I've got to edit a voice recording (removing breath, click, ahhhs, …), but since the track is part of a video, I can't just cut the unwanted parts out, otherwise the lipsyncing would be corrupted. So how can I just select the unwanted parts and overwrite them by a sample of the backround noise? I tried already like this: I copied a long sample of silence, selected my unwanted part and inserted the silence from clipboard — problem here is, that the inserted silence is longer than the selection and therefore extends the total track length which breaks lipsync.
Why not use the correct length of silence. How will using background noise fix the length problem?
Silence will not be noticeable if you have a good S/N ratio. Background noise might be noticeable depending on how it matches and S/Ns.