Delivery formats for HD DVDs

[Hulk]

Now that HDV camcorders are available it seems that we still need a method of delivery.

Are there any DVD Authoring applications that support HD DVDs currently available?

Also I am reading that the HD DVD compression format will include MPEG-2, WMC, and H.264, which I believe is MPEG-4 part 10. Does anyone know how these formats compare? Since they are all temporal formats, what are the major differences? I have heard that MPEG-2 using extremely long GOPs can compare quite well to the other two.

It looks like these are the formats we'll be talking about in the future so I just thought I get this discussion on the table, so to speak.

- Mark

[mmp121]

I think apple has a version of Final Cut Pro HD out or something like that that handles HD. Of course that does you no good.

[Dr Mordrid]

The standard has already been approved for use on both red and blue laser DVD's. MPEG-4.AVC (AVC = advanced video coding) and VC1 (formerly VC9 & based on WM9) will join MPEG-2. Both VC1 and AVC look very good if encoded properly.

I'd say that most red laser players will use MPEG-2 for SD and one of the other two for HD. Blue laser players could use any of 'em, but most likely MPEG-2 unless special features make it run short on space in which case the features could be in either VC1 or AVC.

Dr. Mordrid

[Hulk]

Doc,

I remember reading somewhere that VC1 is a specific resolution and bit rate encompassed by the H.264 format and it contains 90% H.264 code (or is that wmv code?)? Sorry if I'm mixing things up, we have a whole new alphabet soup to learn.

- Mark

[Dr Mordrid]

HD Resolutions are 1280 x 720 (720p) or 1920 x 1080 (1080p) for HD content.

MPEG-4.AVC (advanced video coding) for HD is a subset of H.264. This offers twice the compression and higher perceived quality than the current MPEG-4.ASP (advanced simple coding). AVC can provide DVD quality at less than 1 Mbps while ASP is the low quality member of the MPEG-4 family.

VC-1 (previously known as VC-9) is basically Windows Media 9 for HD and also provides advanced video encoding with higher compression and quality than the "old" WMV.

Dr. Mordrid

[Hulk]

Thanks Doc. I'm noticing that the HDV spec shows 1280x720 and 1440x1080 resolutions. The first is 16:9 using square pixels, I assume non-square pixels are used to achieve 16:9 using the second resolution?

- Mark

[Dr Mordrid]

1440x1080 is an anamorphic non-square pixel HD format vs. 1920x1080 which uses square pixels; similar to how 480x480 SVCD is to 720x480 video. 1280 x 720 is also a square pixel format.

Dr. Mordrid

[Hulk]

Another question. This chart:

http://www.sonyhdvinfo.com/article.php?filename=Comparison-Spec-Table-Between-HDR-FX1,-JVC-GR-HD1-

shows the JVC and Sony HDV camcorders.

Do you know of any other under $5000 HDV camcorders available or on the horizon?

Thanks again,

- Mark

[Dr Mordrid]

It's my understanding that Sharp has two HD cams in the pipeline, but they'll be using the Sony 1080i system and not JVC's more consumer oriented 720p (which would also be cheaper). One will be a single CCD and the other a 3 CCD.

Originally Sharp was going to use JVC's system but this changed when Sony needed another source of LCD's. Sharp is one of the largest makers of them so when the contract was negotiated Sharp gave up using the JVC system to sweeten the pot for Sony.

Dr. Mordrid

[Hulk]

Doc,

I realize I've really been at you over these last few days with questions, but I have another one regarding square and non-square pixels.

Please check my logic here.

If you render a NTSC DV project for DVD playback using square pixels then in order to change the aspect ratio of 3:2 (720/480) to 4:3 for TV playback the DVD player will have to convert the signal to a non-square pixel format. Yes?

If, on the other hand you render the NTSC DV project to DVD using non-square pixels then the DVD player will "natively" play the video signal. Yes?

Is seems that either the DVD player or the video editing software will have to make this conversion but doing it in the editor gives the user greater flexibility with things like still images.

