Blu-ray Judder Disaster

I can see this revelation has left everybody speechless..............

Cheers

Don

is this solely a panasonic problem , or is it more widespread

neil

The Which report suggests that it affects all UK Blu-ray players.

I presume it could be fixed by either changing the players or changing the dvd discs.

HD DVD doesn't seem to have created this self-inflicted problem

Cheers

Just speaking in general, Region 1 DVD has always suffered from judder. It stems from the fact that essentially film-based material starts of as 24Hz and if it's not displayed at a multiple of that frequency (like 48Hz, 72Hz, etc.) you'll get judder. As all DVD players output R1 DVD at 60Hz (because 60Hz is the standard display rate in the USA), and 24 doesn't divide nicely into 60, then judder is innevitable. Some people notice it, others don't.

In Europe where 50Hz displays are standard, Region 2 DVD gets around the judder problem by speeding up the original frame-rate by 5% and encoding the disk at 25Hz and displaying this at 50Hz. The drawback of this approach is incorrect pitch on audio.

Personally, I can't stand the judder from Region 1 DVD, and now HD-DVD and Blu-Ray. The solution I use is to take the 60Hz output from my DVD player or HD-DVD player and use a video processor (I'm using a DVDO VP50) to perform what's known as Inverse Telecine Conversion. The processor takes the 60Hz interlaced signal and uses it to reconstruct the original 24fps progressive signal. The video processor then converts the 24fps signal to 48Hz which is then fed to the display and displayed at that rate. No judder, no speedup.

Don, I expect "Which" are confusing the problem with the general one described above or it's a Panasonic player problem. Blu-ray and HD-DVd are both encoded the same way, 1080p 24Hz.

Allan

quote:

Originally posted by Don Atkinson:
Blu-ray Judder Disaster

I have just had a quick look at "Which".

"...the Blu-ray movies....suffered from jerky movement....during panning shots"

The main reason is that the discs have been formatted to 24fps whilst the machine expects 25fps.

Panasonic accepted this position but couldn't confirm that it would be addressed.............

Astonishing!

Cheers

Don

I have the Sony PS3 player and purchased few blu-ray discs. I don't see this problem at all. Maybe the discs that are issued in North America (Canada and the USA) do not have this technical issues?

American TV's are always inferior...

quote:

Originally posted by Don Atkinson:
Blu-ray Judder Disaster

I have just had a quick look at "Which".

"...the Blu-ray movies....suffered from jerky movement....during panning shots"

The main reason is that the discs have been formatted to 24fps whilst the machine expects 25fps.

Panasonic accepted this position but couldn't confirm that it would be addressed.............

Astonishing!

Cheers

Don

Its doubtful that the disc is encoded at 24fps.

this would be the same as the original film frame rate...

PAL 25fps
NTSC 30fps aprrox

Allan is quite correct.

Hmmm, I do remember reading something about HD or BluRay starting to being encoded at 24fps at 1080p.

There was a lot of discussion of displays that could support that, as it was the closest you could get to the original film.

Roy.

Ah...

There are actually a 1080p-24 and 72 formats.

I can't find the original tech specs on this, but I was sure that what was on a Blu-Ray or HD disc was 24fps 1080p:

http://en.wikipedia.org/wiki/24p#24p_in_high_definition_disc_formats

and then the player converted it to whatever it was meant to be output at.

Roy.

Mmm, I sense a bit of confusion is starting to creep into the thread.

Lets deal with the PAL/European DVD issue first as there is no judder issue here. 24fps film is sped-up to 25fps and encoded onto DVD as 50 interlaced fields per second (each interlaced field contains half the information of a single frame). 50Hz encoding maps nicely to 50Hz displays therefore no judder.

R1/NTSC DVD: Discs are encoded at 60 interlaced fields per second (well 59.994 to be exact), equivalent to 30 frames per second. The problem here is that the source material is 24 frames per second so to make this fit the encoding rate the first field is repeated three times, the second field is repeated two times and so on in a repeating 3:2 cadence. This process is known as Telecine 3:2 Pulldown and once performed, has locked the judder onto the disk. The display at 60Hz will sync nicely with the output from the DVD player but the judder is inherent in the disk itself. The only way to remove it is with a video processor which can take detect the 3:2 cadence and work backwards to reconstruct the original 24fps signal.

