Does BD and HDDVD have borders?

[lightshadow]

Hi,

Does BluRay and HDDVD have borders like DVD's?

[dat720]

It depends on the aspect of the movie, if it is a 16:9 then no... if it is below 16:9 like 2.35:1 etc then yes same goes for DVD

[lightshadow]

Wow. So even so even after so many years, they are still encoding black borders into the movie? I'd hoped they had added those in software.

What about those 16 or 8 pixel borders that (all?) DVD's have? Does HDDVD and BluRay also have those?

[prOnorama]

Wow. So even so even after so many years, they are still encoding black borders into the movie? I'd hoped they had added those in software.

The black borders are needed to keep the original aspect ratio of the movie. Try stretching a 4:3 film to 16:9, it will look like crap. Or blowing up 2.35:1 to 16:9, you will miss a lot of the image of the movie (it's "blown of the screen")

http://en.wikipedia.org/wiki/Image_aspect_ratio

[dat720]

Not all DVD's have borders.... as prOnorama noted already the borders are there to preserve the aspect ratio.

If you Stretch a 2.35 aspect movie to 16:9 it will look odd, alternatively if you pan/scan a 2.35 aspect movie to fill a 16:9 display you will loose some of the video on the right and left side.....

It's nothing to do with the current state technology or "after so many years" borders are there by design for a very good reason.

And as i said it depends on teh aspect of the content......

A 4:3 aspect movie or a 16:9 anamorphic will not have any borders.

[nurbs]

They didn't really have to encode the borders with the video though. The player knows what resolution it outputs, so for example if you have a 2.35:1 video they could have decided to encode at 1920x816 and let the player add borders so it outputs 1920x1080. That would have been very easy to implement when they wrote the spec and you wouldn't waste bits on the black bars. Aspect ratio signalling would also have been an option.

[Flux]

How much typical encoders waste bits on black borders?

Anamorphic images could give more vertical resolution for movies which are wider than 16:9 but how many have devices which could produce something like 2538x1080 resolution for 2.35:1 movies? Does HDTV standard even support anamorphic images?

Another option would had been to use different frame sizes for different aspect ratios like 1920x1080 for 16:9, 2358x1080 for 2.35:1 or 2872x1080 for 2.66:1

[dat720]

nurbs, it's called standards.... if they set particular resolutions as the *standard* resolutions then all the players have to support them and all players should work with all content.....

If you give studios free reign over what res to encode at there may be some instances where for some unknown reason a disc will not playback on a particular device.

nice idea Flux, but that sort of capability would push the prices of players up as they would need way more powerful decoders and CPU's than they currently have.... and in the end it all comes down to dollars and cents....

[nurbs]

I don't buy that they chose the standard that way due to technical limitations. There are plenty of devices out there that use the same decoder chips as blu-ray players and they all can cope with arbitrary resolutions smaller than the maximum. 1080p is not mod16 so support for mod2 resolutions should also be problem. I don't know about VC-1 and mpeg2, but in AVC at least level limits are not specified in resolution, but macroblocks (16x16) per second, and if you also specify a maximum horizontal and vertical hight there is practically no room for problems.

[LoRd_MuldeR]

Yes, technically there is no reason to encode black borders. Padding the video with black pixels to get the desired output size (e.g. 1920x1080) could be done easily. However as long as the specs require a fixed resolution and a fixed aspect ratio, there is no other way than adding the black borders before encoding (unless you want to use pan&scan, of course). The good thing is that the bits required to code the black borders should be very small. In fact the black borders themselves should take almost no bits (given that there is no noise in them). If at all, it's the border between the film and the "black" area that takes a noteworthy amount of bits. And even that can be avoided, if you make sure the border is perfectly sharp and it exactly matches a 16x16 macroblock border. Then the "black" macroblocks will only contain zero coefficients. Hence the black border will be nothing but a giant sequence of zero's, which costs very few bits after entropy encoding is applied. Effect on overall quality will be negligible.

[dat720]

I didn't say technical limitations..... It makes sence tho to have pre defined resolutions, Thats what standards are all about.

If we didn't have standards the world would be bedlam.... even with standards things aren't always how they should be.

