Over the years, I’ve looked a compression speeds in both Adobe Media Encoder and Apple Compressor.
In this article, I want to compare compression speeds between different codecs in both Sierra and High Sierra, as well as how long it takes to compress H.264 vs. HEVC using the latest version of Compressor.
Along the way, I also looked at the speed and file size differences between single pass and multi-pass compression.
NOTE: HEVC (H.265) is only supported in High Sierra (macOS 10.13.x) or later.
Here’s what I learned:
To make results comparable across versions, I used the default YouTube HD720 setting for all versions of Compressor, applied to a variety of source files which were the same for all my tests.
Compressor 4.3.1 was run on a 2013 27″ iMac with an i7 CPU. Compressor 4.4 was run on a 2017 27″ iMac with an i5 CPU. The similarity of these results illustrates that H.264 compression is handled by separate hardware from the CPU which is not directly dependent upon the CPU speed.
Here are the specs for the 2017 iMac. I ran these tests first with Sierra installed, then installed High Sierra and ran them again. So, the hardware was identical for both tests.
COMPARE H.264 SPEED
The codec of the source file makes a difference in compression speed. Each of my test files was a different duration, so we can’t compare, say, the speed of XDCAM EX with ProRes, because the files are different.
We can, however, compare compression speed of the same file across the different versions of Compressor and operating systems.
In all cases, we are compressing from different source file codecs into the same settings for H.264.
When compressing XDCAM EX footage, Compressor 4.4 is slower in both macOS versions. Version 4.4. in High Sierra is 67% slower when compared to 4.3.1.
NOTE: The time value in all charts is minutes and seconds.
When originating in ProRes 422, compression times are essentially the same. 4.4 in High Sierra is less than 1% faster than 4.3.1 and 3.6% faster than Sierra. This, to me, illustrates that the same hardware acceleration chip is used in both older and new computers.
When originating in ProRes 4444, compression times between Sierra and High Sierra are identical to the second. And about 8% faster than Compressor 4.3.1.
COMPARE H.264 TO HEVC
HEVC requires hardware acceleration in order to get done in a reasonable amount of time. (Macs released in 2015 or later have this hardware acceleration built in.) As well, the computer also needs to be running High Sierra (10.13.x).
Here, I took three different files, in three different codecs, and compressed them on the same machine using Compressor 4.4 running on High Sierra. Settings were based upon the default HD720 settings in Compressor. The only change I made was to switch between H.264 and HEVC.
Essentially, HEVC takes at least twice as long to compress than H.264, though for ProRes 4444, it took almost four times longer. File sizes were about 1/3 smaller for HEVC, except for ProRes 4444, where there was less than 1% size difference between the two versions.
H.264 is faster to compress in all cases. Single-pass compression creates smaller files faster than multi-pass. I haven’t seen any reason to use multi-pass settings in Compressor for the last several versions. Image quality is the same, speed is faster and compressed files are smaller with single-pass compression.
And, if you don’t need HEVC, there’s no big speed benefit to upgrading to High Sierra for any system you want to use for video compression.
It is also interesting that compressed file sizes are essentially the same for the last several versions of Compressor.
If you want to look at my numbers, download a PDF of my spreadsheet here. (69 KB)
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