OK I have about 30 m4a files @~380 Meg.
These are essentially like MP3 files with an embedded picture / file cover / art work.
What I want to do ideally is to join the files sequentially in Auda City*, and then convert them to Mp4 - as a audio book type of video - with a single static image, and a narration, and to make a similar file size in mp4.
The book I am creating has some 26 hours of narration.
So I really want a passable low quality audio and a simple fixed image.
The simple technical description, is a hypothetical single frame video that lasts for the entireity of the video, and an attached audio track.
How do I use Handbrake to make an M4A file, possibly with a tagged image, to create an MP4 video file that is as small as possible - say comparing 380 meg initial file, into a 360 - 420 meg final file, instead of a 2.3 - 6.5 Gig video file.
* (the How Too) Auducity - Tracks - Align Tracks - Align End to End. Export as M4A - lowest rate.