What resolution?

[nnever2000]

What is the correct resolution to encode 16:9 video stream? Over the internet usually I see this: 624x352 or 640x368 (the purpose of the video is for non <hd> profile backup).

[neuron2]

16/9 = 1.7777

624/352 = 1.7727

640/368 = 1.7391

640/360 = 1.7777 <- Your winner!

If you have to be mod 16, then 624/352 is the one.

[nnever2000]

16/9 = 1.7777

624/352 = 1.7727

640/368 = 1.7391

640/360 = 1.7777 <- Your winner!

If you have to be mod 16, then 624/352 is the one.

Why the "mod 16" is so important?

[neuron2]

It usually isn't important to have mod 16 but some stupid players may not display it right if it isn't mod 16. Try it with your encoding/viewing chain and then decide.

[LoRd_MuldeR]

Why the "mod 16" is so important?
Because video encoders work on macro blocks, so the video will be cut into blocks of 16x16 pixels. Recent encoders/decoders will handle non-mod16 resolutions just fine. AFAIK they will simply extend the video to a mod16 resolution internally. This way you will loose some encoding efficiency, because more pixel are encoded than you actually see. But the effect should be negligible...