Blackmagic Forum

Hi all,

I'm Benjamin from Octopuce, Paris, and we use (a lot) BlackMagicDesign Decklink SDI & HDMI/Analog cards to acquire video and audio for FocusGroups.

We were using Linux Kernel 3.2 with DesktopVideo 9.5.3 and bmdcapture from a 2013 version of bmdtools ( https://github.com/lu-zero/bmdtools ) without any problem.

We recently upgraded to Linux Kernel 3.16 with DesktopVideo 10.5 a17 and bmdcapture's latest commit. (Everything shall be upgraded since they depend on each other).

As a result we had to upgrade our BlackMagicDesign Decklink HDMI from firmware 0x1e to 0x25.

Since then, and with perfectly random results, we have an inversion of the left and right audio channels when recording. Sometime they are inverted, sometime they are not. Having left and right stable is particularly important to us since one channel have the original language and the other have the real-time translated one...

The randomness of it is quite perfect: half the time, and without a need to reboot or poweroff the hardware: each time we stop / start a bmdcapture process, the left and right are randomly inverted or not...

So the question is

- does anybody here from BMD or others know about such problem already?
- If not, does any of you have an idea about how we could fix this?
- In any case, what can we do (as of now we just downgraded everything back to 9.5.3 and 3.2, but that's not a viable solution...)

We are willing to help BMD debugging this if needed, eg by testing other version of desktopvideo between 9.5.3 and 10.5 if needed, or future versions in our lab.

Thanks for any help you may bring us!

regards,

Benjamin Sonntag

late digging ... nevertheless.

I got exactly the same issue: L and R channel inversion which occurs randomly on the 4 XLR inputs of my decklink.

Details:

win 10 pro x64
desktop video 10.6.2 (latest version)
decklink studio 4 K

This is quite problematic for us too.
I'll file a bug and report back o nthe htread if there are news.

Greetings,
I just discovered this myself with Decklink 4K Extreme 12G.

Desktop Video Utility 10.5
Media Express 3.4.1
SDK API 10.5

Problem for me is that I'm testing a device with left and right output. This condition would be considered a failure for our device as it could indicate something was wired incorrectly.

Any updates on this issue?

Respectfully,
Ed

Greetings All,
Still exhibiting the same behavior.

Is this a bug or what?

It is about to become a "show stopper" for the project I'm working on.

Any info or insight would be very much appreciated!

Ed

Greetings All,
Well I came in this morning to the XLR/Analog audio being completely munged through the Decklink card.

Tested it coming out of my DUT (the source) and it was fine.

Both my custom app using the SDK and the Blackmagic Media Express exhibit the same behavior.

Is this a known issue?

Ed Dow wrote:Greetings All,
Well I came in this morning to the XLR/Analog audio being completely munged through the Decklink card.

Tested it coming out of my DUT (the source) and it was fine.

Both my custom app using the SDK and the Blackmagic Media Express exhibit the same behavior.

Is this a known issue?

yes I posted a ticket and the level 1 support tech reproduced the bug; he filed the bug to the driver dev team .
So hoprfully they will solve the issue.

Greetings Viet,

Thanks for the response and filing the bug report.

Respectfully,
Ed

Greetings All,
Talked to support to get ETA on fix.

They confirmed there was an issue; however, only for Linux.

I was using the 10.5 BMD drivers/desktop video utility and it was suggested to upgrade to 10.6.8.

I've upgraded and have not been able to reproduce the issue....yet. Let's hope it stays that way.

Hello everyone.

This bug seems to have reappeared, at least it's present in 10.11.4a9 of desktopvideo / BlackMagic driver for Linux.

exactly the same behavior : when capturing analog audio on 2 channels, the Left and Right are sometime randomly inverted.

I saw that bug with both bmdtools from https://github.com/lu-zero/bmdtools and the latest ffmpeg with decklink support (at commit 8a1fc95840)

Does anyone from Blackmagic know how to push that up to their software driver team?

thanks !