Is 704x480 with a 16:9 DAR valid for DVD?

[Anonymous344]

As the thread title implies, I would like to have a conclusive answer to this question: is 704x480 with a 16:9 DAR is valid for NTSC according to the DVD specification? I know that there are various DVD guides online that do not list this resolution as valid for anamorphic, but I would like some explanation by someone that really knows about this, rather than links to random webpages, many of which usually contradict each other.

Until recently, I have thought that 704x480 was valid for 16:9. I have authored a number of 16:9 704x480 DVDs that have played perfectly well on DVD players; although that of course proves nothing, because some players will play all sorts of out-of-spec material (and some of course will even refuse to play certain material that does meet the specification!)

I know how to pad 704x480 to 720x480 if that is what is required. It would be nice just to know once and for all what the situation is regarding 704x480.

[SatStorm]

704x480 and 704x576 are not valid for 16:9 DVD Video
704x480 and 704x576 are valid for 4:3 DVD Video.
Also, Half D1 (352x480/576) is not valid for 16:9 DVD video.

Only 720x480/576, full D1, is valid for 16:9 DVD Video (and BluRay)

[Anonymous344]

Thank you very much! Do you have a detailed source for this information that I can look at? I would like something to which I can refer if I need to do so.

[SatStorm]

Well... We use to talk about those things (valid framesizes of DVD) about 9 years ago. There was links back then and so, but don't ask me to find them now.

But the issue about the 16:9 Full D1 framesize it is even refered on wikipedia:
http://en.wikipedia.org/wiki/DVD_video

[Anonymous344]

There was links back then and so, but don't ask me to find them now.

I understand and do appreciate that. Of course I do not want to ask you to dig through past threads.

I really do believe you, but the situation is that I am having difficulty convincing an associate of mine about this. He is extremely experienced and skilled at working with video and very dubious that 704x480 is out of spec for anamorphic DVD because it does play on so many players. That is why I was looking for some kind of documentation (beyond wikipedia) to substantiate my claim.

[Case]

You (your company) could buy the official DVD specification books for ¥ 550,000 + ¥ 2,200 shipping and handling (£ 4,285 as of today), but the fact you are looking for may not be stated explicitly. There have been complaints about vagueness in the specification. Oh, and you can't tell anyone unlicensed about it, because of non-disclosure.
Basically, anything publicly available about the specs is unofficial.

[jagabo]

It will cost you $5000 to find out for sure:

Some of DVD specifications (e.g. for DVD-Video) are not publicly available and can be obtained only from the DVD Format/Logo Licensing Corporation for a fee of US $5000.[12][13] Every subscriber must sign a non-disclosure agreement as certain information in the DVD Book is proprietary and confidential.[12]

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

I've never seen it posted online.

[Anonymous344]

I understand. Thank you both for the information. I did not realize this. It certainly explains why I have found official information so hard to find online!

[edDV]

It is my understanding that 704x480 16:9 is valid for DVD. Also for ATSC, DVB and D1. In fact all SD digital broadcast television is done at 704 horizontal pixels including 4:3 and 16:9.

Also the PAR's used for the 16x9 format are based on 704x480 or 704x576. 720 uses the same PAR so the extra 16 pixels are considered additional width. This facilitates 720x480 to 704x480 conversion for digital broadcast as a simple crop rather than a rescale.

Half D1 DVD (352x480 or 352x576) are 4:3 only.

No time now during the game to search for written docs.


PS: 7th inning stretch

See section 3.6 http://www.dvddemystified.com/dvdfaq.html

From mpeg.org quoting DVD Book B (see Aspect Ratio)
http://www.mpeg.org/MPEG/DVD/Book_B/Video.html

For the most exhaustive detail (99% focused on 4:3 history)
http://lipas.uwasa.fi/~f76998/video/conversion/
wades though all the resolution and aspect ratio history. Read at your own risk.

[poisondeathray]

It is my understanding that 704x480 16:9 is valid for DVD.

I always thought so too , the offical mpeg site list 704 width as valid under coded frame size

http://www.mpeg.org/MPEG/DVD/Book_B/Video.html


@Jeff B. - There are some members at Doom9 forums that have both official DVD book and Blu-ray spec books. PM user "shon3i" if you want to know for sure

[Anonymous344]

No time now during the game to search for written docs.

Say no more! Enjoy the game.