HD-DVD and Blu-Ray: There is no regional differences in encoding, all disks are 1080p 24Hz wherever thay are bought/manufactured around the world. All HD-DVD/Bluray players output interlaced 60Hz*. This is done to maintain compatibility with existing displays but it means the player has to process the signal using the 3:2 pulldown process described above for R1 DVD. The result is exactly the same kind of judder you get with R1 DVD except now it is being introduced by the player instead of being encoded on the disk. If you don't see 3:2 pulldown judder on R1 DVD (hello Tuan!), you won't see it on HD-DVD or Bluray either.

Finally, lets consider the UK Panasonic bluray player that started this thread. Well, it's a bluray player, it outputs a 60Hz interlaced signal, it introduces 3:2 pulldown judder. Maybe the magazine doesn't fully understand that this is 'normal', all hd-dvd/bluray players do this, as does any DVD player playing a R1 disk. Maybe the TV they used was internally converting 60Hz to 50Hz and introducing it's own more severe judder. Perhaps a few more details Don?

* All HD-DVD/bluray players output 60Hz interlaced apart from the Sony and Pioneer bluray players which can also directly output the original 24hz progressive signal (therefore not introducing any judder). The number of players that can do this will increase over time, as will displays that can accept it.

Allan

Thank you for a very comprehensive explanation on this issue.

quote:

Perhaps a few more details Don?

First, apologies for the brevity of the first post - busy week.

Second, "Which" isn't renowned for in-depth technical explanations. Its more of an objective-peception-based magazine. eg "95 % of our test-panel thought the picture on screen A looked better than screen B but 85% of of our panel thought screen B was easier to set up and use"..........

So, at the risk of copyright breach, let me type a few more words from the article.......

They (Panasonic Blu-ray) offer much better pictures than a regular DVD player, as long as you have at least an HD-ready TV to watch. However, a fundamental mismatch between disc and player undermines the benefits (of Blu-ray).......despite the enhanced picture quality, the Blu-ray movies our experts watched suffered from jerky movement, especially during panning shots. The main reason for this was because the discs had been formatted at the film industry standard of 24fps, different from Europe's traditional 25fps. The result: juddering pictures. Panasonic "quite agreed" with our assessment.......nobody could confirm when (rectification of this glitch) would happen.

The juddering is a fact.

How bad it is, is up for discussion.

Why it happens, is up for explanation.

Cheers

Don

The article's headline read

"Picture problems spoil Blu-ray launch"

Which IMHO has done as much for Blu-ray as

"Chancellor's love-child by 15 year-old Muslim school- girl"

would do for Gordon's chances of succeeding Blair...........

Cheers

Don

quote:

Originally posted by Tuan:
Allan

Thank you for a very comprehensive explanation on this issue.

Thanks Tuan,

quote:

Originally posted by Don Atkinson:
The main reason for this was because the discs had been formatted at the film industry standard of 24fps, different from Europe's traditional 25fps

Don, I don't think that reference to 25fps relates to anything the player or display is doing or is expecting (all HD ready displays accept 60Hz). I think all they are saying is that we, in Europe, have a 25fps based system that doesn't suffer judder problems, whereas 24fps based systems (displayed at 60Hz) do. I think it's just normal 3:2 judder they are seeing.

I'm considering a blu-ray player myself so keep my ear close to the ground with respect to what's what and if this really was a problem I'd be hearing about it left and right. It would be odd that a consumer magazine better known for testing fridges and washing machines have blown the lid on a new format 'disaster' that has gone unnoticed by hardened AV journalists and AV nutters.

Allan

quote:

the Blu-ray movies our experts watched suffered from jerky movement, especially during panning shots

Allan, "Which" isn't normally associated with false reporting. So when their experts see jerky movement, I for one, tend to accept that is what they saw.

As to what caused the jerky movement.....well, "Which" isn't normally associated with in-depth technical explanations, so they might have dumbed-down their explanation to the point where its difficult to understand.

The article was definitely making a point viz Blu-ray = jerky movement and Panasonic agree that its a problem.

However, the Bristol Show is with us in a couple of weeks. My guess is it will be filled with Blu-ray and HD DVD machines being used to show-off plasmas/lcds/dlp-projectors et-al. So a chance to observe for one's self whether this jerky movement exists.

Post-show, this forum will be filled with claims that DVD5 (£2,500) is/isn't better than Blu-ray/hd-dvd (£1,250) etc etc

Interesting times ahead

Cheers

Don