All of the H.264 presets are resulting in huge file sizes. I've been asked to reduce the file size of some videos, because they're stored on a server and are cumbersome. I am trying to use Adobe Media Encoder to compress all of them simultaneously. They're webinars, so they're only slides and audio. The video that I'm focusing on for an example is almost 5000MB even on the low bitrate preset. I need to get that down to under 400MB. What am I missing? Why the insane file size?
If I see it correctly you are trying to compress 2,5h video to 400mb file size. I guess without changing resolution any of presets will give you that. Yopu have to chose any preset with your native resolution and then play with some drasticly lover bitrate. There s no other way.
Well, check this out. This is the same type of video (just slides and audio) from the same source. It's only 1.5 hours, but it's only 200 MB on the medium bitrate. So I shouldn't be getting something as high as 5000 MB.
The first image you uploaded has a 4.2Mbps target bitrate and the second has a 0.2Mbps target bitrate.
That's 21x the file size per second right there! Reduce your target bitrate to reduce the file size. If you want to maintain quality and there's no video (only sides) then you could reduce the frame rate on the output and you'll end up with fewer but higher quality frames at a comparable bitrate.
That exactly what we see on those screens. First is as you said with 4,2mbps and second with o,2mbps. Also on first screen we have 24fps and on second 7,5fps - so more than 3 times less to compress.
lower bitrate + lower fps = smaller file size