I believe they're using "bpp" (bits per pixel) to indicate compression efficiency, and in the section about quality they're holding it constant at 0.06 bpp. Th

I believe they're using "bpp" (bits per pixel) to indicate compression efficiency, and in the section about quality they're holding it constant at 0.06 bpp. The charts a bit further down give quality metrics as a function of compression level (however, they seem to indicate that h.264 is outperforming h.265 in their tests which would be surprising to me).