@Jeff B. - There are some members at Doom9 forums that have both official DVD book and Blu-ray spec books. PM user "shon3i" if you want to know for sure

Thank you very much. I shall do so.

[manono]

If you accept what the DVD Demystified guy has to say (and I do), 704x480/576 encoded as 16:9 is perfectly OK:

For anamorphic video, the pixels are fatter. Different pixel aspect ratios (none of 
them square) are used for each aspect ratio and resolution. 720-pixel and 704-pixel 
sizes have the same aspect ratio because the first includes overscan. Note that 
conventional values of 1.0950 and 0.9157 are for height/width (and are tweaked to 
match scanning rates). The table below uses less-confusing width/height values 
(y/x * h/w).

      720x480   720x576
      704x480   704x576   352x480   352x576
4:3     0.909     1.091     1.818     2.182
16:9    1.212     1.455     2.424     2.909

He doesn't even act as if there's any sort of an issue over it:

http://www.dvddemystified.com/dvdfaq.html#3.5

[SatStorm]

People, don't associate mpeg 2 with DVD Video specifics or the DVB broadcasts.
Indeed, mpeg 2 has no limitations to be 16:9 on whatever framesize when all the vertical lines (480 or 576) are present.
Also, most DVB channels can be 352 or 480 or 544 (very popular framesize) or 640 (rare) or 704 (usual) or 720 horizontal X 480 or 576 vertical lines. It is on the DVB specifics, after all the aspect is a single flag. That's why DVB patcher could exist the first place.
But on DVD only 720x480/576 is valid for 16:9 officially. And also officially has GOP limitations (that don't exist on DVB for example).

The last 8 years or so, the DVB receivers and the DVD players share the same mpeg 2 decoder CPUs and also the same build in drivers. So the DVD players end up supporting even 352x576 on 16:9 (I did that kind of DVDs lot's of times in the past decade, and only once I had a problem with a DVD standalone player).
But even if ALL the DVD standalones out there support this framesize and 16:9, it doesn't mean that it is official. And remember, that the old authoring applications use to state what is valid for DVD and what is not.

BluRay adopts the DVD specifications for mpeg 2, so it is natural to say that officially only 720x480/576 is supported for 16:9. Personally I never test that (for obvious reasons, this decade is about H264 not mpeg2)

Also: The same way I trust Wikipedia, I trust dvddemystified, videohelp.com, doom9, etc. We are all unofficial sources, nothing more.

[intracube]

704x480 and 704x576 are not valid for 16:9 DVD Video

I always thought 704x480 and 704x576 were vaild for 4:3 and 16:9, but as you say, the restriction is mentioned on Wikipedia.

If true, I can't think what the reasoning is for this.

This site has some detailed information on frame sizes and aspect ratios (although it doesn't directly mention DVD Video:
http://www.mir.com/DMG/aspect.html

As i understand it, 704x480/702x576 corresponds very closely to the actual 4:3,16:9 usable picture dimensions. The extra 8 pixels each side of a 720 width frame are padding. I *thought* the reason for this was that when digitizing analogue video, any errors in the line sync pulses could cause a slight horizontal shift in the image. Digitizing a wider frame gave some margin of error and avoided part of the image being accidentally truncated. Once in digital form, the image would then be re-centered if necessary.

Perhaps someone knowledgeable could confirm/refute this.

If what I say is correct, shouldn't 704xwhatever be sufficient for properly authored digital content delivered to consumers (via DVD/satellite/etc) - with 720x480/720x576 limited to studios/authoring houses/professional environments?
I've been wondering about this for some time.

[jagabo]

If true, I can't think what the reasoning is for this.

When the DVD spec was written DVD players were extremely dumb devices. Limiting the number of options was necessary. Nobody had a widescreen TV in those days. Maybe they just decided to limit support to 720 pixel wide frames to reduce complexity for the players.

[manono]

Also: The same way I trust Wikipedia, I trust dvddemystified, videohelp.com, doom9, etc. We are all unofficial sources, nothing more.

Then don't use Wikipedia to try and support your claim, as you did earlier.

[Anonymous344]

The last 8 years or so, the DVB receivers and the DVD players share the same mpeg 2 decoder CPUs and also the same build in drivers. So the DVD players end up supporting even 352x576 on 16:9

That sounds like it makes sense. So DVD players are now more capable and can cope with resolutions that were not possible on earlier, less sophisticated players; which is why all my 704x480 16:9 DVDs play even though they might officially be out of spec.