Finally, when playing back a square pixel DV project on the computer at the proper 4:3 aspect ratio, in say, WMP, does WMP convert (rescale) the video signal to 640x480 (4:3)?

I've figured out how to deal with these issues for the most part, but I've never really laid out the logic. I'm hoping you can help, as usual!

Thanks,

- Mark

[Frank Marshall]

"I think apple has a version of Final Cut Pro HD out or something like that that handles HD."

This is exactly right, and readily explains why there are Mac editing suites at many TV stations -- way cheaper than forking out for Avid solutions.

[Hulk]

FCP can handle HDV natively but can't capture HDV from the camcorder without a plug-in. Altough that is suppose to change in the near future.

- Mark

[Dr Mordrid]

720x480 is considered 4:3; part of which is overscan and therefore cut off on a 4:3 TV, so any cropping is done by the TV itself.

AFAIK WMP plays the file as it gets it but since the computer screen is generally a square pixel display.

Non-square is most useful in the following situations;

1. mixing aspect ratios on the timeline (see below)

2. to maintain the aspect ratio of graphics, esp. when they're used with moving paths. This Ulead Learning Center article may be useful;

http://www.ulead.com/learning/msp/msp7_02_1.htm

How the DVD player and HDTV react will vary, but generally a 16:9 rendered project will play full screen on a 16:9 HDTV and 4:3 will be pillared. Played on a 4:3 TV the situation would be reversed with teh 16:9 content letterboxed.

Workflow goes pretty much the same way as long as you have "Perform non-square pixel rendering" turned on in the Project Settings;

Load 4:3 DV footage into a 16:9 DV project and set its Stretch mode to "Keep aspect ratio". When previewed you get black bars on either side (pillaring) with the 4:3 footage in the center.

Load a 16:9 source into a 4:3 DV project, set its Stretch mode to "Keep aspect ratio" and it'll be letterboxed.

In either case if you drag a clip to the Source window the windows aspect ratio will change to match that of the source being worked on.

Does that answer your questions?

Dr. Mordrid

[Hulk]

Doc,

Yes, that pretty much covers it except for one thing.

"720x480 is considered 4:3; part of which is overscan and therefore cut off on a 4:3 TV, so any cropping is done by the TV itself."

I do understand that part of the image is cropped due to overscan, but the DV spec image appears squeezed horizontally compared to when viewed 720x480 on a computer monitor. By squeezed, I should say it appears correct.

Cropping can't account for this squeezing, right? So the PAR (pixel aspect ratio) on a TV must be 0.909:1 vs. 1:1 for a computer monitor. So, non-square pixel rendering should be used for video intended for TV playback. Of course this is what you said, I think I arrived at the conclusion in a different manner though.

This non 1:1 PAR also provides a lot of flexibility when it comes to adding images to video projects since they can be easily rescaled in the video editing application. Again, as you mentioned.

It seems as though, and this is just a guess, that the designers of the DV format created DV with a non-square aspect ratio in mind so that playback would be "natively" correct on a TV screen an not a computer monitor.

No such problems with 720p since playback will be "right" on HD viewing devices, which are all square pixel devices.

1080i for HDV, or 1440x1080 will require remapping of the 1440 horizontal pixels to 1920 of the HD monitor.

Of course, rescaling will be needed whenever the video signal doesn't exactly match the viewing device, right? I assume this rescaling of the signal is accomplished in the digital domain, before the D/A converter?

Sorry for the rambling, I'm just trying to work through all this.

- Mark

[Dr Mordrid]

NTSC TV is indeed .909:1 for "square" pixels.

DV is indeed a bit wider than a TV's screen because an NTSC ATSC D1 (full frame) is 704 wide and not 720. As such there is an extra 8 pixels on each side of a DV or 720 wide DVD frame.

Note also that the DVD spec also supports both 352x480 (halfD1) and 704x480 NTSC video.

Dr. Mordrid