Thank you for purchasing through links and ads on this site.
OWC / MacSales.com...
diglloyd Deal Finder...
Buy other stuff at Amazon.com...
Capacities up to 48TB and speeds up to 1527MB/s

iMac 5K vs Mac Pro, Video Transcode 4K to 1080P

Last updated 2014-11-01 - Send Feedback
Related: Macs, 4K and 5K, Mac Pro, iMac, iMac 5K, Mac

IntegrityChecker(tm) v1.2.3 64-bit, diglloydTools 2.2.7b

iMac 5K 4.0 GHz, 32GB, 1TB SSD, AMD Radeon R9 M295X 4GB GDDR5 -versus-
2013 Mac Pro 3.3 GHz 8-core, 64GB, 1TB SSD, D700

Transcoding 4K video to 1080p is a computation intensive process. The 2013 Mac Pro Xeon CPU lacks the specialized video instructions that the CPU in the iMac 5K and 2013/2014 MacBook Pro have. Thus in spite of its dual GPUs, the 2013 Mac Pro delivers a pathetic performance for this simple task. More elaborate video operations might not behave similarly; it gets very specific. And see comments below.

See also Transcoding Panasonic GH4 UltraHD 4K Video to 1080p: Surprising Speed on 2013 Mac Pro with Final Cut Pro and QuickTime.

A simple transcode of 4K video to 1080p using Quicktime Player (Export).

Transcode 4K video clip to 1080p (OS X QuickTime Player)
iMac 5K 4 GHz Radeon M295X vs 2013 Mac Pro 3.3 GHz 8-core D700

The above is obviously not a professional video / high-end test. But for many users, even the concept of transcoding is new, and simplicity/speed rule. It is thus relevant to the vast majority, but not to video professionals.

Up to 1527MB/s sustained performance

Dez writes with a pro perspective:

The reason for the "pathetic" results "in spite of the dual GPUs", is that Quicktime Player doesn't leverage those GPUs, but it does however, tap into the Quick Sync core in the i3, i5, i7 series chips. Thus the iMac transcode was aided not only by the extra clock speed, but also by the special h.264 encoding core built into the CPU.

Transcoding video with Quicktime player is a poor test of performance for many reasons, the largest being that, unlike most pro video apps (Avid Media Composer aside), it does not leverage GPU acceleration at all, and it's implementation of multi-threading is notoriously poor. A better "real-world" test is to use something like Davinci Resolve, Compressor or Adobe Media Encoder, all of which use GPU acceleration for encoding files. Additionally, Quick Sync only works with h.264, so if you need to transcode to a different codec, you're stuck with vanilla CPU number crunching.

Another reason to avoid the Quick Sync is that the quality of the files are poor when compared to straight CPU (unaccelerated) crunching with a good encoder like Sorenson Squeeze or GPU accelerated encoding via something like Resolve or Media Encoder.

Really, the best test if you want to appeal to pro users is to transcode from 4k RED Camera or Arri Alexa raw files into an intermediate codec such as Apple ProRes 4444 or Avid DNxHD 345x using an application like Davinci Reslove.

If you're not trying to appeal to a pro user, then do the same test to ProRes 422 HQ using Final Cut Pro X or Compressor, which is a common workflow for the DSLR and Go Pro crowd.

MPG: the best test of performance is one relevant to the user and usage scenario.

Durable and fast, up to 1800MB/s
B&H Deal ZoneDeals by Brand/Category/Savings
Deals expire in 7 hours unless noted. Certain deals may last longer.
$1049 SAVE $450 = 30.0% $20 FREE ITEMS Canon EOS 77D DSLR with 18-135mm USM in Cameras: DSLR
$599 SAVE $100 = 14.0% GoPro Fusion in Video: Camcorders
$1697 SAVE $300 = 15.0% Nikon D750 DSLR in Cameras: DSLR
$2197 SAVE $900 = 29.0% Nikon D750 DSLR with 24-120mm in Cameras: DSLR
$3297 SAVE $800 = 19.0% Nikon D810 DSLR with 24-120mm in Cameras: DSLR
$1399 SAVE $100 = 6.0% ZEISS 18mm f/2.8 Batis in Lenses: Mirrorless
$1099 SAVE $200 = 15.0% ZEISS 25mm f/2 Batis in Lenses: Mirrorless
$1299 SAVE $200 = 13.0% ZEISS 21mm f/2.8 Loxia in Lenses: Mirrorless
$1999 SAVE $300 = 13.0% ZEISS 18mm f/2.8 Milvus ZF.2 in Lenses: DSLR

diglloyd.com | Terms of Use | PRIVACY POLICY
Contact | About Lloyd Chambers | Consulting | Photo Tours
Mailing Lists | RSS Feeds | Twitter
Copyright © 2008-2017 diglloyd Inc, all rights reserved.
Display info: __RETINA_INFO_STATUS__