Blackmagic Forum

***re-posting in beta forum, I had posted this bug in main forum...

Rendering is very slow with RED HDRX footage. This is with Dragon 6K footage, not sure about other sensors / cameras.

Using DaVinci Resolve 15 Studio Public Beta 5, It was also happening using previous Resolve 15 Betas. Unsure about Resolve 14.

Renders hang for a couple seconds then a short burst of frames are rendered, freezes again and burst.. 

Did a test with a 5.13sec clip, with HDRX OFF it takes 17sec to render and with HDRX ON it takes 1.57min.

I'm using iMac Pro 10Cores with 64GB Ram and Promise R8

I made a screen capture video showing the issue.


password: resolve

Video breakdown:

00:00-00:08 - Scrubbing through timeline at quarter resolution with HDRX OFF (perfect)
00:08-00:20 - Showing Camera Raw / RED Settings
00:28-00:35 - HDRX OFF playback in realtime (at Quarter Res)
00:40-01:17 - Rendering test clip with HDRX OFF (17sec for rendering)
01:21-01:23 - Switching HDRX ON
01:28-01:39 - Scrubbing through timeline at quarter resolution and Playback with HDRX ON (Playback at around 15Fps which makes sense)
01:44-03:57 - Rendering test clip with HDRX ON (1.57min for rendering)
03:03-03:27 - Showing Resolve Preferences (Did that while rendering.. note that it doesn’t affect render time to go in Preferences)

Installed Resolve 14.1 to check if that was happening in prior versions and it is but the freeze between bursts are shorter.

Anyone ever rendered HDRX footage in Resolve? How does it go for you, same results or is it an issue on my end?

I tried the Resolve 15 Public Beta 8 and the R3D HDRX issue is still there. Resolve still freezes, then a burst of frames is rendered, freeze, burst, etc.. On longer clips it is really taxing on rendering time.

If anyone could help me test this I would really appreciate it - I would like to identify if the issue is on my end only or if it’s happening to everyone.

I made a small HDRX “Gundam” clip (2sec) for testing, click the link below to download if you would like to help.



[url="https://wetransfer.com/downloads/9dd5277739879f3b28595f98ea2d3e4720180806172820/720b9b418885efa72fb6ed8391f2d18020180806172820/d87fa0"]https://wetransfer.com/downloads/9dd5277739879f3b28595f98ea2d3e4720180806172820/720b9b418885efa72fb6ed8391f2d18020180806172820/d87fa0[/url]

My results are:

*All renders are FULL DEBAYER / PRORES 422HQ / 1080P

- REDCINEX (HDRX OFF, A FRAME ONLY) = 5.6sec
- REDCINEX (HDRX ON, SIMPLE BLEND) = 10.3sec
- RESOLVE 15 BETA 8 (HDRX OFF, A FRAME ONLY) = 4sec
- RESOLVE 15 BETA 8 (HDRX ON, SIMPLE BLEND) = 33sec

My hardware specs are:

iMac Pro 10 Cores
64GB Ram
Pegasus R8

Also happening to me on 15b7. Windows 10, Threadripper 1950X, 2x 1080Ti, NVMe storage, 64GB RAM, with your sample. With HDRX off, I get ~16 fps full rez on the color page. When I turn it on, it drops to zero, then goes in bursts of ~4 frames. 1/4 decode is smooth, 1/2 good is similar to full. GPU usage is basically none, CPU around 60%.

Maybe it's not optimized that well, after all you have to decode two full streams of R3D in a compressed wavelet codec. Did you compare what the CPUs are doing if you try to decode HDRx in RedCine-X?
If you don't need qualifiers to combine, but only "Blend" or "Magic", you could transcode in RedCine-X, which can start more than one thread on a capable machine.

Uli Plank wrote:Maybe it's not optimized that well, after all you have to decode two full streams of R3D in a compressed wavelet codec. Did you compare what the CPUs are doing if you try to decode HDRx in RedCine-X?
If you don't need qualifiers to combine, but only "Blend" or "Magic", you could transcode in RedCine-X, which can start more than one thread on a capable machine.

Ok thanks for that - I ran "activity monitor" on my iMac Pro and something looks really off with the CPU when HDRX is on. Not sure what the numbers mean but with HDRX turned ON, the CPU averages 30 and sometimes spikes to 70 very quickly then goes back to average 30.

When running WITHOUT HDRX, the CPU goes through the roof and averages 1930..

Take a look at the screenshot. What does this mean? Is this something about multicores not kicking in when HDRX is on?

Can be two things:

– Your media is not fast enough for two streams, so the CPUs get starved. Test it with a clip on a SSD.

– The parallel decoding is not (maybe can not be) hyperthreaded well. After all, these are not all 'real' cores.

Uli Plank wrote:Can be two things:

– Your media is not fast enough for two streams, so the CPUs get starved. Test it with a clip on a SSD.

– The parallel decoding is not (maybe can not be) hyperthreaded well. After all, these are not all 'real' cores.

I'm running this test on a Pegasus R8, just did a Blackmagic Disk Speed test and I'm getting 1400MB/s read and 1200MB/s write so disk speed should not be the issue.

Hopefully someone from Blackmagic will chime in at one point - this doesn't seem normal.

Did you compare RedCine-X's use of CPU cores?
After all, R3D decoding is done with a kit by Red, they don't allow anybody to write their own routines. Maybe BM can't do anything about it.

Uli Plank wrote:Did you compare RedCine-X's use of CPU cores?
After all, R3D decoding is done with a kit by Red, they don't allow anybody to write their own routines. Maybe BM can't do anything about it.

Yes I did - here's the Activity Monitor screenshot with RedCineX. The CPU is average 1930 with HDRX ON & OFF

That would be really weird if they could not do something about this issue. Hopefully they can let us know here. I really need this feature to work for the application I'm using it for.

Well, they may be able to squeeze out some more then, but I wouldn't expect miracles.

Just installed Version 15.1 and issue still happening.

Over the weekend I had to render a 3.38min HDRX video and it took 1.38 hours.