Blackmagic Forum

Playback from edit or cut page is unstable with playback stopping momentarily and then resuming. Playback rate display (FPS) in edit page sometimes 'unlocks' and then returns to 29.97 when playback crosses an edit point. FPS sometimes stays at 29.97 when clip playback is unstable. CPU is about 40% capacity and GPU is around 15%. Playback directly from original GH5 file or optimized media doesn't make much difference. Project is UHD at 29.97.

Playback from older projects built in R15/16 is much better and only occasionally glitches on an edit point and the odd time during a clip. New projects built using 17B7 from clips in the R15/16 projects have unstable playback. New projects will have playback problems whether built in the edit page or using Speed Editor in the cut page.

Media loading seems slow when projects are opened.

Motherboard is Asus Prime Z270-A with unlocked i7-7700K 4.2 GHz processor, water cooling and 32 GB ram. Asus MB overclocks CPU up to 4.79 GHz. Bios, chipset and Windows is current software. GPU is AMD Radeon R9 380 series. Output is Decklink mini monitor 4K. SSD for C drive and NVME disk for cache and optimized media.

Sorry for the bad news, but a Radeon R9 380 is insufficient for an UHD timeline.

I did further experimentation and found the timeline will playback normally if there are no color corrections of any kind. Frame rate will flicker at clip boundaries using original GH5 files but optimized media solves that problem. Transitions and titles are OK provided they are cached. Any clip with a color correction will not play cleanly but both the CPU and GPU are well below their capacity as noted in the original post. The problem is not reflected in the Task Manager graphs as there is no evidence of hitting 100% CPU or GPU usage at any time.

So, I think using a more powerful GPU masks any underlying problems that might exist in the color correction part of the software. I will replace the Radeon card with something more powerful when graphics cards become available again. Suitable cards are not currently available in the retail market where I live.

Yes, the cards all went to mining.