Is there a plugin to help me export audio again but to re-render only the part that is changed without losing quality on part that i didnt touch at all. I want to change normalization at start and end of an audio where i put wrong normalization, i want to make those parts lower volume.
If the file you’re opening is lossless, set dither to “none” and the untouched audio won’t be changed.
If you are opening an MP3 or other lossy format, the whole thing will be de-compressed when you open it and re-compressed again when you export again and there will be some accumulated loss.
I have AAC files which are losely, is there some way to copy uncompressed part of audio and decompress only part that i want to normalize and compress it again so it can merge with existing uncompressed part that i didn’t touch or i must uncompress everything?
I don’t want to lose any quality on part that i didn’t touch, and on that part i was fixing gaps on audio that lasts 24 minutes, i did that for 14 audio files which took me so much, but i noticed that my start and end part is so increased in volume compared to rest of a file
You should be OK.
AAC is highly immune to multiple generations of compression. I don’t think it will be bit-identical but there should be no audible damage. Sometimes “you gotta’ do what you gotta’ do”.
AAC is much better than MP3. 100-pass re-compression test.
Or you can try mp3DirectCut which can do some limited editing of MP3 & AAC files without decompressing. … I have very limited experience with it and I’ve never tried it with AAC. It looks like you need a couple of additional downloads for AAC.
How can i select Nero Encoder?
I think you have to get and use it separately. You might have to export as WAV and then re-compress it.
But you shouldn’t need that particular encoder. From what I’ve read AAC was designed to minimize accumulated damage. And that test was for 100 passes. You’re only adding one more pass.
… It would be “best” if you had the uncompressed original but I think you’re worrying too much. 
If you play it on different speakers or different headphones that will make a bigger difference.