Question / Help Audio Lag with Youtube Livestream

[JadBJad]

Hi there,


I have the following question/problem with audio lag while livestreaming:


Setup:

I had to run a Livestream on YouTube. The livestream included some pre-produced videos like in a TV show.
As I was not in my normal environment (with extra high upstream rate), I decided to go for 720 on YouTube and produced the videos with 1280x720 and 4000 kbit/s on average; 160 kbits for Audio 48 and AAC.


Then I created all the media sources (Videos + pictures for the fades). In a test run it all worked fine.

At my final location, I run a test again with a private livestream. Here I noticed that 1 Video had an audio lag. As it was the only one, I produced it again. All videos work perfectly in a video player and when I play them in OBS.


The audio problem during the livestream:

While running the livestream I noticed that two videos had an audio lag meaning that picture and voice are not in sync.

What did I do: I showed the cross-blend picture and changed to the next video in the source view (studio view), and clicked "Transition"- I did it the same way with all videos. With the two videos that had the audio lag I noticed that for about 1 second I hear the sound from the video at 10 seconds, then the video starts form the beginning and has the audio lag.


My question are:
What could be the reason for the audio lag?
The way I produced the videos?
The way I used OBS Studio?

Why do some videos have the audio lag some not?


I appreciated any help, as I need to do this kind of livestream setup soon again.


Thanks

 

[Mroczny_Gustaw]

make sure obs runs on nvidia card not intel like it is now
does this laptop have 2x 750m in SLI? if yes you may try display capture to take advantage of sli but this method is less efficient than game capture and may introduce stutters in output material. for game capture you may try "multi adapter compat" in game capture source. if it wont help much disable sli
install CoreAudio, info in my signature
always use vsync in game

 

[JadBJad]

Thanks a lot.
I installed Core Audio, and in a short test the lag seems gone.
I will need to do a longer one again.

Can you/someone tell me how to make OBS run on the NVidia card. I cannot activate the option in settings and this card and (as I read in another thread) it should definitely qualify.

 

[Mroczny_Gustaw]

something like this

From NVIDIA Control Panel
3D Settings->Manage 3D Settings
Tab "Global setttings"
Preferred Graphics Processor
Select : High performance NVIDIA processor

or on exe basis on programs tab

 

[JadBJad]

Thanks a lot. I did that.

But should I not see that in advanced settings below DirectX where I should be able to choose a card?

I asked that in my first thread here with a different Laptop. The resons was that it was an older NVIDIA M card (could have done it manually following a tutorial to go back to an older driver).
The 750M (no it is no 2x 740M SLI) should work fine.

thanks and best regards

 

[Mroczny_Gustaw]

But should I not see that in advanced settings below DirectX where I should be able to choose a card?

this option is not coded yet