I started from a video of 3,5MB (mp4) and a 23MB (mp4). Just join them toghether and put some music (5MB mp3). The results is a huge file of 250MB for an 1’30" video!
I use “youtube” export preset. How can I manage it?
Not enough information for anyone to help you…
You are right! I noticed that decreasing the quality % that is 60% default to 40% the size pass from 250MB to 18MB.
As soon as possible I will write all the parameters
Obviously that would get the job done, but doesn’t it look awful? What I’d like to know is how to reduce the file size, but keep the quality.
You can’t.
Somehow Google achieve it via their automated processing. If you upload a massive video to YouTube then download it, you’ll find that the file size is far smaller, yet the quality is retained.
There’s always going to be some loss whether you can notice it or not. But it depends how much compression was applied to the original footage [before it was unpacked, edited and re packed into another container] as to how much additional compression can be applied before you DO notice it.
There are lossless codecs you can choose so as not to lose IQ, but they won’t change the data size because well, they don’t throw anything away because they are lossless…
Increase the GOP size in Export settings, and you will get much smaller size for nearly the exact same quality. Why is it not longer by default? Because it is the YouTube preset, which is following YouTube’s encoding recommendations (half second GOP). Try 150 frames for GOP, for example.
Interesting, I’ll give that a shot next time, thanks.
I’m OK with any quality loss that goes on behind the scenes as long as the average human ear/eye can’t detect it. It’s all about the viewer’s experience for me.
That’s assuming the end viewer knows what the original un-edited footage looks & sounds like. Otherwise they’d be non-the wiser.
True. I was really thinking in terms of stuff like stray artifacting and crackling audio that grabs you by the neck shouting “I shouldn’t be here”. That makes me cry. 
You’d have to work hard at making good footage that bad 
All of the presets should output decent results from good footage.
I think that is the answer to why so big a file. You exported to a file that was ready to be uploaded to google. this is what google wants you to upload. Recommended upload encoding settings