[nurbs]

My issue lies mainly with your "nurbs, it's called standards", as if profile@level wasn't a standard and your comment that hardware compatibility would be hard to ensure unless there is only a couple of allowed resolutions. I know that the bars aren't a huge drawback, but they could have just as well decided not to use them when they created the blu-ray spec. I think the main difference between those two choices is that now we have people asking why there are black bars in their 1080p images and in the other case they would be asking why there 1080p images are only 1920x816 or 1440x1080.

[CWR03]

Remember that Blu-Ray was created with the main intent of outputting to HDTVs. Blu-Ray video is letterboxed with borders to display properly on that format, and as far as I know they didn't intend for people to be making back-ups of them and trying to understand why there are unnecessary borders mucking up their compression.

[dat720]

So sorry if i offended you..... but your line of thinking doesnt really make much sense....

As if the standard makers could have saw forward and thought that if they put borders in Blu Ray/HD that people would 'ask' why there are borders, who really cares if they ask why...... point them to the wiki page explaining the standard!

Imagine if they had gone the other way and let the studios pick the resolution.... somone would buy a 'Sony MagicSuperAwesomeTron 7000 TV' and a 'Samsung MegaFantastic 1500 Blu Ray' and Joe Blow would be pissed off when he puts in Die Hard 12 only to find that it doesn't play because the MagicSuperAwesomeTron doesn't support the resolution that the MegaFantastic is outputting!

(all names are fictional)

Microsoft created the .NET Framework so there could be a common language supported by all OSes with .NET installed, yet i've seen .NET apps that work on Windows XP but not 2000,2003......

It's all about trying to make a particular format furture proof, so that it will continue to work as it is a 'known' standard with set specifications.

[nurbs]

You didn't offend, I just think defining 1080p in a way where your image is either 1920 wide or 1080 high and the other dimension is determined by the aspect ratio of the movie (maximum number of pixels used, non anamorphic) whould have worked as well. Then I wouldn't have to type the Crop() line in my avs scripts :)

[dat720]

Fair enough..... but just remember these standards are developed by Movie Studio's who want to make it harder for people to copy their product

[Stumpor]

you guys are just looking at output aspect and mixing pixels and aspect ratio. you must start with film which has no predefined aspect ratio and is only limited to choice of film width and height and can be turned for imax and choice of anamorphic lenses that compress images to later by restretching either by projection lens or scanning software. Now you must encode, for those of us without 5 different projectors at home with a lens for each aspect ratio a cinematographer chooses to shoot a film with, in multiple aspect ratios for people with 4x3, 16x9 tvs or 16x10 monitors. not too mention that you can be either progressive or interlaced. I can go on with variation, but as you see here there is such a significant variance between input and output aspect ratios, wich has nothing to do with amt of pixels yet, because you can scan any frame of film to any digital quality you like as long as it can be encoded by studios and output by you, that it would be way too costly to make everyone happy and there isnt even enough space on a blue ray to have multiple aspect ratios of a movie. Old films were distributed with a display lens and the curtains at theaters move to left and right to adjust for aspect ratio. Just for fun, I went to school for video art, I shot video and edited them into strange shapes like stars hexagons and other varios forms some even with missing holes. Can your tv conform to them? What aspect Ratio is a star?

P.S. Sorry for the rant but I dislike the idea that there must be a predetermined format although I understand that it is necessary.

P.P.S. not sure about the date but when television was invented, by law it was illegal to project an image that did not fully cover the screen, hence pan and scan and overscan.

[CWR03]

Your rant has little to do with the original subject, which refers to unnecessary borders on high-def video sources. No one's talking about creating anamorphic video to require specialty lenses on a projector. At least as far as PC playback is concerned, a video cropped of its unnecessary borders will still play at the correct AR unless the software player is configured to force it to fill the screen, zoom or pan-and-scan.

[dat720]

Borders really aren't that much of a big deal, in fact i leave the borders when i encode my HD/BD's, that way if i want to make a AVCHD Disc i can simply mux the file to a BluRay structure with tsMuxer without having to recode the video to replace the borders i previously cropped, which with HD content like this takes 8-12 hours.... or 5 minutes if i leave the borders alone!

Only drawback of this approach is the PS3 has no useful zoom function with files like this, but then again zooming will change the aspect... and that's not on!