Muxing 60s audio with a 66s video

[kurbads74]

I stumbled on a strange problem. I have a cuddly 66s cat video where there is a laud Whatsapp ble ble ble ble ble after the 60s.

I made two videos with Handbreak. One 66s long and one 60s long.

Now when I mux the 66s video with 60s audio in MKVTOolNix, it makes it 60s.

I use ancient version 8.8 on El Capitan.

Where do I uncheck the "truncate to the shortest track" option or how do I fill the last 6 seconds of a 66 second audio with a silence or just lower its volume? Which actually gave me an idea, I will use CoolEditPro for that.

[videoAI]

video2video [v2v], clever FFmpeg-GUI, or losslesscut can do it

[kurbads74]

Thanks for reply. I downloaded Audacity 2.1.1 and ffmpeg 4.1.4 and used QuickTime to export m4a and after editing and saving it as wav in audacity, compressed it with ffmpeg but the sound is metallic as if converted from 48kHz to 44kHz or vice versa. Anyway, I will give it a rest now. That is a cat's video I uploaded to nextdoor.