Bug - Black frames in final render on some 3K footage

[Robino_J]

Finishing a mixed resolution (4k and 3K) project and encountered this annoying bug when reviewing the final render. On some of the 3K shots (over-cranked 48fps in camera and read by Resolve at 23.976) there's a black frame showing up for no reason. In this 3.30min project it happens on 3 shots (3K). It does not happen on any of the 4K shots.

What is strange is that if I render the "problem" clips individually they are perfect - no black frames. I was able to finish my project by rendering the problem clips individually and inserting them in After Effects. (From the delivery page I right-click on the clip and select "Render this clip")

When rendering the full timeline the black frames reappear.

Here's more information:

- I experienced this issue with Resolve 9.0.4 as well as the latest 9.1 which I installed this morning.
- The "problem" shots play perfectly from the timeline in all modules - no black frames seen. (conform, color, deliver)
- Nothing special done on these clips. No keyframing, re-sizing etc.. using same grades as other 3k shots that work fine.
- Black frames happen in all delivery formats (QT ProRes, DPX, TIFFs etc)
- Tried at ful res premium and half res good - bug is still there.
- I'm on MAC / OSx 10.8.2 (iMac 27" 3.4 2012 + GTX 680 MX)
- No Red Rocket

Any help is appreciated.

 

[Björn Benckert]

I got this using the red rocket... random frames in certain clips shows up as black, when rendering without the rocket the black frames are gone...

 

[Robino_J]

I got this using the red rocket... random frames in certain clips shows up as black, when rendering without the rocket the black frames are gone...

Thanks Björn, I currently do not have a Red Rocket in my workflow.

 

[John Tissavary]

Try slowing down your render. In the delivery page, set render speed to something other than 'maximum' and see if that helps. You may need to experiment with a couple of different speeds to find the right one for your system.

 

[Robino_J]

Try slowing down your render. In the delivery page, set render speed to something other than 'maximum' and see if that helps. You may need to experiment with a couple of different speeds to find the right one for your system.

You're on to something.

- When capping the max frame rate to 2, all frames are rendered correctly on the 3K shots. I can see the GPU frame rate while rendering stays at 2 for everything. (4k and 3K shots)

- When capping the max frame rate to 5 , it shows a black frame in the 3K shots. *The weird thing is that even though I'm capping the frame rate to 5 when the play head hits a 3K shot it goes up to 9fps then down to 5, 6, 2 8 etc.. when the playhead hits the next 4K shot it goes back to normal 5fps max..

Is it a software bug or is it an issue with my shots?

 

[John Tissavary]

Since I don't often work with 3K, I can't be sure if it's a Resolve problem or one that is particular to your setup. I did work with some 3K yesterday that rendered fine, not a single black frame, but that's not enough for me to make a claim either way.

best,

John T.

 

[Robino_J]

Now it's dropping at 4K as well.. I had to render capped at 2fps last night just to be sure my render would be fine. So annoying.

 

[Peter Chamberlain]

Hi, we have reports of this but cant consistently reproduce here. First I would try 9.1.1 we just released. If no change try doing a cold boot of your machine, load the project and then render, this will help see if its a lingering ram flush issue. After that, Im suspecting we will need to get logs from your system. The application 'Capture Logs' should be used to grab the log immediately after you experience the issue. it will put the log on your desktop. email it to davincihelp (at) blackmagic design [dot] com with a description.
Peter