Decklink Duo 2 Audio Stuttering On Linux after update to 12

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Helmuth Schmitz

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  • Joined: Tue Jun 21, 2016 5:23 pm

Decklink Duo 2 Audio Stuttering On Linux after update to 12

PostTue Jul 20, 2021 12:29 pm

Hi there. We use Decklink for almost 10 years as official card for product we develop. But, recently, we have been caught by a very unusual issue envolving Decklink Duo 2 + SDK 12.0(or 12.1) on Linux. We was using 11.3 SDK version at our development computers and also on our clients. But then, we decided to update everyone to 12.0 or 12.1. And this brings this strange issue. On every computers that uses Decklink duo2, the audio output starts to stuttering. There are 2 scenarios.

A) Application runs fine for a long time, and suddently, audio begins stuttering.
B) Application already start with auduio stattering.


No matter A or B, the only solution is to reset computer. So, at begginning, as all developer think, we thought that could be something with our product. So, after aduio starts to stuttering, we tryied OBS softwre with Decklink output, and it's audio was stuttering too, what showed us, that was something above software questions.

Configuration of all computers using DUO2 is:
Supermicro x11SAT - i7 6700 - 16GB RAM with Nvidia 1050Ti 4GB
2 Decklink Duo2 cards
Ubuntu 18.04


We really need help for this issue, specially for our clients situation.
Best regards,
Helmuth
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Cessna048

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  • Joined: Fri Jul 23, 2021 9:05 pm
  • Real Name: Bill Arnette

Re: Decklink Duo 2 Audio Stuttering On Linux after update to

PostFri Jul 23, 2021 9:14 pm

We are having this exact problem with the Decklink Studio 4K on Windows using the 12.0 and 12.1 Blackmagic WDM Capture source filter in an always-on DVR application. We are new to Blackmagic Design cards so based on your post I installed Desktop Video 11.7. So far it has been running non-stop for over 24 hours with no audio droputs.

However the Line In source filter still constantly stutters from the moment the graph starts running. This is reproducible in graphedit.
Bill Arnette
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Cessna048

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  • Joined: Fri Jul 23, 2021 9:05 pm
  • Real Name: Bill Arnette

Re: Decklink Duo 2 Audio Stuttering On Linux after update to

PostSun Jul 25, 2021 6:12 pm

We have seen the exact same behavior in our always-on Windows CCTV app using Desktop Video 12.0 and 12.1 with the DirectShow filters for the Decklink Studio 4K. Using the audio pin on the BlackMagic WDM Capture filter we start to see stuttering after 10-12 hours starting intermittently as audio drop-outs but then worsening to where the audio is unintelligible.

If we use the Line In (Decklink Studio 4K) the stuttering is immediate upon starting the graph.

Both of these issues are reproducible with simple graphs in GraphEdit.

Code: Select all
BlackMagic WDM Capture (video pin) -> AVI Decompressor -> EVR
                       (audio pin) -> DirectSound Renderer


or

Code: Select all
BlackMagic WDM Capture (video pin) -> AVI Decompressor -> EVR
Line In (Studio 4k) -> DirectSound Renderer


We have analyzed the timestamps using the GraphStudioNext built-in Analyze filter and they seem to be correct.

We are using the Line in inputs on the card to ingest audio from balanced XLR microphones.
Bill Arnette
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pada__kwaak

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  • Joined: Fri Sep 03, 2021 7:37 am
  • Real Name: Chris Kistner

Re: Decklink Duo 2 Audio Stuttering On Linux after update to

PostFri Sep 03, 2021 3:03 pm

Hi,

Have you been able to resolve this issue yet?

I am wondering if my audio sync issue that I'm having is related to this...
Other than my audio & video not being in sync when I record in OBS, I also experiencing audio stuttering when I monitor the BlackMagic Line Input either via Windows Sound settings' "Listen to this device", recording in Audacity or using OBS' monitoring.

I still need to confirm 100%, but I believe that my audio & video is in sync when I record with BlackMagic Media Express.

I used to be able to record my Blackmagic Audio in Audacity without any issues, but I had to have OBS opened to simply activate the BMD capture card. Too many things changed on my end over the last few months to pinpoint what caused it, because I think I did Windows updates, Blackmagic Desktop Video updates & OBS updates.

I have 2x Windows computers with different BlackmagicDesign capture cards, both of which get their video (with embedded audio) from a ATEM Production Studio 4K, where it get its audio input from XLR with the audio already delayed before reaching the ATEM.

PC1:
  • Windows 10 2H1, OBS 27.0.1, BlackMagic Desktop Video 12.1 driver
  • i5 7400 @ 3GHz, 8GB RAM, GTX1050 2GB
  • OBS Blackmagic Device input source: Intensity Shuttle USB 3 (Input: HDMI, Audio: embedded, 1080i50, No buffering)

PC2:
  • Windows 10 2H1, OBS 27.0.1 (running as Admin), BlackMagic Desktop Video 12.1 driver
  • i7 920 @ 3.2GHz, 10GB RAM, GTX460 1GB
  • OBS Blackmagic Device input source: Mini Recorder 4K (Input: SDI, Audio: embedded, 1080i50, No buffering)

Yesterday I've tried an older version (Nov 2020) of Windows 10, and also Desktop Video 11.7, but I still had audio stutters.
So my next steps might be to see if I can roll back to Desktop Video 10.11.4 or 11.2.

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