Resolve API Render Call Crash

We are trying to write a script for Resolve that renders a timeline using the following code:


import DaVinciResolveScript as dvr_script
resolve = dvr_script.scriptapp("Resolve")
print(resolve)
projectManager = resolve.GetProjectManager()
print(projectManager)
project = projectManager.GetCurrentProject()
print(project)

#'seq_050'
timeline = project.GetTimelineByIndex(3)
print(timeline)
resolve.OpenPage("Deliver")
project.DeleteAllRenderJobs()
project.SetPreset("ProRes Master")
project.SetCurrentTimeline(timeline)
project.SetRenderSettings({"SelectAllFrames": 1, "TargetDir" : "H:/test"})
project.AddRenderJob()
project.StartRendering()


Looking at the Reolve GUI, eveything seem fine, the timeline is added the Render Queue. But, as soon as project.StartRendering() is executed via script, the „Start Render“ button changes to „Stop“, but I get a message box with



„Render jobs for {projectname} are not complete. Would you like to cancel…“ Any button press causes the program to crash.


Bizarrely, if I exclude „project.StartRendering()“ from the code and leave everything else in, Resolve renders the timeline just fine if I manually press the „Start Render“ button.

Any help really appreciated!

clever script!

clever script!

was this irony ? because it crashes...

no...
once it's sorted, it's a very simple / fool proof way of getting renders done, bypassing the chance of an overly tired assist pressing the wrong button late at night

i still think it's clever.... even as a work in progress

well then lets hope some of the BMD developers reads this thread an fixes the bug or pointing out what we are doing wrong...

I assume your host OS is MacOS or Linux based on the "Prores" in the name of the preset.

Could it be that the Windows-like path "H:/test" is throwing a kink in the system? The slash is a Posix style slash used with a Windows style mount point.

Resolve's paths are somewhat slash-type agnostic across platforms. But I don't know if this extends to the scripting API. Still, this would not explain why you can manually start the render and StartRendering() fails.

Its a PC the presetname was just the name. Unfortunately I really think its a bug, since I have no clue what should be the difference when it works with the button press

[Peter Chamberlain]

Resolve on Windows does not render ProRes.
Are you trying to do that?

Resolve on Windows does not render ProRes.
Are you trying to do that?

Hi Peter,
thanks for the reply! It does not change anything when we remove the line. You can check for yourself:

import DaVinciResolveScript as dvr_script
resolve = dvr_script.scriptapp("Resolve")
print(resolve)
projectManager = resolve.GetProjectManager()
print(projectManager)
project = projectManager.GetCurrentProject()
print(project)

#'seq_050'
timeline = project.GetTimelineByIndex(3)
print(timeline)
resolve.OpenPage("Deliver")
project.DeleteAllRenderJobs()
project.SetCurrentTimeline(timeline)
project.SetRenderSettings({"SelectAllFrames": 1, "TargetDir" : "H:/test"})
project.AddRenderJob()
project.StartRendering()

As mentioned when we remove "project.StartRendering()" and just press the physical button everything works fine.

Any help really appreciated!
Thanks a bunch!
Tim

I don't have Python installed, but the same script in Lua works fine. Forward slash like you use in TargetDir should work on Windows, but have you tried double backslashes instead just to make sure?

Here's a Lua version

Code: Select all

resolve = Resolve()
projectManager = resolve:GetProjectManager()
project = projectManager:GetCurrentProject()

timeline = project:GetTimelineByIndex(3)
resolve:OpenPage("Deliver")
project:DeleteAllRenderJobs()
project:SetCurrentTimeline(timeline)
project:SetRenderSettings({ SelectAllFrames = 1, TargetDir = [[C:\temp]] })
project:AddRenderJob()
project:StartRendering()

By the way, when you execute methods for the Deliver page Resolve will automatically switch to that page, so no need for the OpenPage method.

Hi Roger,
thanks for your reply! Unfortunately we have to connect from outside to the running resolve instance. To my knowledge I just can run LUA code inside of resolve, is this correct?

Best
Tim

[Rohit Gupta]

Can you post your project or send me a link to it please (PM)?

Hi Roger,
thanks for your reply! Unfortunately we have to connect from outside to the running resolve instance. To my knowledge I just can run LUA code inside of resolve, is this correct?

Best
Tim

No, you can run external Lua (and Python) scripts in the Studio version of Resolve using %ProgramFiles%\Blackmagic Design\DaVinci Resolve\fuscript.exe

When I looked at this late last year, I found it didn't work headless, i.e. with Resolve.exe -rr

But it worked with the GUI open.

Resolve Studio 15.2.0.033

I'd be more interested in rendering with Resolve if you could render headless. This kind of thing worked for me that's a little different to what you have...

renderFormat = "mov"
renderCodec = "DNxHD1080p36"
outputFilename = "Test-Resolve"
targetDirectory = "C:\"
project.SetCurrentRenderFormatAndCodec(renderFormat, renderCodec):
project.SetRenderSettings({"SelectAllFrames" : 1, "TargetDir" : targetDirectory, "CustomName" : outputFilename}):
project.StartRendering():
while project.IsRenderingInProgress():
print("rendering in progress")
time.sleep(1)

Headless would be indeed the best solution! Did you remember what was the issue in the past?
I will try your code and report back!
Many Thanks
Tim

Here is a Demo Project that demonstrates the API call crash.

