With some Mac you can use the hardware acceleration to encode and decode to H.264. This is very nice as it can lower the use of the CPU. But there are some limitations.
Basically all computers (except Mac Pros) released in or after 2016. Only computers with a Core i3, i5 or i7 (recent Mac mini, iMac, iMac Pros and MacBook Pro) can encode H.264 or H.265 (HEVC) using Intel's Quick Sync hardware acceleration.
Mac Pros can not use that hardware acceleration as they are using a Xeon processor. So they are not a good fit to encode in H.264. You will have much better results with a Mac mini than with a Mac Pro when it comes to H.264 or H.265 encoding...
The hardware acceleration can happen on Intel's built-in GPU, so for example on the 2018 Mac mini, as all models have the same built-in GPU, performances will be the same, and thus the Core i3 quad core model will encode approximately the same number of H.264 or HEVC channels as the Core i7 hexa core.
A few precisions,
- eGPUs won't have an impact on the hardware acceleration
- only H.264 and H.265 (HEVC) can be hardware accelerated on Intel's Quick Sync, all other codecs encoding will be done on the CPU.
What can impact performances?
As the GPU can be used, be aware that if you start another application that is using Intel's built in GPU as well, it may lower the number of channels that you can encode. So be aware of the applications you start.
Effects or overlays in MovieRecorder
In MovieRecorder, when using effects (rotating, deinterlacing,...) or overlays (timecode, image), the GPU will be used an thus H.264 or H.265 encoding performances can be greatly impacted.
For best performances you should use macOS 10.13 or later. Previous versions of macOS only supported 1 channel of H.264 to be hardware accelerated.
Support for H.265 encoding is supported only with macOS 10.13 or later.
Level and Profile limitations
There can be limitations depending on the H.264 profile and level chosen. See below the Max Width, Height, fps and bitrate for each case.
|Level||Max Width||Max Height||Max Frame Rate||Max Average Bitrate (kbps) - With Profile|
When you choose a profile with an "automatic level", the best level will be chosen depending on the incoming video format and the chosen bitrate.
In H.265 there is no selection of Profile and Level because only the "Main Automatic Level" is supported, so the best level will be chosen depending on the incoming video format and the chosen bitrate.
The maximum bitrate of HEVC is currently of 32 Mbit/s.
Currently only 8bit is supported.