Live broadcast : Frame issues & audio-lag

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YerpOno

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  • Joined: Sun May 02, 2021 1:17 am
  • Real Name: Pierre Lauret

Live broadcast : Frame issues & audio-lag

PostFri Jun 24, 2022 7:21 am

Hello,

I hope I post this in the correct section. If not, I'm really sorry.
I work in a music venue and since the corona situation started, we are broadcasting online every of the event we host. It's been two years now and despite some of the few issues we encountered, our broadcast system is having trouble recently.

On OBS the video seems to have some lagging issues (not really when I check the broadcast) and sometimes we also have some issues with sound that will be a bit late (depends on the event even though the system is the same).

First of all, I think it would be the best if I describe our broadcast system. (Our mother company bought the materials before I could check so it would be hard to change it now.) I will do it in order from the camera to OBS.

Camera 1 : HDR-CX470 (1080p, 30fps. HDMI)
Camera 1&2 : HDR-CX470 (1080p, 30fps. HDMI to SDI with converter : Blackmagic Design Microconverter SDI to HDMI)
Camera 3 : HDR-AS300 (1080p, 30fps. HDMI to SDI with converter : Blackmagic Design Microconverter SDI to HDMI)
Camera 4 : Sony FDR AX45 (1080p, 30fps. HDMI)
Camera 5 : PXW-Z90 (1080p, 60fps. SDI out)

Switcher : ATEM Television Studio Pro HD (Video format : 1080p, 59.94fps | Multi-view : 1080p, 59.94fps)
Recorder : Blackmagic Design Hyperdeck Studio Mini (H264 HIGH. SDI)
Monitor : LG27MK430H 1080p 60Hz HDMI (Multiview)

Blackmagic Design Ultrastudio Recorder 3G

PC : MacBook Pro 13inch 2020. macOS Catalina 10.15.7. Processor 2GHz Intelcore i5. Memory 16GB 3733MHz LPDDR4X. Graphics Intel Iris Plus Graphics 1536MB. Flashstorage 500GB (430,41GB still empty)

OBS :
Output : Streaming encoder x264. Bitrate 4000kpbs. Audio bitrate 192.
Audio : Stereo 44,1KHz
Video : Base 1920x1080, Output 1920x1080, Common FB Values : 29,97fps


It's a little bit long sorry. But I'm pretty sure that the issues are coming from the fact that the fps are not the same. Cameras are 30/60fps while the switcher and OBS are 29,97/59,94fps.
The problem is that if the switcher is not on 59,97fps, the cameras and monitor are not showing. The switcher is not capable to be set on 30 or 60fps. OBS can be set on anything but as the switcher is on 59,94fps, I put it on 29,97fps (59,97fps would be too heavy for the broadcast). The cameras are not capable to be set on 29,97fps or 59,94fps.
I might be mistaken but I believe that if I would be able to change the switcher into a 30fps or 60fps mode and then put OBS on the same setting, the issues would disappear. Is there any plugin or converter or something to allow me to set my switcher into a 30fps mode ?

When the issues happened, the CPU were up to 50% when broadcasting. I believe it's because the computer was converting the image coming from the switcher. Then I upload it to Monterey and it became quite a trouble for a lot of reason and clean and reinstall everything as new on Catalina. The CPU are not going to 50% anymore but I believe that soon the CPU, frames and audio-lag will be back with the PC becoming "dirty".And I believe everything is coming from this frame conversion. How can I fix it ?

Thank you,
Sorry my message is quite long. I hope I forgot nothing and that everything is understandable (not native in English). If you need any precision or more informations, please ask me.

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