@Andrei22 I want to revive your questions with a “me too”. I hope you have gained some experience, since you posted your question.
At the moment, my wife is preparing a series of traditional African stories. She puts the audio recordings with a still photo of the speaker.
The audio files are about 8 minutes each, so the video will be just over 8 minutes with a non-moving logo at the start and a credits-page at the end. From an 12mb audio, she is getting crazy 250mb video for YouTube (with our normal YouTube configuration).
Now with all the modern compression algorithms, I would have expected the machine to realize “that it is always the same image”. So why are there some 240mb of “just one photo”?
We hope that there is a setting (frame rate, GOP, whatever) which will keep the audio in full quality and give us minimum file size, while still creating a video which YouTube will accept as valid.
This is a hack in a sense. We do not really have “video” of course. Please do not laugh: I even searched whether we can upload “audio-only” to YouTube. We can, but it will not be listed with our other stuff, it will be offered as “raw” material to other users. So we need to render a valid video file.
We can do our own tests, but our internet (here in Africa) is extremely slow. We know the recommendations of YouTube, but we do not know for example what the lowest video-frame-rate is that will be accepted. So all input is helpful. Thanks.
I also invite @Rock_Heart to share what he or she found out since, because the questions seem related: