Aspect Ratio & Progressive Scan

[Toshi.des]

Hey guys, I am a bit confused with this demonstration of aspect ratios shown in Premiere.

My current understanding is for whatever measurement a 4:3 vs a 16:9 aspect ratio they can have the same pixel area but should have different measurement lengths.

Example: if 720x480 is 4:3 then a 16:9 clip with the same area of pixel should have a longer width and shorter height than 720x480 right?

Premiere's Presets for film though in NTSC shows that they both have the same frame size which doesn't make sense to me.

Fullscreen:
http://img412.imageshack.us/i/fullscreen.jpg/

Widescreen:
http://img688.imageshack.us/i/widescreen.jpg/

Also premiere shows it as a preset in NTSC as all interlaced fields or lower field first. To change this, is all you have to do is change the fields to "No Fields (Progressive Scan)"?
http://img704.imageshack.us/i/progressivel.jpg/

Help Appreciated.

[Kionon]

Or you could use custom, set it to desktop, choose the resolution you wish to edit in, choose the framerate, set to the proper pixel aspect ratio, and then set the fields to No Fields (Progressive Scan).

I usually edit in 848x480, I completely ignore the presets.

[Qyot27]

Hey guys, I am a bit confused with this demonstration of aspect ratios shown in Premiere.

My current understanding is for whatever measurement a 4:3 vs a 16:9 aspect ratio they can have the same pixel area but should have different measurement lengths.

Example: if 720x480 is 4:3 then a 16:9 clip with the same area of pixel should have a longer width and shorter height than 720x480 right?

Premiere's Presets for film though in NTSC shows that they both have the same frame size which doesn't make sense to me.

Firstly, 720x480 isn't actually 4:3 - 640x480 is. The only reason 720x480 is 4:3 is because of the non-square pixels on a TV. If you divide 4/3, you end up with 1.33 repeating. If you divide 640/480, you get the same result. That only works when you assume the pixels are square, though, as you would on a PC monitor.

TV pixels are differently shaped, based on whether you live in NTSC or PAL land. NTSC's pixel ratio is 0.9, which makes it slightly more wide than tall. Divide 640 by 0.9 and you wind up with ~712 pixels. Then four pixels are padded onto either side and voila, 720x480 = 4:3 on a TV set. This is why MPEG-2 and other types of distro formats have aspect ratio flags to compensate for these PAR differences. A flag signifies that it displays as 4:3, or it can specify a ratio of 16:9, which is called anamorphic flagging. MPEG-2 itself also supports a flag for 2.21:1, but the DVD standard doesn't include support that ratio, nor do any movies I've come across use it either.

The same concept applies to 16:9. 16/9 = 1.78 (7 repeating), if you divide 848/480, you get close enough to that for it not to matter (since 848 is a mod16 res; properly, it's supposed to be something like 853.3 repeatingx480). Likewise, if you take 853.3 repeating and divide it by the 1.2121 PAR that Premiere's window is telling you the Widescreen profiles use, you get ~704 pixels, and you'd treat it similarly - pad the extra distance to 720, 8 pixels on each side (although in practice you tend not to see borders that huge, or only on occasion; older releases are somewhat more prone to it in my experience).



To be far more concise than the above, it's treating your footage anamorphically. DVDs often use anamorphic techniques for storing 16:9, so that the encoding process is optimized (the guides have an entire section on this).

This is also why I agree with Kionon; it's much easier to deal with this stuff if you just resize to a proper Square ratio (640x480 for 4:3 or 848x480 for 16:9) and use Custom to make the project adhere to those resolutions instead of using one of the templates - leave any AR adjustment stuff for distro and DVD authoring if you feel the urge.

[Toshi.des]

Thank you so much guys!

[Toshi.des]

Sorry to double post, just thought it might be good to also ask if it matters what video previewing settings I use.



I usually use DV NTSC since I usually use 29.97 FPS and the codec by default says 24p. Should I be using something else though?

[Kionon]

This depends largely on how good your computer is. I tend to use Apple Intermediate Codec, but on windows you don't have that. If you have the space, and your computer can handle it, you can use HUFFYUV. I have a lot of real estate between my HDTV and my Apple Cinema display, so I pretty much demand that I have access to a full quality preview, but if you just want to see how things look without worrying too much about the finest details, Motion JPEG renders super fast and I used it a few years ago when my computer was not fast enough to play out HUFFYUV as a preview codec.

[Toshi.des]

I can export in Huffyuv, but it doesn't seem to give me an option for previewing it in Huffyuv.


Do I need to modify something first?

Also, about PC performance... I built mine about four to five years ago. Intel Q6600 2.4 Quad Core, Nvidia 8800 GTS 320 MB, 4 Gigs DDR2 400 Dual Channel, WD 150 GB HD 10,000 RPM. I have a 1.5 TB HD on it's way cuz I am out of space atm to do much but before I guess even considering using Huffyuv can mine handle previewing with it?

Also I don't even see an option for Motion JPEG, even if mine can use Huffyuv, it sounds appealing for projects that don't require fine detail.

Thanks for your help Kionon!

[Kionon]

I... can't answer this. I've called in the Modkip. You are obviously on windows, and my knowledge of CS4 + windows is limited. I am a mac editor.

I will say this, 150GBs? Yeah, not so good. Quad Core and RAM should be more than enough.

[mirkosp]

Premiere CS4 has some limits with preview codecs, and so will Premiere CS5. I'm using beta CS4 on a 32bit OS so I have all codecs available for preview, but full version does seem to give the same issue on all 64bit OSes and some 32bit OSes "at random."
So basically, you're out of luck... AME is its own application for a reason - that is because premiere seems to have limits with some codecs the way it's built now (and this will especially be true with CS5, since it will be 64bit only and won't be able to use 32bit codecs), so they just have the dynamic linking between the premiere project and AME as a pipe of sorts, so AME can work fine with both 32bit and 64bit codecs without premiere needing to.
Basically, as far as preview codecs are concerned, you just have to bite the bullet and see which of those seems to work best for you. Alternatively, your PC seems to be strong enough to be able to playback most of your editing in real time without the need to preview at all. I know that I myself rarely preview within premiere despite having a broad list of codecs available, because premiere was optimized enough to let playback without rendering feasible. CS5 apparently will be able to let 6 720p tracks play in realtime without the need to render the scene to preview it...

[kickass331]

what most of you aren't making clear is how important it is to maintain timecode. If anything is set to 30fps instead of 24, you might have to redo the timing for your whole amv to get it to render properly. Just a word of warning. Previewing in 24fps is also a good idea.