What's best for Contests?

Myouh · Post by **Myouh** » Mon Sep 24, 2007 7:45 pm

what's best for contests amv screening,
720X480 resolution with a 4:3 display,
or 720X480 resolution with a 16:9 display?

The Origonal Head Hunter · Post by **The Origonal Head Hunter** » Mon Sep 24, 2007 7:46 pm

you mean to tell us the contest doesn't have requirements for entries?

Scintilla · Post by **Scintilla** » Mon Sep 24, 2007 8:06 pm

<i>In general,</i> 720x480 with 4:3 flag is safer, as many conventions play their contests off hardware that doesn't respect the 16:9 flag.

However, you really should get the rules for the specific convention in question.

Myouh · Post by **Myouh** » Mon Sep 24, 2007 10:06 pm

ok and when resizing to 720X480 4:3 display, what should I pay attention to when letterboxing the original video so that it fits its new resolution, the fact that it will be 720X480, or that it will be displayed in 4:3 ?

in other words, letterboxes should be added considering 720X480, or considering 4:3 ?
I hope I've been clear enough...

Willen · Post by **Willen** » Tue Sep 25, 2007 8:02 am

Since the only real change will be black bars (letterboxes) added to the top and bottom of a vertically shrunken video, it shouldn't matter.

Ultimately, the actual video will have a vertical pixel height of (preferably) 352 pixels. Since the video will be flagged as 4:3, the horizontal resolution is unaffected at 720 pixels.

Why a height of 352 pixels high instead of the mathematical ideal of 360 pixels to achieve proper 16:9 aspect ratio for a letterboxed 4:3 videos? Encoding at mod16 (evenly divisible by 16) resolutions improve compressibility for MPEG formats (other non-mod16 issues don't apply here since the total video height is still 480 pixels). So resizing to 352 vertical pixels and adding 64 pixels of black to the top and 64 pixels of black to the bottom (128 total) gets you back to 480 pixels total height.

You could choose to resize to 360 pixel height and letterbox with 60 pixels of black top and bottom (120 total) and I won't crucify you since the only thing you are losing is compressibility.

Myouh · Post by **Myouh** » Tue Sep 25, 2007 4:15 pm

Willen, even though what you said would lead to a 720X480 letterboxed video, 720X352 isn't the equivalent of 608X320 (the original size), that would lead to the deformation of the video.

I found out that the perfect resolution is 720X384, 48pixel of black to the top and 48 to the botom.
(608 devided by 320 approximatively equals (for compressablity matters) 720 devided by 384.

thanks anyway.

but I've got another question:
why can't I create an MPEG-2 video with 3:2 pulldown on playback with a 29fps source video. it's says the source video musn't be 29fps to be encoded with a 3:2 pulldown, is there a solution to this? is it normal first?

Willen · Post by **Willen** » Wed Sep 26, 2007 6:34 am

You do realize that when played back, a 720x480 (non-square, rectangular) pixels 4:3 AR flagged video will display as 640x480 (square) pixels?

My advice is correct for 720x480 resolution video that is using NON-SQUARE pixels. When played back on proper equipment/software and assuming the video is correctly flagged, it will either be displayed with square pixels as 640x480 if 4:3 or 853/848x480 if 16:9. http://www.animemusicvideos.org/guides/ ... atios.html

I assumed the original video source was either 720x480 (rectangular pixels, 0.9 AR, anamorphic) video or 853/848x480 (square pixels, 1.0 AR) video at 16:9 aspect ratio. 608x320 (1.90:1 width-to-height ratio) is an usual resolution/aspect ratio for anime. Most widescreen anime are 16:9 and with square pixels have 853/848x480 resolution and a 1.78:1 width-to-height ratio. Some newer anime movies may be 1.85:1 AR while the majority of older movies are just 4:3 (1.33:1) AR, same as TV shows. Another AR you may run into is 5:3 (1.66:1).

Here's an old thread with some nice illustrative images of the difference between PAR (pixel aspect ratio, i.e. 720x480) and DAR (display aspect ratio, i.e. 4:3) and the importance of proper AR flags: http://www.animemusicvideos.org/phpBB/v ... hp?t=65156

P.S. this reply needs a re-write for better clarity, but I'm tired and it's late.

Scintilla · Post by **Scintilla** » Wed Sep 26, 2007 4:40 pm

Myouh wrote:why can't I create an MPEG-2 video with 3:2 pulldown on playback with a 29fps source video. it's says the source video musn't be 29fps to be encoded with a 3:2 pulldown, is there a solution to this? is it normal first?

The whole point of 3:2 pulldown is to take a 23.976fps progressive stream and make it 29.97fps interlaced.

If your source is already 29.97fps, no pulldown is necessary (or helpful).