a division of duties e.g. interiors were shot by television union workers and exteriors were shot by film union workers.

This came to me third-hand, so I'm open to correction.

Kevin

[cjyo~]

I've worked on a couple of the DVD titles mentioned: X-Files (TV season 1 and movie) and Bug's Life (and 100's of others for Disney, Fox, Paramount, MGM, Sony, Universal and others).

Resolution-wise we work in NTSC full-rez, which is 720x486 (chopped to 480 on the encode)/525 lines, unless we're doing a PAL project. Most of our master tapes are either DigiBeta or D-5. Digibeta is around 2.3:1 compression at around 90mbits, as opposed to DV's 25mbits and DVD's average 5-7mbits.

As already noted, films are telecined directly to tape at NTSC standard definition. Recently, a lot of the newer films are telecined to high definition D-5 masters, then down-converted to NTSC standard definition for encoding. Many TV shows shoot on film, but the telecine process happens before editing.

The Digibeta or D-5 tape goes through a multi-pass hardware encoding process: first the machine goes through the tape and builds a VBR profile, based on a predetermined bitrate (to fit on a single or dual layer). It automatically increases the bits it complicated and high-action scenes, compensating by lowering the bitrate on static or simpler scenes. Then the compressionist will go through a tweak all the problem areas, raising and lowering the bit-rate all the way through the film. Then the film is encoded. Audio is encoded separately on a different encoder. Once it goes through authoring (programming menus and logic), it is emulated off hard disk. If video errors or problems are found, certain segments may be re-encoded.

I guess we'll see when Episode II comes out, but professional telecine from 35mm film to tape still has a greater resolution and tonal range than the highest resolution high definition video shot to the same tape. And of course, even Episode II will be projected on film in most theaters.

KRSESQ - I hadn't heard that explanation before but it does make sense, knowing all the craziness that can go on in the industry, whichever side of the Atlantic. I've been watching some old Tom Baker Dr. Who tapes lately, but I always figured it was just because the studio cameras in those days were the big sit-down type of cameras you see on news sets or the Tonight show.

[cjyo~]

Here's a more detailed article:

http://www.dvdfile.com/news/special_...z/compression/

[ccoltas]

The question of resolution is an interesting one. Does anyone know the resolution of film formats. We all know about the lines of video for PC monitors and NTSC TV's, but what is the resolution for a film print start at?

[KRSESQ]

Film resolution is hard to compare to video resolution as they are measured differently.

Film resolution is a function of its light gathering ability, or ASA number. This, in turn, is governed by the size of the molecules of silver halide in the emulsion. ASA 100 film has lower light gathering ability due to the smaller size of the molecules (fine grain). ASA 400 is excellent for low light but has coarser grain, which becomes apparent as the image is enlarged.

I've seen stats which indicate that 35 mm ASA 100 film approximates to 30 megapixels. The current crop of commercial digital cameras range around 3 megapixels.

Professional digital equipment is, of course, far superior to that. However, it should be theoretically possible to blow up a film frame from "Toy Story" and actually count the individual pixels reproduced in the emulsion!

Kevin

[Maggi]

Interesting thread ...

We do our digital movie work in 2048x1536 while having 16 bits per channel (RGB) colordepth.

We work in 4:3 so that we can shift the picture around if neccessary (that famous mike keeps poking into frame ... )

www.vcc.de for more details

Cheers,
Maggi

PS: KRSESQ ... what cjyo~ said ... you never know what's up in their sleeves ...

[Phire]

Ok thanks for your input everybody. Just a few more questions . How come they can't directly transfer the telecine to a PC rather than transfer it to tape? I guess you can't do a direct encode to MPEG-2 since it's required to do VBR, but what about to an uncompressed format, maybe HuffYUV? . But it's probably unlikely that 90mbits show any artifacting anyway . Also, what sort of encoder do these studios use? I would guess it's that expensive Cinemacraft encoder. I had always thought that MPEG-2 was a constant bitrate on DVDs, or do you mean that it's VBR when it's 90mbits on tape and then transfered to 7-8mbits CBR on DVD?

