Advice to reencode audio (25fps to 23.976fps)

[BKloud]

Hello,

I'm trying to match an audio from a PAL video in 25fps to another video with a framerate of 24/1.001, I used eac3to with the command line "slowdown" and it works pretty well.

The audio format of the first tracks are AC3 192kbps for stereo and 448kbps for 5.1 (I have 2 tracks).
The problem is I will lose quality if I reencode, I would like to limit this loss.
I converted first to flac to add and remove silence between scenes (mostly black transitions) to match the image of the video and after I will reencode to AC3 for compatibility.

As the files are already lossy, can I use the same bitrate to reencode ? Or I have to choose a little above like 320kbps for stereo and 640kbps for 5.1 or maybe another format than AC3. I know that flac is lossless but I would like to keep compatibility with common devices.
The track is mostly talks, no much music.

I used those commands for the stereo track :

eac3to input.ac3 output.flac -slowdown

and after add/remove silences

eac3to input.flac output.ac3 -192

[ProWo]

You could also use clever FFmpeg-GUI for this task.
It can not only slowdown or speedup any audiotrack, but also adjust the pitch.


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