Why can't I edit 4k?

Amazing. Would be nice to have that M1 but hard to trade in my $7000 iMac Pro after only a couple of years - especially because of performance issues! Thanks for the video.

mortonrick wrote: I have an iMac Pro - 3.2Ghz - 8 core. I constantly have a problem with stuttering, or worse, when editing - especially 4k. Yesterday I shot a bunch of clips on a GoPro 9 in 4k-60..Trying to simply PLAY the clips without stuttering and dropping frames was a problem. I don't get what I'm doing wrong...

It's likely caused by the HEVC accelerator in the T2 chip. Because Xeon does not have Quick Sync acceleration, Apple had to build that into the T2 chip, and it was their first-generation attempt. I have a 10-core Vega 64 iMac Pro and it's quite sluggish on several 4k H264 and HEVC codecs.

I also tested your footage on my 2019 MacBook Pro 16 (also running FCP 10.5.2), and it was smoother than the iMac Pro. The 2019 MBP 16 has Intel's Quick Sync, also T2 but I'm guessing it uses Quick Sync. That machine has the "Coffee Lake" version of Quick Sync which is significantly improved over prior versions.

There is nothing you can do to fix this except transcode to proxy or optimized media. FCP now has improved proxy support so if you have intermixed 4k and 1080p you can use "proxy preferred", which avoids creating low-res proxies on 1080p.

As already stated the M1 and subsequent Apple Silicon CPUs have vastly improved hardware acceleration for video decode and encode. Intel has been somewhat slow to add and upgrade Quick Sync, e.g, it's not on Xeon to this day. Going forward Apple will likely be much more agile on that issue, due to fully owning their own CPU design.

We speak of codecs like H264 and HEVC as if they were just two things. However internally there are many variations, and acceleration for each variant must be directly implemented in "fixed function" hardware. If a camera company tweaks their codec, the decode accelerator may fall back to software decoding. Yet the lead time (esp. for Intel) to implement updated hardware acceleration can be years. So it's a constant "catch up" situation. At least Apple is moving quicker on that front.

Agreed. And it's not just about HEVC processing.

I just finished a full project on an M1 with around 240 clips on a 4K25p timeline. Footage was a mix of 5K50p ProRes from ARRI, 4K30p DJI H264, Canon R5 4K24p and some 25p HEVC clips.

Edit plays smoothly unrendered, at Best Quality with color correction, ARRI LUT, some green keys, sharpening, stabilizing, titles, audio processing and whatnot. There's even an animated 31477 x 4777 panoramic photo from the Leica S2 in the edit that plays without a hiccup. Will post about this as soon as I get permission to do so. Cannot wait to see what Apple will do with the next-gen M chips!

- Ronny

I am using an iMac Pro, Vega 64, 10 core, 64 GB RAM, and I do 4K multicams almost daily. Not the smoothest playback by a long shot, but good enough to be able to edit with decently. It's not great, but it's not horrible.

I tried your clips on a 2013 Mac Pro trash can on a 4k60 timeline in FCP 10.4.10 (can't upgrade because I want to keep this machine on Mojave). No Quick Sync on this machine! Clips played back mostly pretty smooth with the occasional stutter here and there. Better Quality or Performance doesn't seem to matter, in fact Better Quality may have been a little bit smoother, weirdly. Playback was from an SSD drive attached via USB 3, but the 2013 Mac Pro trash can has fake USB 3 (not full spec but good enough I guess).

The clips, however, play perfectly smooth in VLC with zero stutters ever at full resolution. VLC is able to process video more efficiently than Final Cut Pro is. Apple should hire the VLC people to write the playback engine in FCP.

M1 is perfect for 4K editing