by Willen » Mon May 21, 2007 5:20 am
It's probably due the video being in an improper resolution after cropping.
Generally, you can get away with the video just having pixel dimensions with even numbers. But it's recommended to use multiples of 16 (mod16) for the best compression. Using multiples of 8 (mod8) is acceptable, and for certain codecs, as good as using mod16.
Usually, if you are cropping video you'll have to do some resizing (and possibly adding borders) to get to an acceptable resolution.
Here are some typical resolutions:
For 4:3 videos:
640 x 480
512 x 384
480 x 360 (4:3, but not mod16)
480 x 352 (not exactly 4:3, but mod 16)
384 x 288
320 x 240
For 16:9 videos:
1920 x 1088 (not exactly 16:9, but mod16)
1920 x 1080 (16:9, but not mod16)
1280 x 720
1024 x 576
848 x 480 (not exactly 16:9, but mod16)
768 x 432
720 x 400 (not exactly 16:9, but mod16)
704 x 396 (16:9, but not mod16)
640 x 360 (16:9, but not mod16)
640 x 352 (not exactly 16:9, but mod16)
512 x 288
480 x 272 (not exactly 16:9, but mod16)
As long as you follow the guidelines, you can resize to any resolution (within reason). But remember, higher resolutions mean higher file sizes.
Having trouble playing back videos? I recommend:
