Calculating the Bandwidth Need

Xsan throughput lets you work well within the bandwidth requirements for most common video formats.

This table shows examples of the average bandwidth used for various video formats. They will vary slightly depending on which card or device is used for capture. Also bear in mind that these numbers reflect a perstream value.

Bandwidth Requirements

Standard Definition	Bandwidth per Stream
MiniDV, DVCAM, DVCPRO	3.6 MB/s
DVCPRO 50	7.1 MB/s
Uncompressed SD (8-bit) 30/25 fps	20 MB/s
Uncompressed SD (10-bit) 30/25 fps	27 MB/s
Compressed High Definition
HDV	3.6 MB/s
DVCPRO HD	5.7 MB/s to 14 MB/s
Uncompressed High Definition
720p 24fps (8-bit)	42 MB/s
720p 24fps (10-bit)	56 MB/s
720p 60fps (8-bit)	104 MB/s
1080p 24fps (8-bit)	93 MB/s
1080i 30fps (8-bit)	116 MB/s
1080p 24fps (10-bit)	124 MB/s
1080i 30fps (10-bit)	155 MB/s

Bandwidth need is based upon the following:

1. The number of clients you will have on the SAN

2. The highest level of video, film, or audio formats your facility uses

3. The maximum number of real-time streams you require to work on recurring projects

To calculate bandwidth need, simply multiply these three considerations. This yields a value, in megabytes per second (MB/s) that determines the theoretical maximum need at any given moment.

Two examples will illustrate the calculation:

• A 10-seat SAN for a news facility works entirely with package editing using the DV25 format. Each editor uses primarily an A/B roll technique, as well as multiple images onscreen simultaneously, and therefore needs up to three streams of real-time availability.

  So this SAN's bandwidth need is
  10 clients x 3 streams x 3.6 MB/s= 108 MB/s

  
  

• A three-seat boutique post facility SAN uses SD most days, but is flirting with doing high-end 720p 24-frame-based work in 10-bit uncompressed as well. We'll give them a luxurious three streams of real time in this format, provided that they have the top-of-the-line G5s to do it.

  So this SAN's bandwidth need is
  3 clients x 3 streams x 56 MB/s= 504 MB/s