Changing the frame rate

[sixfriends]

I need to change the frame rate of an avi file from 23.973 fps to 24, 25 or 30 fps w/out changing the final lenght of this movie. I allready trieded w/ TMPGEnc but I think the prog does not calculate the new rate exact enough. So I get a desync of a few seconds. (I know the prog doesn't mean to change the final lengh of the movie, because otherwise it would be about 4 minutes of desync).

Is there a tool I can use for this. I prefer freeware or shareware and if there is no such prog then that evil software you have to pay for

cya - sixfriends

[bugster]

you can convert mpeg movies from NTSC(film) at 23.97fps to NTSC at 29.97 simply by inserting the 3:2 pulldown flags. Tmpgenc can do this during the conversion from avi to mpeg, look under settings on the advnaced tab. If you hav already encoded to mpeg at 23.97 fps pulldown can be applied using pulldown.exe, search on google to find it.

(BTW 23,97 and 29.97 are the correct framesrates for NTSCfilm and NTSC but are often referred to as 24 and 30fps, 25fps is the PAL framerate)

Hope this helps

[sixfriends]

Not really. I'm from Germany and the frame rate I need is exactly 25.000 fps --> PAL. TMPGEnc has problems changing the frame rate from values like 23.973 to values like 24.000, 25.000... You get the point?

What I need is a prog that can convert from this 23.973 fps to a value without decimals like 25.000 fps.

[adam]

If all you needed was pal output than you should have just said so.

Its not that TMPGenc has a problem with converting framerates with decimals, its just how it converts all framerates in general.

Conversions to ntsc require a 3:2 pulldown, a process whereby new frames are created. TMPGenc has a specific filter which can accomplish this. Bugster gave you the correct answer. To do this conversion (23.976fps->29.976fps) you need to either hard telecine it using the 3:2 pulldown option in TMPGenc's filters or you need to enable the 3:2 pulldown stream in your mpeg2 file so that the playback device can perform the telecine.

With pal conversions no frames are added, film is simply sped up to 25fps. This process is referred to as a 2:2 pulldown but TMPGenc does not have an option for this.

Anytime you simply set a framerate that is different from your source in TMPGenc it will just repeat or decimate frames to make up the difference. So if you convert from 24 to 25 fps it will simply repeat one frame every second. The playtime should not change and actually it should still be in sync though the playback may appear choppy. This is NOT the proper way to do the conversion, however.

Sorry for the rant, I'll just tell you what to do.

To convert 24fps to 25fps you need to speed up both your audio and video by %4. To do this get virtual dub in the tools section and simply change the framerate to 25, look in video/framerate. Unless you are converting to avi you will need to frameserve from virtual dub to your mpeg encoder. Look in the guides on this site to find out how. To convert the audio I recommend you get BeSweet and use the gui. It has an ntsc->pal option. You can also use Cooledit or something similar, again just speed it up by %4. Also your pitch will now be %4 higher too. You can either leave it alone or lower the pitch %4 to offset it. Which one sounds better depends on the source so its up to your own ears.

To convert 23.976fps to 25 fps just follow the same procedure as above for the video. For the audio you actually need to speed it up by %4.03 but just speeding it up by %4 should cause no noticable sync problems so you can basically just follow the same steps as above.

Converting to pal WILL shorten the playtime. If your playtime isnt changed than you are not doing the conversion correctly. The key is that you must also shorten the playtime of the audio to match the video, but TMPGenc will not do any of this.

[banjazzer]

I have started to use this method with NTSC(film) DivX to convert to PAL SVCD and it works perfectly. The only occasions it has failed are when there were errors with the source DivX. I find Soundforge does the audio shrinking/stretching very easily and I don't notice the change in pitch. I believe with CoolEdit there is an option to retain the original pitch when altering the audio length, but I don't think this is necesary, unless you are blessed with perfect pitch!