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mhafner
PostPosted: Tue Feb 25, 2003 3:39 pm 
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Joined: Mon Dec 03, 2001 8:14 pm
Posts: 1086
:bangbang: :bangbang:

While watching the DVD of Humraaz I noticed a problem
I had seen before but was too lazy to really think about
it. I have looked at the problem in detail now and have
verified it applies to the following Eros DVDs I have
reviewed/watched:
- Company
- Humraaz
- Na Tum Jaano Na Hum
- Devdas
I suspect it applies to many others too. The reviews will
be updated. Input as to which other titles are affected
is welcome.
It's about the 2:3 pulldown of Eros titles.
We all already know that Eros does not master the DVDs
progressively but in video mode with 60 fields per second.
While the DVD player output has a correct 2:3 pulldown
the flags are not properly set so only players and video
processors that analyse actual fields are able to retrieve
the original film frames.
There is an additional problem though that no player or
processor I know can fix, but is fixable in theory with
software if you have access to all the fields.
The problem is as follows.
Above mentioned Eros DVDs do a correct 2:3 pulldown
BUT ONLY FOR THE LUMINANCE PART of the fields. The CHROMINANCE PART does not have a correct 2:3 pulldown.
On DVD luminance (Y) and
chrominance (U,V) are stored and compressed separately.
The chrominance part of the picture shows this behaviour:
Fields from film frame 1 are shown 2 times. Fields from frame 2 are shown 4 times. Fields from frame 3 then 2 times. Fields from frame 4 then 2 times. The result is
that every other 2:3 sequence is incorrect and the
chrominance field is lagging one field behind the luminance
field for the duration of one field, and this twice per
2:3 sequence.
The result is that objects in motion with strong colors
have a strange look as the color delay becomes visible to
the eye.
The reason for the problem is most likely a buggy or
misconfigured MPEG-2 encoder.
Whoever was doing these DVDs for Eros must be told this so
they can fix the problem.
(An ideal example to study this is the third song of NTJNH
with red dancers on b&w background.)

:bangbang: :bangbang:
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rana
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PostPosted: Tue Feb 25, 2003 4:17 pm 
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Joined: Sun Dec 16, 2001 7:27 pm
Posts: 6146
Good finding and explanation, Michel.

I and many others always wondered about the color changes in the repeated fields. I thought, it was just an un-neccessary info in the repeated field or may be it was a result of repeated shot in the Cine-tel transfer. So, does it matter in detecting the 2-3 pull down and in re-assembling the original frames (while throwing away the un-neccessary repeated fields).

I think most of the present transfers are like this. Hopefully, exceptions are those DVDs that were originally Progressive and became Interlaced in later issues. EVP DVDs are probably OK in this respect. Of course, the original Progressive DVD is the best bet.

Rana
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mhafner
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PostPosted: Tue Feb 25, 2003 4:26 pm 
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Joined: Mon Dec 03, 2001 8:14 pm
Posts: 1086
rana wrote:
Good finding and explanation, Michel.

I and many others always wondered about the color changes in the repeated fields. I thought, it was just an un-neccessary info in the repeated field or may be it was a result of repeated shot in the Cine-tel transfer. So, does it matter in detecting the 2-3 pull down and in re-assembling the original frames (while throwing away the un-neccessary repeated fields).
Rana

Players that look at the luminance only will not be
affected for reverse pulldown. Players that look at
chrominance too might get confused at times. I don't
know if chrominance is looked at in this context. Most
information is in the Y channel so this one is used for
sure.
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Zoran009
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PostPosted: Tue Feb 25, 2003 4:38 pm 
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Posts: 14989
[EVP DVDs are probably OK in this respect. Of course, the original Progressive DVD is the best bet.]

Evp dvds, indeed, dont show color change, just kinda overlaped, every 4th and 5th frames!!
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rana
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PostPosted: Sat Mar 01, 2003 10:15 pm 
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Posts: 6146
Availability of 2-3 pull down for only one component of the picture, chrominance or luminance, may be the reason why some line doublers succeed in indicating a certain signal to be originating from Film where as others don't.

Rana
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ali
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PostPosted: Sun Mar 02, 2003 5:31 pm 
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Joined: Wed Nov 14, 2001 2:06 pm
Posts: 4944
Location: UK
Reviews of Company and Na Tum Jaano Na Hum updated to reflect the above info by Michel.

