What is the best format to save a long lecture that is images from a presentation plus speaker audio?

Question

Video

That is, in fact, these are static images that occasionally replace each other, and a sound track. Conditionally 100 slides + sound for 2 hours.
Focus on small size. And it is desirable that it is not too difficult to run and view on any device.

Answer 1

Use an MP4 container, H.264 codec, but do not specify a bitrate for compression, but use CRF. Something around 25-30 should be enough. The higher the number, the worse the quality, but the smaller the size.

This command encodes a video with good quality, using slower preset to achieve better compression:
ffmpeg -i input.avi -c:v libx264 -preset slow -crf 22 -c:a copy output.mkv

https://trac.ffmpeg.org/wiki/Encode/H.264
This can be done either through ffmpeg or through any of its GUIs, such as Handbrake .
Additionally, the file can be compressed more strongly if you reduce its FPS. Since this is a slideshow, 1 FPS should be enough for the eyes if the images are static.
With a finished video after ffmpeg, this can be done, for example, using mp4box :
What kind of lecture do you have? Already finished video file?

Answer 2

In my opinion, MPEG4 (H264) compresses static video well. If earlier cameras wrote to disk using motion detection to save space, now you can write continuously and this will not greatly increase the file size. The video format is good in that there frames are always tied to video tracks (time synchronization).