FCP .mp4 Compression question

[choreo]

I have an mp4 video I received from a client. It is 1hr 15min in length and is 1920x1080 at 30p with a file size of 474mb and looks great.

I imported it into FCP, just added a static overlay to the entire video (all frames - like a watermark) and did an export (same length and pixel dimensions as the original), but the file size came out 2.75GB! I tried using Compressor and it only got down to about 2.5GB. I went ahead and purchased Faasoft Video Converter and could only get it down to 3.2GB?

What am I missing, How is the original file a better quality than what my files are, yet ALL my compressed files are several times the file size as the original?

 

[Ritsuka]

Every time you recompress an already compressed file to the same video format you will lose either some quality, or you will need an higher bitrate.

But that's not the issue here. The issue is that Final Cut uses an average bitrate that can't be changed.
A solution is to use Compressor and set a lower average bitrate. Or use HandBrake and set a quality level or an average bitrate, until you get a file that's small enough and look good enough.
HandBrake will get you a better quality at the same file size than Compressor.

 

[lostless]

You added static. Needs more bit rate to retain quality. Think of it like this, when you import a video into an editor, regardless of its format, it acts as if its uncompressed in the editor. When you recompress, it takes that uncompressed source and and tries to retain quality, but also throw out as much as possible by seeing what it can use and pull from other frames. If you add static (noise), it really cant use much from other frames, as each frame is full of random noise and needs a higher bit rate to retain the randomness of the static.

 

[Boomhowler]

I think the thread starter ment static as in "not moving", and not as "noise".

There are many variables that will decide the "necessary" bitrate when encoding a video. Did the original video use yuv420p pixel format perhaps and the final cut has 422 or even 444? What about resolution, did it change?