Issue scheduling frames to BMD from gstreamer

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tpat36

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  • Real Name: Taylor Patton

Issue scheduling frames to BMD from gstreamer

PostTue Nov 12, 2019 7:55 pm

Hi,

We are having occasional issues with the BlackMagicIO driver for linux. We are using gstreamer's decklink plugin (version 1.16.1), desktopvideo version 10.8.5-a4, DeckLink Duo 2. The issue presents itself as follows:

* gstdecklinkvideosink.cpp (from gstreamer decklink plugin) will start logging "error: Failed to schedule frame: 0xffffffff80000008" repeatedly
* Immediatly after, BMD logs "BlackmagicIO: WARNING: Ran out of free frames."

During this issue the output video on the decklink starts lagging and audio sounds distorted. We've seen this issue happen in the middle of playback or at the beginning of playback. We are trying to get to the bottom of this issue of why the decklink plugin cannot schedule frames in time to the BMD driver. Is there any logging we can add to the BMD driver to help determine the root cause of this issue? If frames are being delivered too late to the BMD driver, could we get additional BMD logs for that scenario? Would there be any other reason that frames could not be scheduled successfully to BMD?

We have been working with the gstreamer community to improve scheduling frames which they have done for us. When this issue happens we are not seeing any late/dropped frames being logged from gstreamer. It's very difficult to reproduce this so we need to know exactly why the frames are failing to be scheduled to BMD before we can get a fix from gstreamer.

In case it helps, this is what the decklink output looks like in this scenario:

https://pulse.elevationchurch.org/link/ ... 0d1dff5de3
The issue starts around the 11 second mark and is ultimately resolved when we detect the error and reset the entire gstreamer pipeline.

OS: Centos 7
Kernel: 3.10.0-693.el7.x86_64
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Ian Morrish

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Re: Issue scheduling frames to BMD from gstreamer

PostTue Nov 12, 2019 11:07 pm

Presume you are not running a virtualization host on the same machine, Xen or KVM. These can cause problems (I have similar problem on Windows with HyperV host also running)
Regards,
Ian Morrish
Video Integrated Scripting Environment
(Windows PowerShell with ATEM driver + more)
https://ianmorrish.wordpress.com
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tpat36

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Re: Issue scheduling frames to BMD from gstreamer

PostTue Nov 19, 2019 1:07 am

Not running a virtualization host, xen or kvm
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saschal

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  • Real Name: Sascha Liebsch

Re: Issue scheduling frames to BMD from gstreamer

PostThu Jan 30, 2020 7:26 pm

Hi,

I'm following up on this because I've got the same issue. Symptoms are the same, the only difference being that my Gstreamer pipeline runs fine for 24 hours (+- a few minutes) before running out of frames.

I've created a bug report to Gstreamer here https://gitlab.freedesktop.org/gstreame ... ssues/1197, with some more details.

Can we have some feedback from the Blackmagic devs, please?
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saschal

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  • Real Name: Sascha Liebsch

Re: Issue scheduling frames to BMD from gstreamer

PostFri Jan 31, 2020 8:59 am

saschal wrote:Can we have some feedback from the Blackmagic devs, please?
I just realised this may sound a bit harsh, so let me elaborate a bit more on this:
My company has dozens of Decklink 4K Extreme cards in use. In order to be able to move forward with our products, we need to keep up-to-date with current Linux and various open source software. Due to the problem described, we're currently stuck with a four-year old OS, an out-of-date variant of the Linux 4.4 kernel, the decklink 10.8.5 driver, and Gstreamer 1.12, that being the only combination of kernel, drivers, and software that works stable.

Obviously, this situation is pretty uncomfortable, that's why we'd very much appreciate to get some feedback.

Thanks and best regards
Sascha

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