Any help really appreciated

I installed Python v3.6.8 and your script runs fine on my machine with your project. It renders 154 exr frames.

Sorry, no idea why it's not working for you. The only thing I can think of is if you're running through remote desktop. Then the GPU might not be correctly initialized and rendering can't start.

Hi Roger,
thats strange, I tried it on several machines with no remote Desktop and Also with Python 3.6.8.
Same crash on every machine with Dialog Screen (see attachment)

I am on a Windows 10 machine by the way. Are you on MAC ?

No, this was on Windows 10 as well. Resolve Studio v15.3.

PythonRendering.png (252.18 KiB) Viewed 3510 times

Thats so weird.... now I dive into the dxDiag again....

Are you on nVidia GPU or AMD?

This is just a small dev machine without a dedicated GPU, so it's an integrated Intel GPU. Can't test on my workstation right now, but I've not seen that issue on any of my machines earlier (Windows 10 with nVidia GPUs, Mac Mini 2018, MacBook Pro 2015).

Okaaayyyy.. Closing in on this Issue, it happens when you are on a PostgresSQL Database, it renders when the project is imported in the local databases...
@BMD Any ideas what might cause this crash on the Collaborated PostGresSQL Database Connection?

Since I could verify that the API Rendercall crash happens when one uses a PostgreSQL Database connection instead of a local one, are there any ideas how to solve this issue or does this qualify as a bug?

I tried both a disk database and a remote PostgreSQL database without issues. Haven't tried a local PostgreSQL though.

Hi Roger,
how did you setup your remote postgresSQL ? What version did you use and on what system did you run it?
Thanks
Tim

The remote database was installed/configured by the DaVinci Resolve 15 installer on a Mac Mini. Not sure which version Resolve uses nowadays. According to the download page it's v9.5.4: "Starting from DaVinci Resolve 12.5.3, new installations will include PostgreSQL version 9.5.4."

Could it be a software firewall issue?

Thanks Roger!

we have installed postgres 10.5 on windows server 2016

https://www.enterprisedb.com/downloads/ ... -downloads

I will look into the firewall matter, but the connection to the database works normal and I still can press the start render button manually. So I am wondering in what way the API call project.StartRendering(): differs from manual pressing the button..

@BlackmagicDesign
are there any compatibility issues with the windows Version of postgres or a version conflicts, that might cause the crash?

Addendum: Just tested it the a linux connected postrgres database on a qnap with the same error

Dear BlackMagickDesign Developers,

Cleaning all logs and starting fresh,
attached you will find log files

It crahes
[0x000049b4] | BtCommon | FATAL | 2019-03-20 14:21:47,612 | Error: Incorrect mutex locking order detected
[0x000049b4] | Main | INFO | 2019-03-20 14:21:47,614 | Caught termination signal SIGABRT, triggering termination routine

To state the matter again. When we remove the project.StartRendering() and press the button the rendering works as expected.

Any help really appreciated!
Best
Tim

Hm, no reply from the BlackMagicDesign Support?

still no reply .....

Well, it's a user forum so you might say you were spoiled by getting replies from two different BMD managers in the same thread.

Official support is available here: https://www.blackmagicdesign.com/support/contact/email.

The support already got plenty of mails from me on this topic

So, I now know a bit more:
If the project is set to "enable collaboration" and you want call rendering via python it gets a mutex lock error exception an crashes.
If I disable collaboration, resolve starts to render.

Is there a way to get both, collaboration AND api render call support?

That's good to know. What's a "mutex lock"?

Hey Igor,

no idea, maybe something with postgresql


[0x000049b4] | BtCommon | FATAL | 2019-03-20 14:21:47,612 | Error: Incorrect mutex locking order detected
[0x000049b4] | Main | INFO | 2019-03-20 14:21:47,614 | Caught termination signal SIGABRT, triggering termination routine

Only blackmagic could really debug this

Mutex is a mechanism that prevents different concurrent threads/users/parties operating on the same piece of data, basically it allows only one party to touch something at the same time. Mutex is locked to do something and other lock calls wait until mutex is released. Mutex lock exception sounds like mutex is already locked by the same party that tries to lock it again (resolve python instance?), which causes undefined behavior or basically it would wait indefinitely for lock to release and thus throws an exception to prevent that.

Why python api call would act differently than simply pressing render in ui though...? I assume you can manually render just fine in collaboration mode?

Hi Hendrik,
correct, when I remove the StartRendering call I can normal press on the StartRender Button.
So I assume that the api access does not get full ownership during the call and it conflicts with the "logged" on GUI session... just a wild guess