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1st impressions on 2018 Mac mini transcoding x264 to x265 using T2 chip


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This is a continuation from another thread as I thought it might be of general interest as there's not much real use case information about the Apple T2 chip and its role in hardware acceleration for their 2018 models.

First, I'm an under 24 hours Emby user and I  paid for my initial month of Premier membership not because I intend to use most of the services; I know I won't, but rather that I appreciate the time and effort it takes to keep something like Emby afloat. Hopefully the month will go well so that I can move to a yearly subscription.
As mentioned in another post I'm a long time Plex user who's now a refugee after finding their new direction not one I wish to follow.
So far every thing has gone unusually well. I'm sure something will come up. It always does; its the nature of the beast.
I've recently put a 2018 Mac mini, MacMini8,1 with an 3.0GHz 6 Core Intel Core i5 Processor, 512 GB SSD and 16GB RAM running macOS Mojave 10.14.2 into service running Emby Server 4.0 24x7 in the background.
It'll also be my primary desktop replacing a 2015 13" MacBook Pro with a buit-to -order i7 that wasn't cutting it as far as transcoding x264 files to x265 using HandBreak was concerned. It was used in the closed "clamshell" position attached to a 27 inch monitor, external trackpad, etc. etc. so the transition on my desk is almost painless.
I also have a 2012 15" Macbook Pro 16GB RAM, modified with a 500GB SSD that never leaves the desk (too heavy) and has been my Plex server and does general utilities plus downloading/uploading and file transcoding as it was faster to transcode than the 2015. I archive all the video files I wish to keep initially to external drives, and then to 25GB BluRay disks as I spend part of the time in other lands.
With Apple extending the T2 chip previously only on their 2017 Pro model to all their 2018 Mac line, I thought I'd share my initial impressions on how it has changed my transcoding workflow.
The T2 chip, although primarily designed for security purposes, including continuously encrypting and decrypting data, is being used for additional purposes. One is acting as a digital to audio processor that makes a noticeable difference to my externally powered desktop speakers which I thought already sounded quite good. The T2 also provides hardware acceleration to applications using Apple's HEVC_VideoToolBox codec. 
Example of tests performed with a base line 1.14GB 720p x264 video file:
2012 MacBook Pro using HandBreak:  296 MB x265 file & 75 minutes to completion.
2018 i5 Mac mini using HandBreak:  295.4 MB x265 & 41:19 minutes with processor load of 97%.
Not having seen any proof that the T2 chip was involved I installed ffmpeg 4.1 using HomeBrew and then the GUI for ffmpeg, ff·Works,found at http://www.ffworks.net. At that point I hadn't realized how few variables the Apple encoder had as there are only 2 that you can move around to get the best combination of quality versus file size.
2018 i5 Mac mini using ffMPEG and T2 hardware acceleration: 407.1MB and 3:57 minutes with a combined 7% T2/CPU load. (Trying two simultaneous transcodings took the same amount of time but with double the T2/CPU load.)
Later on I tried a 15.94GB x264 file that resulted in a 3.34GB x265 file that took under 15 minutes to complete.
My conclusions are that even though I don't achieve the smaller file sizes available via the libx265 encoder in HandBreak the time savings is worth my using the T2 as my daily encoder.
Finally, I'll mention again that the T2's chip performance should be the same across all 2018 macOS models and beyond with the i7 models having better CPU performance because of the hyper-threading which is not available in the i5 even though both have 6 cores and similar clock speeds. That would be a factor only if I used HandBreak.
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As I mentioned, I'm new to Emby and have had little time using it. Less than a few hours. I know I won't be able to try to tax the system until I put every device I've got online simultaneoulsy. That's going to take some time as I've got to get Chromecast and a Fire stick going on some monitors. I think I've only tried the Fire one or twice. I may not have any Rokus left as I gave them away. I've got a Chromecast despite giving two away because I couldn't pass up the $9 price for it and its still unwrapped. I guess I could have added the second AppleTV but I think it's going to be linear based on the simultaneous transcodings I did directly with ffmpeg.


I took some screenshots of the processor load while viewing the same video on an iPad and then on an AppleTV4K. Other than some 1 second spikes every minute or so, I assume it was idling while most of the stream was going, The loads were almost unnoticeable.


There's nothing active other than Emby but I've got 19 apps open. I though about a video of the monitor but Quicktime would spoil the readings. 


Here's the comparison screenshot.

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