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Decklink Consumer: Audio disappears after some time (buffered-audio graph goes to zero) #24

Open leftearsons opened 5 years ago

leftearsons commented 5 years ago

Hello all,

After more than 6 years of using CasparCG professionally without any (unsolvable) issue, a really strange issue has come up for a new channel i am building, which relates to SDI audio output when using Decklink Consumer in 720p5000 and 1080p5000 modes.

I will first show some screenshots of Diagnostics window that depict the problem and then i will explain the setup/configuration used for further investigation and help.

Below you can see the diagnostics from the real project setup when the audio issue has occured The channel's output mode is 720p5000 and has the following loaded:

issue with graphics and multiple sdi inputs

As you can see the buffered-audio graph is at the bottom. When this starts to happen, the SDI output has no audio! At the beginning when starting the server and loading all layers, everything is ok regarding the output audio. It is a matter of time (at random point) for the problem to begin. Once it happens though, it does not fix by it's own. I have to note that audio is present when system-audio or even File consumer are used. It is only the SDI output that has no audio.

The same problem occurs even if i only load 1 Decklink Producer and 1 Decklink Consumer of the same video mode (720p5000 or 1080p5000) without any other layers used. Below you can see the Diagnostics snapshots for both 720p5000 and 1080p5000 cases, before and after the problem shows up.

Below you can find some facts that describe the issue in more detail:

The specs of the Server used are the following: CPU: i7-8700 @ 3.2GHz RAM: 16GB HDD: 2x 250GB SSD (Raid 1) OS: Windows 10 Pro Decklink: Quad 2 GPU: NVidia Quadro P2000

Is this a known issue or has anyone else dealed with it in the past? I did not managed to find any other issue related to this. Is it the Decklink Driver? The OS (Windows 10)? The Quad 2? The GenLock or it's type? Any combination of them all?

Many thanks and kudos to Devs and the CasparCG community!

5opr4ni commented 5 years ago

Just a first thought, have you tried Trilevel sync, later decklink drivers require that type of sync to work in HD.

/Olle

leftearsons commented 5 years ago

Thanks for your reply Olle.

No, i have not tried Trilevel sync, yet. I just wanted to have an expert response first, since the sync type requires some effort on our side and could cause issues with other existing channels. This is exactly the reason that i tested 10.8.3 Decklink driver, which is said to have a stable behavior with Black-Burst sync type. In any case, thanks for sharing this information. I didn't know that (latest) decklink drivers require Trilevel sync type in order to work in HD. Is there any possibility that Trilevel genlock type switch, will cause any issues on our existing PAL channels?

Thanks, Lefteris

5opr4ni commented 5 years ago

Hi

As i said, this’s what first popped up in my head. I am not sure regarding implications regarding PAL. Sorry

/o

leftearsons commented 5 years ago

It's ok. In any case, i have got something new to try! I will do some further research on GenLock Types and have a try in our test environment. Will let you know about the results.

Phillipjacob commented 3 years ago

@leftearsons did you find a solution to this problem?

leftearsons commented 3 years ago

Hi @Phillipjacob. I managed to find a workaround to bypass the problem, but I don't think it can be considered as a proper solution.

Unfortunately due to some technical limitations in our setup, we did not have the chance to test the trilevel sync that @5opr4ni proposed. The PAL genlock is still being used. What I am doing instead, is to periodically reload the SDI consumers (every 30 minutes for 1080 outputs and every 60 minutes for 720 outputs), which by the way does not create any flickering on the channel output, making it invisible.

Hope this helps!

Phillipjacob commented 2 years ago

Hi @Phillipjacob. I managed to find a workaround to bypass the problem, but I don't think it can be considered as a proper solution.

Unfortunately due to some technical limitations in our setup, we did not have the chance to test the trilevel sync that @5opr4ni proposed. The PAL genlock is still being used. What I am doing instead, is to periodically reload the SDI consumers (every 30 minutes for 1080 outputs and every 60 minutes for 720 outputs), which by the way does not create any flickering on the channel output, making it invisible.

Hope this helps!

Hey @leftearsons Okay thanks. We'll test Tri-level by the end of summer. Then I'll let you know the result. How do you reload the SDI consumers automatic?

leftearsons commented 2 years ago

Hi @Phillipjacob. Thanks for the update. Will look forward for your Tri-level results.

The SDI consumers "reloading" is being done by simple re-adding any existing Decklink consumer on the channel. I am using CasparCG v2.07 (have not tested on later versions though), which by re-adding the same consumer, simply resets it's state without affecting the output content (flickering etc).

standekker commented 2 years ago

I am running into the same issue after increasing my setup from 2 to 3 channels all running in 1080P2500. After a few days, the audio seems to drop out and I am also seeing the same flatline on the buffered audio after the audio is gone.

I ran into this issue https://github.com/CasparCG/server/issues/1312 which points to either sync issue when using an internal keyer or performance issues causing the audio buffer to underflow and never recover. No solution yet but it seems that increasing the specs might fix the issue.