VCDQuality Forums - DVD rip vs. BD "720p" rip

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Posted by Linnets on 04-08-2009 01:57 PM:

DVD rip vs. BD "720p" rip

I'm sure this kind of thing has been discussed here before but I just spent an hour going through old posts and can't find it.

I've bought myself a WD TV HD and I am slowly going about acquiring HD media for it. However, I have noticed a lot of scene releases for 720p material is actually only say 540 pixels high. Example. Now my question is, would I be better off just downloading the DVDr which I would assume would have the full DVD resolution of 576(?) pixels with a smaller file size. I say I assume, because I've never d/l'd DVDr's I've gone straight from XVid avi's to x264 HD rips.

Obviously the bitrate is higher on the "720p" copy and it has DTS sound which I may or may not be fussed about depending on the film, but what effect does this higher bit rate have on the quality of the picture?

I suppose I'm only interested from a theoretical point of view, because I don't think I'd be all that fussed about saving a gig or 2 of bandwidth, I'm just interested to know.

Posted by ntscuser on 04-08-2009 02:02 PM:

Re: DVD rip vs. BD "720p" rip

quote:
Originally posted by Linnets
I'm sure this kind of thing has been discussed here before but I just spent an hour going through old posts and can't find it.

I've bought myself a WD TV HD and I am slowly going about acquiring HD media for it. However, I have noticed a lot of scene releases for 720p material is actually only say 540 pixels high. Example.

If a movie is letterboxed at 2.35:1 it is never going to have the full number of lines is it? That applies to DVDs as well.

Posted by punzada on 04-08-2009 06:14 PM:

Re: DVD rip vs. BD "720p" rip

quote:
Originally posted by Linnets
I'm sure this kind of thing has been discussed here before but I just spent an hour going through old posts and can't find it.

I've bought myself a WD TV HD and I am slowly going about acquiring HD media for it. However, I have noticed a lot of scene releases for 720p material is actually only say 540 pixels high. Example. Now my question is, would I be better off just downloading the DVDr which I would assume would have the full DVD resolution of 576(?) pixels with a smaller file size. I say I assume, because I've never d/l'd DVDr's I've gone straight from XVid avi's to x264 HD rips.

Obviously the bitrate is higher on the "720p" copy and it has DTS sound which I may or may not be fussed about depending on the film, but what effect does this higher bit rate have on the quality of the picture?

I suppose I'm only interested from a theoretical point of view, because I don't think I'd be all that fussed about saving a gig or 2 of bandwidth, I'm just interested to know.

the aspect ratio has nothing to do with the visual quality of the film, it's all about bitrate/resolution as you assumed.

You have to remember while a dvd is 720x480 pixels (for ntsc) the higher bitrate 720p rips are 1280x720/540 so you're still gaining nearly twice the horizontal resolution over dvds, which with the higher bitrate resorts to a more scalable picture (due to the higher resolution) and less blocky/more 'clear' (due to the higher bitrates).

Unless you're watching it on a standard def set or something, stick with the hd rips, you're getting the best quality that way and storage is cheap now

Posted by Linnets on 04-08-2009 11:29 PM:

Cool, thanks for the reply. As it happens I am watching on a SD set, but working hard at being able to afford a HD one! And I thought I might as well d/l the HD stuff now rather than download the same stuff in SD then again in HD when I do finally get around to (can afford) buying a proper telly.

::EDIT::

What do scene rules say about cropping/resolutions on HD/BD rips? Why would you want to crop a 720 or 1080 rip to less than what the original disc was authored at?

Posted by punzada on 04-09-2009 01:22 AM:

quote:
Originally posted by Linnets
Cool, thanks for the reply. As it happens I am watching on a SD set, but working hard at being able to afford a HD one! And I thought I might as well d/l the HD stuff now rather than download the same stuff in SD then again in HD when I do finally get around to (can afford) buying a proper telly.

::EDIT::

What do scene rules say about cropping/resolutions on HD/BD rips? Why would you want to crop a 720 or 1080 rip to less than what the original disc was authored at?

well it all depends on aspect ratio, a 16:9/16:10 will be close to 1280x720 but those odd 2.21:1 rips will have different vertical resolutions, if you try to stretch it to meet 720p pixels you would either stretch the image out so it looks distorted or add pointless black bars into the rip which are just pointless, it all depends how the film was shot.

regardless if you're going to stay on standard def you wont' realize the difference but it is there, once you hook it up with a digital signal (hdmi, accept no substitute and dont pay any more then $10USD for the cable) you will definitely see it between dvdr and 720p/1080p

Posted by valvehead on 04-13-2009 05:29 PM:

How is the video stream stored on blu-ray discs?
Say a movie with 2.35:1 at 1080p, is it 1980x1080 and all the pixels are used up, or is it 1980x840 and letterboxed to fill up the remaining pixels. I'm assuming the latter which seems kinda low-tech and backwards when they could probably use up the whole picture and add a flag to the video stream to make it play at the correct ar.

Also, rips should go by the horizontal res 1980/1280 instead, what with the cropping and shit, it would cause less confusion.

Posted by Linnets on 04-13-2009 05:51 PM:

quote:
Originally posted by valvehead
How is the video stream stored on blu-ray discs?
Say a movie with 2.35:1 at 1080p, is it 1980x1080 and all the pixels are used up, or is it 1980x840 and letterboxed to fill up the remaining pixels. I'm assuming the latter which seems kinda low-tech and backwards when they could probably use up the whole picture and add a flag to the video stream to make it play at the correct ar.

Also, rips should go by the horizontal res 1980/1280 instead, what with the cropping and shit, it would cause less confusion.

This all makes complete sense to me. Although I know there's gonna be a good reason for the black bars top and bottom. And I think it's that cinema screen AR's are just different to TV screen AR's. Given that I suppose there's no point in encoding the black bars, therefore you aren't actually cropping anything other than black which your TV will just put back in. However, can someone tell me whether original BD's have black bars top and bottom. I suppose they must have. Not having a BD player means I've never seen one to know myself.

::EDIT::

I thought I had it sorted in my head, but having just checked the HDRip section and IMDB, I'm confused again.

Slumdog:

Original cinema release AR (according to IMDB) = 2.35:1
Refined's "720p" release = 2.35:1 (1280x544)
UBR's "Complete" release = 16:9 / 1.77:1 (1920x1080)

Can anyone confirm whether UBR's release would fill a 16:9 WS tv without black bars, or have they encoded the black bars, or did they crop the black bars and just call it 1080 when in fact they have only encoded 817 actual pixels?

Posted by Spiderman2003 on 04-21-2009 06:05 AM:

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