Ali
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DragunR2
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PostPosted: Fri Mar 14, 2003 8:10 pm 
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Joined: Wed Dec 05, 2001 3:16 am
Posts: 4259
On my Sony S530D, there are 2 Pause Modes (quoted from the manual)

AUTO: A picture including subjects that move dynamically is output with no jitter. Normally select this position.

FRAME: A picture including subjects that do not move dynamically is output with high resolution.

I had the player set to Frame, but yesterday I set it to Auto to see what the stills would look like on a pseudo-prog DVD.

On Auto, I stepped through a high motion portion of Devdas (the beginning where everyone's running around). Here's what I found. I stepped to the first frame of one second in which there was a lot of motion:

1st frame- colors (chrominance?) lag behind
2nd - color shifts back into place
3rd - normal step through
4th - " " "
5th - " " "
6th - colors lag behind

And so on in this rather crude method. The color lag is not visible while normally watching it on my interlaced player and TV, so I assume this is only evident for me when stepping through individual frames in Auto mode. The color lag even happens sometimes at edits, where you can see the colors from the last frame of one shot on the first frame of the next shot. This did not occur on pseudo-prog DVDs from Ayngaran (Thiruvilayadal) and EVP (Sankarabharanam).

In Frame mode, pseudo-prog DVDs will show combing when stepping through frames, while in Auto mode I see double images.



Edited By DragunR2 on 1047672635
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rana
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PostPosted: Fri Mar 14, 2003 8:44 pm 
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Posts: 6146
1) I think my Sony DVD player is S550. So, it shoud have the same features. I'll check the manual tonite. I never discovered, this Pause frame vs auto trick.

What you wrote, makes perfect sense. In Auto mode, it does select whether to Force Weave or Force Bob (like Power DVD). In Pause Frame mode, it does Force Weave as Frame is made of 2 fields.

Clarfication: I started using the slang terms; Interlaced, Progressive, Pseudo-progressive etc. This is only for convenience. Recorded material on present day discs is always field by field and hence Interlaced.
What I call Progressive, are the discs where flags are set telling the player which field is to be merged with which field if the two fields came from a single frame.
What I call Pseudo-prog, are the discs where flags are not set but each film frame is recorded in 2 or 3 fields and each field contains info from one frame only. Some Line Doublers can detect this.
What we call Field Averaged Interlaced are those discs where each field contains info from more than one film frame. This results in double images, fuzzy images and even missing limbs. Motion frames are fuzzy but the movie is fine (except for artifacts).

Chroma signal running independent of the rest of signal can cause problems in Line Doubler's detection of film frames. Even if it does detect the orig film frames, the resulting pic will have the chroma signal, out of the discarded field, missing. Once the Line Doublers programmers realize that this stupidity is a possibility too, they may cure this problem too.

And yes DragunR2, You are right. None of the EVP DVDs, that I have seen, suffer from this Chroma lag problem. I think Chroma lag problem will not exist in those DVDs that were Progressive in the initial batches and turn Interlaced in later batches (VS, EVP etc).

Rana



Edited By rana on 1047675127
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mhafner
 Post subject:
PostPosted: Sun Mar 16, 2003 9:02 am 
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Joined: Mon Dec 03, 2001 8:14 pm
Posts: 1086
DragunR2 wrote:
On my Sony S530D, there are 2 Pause Modes (quoted from the manual)

AUTO: A picture including subjects that move dynamically is output with no jitter. Normally select this position.

FRAME: A picture including subjects that do not move dynamically is output with high resolution.

I had the player set to Frame, but yesterday I set it to Auto to see what the stills would look like on a pseudo-prog DVD.

On Auto, I stepped through a high motion portion of Devdas (the beginning where everyone's running around). Here's what I found. I stepped to the first frame of one second in which there was a lot of motion:

1st frame- colors (chrominance?) lag behind
2nd - color shifts back into place
3rd - normal step through
4th - " " "
5th - " " "
6th - colors lag behind

And so on in this rather crude method. The color lag is not visible while normally watching it on my interlaced player and TV, so I assume this is only evident for me when stepping through individual frames in Auto mode. The color lag even happens sometimes at edits, where you can see the colors from the last frame of one shot on the first frame of the next shot. This did not occur on pseudo-prog DVDs from Ayngaran (Thiruvilayadal) and EVP (Sankarabharanam).

In Frame mode, pseudo-prog DVDs will show combing when stepping through frames, while in Auto mode I see double images.

On PowerDVD these DVDs show 3 correct frames followed by two
mixed ones, as far as I remember. From a player that does
correct pulldown based on field analysis the lagging chroma
is quite visible at normal speed if there's enough motion.
It looks really weird.
cheers
Michel
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