Two Blackmagic Web Presenters on one Mac/PC

Hello,

has someone already tried if a PC or Mac can handle two Blackmagic Web Presenters at the same time? And does anyone knows if it's possible to request a MJPEG (or H.264) feed from the device, which is, according to my information, necessary to operate several HD Webcams at the same time on one PC or Mac, regarding to USB bus speed limitations. I can not find such codec informations on technical specs.

I'm only wondering if two Web Presenters could be a replacement for something like the AJA IO 4K to get more HD sources on one Laptop with Wirecast or vMix. Of course with the drawback of manual switching between the two soruces on every device.

Thanks and Regards.
Andreas

No, the new Web Presenter only outputs a 720p signal. To get h.264, you would need to add a h264 ProRedorder between the Presnter's SDI out and the PC. At that point, you might as well get the new ATEM TVS HD and add the h264 recorder to its output, and have it to handle your multiple cameras switching.

Hello Denny,

thank you.
My question was related to the video codec within the usb data feed.
Webcams usually uses some kind of video format to communicate with the Computer (YUY2, H.264, MJPEG).
For example, within vMix you can choose a codec for communication with the webcam. When the webcam supports MJPEG for example, the computer requests the MJPEG video signal. Because the Web Presenter acts like a webcam, I wonder which codecs are available for communication between PC and Presenter. This could indicate whether two devices are possible on one computer or not.

Regards
Andreas

From,what Grant said in his presentation, the Web Presenter's output is a 720p HD video signal with the frame rate set to match the computer/streaming required fps rate. For example 720p30 for Facebook live.
The Presenter has down converter to take the incomeing signal and convert it to 720p at a variable frame rate depending on the streaming software requirements and internet bandwidth available. The computer see the Presenter as if it were a "WebCamera" if this helps.
Cheers

Denny,
unfortunately, this does not help me directly.
But thank you very much for taking the time.
I have sent my question to BM Support. Will see what the answer is.

Do you know the quality of teranex converting? Especially for 50fps to 30fps or 60fps to 25fps. From software based solutions I know that the output can be a bit choppy or jerky.

Looking into the users Manual you can see, that all video outputs are before conversion !

But ther is no dedicatet Information about the used dataformat at USB-out - only, that the Computer detects the unit as 720 Webcam. So what normally is the data-format für USB webcams ?

As far as I know YUY2 (uncompressed) is the most common format for webcams.
But like I mentioned before, on some models you can choose others like MJPEG or H.264.

Thomas, what exactly do you mean with "all video outputs are before conversion!"?

Thanks
Andreas

Manual, page 5

You might notice there is both loop SDI and loop HDMI outputs and you can use these outputs
if you want to connect Web Presenter in line with a video connection to other equipment. For
example, you could loop the SDI output to a deck or monitor or you could connect Web
Presenter in between a computer’s HDMI output and the HDMI input of a video projector.
There is also a program SDI output and this will output video after the SDI and HDMI switch, but
before the down conversion to 720p video. This SDI program output is the same resolution as
the video inputs, so is perfect for connecting to a deck for master recording.

So only the USB out will be converted to 720p - not any SDI or HDMI-out.

Ah ok, now I understand what you mean.
I actually meant the USB output with my teranex converter question. Do you have experience with the quality of teranex converting? Especially when converting from 50p to 30p or 60p to 25p, So on different standards?

No, but I'm interested in a versatile solution for my sports streamings, and the Web Presenter may be such a solution.

OK, I understand your question. We know it is not H.264, more likely YUY2, which is the most common video codec for consumer web streaming, like Facebook, etc. But, this is not documented very well by BM. Also the output codec is not selectable.
Cheers

I got response from support.
Output codec via USB is MJPEG.
So it is more likely that multiple Web Presenters can run on one PC/Mac at the same time.

OK, good. BM is being responsive, and thanks for the update.
Cheers