As i understand it, 704x480/702x576 corresponds very closely to the actual 4:3,16:9 usable picture dimensions. The extra 8 pixels each side of a 720 width frame are padding.

It's certainly true that the eight pixels on either side are there because of nominal analogue blanking. If I resize HD material for conversion to to DVD, I always resize to 704x480. My doubt was whether or not I could just author a DVD at that resolution, or whether I had to pad to be compliant. It looks like I do.

[edDV]

But on DVD only 720x480/576 is valid for 16:9 officially. And also officially has GOP limitations (that don't exist on DVB for example).

What is your reference for this? We have quotes from DVD Book B plus the other references and even Wiki DVD says

http://en.wikipedia.org/wiki/DVD
Although many resolutions and formats are supported, most consumer DVDs use either 4:3 or anamorphic 16:9 aspect ratio MPEG-2 video, stored at a resolution of 720/704×480 (NTSC) or 720/704×576 (PAL) at 29.97, 25, or 23.976 FPS.

My background in this was from the broadcasting side. That was CCIR-601, MPeg2 editing in an analog or D2 world, then the slow development of DVD, DV and ATSC/DVB. In all the discussions of wide formats at that time, 704* was always the starting point with 720 being an extra wide version where the extra pixels were assumed to be out in the overscan region. The idea of active picture out to 720 began with the anamorphic wide DVD and DV format. The concern there was conversion compatibility between "standard 704" and 720 formats. For example, how would 720 DVD, DV or DVCPro be played to broadcast 704 transmission or dubs for broadcast recording?

It was decided 720 would use the same PAR as 704 so that a simple crop would be sufficient for broadcast and that 704 would be a valid wide DVD format (i.e. no pad pixels needed for broadcast source). 720 had extra pixel width extending into blanking and hence was cropped by blanking when converted to analog. 704 defined the 16x9 active picture area.


* For PAL this was 702x576 but for compatibility PAL formats were padded one pixel each side to 704x576.

[The_Doman]

My older Panasonic DMR-E55 DVD recorder also records in 704x576/480 PAL/NTSC.
It will recognize a 4:3 or 16:9 anamorph signal and records in both of those formats without problems.

[edDV]

My older Panasonic DMR-E55 DVD recorder also records in 704x576/480 PAL/NTSC.
It will recognize a 4:3 or 16:9 anamorph signal and records in both of those formats without problems.

Yes because recording SD analog or digital broadcasts requires 704 or you get eight black (blanking) pixels left and right with 720. In the PAL case you get 9 pixels left and right.



There are many commercial 704x480 DVDs out there, mostly the letterbox DVDs made from Laserdisc masters. For example "Dances with Wolves"...
http://www.dvdbeaver.com/film/DVDCompare2/danceswithwolves.htm

[intracube]

It's certainly true that the eight pixels on either side are there because of nominal analogue blanking. If I resize HD material for conversion to to DVD, I always resize to 704x480. My doubt was whether or not I could just author a DVD at that resolution, or whether I had to pad to be compliant. It looks like I do.

Thanks Jeff and edDV for confirming this. I'm wondering how many commercial DVDs are incorrectly formatted.

For example, House M.D. is produced in HD (1920x1080?) and as you say, the picture should be scaled to 704x576 then padded to 720x576 - for 625 line folks. I've just used mplayer to dump a chapter straight from the disc, and the whole 720x576 frame is used. I've got quite a lot of discs like this. Sloppy DVD authoring?

[Anonymous344]

As far as I am aware, there has been some dispute as to whether studios still take nominal analogue blanking into account when they author discs. Sometimes they definitely do, and sometimes it seems that they don't.

In my personal opinion, resizing to 720x480 rather than 704x480 is sloppy DVD authoring because not everyone has a television with a 1:1 scan mode and there is nothing in the MPEG-2 stream to tell compliant players not to take nominal analogue blanking into account. (There are of course some players that might not resize the image properly anyway, but that's neither here nor there.)

[SatStorm]

Sometimes I don't even know why I keep posting in this forum anymore...

[jagabo]

In my personal opinion, resizing to 720x480 rather than 704x480 is sloppy DVD authoring because not everyone has a television with a 1:1 scan mode and there is nothing in the MPEG-2 stream to tell compliant players not to take nominal analogue blanking into account.