[cjyo~]

(*warning: link mania below)

You can telecine to hard disk, but tape is cheaper and lasts longer. Some film crews have a live feed on the set going to an AVID raid array for immediate rough cutting on location. They still go back later and cut the film, then telecine for video release.

There are various encoders, I used to work for a company owned by Matsushita/Panasonic, where we used a proprietary encoder board. Where I work now, we have an old Minerva encoder (not sold anymore) and a new Sony Encoder, that is a PCI board upgrade of the DVA-1100 system, but it's still pretty buggy. Digital Vision and Spruce (of Maestro authoring software) also make their own boards. We are actually playing with the new Mac software encoder/transcoder at high bit rates for short menu clips, so we don't have to go to tape (all our AfterFX work is Mac based).

I haven't heard of anyone doing studio production work that uses Cinemacraft (software?) encoder.

One of the major keys to DVD/MPEG-2 video is Variable Bit Rate. There may be a few titles out there encoded CBR, but that would be very rare - maybe in the case of a short film, where there would be plenty of bits left over, so you could max it out all the way through.

You couldn't squeeze a normal feature-length movie on a disc without VBR. The art of compression is balancing the bit rate throughout the film so you get the best overall picture based on the bit-budget determined by length of the film, number of soundtracks (DTS is a bithog), extras, and whether the disc is single, dual layer or double sided. 8-9mbits would be a high spike on a detailed high motion scene, most films stay in between 5-7mbits, but dip into the 4's for static scenes. A number of set-top players have a bit rate viewer (Sony's do for sure), so you can see the rough bitrate fluctuate as you watch the movie.

The tape formats we most frequently work with for studio DVD production are Digibeta, D-1 and D-5.


Much linkage, read and enjoy:


Check this discussion out (talking about the data rate of uncompressed film):

"For a 35mm Full Screen format camera negative: 41.3 MB/frame and for a
90-min feature negative: 5,573 GB. "

http://palimpsest.stanford.edu/byfor.../msg00170.html


DIGITAL TAPE FORMATS:

http://cilect.org/digital%20tape%20formats.htm


"D-5 has a 270Mb/s data rate in a 4:2:2 component form. There is now an upgrade module which applies 4:1 compression for HDTV."

http://www.electric-words.com/dict/d/d5.html


"D-1 the video bit-rate is extremely high at 216Mb/s."

http://www.electric-words.com/dict/d/d1.html


How good are the DV formats compared to other formats?

http://www.dvformat.com/htm/features...format_faq.htm


Film Formats and HDTV: A Case for the Future-Proof Standard:

http://www.henninger.com/library/hdtvfilm/


-----

High end hardware encoders:

Sony DVD encoder:

http://www.pro.sony-europe.com/bpeproj/classes/Presentation.ProdProductPage?product_ id=621

Digital Vision:

http://www.digitalvision.se/datashee...d_prodblad.pdf

Minerva:

http://www.marcorp.com/pdf/c250_ds.pdf

Panasonic:

http://www.postmagazine.com/features.../panasonic.htm

[This message has been edited by cjyo~ (edited 25 February 2001).]

[Biker]

I need to know how to make DVD's as well!

Re: I make multimedia PC programs. How do I make a mm DVD program, as regards index's for program selection etc.?

Is it just a case of getting software thats supports it?
If so anyone know what software supports it?

Thanks.

------------------

[cjyo~]

You need an authoring program. There are a few entry level programs to get you started: MyDVD, DVDit, ReelDVD, DVDMotionCE and SpruceUp to name a few.

http://www.spruce-tech.com/products/spruceup/

http://www.dvdit.com/

http://www.mydvd.sonic.com/

http://dvd.acedaikin.com/products/ReelDVD/ReelDVD.htm

http://www.mtc2000.com/dvd/index.html#DVDMotion