I think I went through MainConcept AVC/AAC, which gave me an .mp4 file in the end.

I realized I made a mistake when I asked my question, I also did a render where the settings are very high and THAT is what gave me the huge file size. It looks good, but the bitrate is 3089kbps, total bitrate is 4626kbps.

The other file with setting data rate 187kbps is smaller, but looks really bad. I didn't render the whole thing, only 7 minutes of it to experiment.

I don't know what you mean by get the original bitrate higher, the video has already been recorded and I can't redo it.

Also, I did find a solution to my problem. I re-encoded the giant output video using Prism by NCH Software and it shrank down to 133 MB from 2.36 GB and also looks excellent. It used AAC and I got an mp4 as output. But it seems strange that this should be a 2-step process with a different program.

I meant, do you screen cap settings allow you to record your original file at a higher bitrate? 150Kbps quality is not something i would know how to improve.

Maybe you have to use a good program for making screencapture?
Look here: https://www.vegascreativesoftware.info/us/forum/faq-what-obs-studio-settings-work-well-with-vegas-pro--109925/

I have to use Zoom to record meetings for schoolwork, and then I edit the meeting videos and share them with the other students. There is an option in Zoom for `optimize for 3rd party video editor' which I think might let me get better bitrate (I'll have to try it to see how it does).

So the point is, using Vegas, the re-encoding will always be lossy so even if my original video looked great at 150kbps, it will not look good at the same output bitrate? I am required to use a bitrate 20x higher to get basically the same video quality out?

I cannot check yours.
View quality depends mostly as for the video quality on bitrate combined with the used codec.

So the point is, using Vegas, the re-encoding will always be lossy so even if my original video looked great at 150Mbps, it will not look good at the same output bitrate.

That is correct. You can also encode to a lossless codec, that is not deliverable.

If you will post your file properties, I think you will find it is 150 Kbps. It does not look great, I can promise.

I am required to use a bitrate 20x higher to get basically the same video quality out?

Of course not. That's silly. You can encode at double bitrate, which will get you closer. All lossy encoding involves losses, clear enough?

But please do not divert from the actual problem.

Until you figure out how to record at a sane bitrate, (a sane bitrate for me would be 1500 - 2500 Kbps), there is no more I can suggest. Maybe a decent screen cap app like OBS. Good luck.

I just recorded a few minutes using Zoom with my PC's internal webcam, MediaInfo states, the bitrate as around 400 kbps, which would explain poor quality to begin with. Increasing the render bitrate would certainly not make it better.

+1

Rereading your posts, I am thoroughly confused. Are you using webcam or screen cap? Be specific.

Sorry, let me try to explain again.

My original video was 150kbps. It consists mostly of slides (which I did as a screencap), just black text on white background. Any movement only happens when the slides are changing. For my purposes, this looks very nice. There's no animation so there's not much information to save, right?

I liked how it looked. I edited in Vegas.

Experiment 1: output at approximately the same levels, looks very bad. The black text gets splotchy gray blocks over it. It's weird to me, because this is a still image. Text becomes unreadable.

Experiment 2: output at really high levels, looks the same as original. However the file goes from 136MB to 2.36GB.

Finally, I took the big output file and re-encoded it using Prism. It shrank it down to 123 kbps, and gives me a file that looks exactly how I wanted, i.e. looks approximately the same as the original.

As 3Point says, it seems that this is not possible in Vegas, as there is no smart rendering. I'm required to use a higher bitrate (maybe 2x rather than 20x) to get a video that looks the same, as the encoding is lossy.

If you don't mind me asking: why did you choose to record at 150 kbps? Why go that low?

Thanks.

It's the automatic output of Zoom, which does not seem to have many options for changing the quality. The original video looked nice so I never thought to try to raise it until now, also.

I've been doing screen captures including zoom sessions but I don't do it via zoom. Or Vegas. I do it off my AMD video card using its Relive facility. Works really well with remarkably low load. Quality is very good too, especially if the video card is talking to a 4k display. I understand Nvidia has a similar capability.