How to efficiently create a video from an mp3 and a single jpeg using ffmpeg?

Question

I have a 329MB MP3 file and a 200K JPEG image, which I'd like to combine into an MP4 file which simply plays the MP3 with the image in the background.

The way I go about it today is by using FFMPEG with the following command:

ffmpeg -loop 1 -i "$image" -i "$audio" -c:a copy -c:v libx264 -shortest output.mp4

This, however, generates a 818MB MP4 file - Taking a long time to encode, network bandwidth to upload later on, etc.

What's a more efficient way of creating the file, so the output is also of a smaller size? Surely there must be a way to get a video file which doesn't need to inflate the overall size by that much?

Answer 1

The best I could find was adding the -r 1 parameter, to indicate a lower frame rate. This helped quite a bit, though the output file size is still larger than I'd have expected it to be.