Aspect Ratios - Adobe Premeire Pro

[jeffareid]

I occasionally make a short clip from a DVD VOB file. Premiere gives you some options on interpreting video clip aspect ratios, one of which is D1 DVD widescreen, where the width is increased by a factor of 1.2. My thinking is this should be 1.185 (1.185185185...) changing 720x480 to 853.3x480 or 854x480 is close enough. Instead with 1.2, it's using 864x480. Is this a compromise between the clarity of expanding by 1.2 versus 1.185 and ratio accuracy?

Also, when encoding a video clip (I use Windows Media 9 format), is it better (cleaner video) to have Adobe do the width expansion and create a WMV file with 1:1 pixel aspect ratio, or export a 720x480 video and specify it with 1.2:1 or 1.185:1 pixels and let the viewer's Windows Media player do the expansion?

I'm still working on the cleanest way to eliminate black bars on VOB clips with 2.11 to 2.13 ratios. Will see if cropping them on ouput works, as opposed to creating a new project with fewer vertical pixels.

[ammck55]

You'll probably get better looks at this one in the NLE Forum. Moving....

[jeffareid]

Thanks

[defaulk9]

Originally Posted by jeffareid

I occasionally make a short clip from a DVD VOB file. Premiere gives you some options on interpreting video clip aspect ratios, one of which is D1 DVD widescreen, where the width is increased by a factor of 1.2. My thinking is this should be 1.185 (1.185185185...) changing 720x480 to 853.3x480 or 854x480 is close enough. Instead with 1.2, it's using 864x480. Is this a compromise between the clarity of expanding by 1.2 versus 1.185 and ratio accuracy?

That's what it sounds like to me. I don't have my copy of Premiere in front of me here, nor do I know what the intent of the adobe devs, but that sounds about right.

Originally Posted by jeffareid

Also, when encoding a video clip (I use Windows Media 9 format), is it better (cleaner video) to have Adobe do the width expansion and create a WMV file with 1:1 pixel aspect ratio, or export a 720x480 video and specify it with 1.2:1 or 1.185:1 pixels and let the viewer's Windows Media player do the expansion?

Since you're importing video at 720x480, I think it makes sense to interpret it as 1:1 and leave it that way. Let the player resize. But it depends on your audience I would think. Probably the most compatible way to do this is to let Premiere stretch your video so your player plays it 1:1.

Originally Posted by jeffareid

I'm still working on the cleanest way to eliminate black bars on VOB clips with 2.11 to 2.13 ratios. Will see if cropping them on ouput works, as opposed to creating a new project with fewer vertical pixels.

Have you tried using VirtualDub to encode? I like it much better than using Premiere. Just set up a frameserver in Premiere. Then crop in vdub to your heart's content.

[jeffareid]

Thanks for the response.

Have you tried using VirtualDub to encode? I like it much better than using Premiere. Just set up a frameserver in Premiere. Then crop in vdub to your heart's content.

Look at my message under newbies section".

When I used VirtualDub to open one particular VOB file it opens up a warning box with a lot of messages stating: "Anachronistic or discontinous timestamp found in audio stream 29 at byte position xxxxxxxx (may indicate improper join)." The end result was that the audio ended up out of sync with the video, even if I tried the various settings in VirtualDub.

DGDecode worked though, and Adobe Premiere will auto de-interlace when creating a windows media file (for other formats, you have to choose de-interlace as a pre-encoding task).

I was just curious as to why Premiere considers the pixel width for widescreen DVD to be 1.2 (864x480) when it should be 1.185 (853x480 or 854x480). I can set "interpret footage" to 1:1, and then use effects control "motion" to scale width to 118.5. If the windows media player can do the width expansion fast enough on even slower systems, then I could just use 1:1 in the render and tag the WMV file as 1.185:1.

Next step is to crop out the black bars when the VOB file is 2:1 to 2.13 to 1.

[ammck55]

Originally Posted by jeffareid

Look at my message under newbies section".

If you want people to look at info in a different thread, all you have to do is insert a link, like this:
http://forum.doom9.org/showthread.php?t=104761

A short answer right here in this thread would probably have been just as effective and kept the thread more cohesive, don't you think?

