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bad DVD authoring


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#1 David Mullen ASC

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Posted 02 September 2006 - 12:11 PM

As I've been pulling frame grabs from "Akeelah" I've been noticing how bad some of the MPEG mastering is. Sometimes it even seems like the movie is switching from 480P to 480i because a few frames have toothcomb artifacts. And the compression on some moving shots is ridiculously high.

Bad compression on a moving camera shot:
Posted Image

Here's an enlargement:
Posted Image

Interlaced-scan artifacts:
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#2 John Holland

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Posted 02 September 2006 - 12:15 PM

Is this ploy to make us all buy H.D. Blue Ray or what the other one is called ,expensive new toys ? John Holland .
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#3 Frank DiBugnara

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Posted 02 September 2006 - 01:15 PM

Is that from the Studio's final DVD release? Seems like you only see very poor quality like that when they are trying to cram a bunch of extras in addition to the film on the DVD. Also, the "toothcomb artifacts" can come from a field reversal problem which I've found to be pretty common (I made the mistake myself this week) where you make the lower filed dominant when it should be the upper, etc. With that mistake you only notice the problem on some motion, but it is pretty bad.

I've been constantly impressed with the image quality that Compressor and DVD Studio Pro are able to provide when the proper settings are applied. After watching uncompressed Digital Betacam footage for hours and then going home and watching the same film on DVD, I'm very not-bothered by the compression. That's impressive considering the file is less than 1/16th the size of the original uncompressed SD footage.
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#4 Scott Fritzshall

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Posted 02 September 2006 - 01:44 PM

Geez, that's got to be frustrating for you. Is there anyone that would listen if you complained about it, and fix the next batch?
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#5 timHealy

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Posted 02 September 2006 - 02:06 PM

In most cases it would be out of the cinematographers hands.

Best

Tim
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#6 Adam Frisch FSF

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Posted 02 September 2006 - 04:18 PM

That toothcomb-thing is standard procedure on most frame-grab DVD's, unfortunately. Sometimes you can de-interlace it with the video setting in Photoshop, but it doesn't always work. As suggested, it has to do with interlacing (interlacing, btw, is pure evil - they screwed video over for 50 years when they invented that s**t).

If you rip the DVD and use the files to convert to Quicktime films I can recommend a freeware software called JES DeInterlacer that's absolutely brilliant. It converts interlaced to progressive, and vice versa, better than anything out there - no jagged edges or aliasing. It's also THE only software that does a convincing PAL to NTSC conversion (or vice versa).
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#7 Thomas Worth

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Posted 02 September 2006 - 04:44 PM

Generally speaking, DVDs of feature films aren't interlaced. The MPEG data in the VOB is 23.976p, flagged as 29.97 so the DVD player knows to add the 3:2 pulldown during playback (the hardware MPEG decoder does this on the fly). If this DVD was encoded as 23.976p (as it should have been), then the problem could be the flagging, or simply the DVD software you are using to capture the frames.

Seems like you only see very poor quality like that when they are trying to cram a bunch of extras in addition to the film on the DVD.

On the contrary, a progressive stream takes up less space in addition to looking better (24fps as opposed to 30fps).

interlacing, btw, is pure evil - they screwed video over for 50 years when they invented that s**t

Yeah, interlacing sucks, but you don't have to let it affect your post process at all. Films can be telecined, cut and authored all progressive scan. Interlacing only happens if the output device you are playing on is interlaced, and that is all done on the fly at the time of playback. You'll see less and less of this problem as progressive scan players and displays become more common.
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#8 Keith Walters

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Posted 02 September 2006 - 06:39 PM

When DVD movies first began to proliferate, I kept seeing references to a brand-new species of editing professional, the "compressionist". This was supposed to be a technician whose job was to run through the uncompressed master tape and flag any picture content likely to generate compression artifacts. After that (presumably in conjunction with with other types of editor) any offending footage would then be "doctored" or even deleted altogether to minimise or remove the problem.

However this idea certainly seems to have fallen by the wayside. Or maybe it was just something that somebody thought might happen, and was turned into "fact" by the media. :lol:
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#9 Keith Walters

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Posted 02 September 2006 - 06:57 PM

(interlacing, btw, is pure evil - they screwed video over for 50 years when they invented that s**t).


If it wasn't for "that s**t" either NTSC would have had only 240 visible scanning lines, (288 for PAL)
OR you would have only been able to have three or (absolutely maximum) four TV channels in each city,
OR you could have had 480 visible lines but at only 30 frames per second, which would have flickered intolerably. (288 at 25 fps for PAL which would have even worse to look at).

