On Fri, 23 Jun 2017, Hans Wilmers wrote:
Maybe kdenlive or openshot?
You can add audio to existing video+audio, pretty easy to do.
These GUI driven programs promise easy usage, but I guess it is a
disadvantage that they usually unpack the original video stream and repack
it again with additional compression artifacts. If the speech audio stream
is ready then you can use ffmpeg with the option "-vcodec copy" such that
the video stream is copied without modification and only the audio tracks
are mixed and re-encoded.