Blackmagic Forum

After having gotten off the phone with Blackmagic customer support, their answer to all of my issues was: sorry, we know about it and are working on it. Which is fine, but that means that their product doesn't do what it says it will do and I have no idea when it will work.

Off my soapbox, on to the problems. Does anyone know of work arounds for these issues?

1. Audio sync. I am running 2 Canon C100s into the Web Presenter and one XLR from a mixer. It sounds good, but there is no audio sync with Facebook Live. Sometimes it's better than others, with seemingly no reason for the improvement. I have not tried sending the audio into the cameras. Currently those audio inputs are set to off. I'm using OBS on a Mac so my next step is to try delaying the video in that program. Does anyone know how long to delay in milliseconds or is it a trial and error type of thing?

2. Cutting to black when switching between 1 and 2. It also drops audio completely during the blackout, even though the audio is going into the XLR port and is not associated with the cameras. I've seen that this is a problem with using different sources, but I'm using 2 identical cameras. Anyone else have this happen?

With these issues, it makes the product pretty much useless. The audio drift is very noticeable and the blackout is problematic. Who is using this thing and how are you making it work properly?!

I am having trouble with audio sync also.
I set the audio delay to 100 ms then test.
I added a metronome app to my phone that gives visual and audio sync, then test before the event.
lower bitrate about 1000Mbps helps hold sync on average network.

The cameras must output the exact same setting Ex: 1080i@59.94 it will give a clean dissolve with no audio drop.

I wonder if I sent the audio feed into one of the cameras, I would get less sync issues? I had assumed that when it cut to camera 2, the audio from camera 1 would drop out.

As to the dropouts, my cameras are exactly the same with the same frame rate going out, but Web Presenter sees them both as 60i even thought It is set to 24p on both cameras. The support guy said that was a bug that hadn't been fixed yet. So even if the frame rate is wrong, they are both set to the same one.

I'm assuming you did the Firmware update. I too was having the same issue, but it was just the audio dropping out (no black). I have decided to use the Blackmagic HD Switcher inline before the BM Presenter. I just received the switcher today so give me some time to see if that works. I was planning on adding the switcher eventually since I need 3 cameras and computer input.

As far as audio delay, I am currently adding a 50ms delay in OBS and it's real close, maybe not exactly but close enough for now.

Still testing.

Carol, are you sure the C100s are actually outputting 1080p24, originally, the C100 would only output 1080i from HDMI/SDI, regardless of the camera settings. You can test this with a monitor connected to the cameras to get what the camera output actually is.
Cheers

You're right, it is outputting 60i. I had originally run one into a PIX-E7 to get the SDI out, but the PIX was smart and was converting it to 24p. So instead I got an HDMI to SDI adapter and now they are both saying 60i and I don't have the issue with dipping to black. But my audio is still really out of sync.

Mike, where are you adding this 50ms delay in OBS? at the mixer properties or are you adding a filter to the camera and doing it there? I'm still trying to figure this OBS software out.

Thanks!

Yes, as I thought,mthe Canon is adding a 2:3 pull down to the 1080p24 signal to get a 1080i60 output, which the Pix was set to convert back to 1080p24. For streaming, 1080i60 should be fine.
Cheers

Were you able to resolve this issue? I am experiencing the exact same thing.

No, I never resolved the problem, despite experimenting with different audio delays. The sync would drift in both directions during the Facebook Live. I'm looking for other solutions due to the Web Presenter's audio issues.

I'm running into a similar problem. Sound is 2-3 frames ahead of the video when connected to Webinarjam Studio. Video is coming in via HDMI from a Nikon D4 and the Audio is coming in through the XLR from an Allen & Heath ZEDi10 mixing board. Blackmagic... is there a way to add an audio delay option to the menus in a firmware update.

No there is not.. On all BMD products you have to create the audio delay yourself!
So get a different audio mixer that supports delaying the outputs.. (most digital mixers will do) or get a hardware box that will add a delay..

I am having the variable sync issue described above also. I have delayed the audio through a digital mixer, did a test on facebook live and it was perfect. Then during the event, the audio was variably in and out of time over the course of the broadcast. I’m running hdmi camera into ATEM TVS HD then sdi into webpresenter and macbook pro with OBS to facebook live. Had to add another 100 ms delay in OBS to get it right too so there must be some additional sync issue caused in the webpresenter converting the sdi input to 720p webcam input in OBS.

I turn buffering on for each video source.
I add 250ms audio delay in audio mixer in OBS.