Actually, I believe there is. There was a discussion here a few months ago about this -- whether the 16:9 image was in the full 720x480 frame or a 704x480 sub-frame. Someone who had the the DVD spec said it could be either and that there is a flag in the MPEG 2 data that indicated which was the case. He referenced some commerical software which could report the flag but I've never seen any myself.

[edDV]

It's certainly true that the eight pixels on either side are there because of nominal analogue blanking. If I resize HD material for conversion to to DVD, I always resize to 704x480. My doubt was whether or not I could just author a DVD at that resolution, or whether I had to pad to be compliant. It looks like I do.

Thanks Jeff and edDV for confirming this. I'm wondering how many commercial DVDs are incorrectly formatted.

For example, House M.D. is produced in HD (1920x1080?) and as you say, the picture should be scaled to 704x576 then padded to 720x576 - for 625 line folks. I've just used mplayer to dump a chapter straight from the disc, and the whole 720x576 frame is used. I've got quite a lot of discs like this. Sloppy DVD authoring?

Original question was "Is 704x480 with a 16:9 DAR valid for DVD?"

I've been arguing yes and the reasons why then and now. Too bad standards don't summarize the arguments for the decision.

Your question how to downscale 1920x1080 to DVD today is a bit more complicated to answer. No time now. Back later.

Hint: It comes down to aspect ratio accuracy and target players.

[edDV]

Sometimes I don't even know why I keep posting in this forum anymore...

Man up Satstorm. Make your case.

[poisondeathray]

In my personal opinion, resizing to 720x480 rather than 704x480 is sloppy DVD authoring because not everyone has a television with a 1:1 scan mode and there is nothing in the MPEG-2 stream to tell compliant players not to take nominal analogue blanking into account.

Actually, I believe there is. There was a discussion here a few months ago about this -- whether the 16:9 image was in the full 720x480 frame or a 704x480 sub-frame. Someone who had the the DVD spec said it could be either and that there is a flag in the MPEG 2 data that indicated which was the case. He referenced some commerical software which could report the flag but I've never seen any myself.

Very interesting - I've never heard of a flag for 704 vs. 720 ? Can you find that post ?

@Jeff B. - Did you PM shon3i ? That should settle what is "legal" by the book

[Anonymous344]

Actually, I believe there is. There was a discussion here a few months ago about this -- whether the 16:9 image was in the full 720x480 frame or a 704x480 sub-frame. Someone who had the the DVD spec said it could be either and that there is a flag in the MPEG 2 data that indicated which was the case. He referenced some commerical software which could report the flag but I've never seen any myself.

Wow! That really is news to me. That information would certainly refute my opinion.

If there really is such a flag, I wonder how MPEG-2 encoders such as HC Enc and CCE set this flag, because that could well determine what I would do when resizing HD material.

@SatStorm, what has upset you? As far as I can see, people are just trying to discuss the issue objectively.

@Jeff B. - Did you PM shon3i ? That should settle what is "legal" by the book

I haven't yet, but I will.

[edDV]

I searched the internet last night and concluded we are in cold case investigation mode with this 704 vs.720 issue. We need more eyewitness accounts why the DVD authoring industry jumped to 720. I suspect it was a break with broadcasters. Broadcast would stick with 704 and the consumer DVD industry would widen out to 720. Aspect ratio accuracy was the victum.

Yet the standard keeps the same PAR for 704 and 720.

[jagabo]

In my personal opinion, resizing to 720x480 rather than 704x480 is sloppy DVD authoring because not everyone has a television with a 1:1 scan mode and there is nothing in the MPEG-2 stream to tell compliant players not to take nominal analogue blanking into account.

Actually, I believe there is. There was a discussion here a few months ago about this -- whether the 16:9 image was in the full 720x480 frame or a 704x480 sub-frame. Someone who had the the DVD spec said it could be either and that there is a flag in the MPEG 2 data that indicated which was the case. He referenced some commerical software which could report the flag but I've never seen any myself.

Very interesting - I've never heard of a flag for 704 vs. 720 ? Can you find that post ?

Found it:

https://forum.videohelp.com/threads/299570-Correct-size-Resolution-for-AVI?p=1989388&vi...=1#post1989388

See page 47: http://neuron2.net/library/mpeg2/iso13818-2.pdf