duplicating fps

[32flavors]

first of all, i did try a search, and found no answer to this Q, but i do apologize in advance if this Q was asked and asnwerd before.. (also, as this is my first post - i'm sorry if this is a stupid Q).

is there a way to convert an AVI movie from 12.5 fps to 25, using OLNY vdub/vdubmod (not with avisynth) without creating an audio/video sync problem?

and if there is - would there be any problem converting the new AVI to MPEG 2 using TMPGEnc?

[stephanV]

i cant imagine this isnt discussed somewhere but anyway

go to video--->frame rate and fill in the correct value in 'convert to fps' under frame rate conversion (not in 'change to' under source rate adjustment, this will speed up the video)

as youre changing to 25 fps, im assuming your making a PAL SVCD or DVD; cant TMPGEnc change the frame rates for you?

[edit]i forgot one important part: make sure to select 'direct stream copy' for both audio and video before saving

[32flavors]

first of all - thank you. (and i did a search.. honest. typed all sort of combinations of words..)

now, during my search, i found posts suggesting that TMPGEnc's convertion resolt in a jerky video.. that's why i asked. is that true? and if so, why?

[stephanV]

it would if youre converting the framerate from e.g. 24 to 25 fps. what happens with converting framerates is that VDub/TMPGEnc will duplicate frames, so from 24 to 25 fps would result in a duplicate frame every 24 frames. thus, one frame will appear to be played twice as long as the other ones. this will of course result in jerky playback.

you however, have a fortunate case of converting framerates: 25 is exactly 2*12.5 so each frame will be duplicated instead of a couple of ones. every frame will still appear to play with the same length.

might you ever need to convert from 24 to 25 fps, the best thing would be to speed up (instead of converting) the movie to 25 fps and speed up the audio along with that. this is also done when preparing movies (24 fps) for PAL (25 fps)

[32flavors]

ok! now everything i read here makes sense.. thank you.