[zambelli]

Originally Posted by jeffareid

I occasionally make a short clip from a DVD VOB file. Premiere gives you some options on interpreting video clip aspect ratios, one of which is D1 DVD widescreen, where the width is increased by a factor of 1.2. My thinking is this should be 1.185 (1.185185185...) changing 720x480 to 853.3x480 or 854x480 is close enough. Instead with 1.2, it's using 864x480. Is this a compromise between the clarity of expanding by 1.2 versus 1.185 and ratio accuracy?

Actually, 1.2121 is the correct pixel aspect ratio for NTSC widescreen video. The pixel aspect ratio is based on 704x480 image size, not 720x480, because that's how it's defined in ITU-601.

704x480 * 10/11 = 640x480
704x480 * 40/33 = 853.3x480

Also, when encoding a video clip (I use Windows Media 9 format), is it better (cleaner video) to have Adobe do the width expansion and create a WMV file with 1:1 pixel aspect ratio, or export a 720x480 video and specify it with 1.2:1 or 1.185:1 pixels and let the viewer's Windows Media player do the expansion?

Export as 720x480 and specify non-square pixels. You'll get better quality because you won't be wasting bitrate on interpolated pixels (720x480 compresses better than 852x480 at the same bitrate).


I believe setting the widescreen aspect ratio in Premiere doesn't actually resize the video internally 720x480 to 852x480 unless you specify 852x480 as your video project resolution. For example, if your project is 720x480 with 0.9 PAR (i.e. 4:3 DAR) and you import a clip that's 720x480 with 1.2 PAR (i.e. 16:9 DAR), the imported clip will get resized to 720x360 with black bars when placed on the timeline. Premiere is merely conforming it to the specifications of your project. A 720x480 1.2 PAR clip imported into a 720x480 1.2 PAR project will not get resized at all, ever, because it already conforms to the project size.

[jeffareid]

Thanks for the info all.

I'll just refer to the thread ip next time as suggested.

I assume the 704x480 instead of 720x480 is due to expected overscan, and so the 1.2 is the correct aspect ratio instead of 1.85.

So the only black bars to get rid of is for clips with higher aspect ratios, usually around 2.11 to 2.13 from what I've seen (black bars on top and bottom when displayed at 16x9).

[zambelli]

Originally Posted by jeffareid

So the only black bars to get rid of is for clips with higher aspect ratios, usually around 2.11 to 2.13 from what I've seen (black bars on top and bottom when displayed at 16x9).

I'm not sure why you're cropping the black bars. Are you doing a pan-n-scan to 1.78:1 or something? A widescreen enhanced NTSC DVD with a 2.35:1 movie has the same resolution as a 1.85:1 movie, so you wouldn't really gain anything in cropping and blowing it up to fill the 16:9 screen. In fact, it'd probably just look blurrier because of the 33% blow-up.

[jeffareid]

My output is a window movie file, so I'm cropping out the black bars. With a pixel aspect ratio of 1.2:1, movie aspect ratios translate into pixels as follows:

2.35:1 => 720x368
2.00:1 => 720x432
1.85:1 => 720x468
1.80:1 => 720x480

Since the dvd standard is apparently 704x480, and this would make the pixel aspect ratio 1.212121...., and Adobes 1.2 ratio is within 1% of this.

I don't copy dvd segments to other dvds, but if I did, I wouldn't change the aspect ratio.

I have a Sony HC1 HDV camcorder, and I can use Adobe Premiere Pro to tranfer and create high quality windows movies. I'm waiting to see how the HD DVD players and recorder issues work out.

[zambelli]

Originally Posted by jeffareid

2.35:1 => 720x368
2.00:1 => 720x432
1.85:1 => 720x468
1.80:1 => 720x480

Another solution would be to keep the project 720x480, don't crop anything in Premiere, but use DebugMode frameserver to export the clip to Avisynth, crop within Avisynth and feed the resized clip to WME9. It might sound more complicated, but it would actually simplify editing by taking most of the resizing and aspect ratio mumbo jumbo out of Premiere. All you'd have to worry about in Premiere would be specifiying the correct aspect ratio on input clips and the project (1.2 if widescreen, 0.9 if full screen). Premiere would then make sure everything plays well together. Once exported, you could process and encode the final video (i.e. crop 720x480 to 720x368 and set 40:33 PAR in WME9).