If you went for the second option, the 12MHz or more channel bandwidth also needed would have required much more expensive antenna systems both at the transmitter and in the home, and home videotape would probably never have become affordable if it ever became practical at all.

If you ever get hold of one of the television engineering handbooks written by Fink and others in the 1930s, you'll see that an enormous amount of thought went into the original NTSC TV standard, which also formed the basis of the CCIR standard used in Europe and elsewhere.

Basically, the 525 line interlaced scan system they laid down in 1941 was the highest performance broadcast system that was considered practical either then, or in the forseeable future. It's taken 50 years to come up with anything that's both affordable and significantly better, so they obviously knew what they were doing.

Edited by Keith Walters, 02 September 2006 - 07:00 PM.

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#10 Frank DiBugnara

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Posted 02 September 2006 - 07:55 PM

On the contrary, a progressive stream takes up less space in addition to looking better (24fps as opposed to 30fps).


I was not talking about progressive vs interlaced. I was referring to the sheer amount of video they try to cram on some DVDs. There is so much video that the encoding quality is reduced to to fit more video at a lower bit rate.
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#11 Tim Tyler

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Posted 02 September 2006 - 08:04 PM

Since you didn't do a DI on Akeelah (did you?) I bet they telecine'd the film to an interlaced format and then struck the DVD from that. It's too bad.

If you bought the DVD at Starbucks, I would wonder if Starbucks had their people make DVD's they could distribute seperately from the studio's distribution, since a studio would know how to make proper DVD's.

Guess I'll have to wait for the Criterion DVD of Akeelah :)
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#12 Thomas Worth

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Posted 02 September 2006 - 08:33 PM

I was not talking about progressive vs interlaced. I was referring to the sheer amount of video they try to cram on some DVDs. There is so much video that the encoding quality is reduced to to fit more video at a lower bit rate.

Well, I assumed the "poor quality" you were referring to was the interlace artifacts, and I am saying that if they were really trying to cram a bunch of crap onto the DVD, the movie wouldn't be interlaced. Interlaced implies 29.97fps, which obviously requires more space to store than 23.976fps (6 more frames, which are redundant anyway, only to satisfy NTSC requirements). Plus, with DVD9, you have plenty of room to store a 2 hour movie VBR encoded at a bitrate of 6-7mbits/sec, plus tons of extras.

This is assuming, of course, that the movie is encoded the "proper" way.

Since you didn't do a DI on Akeelah (did you?) I bet they telecine'd the film to an interlaced format and then struck the DVD from that. It's too bad.

Even if it was telecined to an interlaced format (unlikely, considering there are HD trailers for the movie on Apple's site), the MPEG2 encoder would automatically remove the pulldown and restore the original 24 progressive frames before compressing them. Again, this is assuming the DVD was authored the way it should be.

I would have to rip and take a look at one of the VOBs for the main movie to know for sure.
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#13 Frank DiBugnara

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Posted 02 September 2006 - 08:50 PM

Well, I assumed the "poor quality" you were referring to was the interlace artifacts, and I am saying that if they were really trying to cram a bunch of crap onto the DVD, the movie wouldn't be interlaced. Interlaced implies 29.97fps, which obviously requires more space to store than 23.976fps (6 more frames, which are redundant anyway, only to satisfy NTSC requirements). Plus, with DVD9, you have plenty of room to store a 2 hour movie VBR encoded at a bitrate of 6-7mbits/sec, plus tons of extras.

This is assuming, of course, that the movie is encoded the "proper" way.
Even if it was telecined to an interlaced format (unlikely, considering there are HD trailers for the movie on Apple's site), the MPEG2 encoder would automatically remove the pulldown and restore the original 24 progressive frames before compressing them. Again, this is assuming the DVD was authored the way it should be.

I would have to rip and take a look at one of the VOBs for the main movie to know for sure.


Oh, I see what you are saying. I was talking more about having to reduce the bit rate to what looks like much below 6 to fit the two hour movie plus a whole lot of other video, mini-documentaries, etc. The type of compression on DVDs that bothers me the most is when the dark areas in particular get very "blocky" where there are these huge chunks of compression. Looks like the software took a large dark portion of the frame and turned it into large squares of compression. This for some reason bothers me even more than the toothcomb thing.
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#14 David Mullen ASC

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Posted 03 September 2006 - 12:07 AM

Since you didn't do a DI on Akeelah (did you?) I bet they telecine'd the film to an interlaced format and then struck the DVD from that. It's too bad.

