I hope that the previous part in this series titled “The data-centric pipeline” was helpful. I am going to build on it now in discussing how we can calculate the uncompressed data rate of media at various resolutions and color bit depths.I have to warn you that this takes some basic math skills. The required data rate for a particular video format (in a uncompressed state) can be easily calculated as long as we know its resolution, color depth (regardless of whether it is log or linear) and frame rate.Let’s take a look at 1920 x 1080 HD in 10 bit 4:4:4 RGB. We start by calculating the file size of a single frame.We multiply the horizontal resolution in pixels by the vertical resolution in pixels, for 1,920 x 1,080 this is a total of 2,073,600 pixels. However, we are storing colour information separately for Red, Green and Blue channels, at 10 bits per channel. So, we can multiply 2,073,600 x 10 bits to give us a total number of binary bits for one channel, this comes to 20,736,000 bits, which we can then multiply by 3 for the three channels to give us 62,208,000 bits per 10-bit RGB frame.To convert this into more understandable units, we can divide this by eight to give us a value in bytes (1 byte = 8 bits), this comes to 7,776,000 bytes. We can further divide this by 1024 to give us a value in KB (1KB = 1024 bytes), and this results in 7,593.75KB. We divide one more time by 1024 to give us the value in MB (1MB = 1024KB), which comes to 7.41MB per frame.By multiplying this by the frame rate (lets say its 24p) we arrive at a per second data rate of 177.97MB/sec for uncompressed 1920x1080 10-bit 4:4:4 RGB video.Here is a breakdown of data rates for SD, HD, 2K and 4K at 8-bit, 10-bit, 12-bit and 16-bit RGB colour depths.Format8-bit 10-bit 12-bit 16-bit SD PAL 720 x 576 29.66MB/s37.07MB/s44.49MB/s59.32MB/sSD NTSC 720 x 486 30.00MB/s37.50MB/s45.00MB/s60.00MB/sHD 1280 x 72063.28MB/s79.10MB/s94.92MB/s126.56MB/sHD 1920 x 1080142.28MB/s177.97MB/s213.57MB/s284.76MB/s2K 2048 x 1536216.00MB/s270.00MB/s324.00MB/s432.00MB/s4K 4096 x 3112 875.25MB/s1094.06MB/s1312.87MB/s1750.50MB/sDetermining demand:For the sake of this article we’ll assume we are working in 12-bit color at 24p in all resolutions. In many scenarios we may want to play more than one stream of video concurrently, this could be due to two separate DI suites working at the same time, or we could be compositing multiple layers of uncompressed media in real-time on one DI suite.If offline media is also stored on the same drive array, there may be one or more offline edit suites pulling compressed SD or HD media at the same time as an uncompressed 2K grade is taking place. There may also be extra read or write demand at any time from an Animation or VFX department.We are limited in such scenarios by the maximum data throughput we can demand from the drive array, and the bandwidth of our networking. Determining this demand at a systems design level, and managing it on a day to day operational level are extremely important to the efficient operation of any post facility choosing to implement a SAN configuration.In part 3 we will look at an example facility and determine the likely day to day demand on its storage area network. We will also look at supplementing central high bandwidth storage with local storage on an individual workstation level, and managing the movement of data from local storage to central storage when system demand is low.