Most camera source files are highly compressed. Camera compression varies depending on spatial resolution and frame rate, but in general is about 30:1 and some formats are compressed even more at about 80:1!
To get to such high compression, many computationally complex algorithms are used. When these highly compressed files are used as the source for editing, a couple things result: 1) poor editing performance, and 2) lower quality when rendering.
The GoPro CineForm codec was designed to provide very high performance, and very high visual fidelity. Part of the technique we employ is to allow the sizes of the files to grow compared to the source. This creates lots of “headroom” for manipulating your source material in post. It is this extremely high fidelity that has allowed the GoPro CineForm codec to be used by major feature film post production facilities and studios.
So how large will your Cineform files be? Generally about 5X to 8X the size of your original mp4 files.The GoPro CineForm files are about 10% the size of what the file would be if it was un-compressed.
More about this can be learned in the “Why Convert to the GoPro CineForm Format?” section in the GoPro Studio User Manual.