IPX: Video bandwidth calculation

When configuring an IPX system with more than one network switch, bandwidth calculations must be performed to ensure that your uplinks do not get saturated. For example, if you have two switches with a 40Gb uplink between them, then you will only be able to send/receive up to 40Gbps of video bandwidth to/from each switch. To calculate approximate maximum network bandwidth for given video resolution, the following formulas can be used:

LineFq (KHz) = Ver_res_total * fps
Network BW (Gbps) = Hor_res * Ebpp * LineFq * 1.05 / 1,000,000

• LineFq: Video line Frequency in Khz
• Ver_res_total: Total number of lines including vertical blanking
• Hor_Res: Horizontal pixel resolutions
• Ebpp: Effective bits per pixel. For example, RGB 8 bit has 24 effective bits per pixel. Meanwhile YUV 420 8 bit has 12 effective bits per pixel while YUV 422 8 bit has 16 effective bits per pixel. Similarly, RGB or YUV 444 10 bit has 30 effective bits per pixel while YUV 420 10 bits has 15 effective bits/pixel while YUV 422 has 20 effective bits/pixel.
• 1.05: Scaling factor to take into account approximate network overhead based on packet overhead, packet payload size, packet preamble and minimum inter packet gap.
• 1,000,000: Scaling factor to bring network Bandwidth to Gbps unit
  

Let’s use this formula now to calculate Network bandwidth for 2 different resolutions

Resolution 1920x1080 60Hz RGB 8 bit LineFq = 1125 lines * 60 Hz / 1000 = 67.5 NetBW = 1920 * 24 * 67.5 * 1.05 = 3.27 Gbps

Resolution 3840x2160 30Hz YUV 8 bit LineFq = 2250 lines * 30 Hz / 1000 = 67.5 NetBW = 3840 * 24 * 67.5 * 1.05 = 6.53 Gbps

The table below shows approximate maximum network bandwidth for few select resolutions. Resolutions that require network bandwidth over 10Gbps will be automatically compressed at a 1.3:1 ratio to keep the bandwidth at or under 10Gbps. To calculate approximate maximum network bandwidth for other resolutions, use the formulas above.

Originally posted 2/12/2021