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make a 24 fps mpeg2 into 25 fps?

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  • Video
  • FPS
  • Graphics
Last response: in Graphics & Displays
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April 25, 2004 4:37:27 PM

Archived from groups: rec.video.desktop (More info?)

is there a way to edit an mpeg2 file that is encoded as 24 fps so that it
would play back at 25 fps and still maintain sync with the audio?

this is to allow me to burn a movie (after inverse telecined) as a
progressive PAL dvd with no duplicate frames

More about : make fps mpeg2 fps

Anonymous
April 25, 2004 6:27:06 PM

Archived from groups: rec.video.desktop (More info?)

> is there a way to edit an mpeg2 file that is encoded as 24 fps so that it
> would play back at 25 fps and still maintain sync with the audio?
>
> this is to allow me to burn a movie (after inverse telecined) as a
> progressive PAL dvd with no duplicate frames
>
If your MPEG2 file is 24fps(23.976?), then it's probably NTSC and will have
to be re-encoded to PAL resolution. You need to re-sample/stretch the audio
to fit the new duration. It's about a 5% speed change and isn't very
noticeable.

If you absolutely want to keep the original sound/pitch, you could convert
the NTSC video to interlaced PAL. That's the ugly option. Most professional
conversions of progressive material are done with the speed change. Either
way, you will have to do some sort of re-encoding.
Anonymous
April 25, 2004 6:27:07 PM

Archived from groups: rec.video.desktop (More info?)

On Sun, 25 Apr 2004 14:27:06 +0000 (UTC), "Speed Dialer"
<dontyousp@m.org> wrote:

>> is there a way to edit an mpeg2 file that is encoded as 24 fps so that it
>> would play back at 25 fps and still maintain sync with the audio?
>>
>> this is to allow me to burn a movie (after inverse telecined) as a
>> progressive PAL dvd with no duplicate frames
>>
>If your MPEG2 file is 24fps(23.976?), then it's probably NTSC and will have
>to be re-encoded to PAL resolution. You need to re-sample/stretch the audio
>to fit the new duration. It's about a 5% speed change and isn't very
>noticeable.

As has been pointed out, the resolution will require tweaking,
so you're going to have to reencode it with the new frame size and
frame rate. The easiest way to convert it is to use AVISynth (and its
MPEG decoder plugin) with a very simple script. It would look
something like this:

MPEGSource("DRIVE:\FILENAME.MPG")
AssumeFPS(25,sync_audio=true)
LanczosResize(720,576)

Go to www.doom9.org and look up info there on how to use
AVISynth for something like this. Their forums are also full of info
about NTSC to PAL conversions.
-----------------------------------------------------
Neil Nadelman arvy@navzr-genafyngbe.pbz (ROT13)
-----------------------------------------------------
I have no fears in life,
for I have already survived Theta-G!
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Anonymous
April 25, 2004 9:39:21 PM

Archived from groups: rec.video.desktop (More info?)

On Sun, 25 Apr 2004 12:37:27 GMT, "peter" <nospam@nospam.com> wrote:

>is there a way to edit an mpeg2 file that is encoded as 24 fps so that it
>would play back at 25 fps and still maintain sync with the audio?

Typically, as I understand the "simple" conversion processes used
commercially, they simply run the 24fps video as 25fps, and resample
the audio for sync. Any decent audio editor (if not your NLE itself,
though an audio friendly NLE like Vegas has this) will have a
rate-convert function that maintains pitch. Scale your audio by
25/24ths (or, technically, 25/23.975 if this is from an NTSCfilm DVD
or other typical film-on-video source) and you're back in sync.

Dave Haynie | Chief Toady, Frog Pond Media Consulting
dhaynie@jersey.net| Take Back Freedom! Bush no more in 2004!
"Deathbed Vigil" now on DVD! See http://www.frogpondmedia.com
Anonymous
April 26, 2004 2:18:35 AM

Archived from groups: rec.video.desktop (More info?)

"Dave Haynie" <dhaynie@jersey.net> wrote in message
news:408bf6ec.2900841219@news.jersey.net...
> the audio for sync. Any decent audio editor (if not your NLE itself,
> though an audio friendly NLE like Vegas has this) will have a
> rate-convert function that maintains pitch. Scale your audio by
> 25/24ths (or, technically, 25/23.975 if this is from an NTSCfilm DVD
> or other typical film-on-video source) and you're back in sync.


Or you could use BeSweet from http://dspguru.doom9.net, which is made
specifically for that purpose. Download the latest Beta, not Stable,
version. I've tried a couple of low-end audio editors to rescale audio, and
they just weren't very precise--the audio track was always slightly longer
or shorter than the length of the rescaled video.
__
Alex
pcalex (at) hotpop.com
Anonymous
April 26, 2004 11:28:16 AM

Archived from groups: rec.video.desktop (More info?)

My understanding was that it was common practice to run
Hollywood (US, 24FPS) movies at the local standard of 25
FPS and just live with the slight pitch difference. Do they
now convert 24FPS film to 25FPS film? Or are we just taking
advantage of technical tricks when we import as video files?
!