converting HD to SD with AE at DVinfo.net

Robert Bobson · May 11th, 2009, 05:21 PM

I need a little help thinking this through...

I have some HDV footage (16 x 9 aspect ratio) that I want to convert into 720 x 480 (4x3 aspect ratio)

So I'm thinking I want to import into AE and place in a composition that had a 4x3 aspect ratio - thus cutting off some of the widescreen video and making it non-widescreen. Then I'll render this composition to a 720 x 480 avi file.

but my original footage isn't 1920 x 1080. It's either 1440x1080 or 1220x1080.

If I make a composition that has the 4x3 aspect ratio, it would be 1440x1080 square pixel.
So it seems I should just interpret the footage with it's native pixel aspect ratio, then place it in the 1440x1080 sq pixel compostion.

or for the native 1440x1080 footage (which has a 1.333 pixel aspect ratio), should I create a compostion of 1080 x 1080 with 1.333 pixel aspect ratio and load my 1440x1080 footage into it? this should actually create a 4x3 image when the pixels are stretched sideways by the factor of 1.333.

any ideas? I'm going to start experimenting, but if anyone knows the definitive best way to proceed, please let me know!

~update~
I just created a 1440 x 1080 sq pixel composition (4x3 image ratio) and imported my 1440x1080 footage with the 1.33 pixel (16x9 image ratio)
and it seems to do the trick.

But in rendering it only lets me render out at 1440x1080, but then I can "stretch" it smaller to standard NTSC DV 720x480 (.9 pixel ratio)

However, it says that the width is being reduced to 50%, but the height is being reduced tp 44.44%, because of the non sq pixels.

seems like this might add some odd percentage distortion... (?)

Tripp Woelfel · May 12th, 2009, 05:08 AM

Robert... The numbers look right because you're going from a PAR of 1.33 to .9. Have you tried outputting a small work area segment of the footage to see what it looks like? Based upon what you've posted here, your setup looks right.

Robert Bobson · May 12th, 2009, 09:31 AM

I did a test where I had the raw clip on one side of a split screen and the cineform intermediate created from that same clip on the other side in a 1440x1080 comp.

did the "stretch" down to NTSC DV standard and exported to a Cineform AVI file.

Then I imported that into a PPRo CS4 timeline, and encoded for DVD.

The two sides of the video looked the same all the way thru - and both looked good on an SD monitor.

May 11th, 2009, 05:21 PM	#1
Robert Bobson Major Player Join Date: Feb 2003 Location: Bay City, Michigan Posts: 585	converting HD to SD with AE I need a little help thinking this through... I have some HDV footage (16 x 9 aspect ratio) that I want to convert into 720 x 480 (4x3 aspect ratio) So I'm thinking I want to import into AE and place in a composition that had a 4x3 aspect ratio - thus cutting off some of the widescreen video and making it non-widescreen. Then I'll render this composition to a 720 x 480 avi file. but my original footage isn't 1920 x 1080. It's either 1440x1080 or 1220x1080. If I make a composition that has the 4x3 aspect ratio, it would be 1440x1080 square pixel. So it seems I should just interpret the footage with it's native pixel aspect ratio, then place it in the 1440x1080 sq pixel compostion. or for the native 1440x1080 footage (which has a 1.333 pixel aspect ratio), should I create a compostion of 1080 x 1080 with 1.333 pixel aspect ratio and load my 1440x1080 footage into it? this should actually create a 4x3 image when the pixels are stretched sideways by the factor of 1.333. any ideas? I'm going to start experimenting, but if anyone knows the definitive best way to proceed, please let me know! ~update~ I just created a 1440 x 1080 sq pixel composition (4x3 image ratio) and imported my 1440x1080 footage with the 1.33 pixel (16x9 image ratio) and it seems to do the trick. But in rendering it only lets me render out at 1440x1080, but then I can "stretch" it smaller to standard NTSC DV 720x480 (.9 pixel ratio) However, it says that the width is being reduced to 50%, but the height is being reduced tp 44.44%, because of the non sq pixels. seems like this might add some odd percentage distortion... (?)

May 12th, 2009, 05:08 AM	#2
Tripp Woelfel Trustee Join Date: Jan 2008 Location: North Conway, NH Posts: 1,745	Robert... The numbers look right because you're going from a PAR of 1.33 to .9. Have you tried outputting a small work area segment of the footage to see what it looks like? Based upon what you've posted here, your setup looks right.

May 12th, 2009, 09:31 AM	#3
Robert Bobson Major Player Join Date: Feb 2003 Location: Bay City, Michigan Posts: 585	I did a test where I had the raw clip on one side of a split screen and the cineform intermediate created from that same clip on the other side in a 1440x1080 comp. did the "stretch" down to NTSC DV standard and exported to a Cineform AVI file. Then I imported that into a PPRo CS4 timeline, and encoded for DVD. The two sides of the video looked the same all the way thru - and both looked good on an SD monitor.