Chapter 9 CONFORMING AND FINISHING 219 compression ratio is approximately 5.7:1 for 1080i and 2.5:1 for 720p. DNxHD 220: 8-bit 4:2:2 Y C B C R full-raster (1920 1080 or 1280 720) 220 Mb/sec compressed media. The compres- sion ratio is approximately 4.5:1 for 1080i and 2.0:1 for 720p. DNxHD 145: 8-bit 4:2:2 Y C B C R full-raster (1920 1080 or 1280 720) 145 Mb/sec compressed media. The compres- sion ratio is approximately 6.8:1 for 1080i and 3.1:1 for 720p. Audio Format Options When conforming an online, 99 percent of the time you should work with 48-kHz audio samples using 24 bits per sample. The other 1 percent of the time you typically work at 48-kHz audio using 16 bits per sample. Why? Simply because digital decks all run at 48 kHz natively using either 16, 20, or 24 bits per sample. Working at 48 kHz means you can output baseband to an HD or SD deck via SDI (serial digital interface). Mastering at 44 kHz just isn't done anymore. With that choice made, the only other audio mastering deci-