Edit: it's 0.0330s delay, not half a second sorry. ALso the problem occurs when converting the wav to .m4a in ffmpeg using the basic ffmpeg -i input.wav output.m4a, and I used the newest release of ffmpeg for that.
I had a large number of audio pieces as .wav s16's and I mixed those down into a single .wav f32 track. I then wanted to export this track to an aac with highest bitrate (320 seems to be highest audacity allows) in order to place it in an .mp4 container (is this the highest quality codec I can convert to and fit in a mp4? I want the highest audio quality I can get).
When I follow the instructions and export it creates a sync delay by about half a second or so...enough to give a noticable echo when they are played in tandem. I corrected it manually in audacity with my eyes. But when I export....it puts it out of sync once more, and I'd also rather avoid the loss generated by exporting an aac as an aac.
Is there a fix I can do using audacity (using newest version 2.3.0) or some other freeware program? I have ffmpeg command prompt, and handbrake, if there's a command that can manually trim the audio or assign the right alignment.
I notice audacity uses ffmpeg 2.2.2 version, and ffmpeg has many newer versions since then...could using those newer versions fix the issue maybe? Under preferences library it says:
ffmpeg library version: F(55.33.100),C(55.52.102),U(52.66.100)
And how would I make audacity use the newer versions? I don't really understand if it just calls up ffmpeg or if it needs to be this 2.2.2 version because they designed it to allow and work with that version specifically.
You can see how I exported the original .wav file in the picture below: