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  1. I am trying to sync a 25fps audio source from one foreign Blu-Ray to a 24fps video source on another Blu-Ray.

    I do not wish to simply slow down the playback speed because that will alter the voice pitches.

    I have converted 25fps higher pitch audio to 23.976fps before, by slowing it down in audacity, and changing the speed by -4.096%. That -4.096% is specifically for 25fps to 23.976fps though, and when the audio pitch is already slightly higher from being sped up to 25 fps to begin with.
    This is 25 fps with correct voice pitches that are not slightly higher from being sped up, so slowing down would not correct the audio pitch like before, and would lower it in this case.

    Is there a way to slow it down to 24fps playback speed, and keep the same voice pitches?
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  2. This can be done with clever FFmpeg-GUI, Audio conversion section.
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  3. Audacity has the ability to change length without changing pitch.
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  4. Originally Posted by jagabo View Post
    Audacity has the ability to change length without changing pitch.
    Where would that be in Audacity? I see a change speed or change pitch, but not change length with pitch correction or original pitch.

    Is there also an avisynth alternative I could try?
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  5. Originally Posted by ProWo View Post
    This can be done with clever FFmpeg-GUI, Audio conversion section.
    I tried it and it didn't work right. It made the audio over 8 hours long. It was super slow, and super low pitched.


    EDIT: It works fine when I select change length only, but as soon as I select change length and pitch, it comes out as an 8 hour long audio file that sounds awful.

    EDIT 2: I used an older version instead of the newest and it works fine now. Apparently they broke it in the newest release.
    Last edited by killerteengohan; 13th Apr 2021 at 10:33.
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  6. I'm a Super Moderator johns0's Avatar
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    In audacity choose change tempo to change length but keep pitch the same.
    I think,therefore i am a hamster.
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  7. Originally Posted by johns0 View Post
    In audacity choose change tempo to change length but keep pitch the same.
    I don't see anything about changefps in change tempo settings, but I do see percent change like I used before. I know the percentage to use for 25 to 23.976fps (-4.096), but I don't know what % to use for 25 to 24fps.

    EDIT: I found a math equation to calculate it. If I am correct, would I use -4.0% in this case?
    Last edited by killerteengohan; 13th Apr 2021 at 11:01.
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  8. I'm a Super Moderator johns0's Avatar
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    -4.167 %.
    I think,therefore i am a hamster.
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  9. I'm a Super Moderator johns0's Avatar
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    -4 is right,i used the reverse 24 to 25fps.
    I think,therefore i am a hamster.
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  10. Thanks guys, I will give it a try and see how it works out.
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  11. Originally Posted by killerteengohan View Post
    Originally Posted by ProWo View Post
    This can be done with clever FFmpeg-GUI, Audio conversion section.
    I tried it and it didn't work right. It made the audio over 8 hours long. It was super slow, and super low pitched.
    Corrected in the newest beta.
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  12. The change tempo did indeed appear to work perfectly. I have not noticed any playback issues yet in the many parts I have listened to. It seems to have came out free from any slight distortions, or small audio glitches as its playing back.

    I thought I was going to have to slow it first by a specific %, then change the pitch afterwards with specific % numbers, but change tempo did both for me with less audio editing. I was not aware tempo was both until now. Thanks for pointing that out.
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