Quote Originally Posted by Buffalobiian View Post
According to this site, youtube will only play back 128kbps aac regardless of video quality, so there's that as your quality cap. The audio files that Windows Movie Maker accepts is a bit limited, but there's always wav, so you can give it a lossless source if you're worried about transcoding too many times. It'll still have to happen twice by the time youtube's done with it.
According to Google you can use quite a bit better audio than that in a 1080p video. That 128kbps is for mono audio!

It would seem to me one should convert the original lossless audio to the intended aac (384 kbps) directly. That way Youtube wouldn't need to transcode it for a second time, with ruinous consequences. Youtube accepts mp4, surprise surprise, so I don't think it ought to be too difficult to put it together. That being said, I have never made a video I'd consider uploading to Youtube, so my expertise is purely of the armchair variety.