If you bought the DVD at Starbucks, I would wonder if Starbucks had their people make DVD's they could distribute seperately from the studio's distribution, since a studio would know how to make proper DVD's.

Guess I'll have to wait for the Criterion DVD of Akeelah :)


The movie was transferred to 23.98P/1080 HD-D5 -- I know, I supervised the transfer. Of course, the DVD is made from a downconversion, but still, I've never run into this problem before in the last few years of grabbing frames off of a DVD. Most movies, if shot in film or 24P, are 480P on a Region 1 DVD. Only the behind-the-scenes clips tend to be 60i.
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#15 Michael Collier

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Posted 03 September 2006 - 04:30 AM

David- How are you grabbing the frames? If its software then they encoded with the pulldown or interlaced for some reason. If your running a DVD player output to a digital converter, you may just happen to hit capture during one of the pulldown frames.

As for the quality of compression-it does look pretty bad. I can't believe a professional DVD authorer would let a movie go like that. We compressed 'Nice!Gordon', a cheap snowboarding movie, with an equally cheap DVD authorer, and the compression was very good. I didn't notice much artifacting between the projected mini-DV premiere and the DVD.

Also a possible reason for the low quality could be a late-generation clone of a master tape (HD-CAM to Digibeta to Digi to digi to beta SP to DVCAM to SP to DVD authoring or something equally redundant.)
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#16 Thomas Worth

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Posted 04 September 2006 - 10:51 AM

The movie was transferred to 23.98P/1080 HD-D5 -- I know, I supervised the transfer.

Hey David, what machine did you use to do the transfer and at which post house? I thought the HD trailers looked great!
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#17 David Mullen ASC

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Posted 04 September 2006 - 10:56 AM

It was transferred on a Spirit over at Modern Film & Video.
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#18 Adam Frisch FSF

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Posted 04 September 2006 - 12:14 PM

If it wasn't for "that s**t" either NTSC would have had only 240 visible scanning lines, (288 for PAL)
OR you would have only been able to have three or (absolutely maximum) four TV channels in each city,
OR you could have had 480 visible lines but at only 30 frames per second, which would have flickered intolerably. (288 at 25 fps for PAL which would have even worse to look at).

If you went for the second option, the 12MHz or more channel bandwidth also needed would have required much more expensive antenna systems both at the transmitter and in the home, and home videotape would probably never have become affordable if it ever became practical at all.

If you ever get hold of one of the television engineering handbooks written by Fink and others in the 1930s, you'll see that an enormous amount of thought went into the original NTSC TV standard, which also formed the basis of the CCIR standard used in Europe and elsewhere.

Basically, the 525 line interlaced scan system they laid down in 1941 was the highest performance broadcast system that was considered practical either then, or in the forseeable future. It's taken 50 years to come up with anything that's both affordable and significantly better, so they obviously knew what they were doing.


I won't go into polemics about this, because I'm simply not knowledgeable enough on the subject.

But I clearly recall reading that most agree that a progressive frame only needs half the lines to achieve the same resolution as an interlaced one. Hence, if the NTSC signal was 240p, it would be exactly as what you have today. That's also why a 720p HD signal will look the same as a 1080i one, in fact often better and with more 'apparent' resolution.

As for blanking - that could be added to progressive frames to trick up the renewal just as it's been done on projectors for years. And I distinctly seem to recall that the only reason the frame rates of 30fps for NTSC and 25fps for PAL were chosen was that it divided easily into the current - 60Hz and 50Hz. That's also why they chose interlaced so that every Hz would correspond to one carrier update. I don't blame them - that's what the extent of the technology could do back then. But it wasn't for our benefit as viewers, it was for their benefit - to make it easy for THEM. Not necessarily what would have been the best quality.
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#19 Thomas Worth

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Posted 04 September 2006 - 12:47 PM

That's also why a 720p HD signal will look the same as a 1080i one, in fact often better and with more 'apparent' resolution.

720p video has 25% more resolution per 1/60th of a second than 1080i, but keep in mind this is only with 60 Hz material (i.e. 60p, 60i). With 30p and under, 1080p wins.

720p is clearly better for "reality" or news-type footage.
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#20 Chris Cooke

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Posted 04 September 2006 - 01:07 PM

With 30p and under, 1080p wins.


Didn't you mean 1080i? 1080p pretty much wins over any HD format.
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