Question about HD and HDV resolutions
 

Hi, I have a question. Reading around on the 'net I have found references to several HD image resolutions. I was led to beleive that HDTV would always have 16:9 aspect ratio and square pixels, so what is the deal with the 1440x1080 HDV resolution? Can somebody please clear this up?

The formats I have read about are:

HDTV ITU 709 (1920x1080 progessive? interlaced?)
HDCAM (135 Mbps, 1440x960)
DVCPROHD, D-9HD (100 Mbps, 1280x720)
HDV (25 Mbps MPEG2, 1440x1080 interlaced)
HDV (17Mbps MPEG2, 1280x720 progressive)

You do raise an interesting question.

ATSC HDTV is native 16:9, square pixels. HDV's 1440 x 1080 doesn't fit that mold.

The old Japanese HDTV standard apparently included 1440 x 1035i as one of its sizes. And pre-2000, HDTV sets could be found that supported 1440 pixels horizontally. But HDV is supposed to be compatible with ATSC HDTV, right? If so, it should have to comply with 1920 x 1080.

One possible guess is that the 1440 x 1080 is intended to be viewed anamorphically, with a 1.33x squeeze. If you used a 1.33x anamorphic lens you could squeeze 1920 pixels worth of image onto 1440 pixels of surface area. So one could imagine (wild speculation, of course) that the 1440 x 1080 is intended to be uprezzed and viewed at 1920 x 1080, and I would suspect that either the camera will provide an automatic resizing capability, or it would be incumbent on the editor to unsqueeze/resize the image in order to make it compatible with the ATSC HD standards.

Another thing to consider is that early HDTV encoders couldn't fit 1920 x 1080 into a 6MHz channel without objectionable compression artifacts showing up, so some encoder manufacturers opted to subsample at 1440 x 1080 in order to fit the full data stream. Perhaps that's the same situation being faced with HDV, and if that's so, I'd guess that there's no anamorphic business going on, they would just intend to uprez to 1920 upon output.

But, hey, who knows? We'll see when more info is released.

I have seen this number before. About a year ago I went to a demonstration of the CineAlta camera here locally, and the DP's that were demonstrating it told us that these supposed 1920*1080 camera in fact were only capable of resolving 1440*1080 and that's why there's little visual difference between 720p and 1080p. Just a point I thought might be of interest.

Nothing to weird about 1440x1080 -- that is the shooting resolution of HDCAM.

http://www.hd24.com/shooting_high_definition.htm

It is still 16:9, just that the pixels aren't square.

The Sony F9xx series cameras are plenty capable of resolving 1920x1080 just perfectly, just not to tape. 1440x1080 sounds like a hack. Non-square pixels have been annoying for years and years and years which is why HDTV specifically created all square formats. This bastardization probably is as Barry said, for bandwidth issues, or compression rate issues. argh. (FYI, the supposed "High-Definition" WMV file included on the newest terminator 2 DVD is also 1440x1080 or something like that. it still looks amazing, but its not a true HD resolution).

Yes what charles said. We have 1440x1080 as teh hd "standard" over here for FTA DTV. Its mainly a bandwidth saving idea by the tycoons of course. And its the horizontal resolution that gest cut back becuase "they" say the human eye can not tell the differnece horiztonatlly as it can with a virical resolution change. PLus the MPEG encoders need less definition blocks (cant remember the name for it now) to compress for 1440 as opposed to 1920. etc etc (you get teh drift.. its friday i'm in weekend mode already). :P

its a shame.. i'm sick of losing horizontal resolution all for teh sake of bandwidth. *shakes head*

Correct, 1440 is the horizontal resolution of the recorder section of HDCAM, it's not an aspect ratio change.

I believe the new f950 that records 4:4:4 captures the entire resolution of the camera.

Jay

While we all wait for DTV...
 

It seems that personal computers can already be considered a good medium for HD delivery, especially at 1280 x 720. There is an interesting article at DV.com written by Ben Waggoner about this.

Re: While we all wait for DTV...
 

<<<-- Originally posted by Ignacio Rodriguez : It seems that personal computers can already be considered a good medium for HD delivery, especially at 1280 x 720. There is an interesting article at DV.com written by Ben Waggoner about this. -->>>

As long as it has enough power to play at 30fps without gliches. Not easy to get with HD resolutions at full-screen output.

Does anyone know anyway on a Mac to encode to WM9?

What about DivX
 

I wonder why Ben Waggoner did not include DivX. It's a very popular codec, encoding and decoding is available for many platforms and it handles SD very well. I have used mencoder (through ffmpeg) and at a same bandwidth DivX looks so much better than Apple's MPEG4. And you can play it back through QuickTime and Windows Media Player.

The advantage of WM9 is that it is designed for HD.