Lesson 13: Performance and reliability

Lesson 13 of 14

A live production has no second take. This lesson is about reliability: the computer to use, the habits that keep ZoomISO smooth, the bandwidth limits that catch people out, and a built-in window for watching your performance in real time.

What the computer needs

ZoomISO runs on macOS 14, 15, or 26, on Apple Silicon Macs, meaning an M1 chip or later. How hard your Mac has to work depends mostly on how many outputs you create and which methods and formats you use. Testing has shown strong performance even on the original M1. If you will use the newer, heavier features, such as Grid View, Output Effects, and Recording, or you want many high-resolution feeds at once, a newer machine like an M4 Mac Mini is the safer choice.

Two extras worth noting: the Zoom Enhanced Media licence can noticeably improve the quality and frame rate of participants and shared content, and unlocks High Bandwidth Mode for more simultaneous feeds. And if you use Blackmagic equipment, install its Desktop Video software version 15 or later, with 14.3 as the minimum.

Treat the computer like an appliance

The single best habit is to dedicate the machine to ZoomISO. The makers recommend exactly this. In practice:

  • Do not run other applications alongside it during a show, so all the resources go to ZoomISO.
  • Test your exact setup in advance, and evaluate any macOS update carefully before trusting it on show day.
  • Do not minimise the app while it is producing live feeds.
  • Do not use multiple virtual desktops with ZoomISO. This is not supported and can freeze the return feed to Zoom or some of your outputs.
  • Keep the Mac well cooled. Passively cooled machines like a MacBook Air, or any Mac in a hot, airless spot, can slow down as they heat up, so they are not ideal for sustained work.
  • Between back-to-back productions it can help to restart ZoomISO. Use the Clear Cache option when moving between versions of the app, or whenever you suspect something is misbehaving.

The bandwidth limit that catches people out

Zoom limits how much data it will send down to any client app, including ZoomISO. By default this is 30 megabits per second. Buying the Zoom Enhanced Media add-on and switching on High Bandwidth Mode, on the meeting owner’s account, raises it to 100 megabits per second.

If you ask for more than your limit allows, participants in ZoomISO will slow down badly, or even turn transparent or black. The fix is to keep the total of all your feeds under your limit. These are the rough costs per feed:

  • 1080p at 60 frames per second: about 8 to 12 Mbps.
  • 1080p at 30 frames per second: about 4 to 8 Mbps.
  • 720p at 30 frames per second: about 2 to 4 Mbps.
  • 360p at 30 frames per second: about 1 Mbps.
  • 180p at 15 frames per second: about 0.5 Mbps.
  • 90p at 5 frames per second: about 0.1 Mbps.

The two ranges marked for 1080p shift up or down depending on whether the High Bitrate part of Enhanced Media is on. Add up the feeds you plan to run and check the total fits inside your downlink limit, remembering the screens and the app itself also use a little.

Worked example. On a standard 30 Mbps account, four guests at 1080p30 could need up to 32 Mbps between them, which is already over the limit. Dropping to 720p30, or fewer simultaneous high-quality feeds, brings you safely back under.

Watching performance live

ZoomISO has an experimental Performance Details window for checking how each output is doing, using live statistics from its rendering engine:

  • Incoming resolution and frame rate: the quality of the video arriving from Zoom.
  • Engine cycle time: how often ZoomISO sends fresh frames out to the destination.
  • Engine latency: the delay between receiving a frame from Zoom and sending it out, handy for keeping things in sync.
  • Target resolution and frame rate: the format you set on the Outputs page.

It can also show overall system use: processor, graphics, memory, disk, and network, with rolling average, maximum, and minimum readings for benchmarking. You can start a data capture that graphs everything over time, scrub back through the timeline, and export it to a spreadsheet file for later study. Turn the whole thing on or off in the General settings, and bear in mind that using it, especially during a capture, can itself cost a little performance.

In short

Use an Apple Silicon Mac, ideally a cooled and dedicated one, and treat it as an appliance: nothing else running, no minimising, no multiple desktops, tested in advance. Keep your total feed bandwidth under your Zoom downlink limit of 30 or 100 Mbps. The Performance Details window lets you watch and record how it is all holding up.