Compression ratios impact image quality. Lower compression ratios produce smaller file sizes, but also lower image quality. The compression ratios vary depending on the compression program you use.
The key frame rate impacts image quality if you make changes in the graphics area quickly. The rate is how often an exact copy of the screen display is saved. Each frame includes only what has changed since the last key frame. If you have excess variation between frames, lower the key rate.
To set video compression: