PAL to 24fps, best way to slow it down and fix audio pitch

[4ie2]

I know that handbrake is unable to do it. What methods are people using to convert sped up PAL releases of 24fps content? The semitone increase in pitch is irritating. I can play back in VLC at 96% speed but is there a simple way to convert a 25fps file back to 24fps?

[KarMa]

If it were me, I'd use assumefps(24) in avisynth at the very end of the script and encode the video that way. Then take the audio into Megui and use the option of audio time modification "slow down 25 to 24 with pitch correction".

[jagabo]

You can often set the video frame rate and audio playback rate in the container header. That avoids any re-encoding but not all players will respect those flags and the audio playback may maintain the pitch (depending on the player).

Otherwise, I would do the same as KarMa suggested.

[johnmeyer]

You can often set the video frame rate and audio playback rate in the container header. That avoids any re-encoding but not all players will respect those flags and the audio playback may maintain the pitch (depending on the player).

AVIFrate, if it is an AVI container.

[4ie2]

If it were me, I'd use assumefps(24) in avisynth at the very end of the script and encode the video that way. Then take the audio into Megui and use the option of audio time modification "slow down 25 to 24 with pitch correction".

Thanks everyone esp KarMa. I should add that I am using a mac. Is there another (cross platform) tool? I was thinking of using premiere pro, seems like overkill. Also wondering about 23.976 to 24fps-- are frames added/removed or its a simple speed adjustment just like 25>24?

[sneaker]

If it's done properly 23.976<>24 is just a speed adjustment as well. Personally, I'd target 23.976 as that seems to be more compatible than 24. The latter is usually only found on Blu-rays outside of North America (ignoring cinema) while the former is found around the world and seems to be preferred for streaming as well. The differences in tempo/pitch between 23.976 and 24 are too small to be noticed.

For mac software there are several options:
- ffmpeg (all-in-one or as tool in combination with others)
- combinations of ffmpeg + SoX + mkvtoolnix
- maybe even AviSynth using WINE (same for eac3to)

[4ie2]

If it's done properly 23.976<>24 is just a speed adjustment as well. Personally, I'd target 23.976 as that seems to be more compatible than 24. The latter is usually only found on Blu-rays outside of North America (ignoring cinema) while the former is found around the world and seems to be preferred for streaming as well. The differences in tempo/pitch between 23.976 and 24 are too small to be noticed.

For mac software there are several options:
- ffmpeg (all-in-one or as tool in combination with others)
- combinations of ffmpeg + SoX + mkvtoolnix
- maybe even AviSynth using WINE (same for eac3to)

is there an assumefps equivalent in ffmpeg?

[KarMa]

Thanks everyone esp KarMa. I should add that I am using a mac. Is there another (cross platform) tool? I was thinking of using premiere pro, seems like overkill. Also wondering about 23.976 to 24fps-- are frames added/removed or its a simple speed adjustment just like 25>24?

The reason there's NTSC FILM rates of 23.976, is because the source FILM is shot in 24fps but it's slowed down to 23.976 and so is the audio slightly. An extra frame is added after every 4th frame to get it up to 29.97fps, if it's to be broadcasted or put on a disc with telecine.

Maybe decades past I would say go with 23.976 if you are in a NTSC county, but anymore stuff can play original 24fps pretty well and there is no point to using the weird fraction NTSC frame rate if you don't have to.

is there an assumefps equivalent in ffmpeg?

Probably but I don't know ffmpeg very well so maybe someone can point to it.

[4ie2]

Thanks everyone esp KarMa. I should add that I am using a mac. Is there another (cross platform) tool? I was thinking of using premiere pro, seems like overkill. Also wondering about 23.976 to 24fps-- are frames added/removed or its a simple speed adjustment just like 25>24?

The reason there's NTSC FILM rates of 23.976, is because the source FILM is shot in 24fps but it's slowed down to 23.976 and so is the audio slightly. An extra frame is added after every 4th frame to get it up to 29.97fps, if it's to be broadcasted or put on a disc with telecine.

Maybe decades past I would say go with 23.976 if you are in a NTSC county, but anymore stuff can play original 24fps pretty well and there is no point to using the weird fraction NTSC frame rate if you don't have to.

is there an assumefps equivalent in ffmpeg?

Probably but I don't know ffmpeg very well so maybe someone can point to it.

What does handbrake do to the video to convert from 23.976 to 24? Just a speed up or is it adding/dropping frames? I ask because I tried to convert a PAL source to 24fps and handbrake did that by dropping every 25th frame, which is obviously not the right way to do it. Why does it even offer an framerate conversion when it does it incorrectly.

[jagabo]

To convert from 23.976 fps to 24 fps Handbrake will add one frame every 1000 frames.

[sneaker]

....

[hello_hello]

If it were me, I'd use assumefps(24) in avisynth at the very end of the script and encode the video that way. Then take the audio into Megui and use the option of audio time modification "slow down 25 to 24 with pitch correction".

For the MeGUI part I'd use it to change the audio speed, but without pitch correction. "With pitch correction" keeps the audio pitch unaltered, but as 4ie2 discovered, most "film" audio isn't pitch corrected when it's sped up for PAL, so you want to apply an equal lack of pitch correction when slowing it down again.

[thickglass]

ffmpeg is the best choise to go, you can extract audio and downgrade pitch in FL studio and megre it to video back