How to best convert 720x480 60i to 320x240 30p?

[adoniscik]

I am encoding for the Web, so I need to reduce the size of my videos. I thought a good idea would be to somehow combine the 360x480 fields to get 30P then to correct the aspect ratio to get a 320x240.

I would prefer to do this in Vegas or After Effects.

[Mug Funky]

if you're after combining the fields, just do a straight resize. bicubic if you can.

halving the vertical res means field 1 gets mushed into field 2, but in a way that doesn't bollock anything up.

this'll be the fastest method.

[adoniscik]

Are you saying that simply resizing 720x480 to 320x240 is the optimal solution? What about the frame rate conversion? After resizing I will still have a 60i file...

[Mug Funky]

if your footage is interpreted as progressive, the resize will turn 60i (60 fields interlaced into 30 full frames) into 30p - the interlace is destroyed by the resize.

[Guest]

How to best convert 720x480 60i to 320x240 30p? Please read and follow forum rules, specifically, rule 12: do not ask what's best. Thank you.

[adoniscik]

I forgot about that one! For this particular case of halving the resolution I think there was a recommended procedure, and I could not remember it.

[Backwoods]

Please read and follow forum rules, specifically, rule 12: do not ask what's best. Thank you.

Do you search for "best" every so often?

[Guest]

Do you search for "best" every so often? I read every post. :)

[Sulik]

In some cases, there is a valid 'best' answer, or in this case three with different tradeoffs:

1. no loss of spatial or temporal resolution: deinterlace to 480/60p then downsample to 240/60p. Unfortunately, this is impractical sonce 60Hz encoding doesn't make sense at such low resolutions (probably implies a low bitrate as well).

2. (preferred): deinterlace 480i to 480/30p, then downsample to 240/30p. This is the most common way, and the quality will be as good as the deinterlacer can provide (the only loss here is temporal resolution, no different than DivX/WMV etc).

3. (different tradeoff): directly scale from 480i to 240p, blending both fields together. This has the advantage of making fast motion appear smoother, by creating a blur-like effect, but will also produce ghosting artifacts, that are usually more annoying than #2.

[LocalH]

Also be sure to crop to 704px width before resizing to 320px, to preserve proper aspect.