How to change 23.976 fps to 24fps?

[Harper66]

Hi, I'm new here.
I need some advice, through mkv cleaver I pulled audio (AC3 5.1) from a bluray file where the video has 23.976 fps. I need to put the audio into a 4K bluray video that has 24,000 fps.

Since I have no experience with changing fps, can someone describe me step by step how to change fps in eac3to from 23.976 to 24 fps? I have eac3to version 3.36.

Thank you for your advice.

[hello_hello]

If it was me I'd change the 24fps Bluray frame rate to 23.976 (unless there's a reason not to). That way you can add the 23.976 audio as is, because changing it to match the 24fps video means it has to be re-encoded, whereas the video doesn't require re-encoding to change it's frame rate.

I'm hopeless with command lines but for the record, this is a command line similar to the one MeGUI's HD Streams Extractor used for extracting the audio from an MKV and changing it's speed.

"C:\MeGUI\tools\eac3to\eac3to.exe" "E:\video.mkv" 2:"D:\video_T2_Audio - English.ac3" -changeTo24.000 -progressnumbers

I'd be changing the video frame rate instead, but I don't seem to have a 24fps MKV handy as an example. It'd be something like the command line below though. The arguments are either -slowdown or -speedup for changing the video speed, or -changeTo24.000 for adjusting the audio. https://forum.doom9.org/showthread.php?t=125966

"C:\MeGUI\tools\eac3to\eac3to.exe" "E:\video.mkv" 1:"D:\video_T1_Video - English.mkv" -slowdown -progressnumbers

MeGUI's HD Streams Extractor with the arguments added to show you what it'd look like.


[Attachment 69987 - Click to enlarge]

[johns0]

The audio might match if it the 24 fps video was already adjusted for the time or if the blu-ray version is slight different then it will take more that an adjustment to get the files to sync.

[ProWo]

Use clever FFmpeg-GUI.
Load your AC3 5.1 file, click main, click encode audiostream, click go to the encoder, set the change length & pitch section like in the picture, click encode.
Done.


[Attachment 69990 - Click to enlarge]

[Harper66]

I have a 4K BD remux, so I need to first convert the audio from 23.976 to 24fps and then trim 10 seconds at the beginning. But now to sort out the fps first.

[Harper66]

Use clever FFmpeg-GUI.
Load your AC3 5.1 file, click main, click encode audiostream, click go to the encoder, set the change length & pitch section like in the picture, click encode.
Done.


[Attachment 69990 - Click to enlarge]

Thanks for the instructions, I'll give it a try. How can I verify that the fps has really changed?

[johns0]

You can't verify fps with audio,just the time difference.

[Harper66]

I downloaded FFmpeg-GUI 3.0.9 but does it need any more extensions? Where do I download the rest to make the program work? A message pops up about some FFprobe and FFplay. Does it somehow install in the same folder? https://www.videohelp.com/software/clever-FFmpeg-GUI

[johns0]

Look in the readme.txt file thats in the zip file you downloaded.

[Harper66]

I downloaded ffmpeg-master-latest-win64-gpl-shared and copied the folder to the clever_ffmpeg_gui_309 folder.
After running ffmpeg, I selected the bin folder and another folder where the work will be saved. Is this rigt?

[johns0]

See if works.

[Harper66]

Looks like it works, including the fps change procedure from user ProWo! Thank you so much! But is there any method where I can verify that the fps has changed?

[ProWo]

Looks like it works, including the fps change procedure from user ProWo! Thank you so much! But is there any method where I can verify that the fps has changed?

You can check the stream duration. It should be shorter than the original ac3.

[Harper66]

Ok thanks

[Harper66]

Now that I've changed the fps, I need to trim about 10 seconds of the beginning of the audio from the 5.1 audio to avoid any loss of quality. Can you advise me in which program to do this? Do you use maybe Audacity or another program altogether?

[Harper66]

I tried to trim the beginning of the audio according to this video in Audacity https://www.youtube.com/watch?v=cQRABLLrhyo&t=27s&ab_channel=MikeRussell but if I use the selection tool to delete 10 seconds after the audio is played, that part of the audio is still there and it also shortens the length of the audio recording.

Would anyone know how to do this?

Please help me.

[davexnet]

In Audacity, select the audio you want to keep -
file/export/export selected audio

[Harper66]

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