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Several audio feeds with ATEM 1 or 2 - how to?

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Ludovic Chale
Several audio feeds with ATEM 1 or 2 - how to?
on Feb 26, 2012 at 6:15:41 pm

Hi everyone, I am just starting in the video/audio streaming field and sorry if I sound like a noob. I would like your opinion on the following:

For a project involving 8 HD/SDI feeds running in parallel, I am thinking about getting the Blackmagic ATEM 2 switcher which has 16 inputs and enough outputs to send the feeds to PCs each through SDI. Unfortunately before I acquire all of that, I am still clueless as to how to get 16 different AUDIO channels in that switcher or in a different way. 16 channels because each video feed has two independent audio channels (l & r).

My knowledge is quite limited and I know the audio is stripped away from the SDI input, so I am still looking for a working solution to get the sound in. At the moment what is the most efficient format (XLR?AES?) to capture that sound?


Thanks
ludovic


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Mike Squires
Re: Several audio feeds with ATEM 1 or 2 - how to?
on Feb 26, 2012 at 8:35:18 pm

You would need a 16-channel audio mixing board. Think of the SDI as being video only, and whatever your playback is (camera, VTR, PC), the audio needs to be fed to the mixer. Then connect the output of the mixer to the ATEM.

You also need to determine if your source is outputting digital or analog audio. This will determine the type of audio mixer you need, or if you need any A/D, D/A converters (some mixers take both digital and analog).


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Ludovic Chale
Re: Several audio feeds with ATEM 1 or 2 - how to?
on Feb 27, 2012 at 3:03:08 pm

Thanks Mike, however the Atem has an analogue inputs that can be used to embed only 2 channels of audio into the program output over SDI. So I guess there is no way to have 4 different audio channels streamed in parallel in that case (imagine two matches being played at the same time).


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Mike Squires
Re: Several audio feeds with ATEM 1 or 2 - how to?
on Feb 27, 2012 at 3:25:27 pm

That's exactly what an audio mixer does. It'll mix however many channels you want into just 2. Here is an example:

http://www.bhphotovideo.com/c/product/637952-REG/RDL_EZ_MX4L_EZ_MX4L_Stereo...


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Justin Strauber
Re: Several audio feeds with ATEM 1 or 2 - how to?
on Feb 27, 2012 at 4:56:57 pm

You would need a real audio mixer to do what you're trying to do, though I must admit i'm not entirely sure what you're trying to do.

Anyway, in regards to 16 sources mixed down to four channels of output, you would need an audio mixer with at least 4 'busses', so that you can assign input faders to the different busses. That way you could take four inputs and route them to one output (if you're doing say, four mics down to one output)

To get the audio to the board you would either need to run the audio separately from the cameras, or purchase audio de-embedders to go from SDI-embedded to analog. Alternatively you can try and find a mixing console with SDI inputs, but that may not be cost effective.


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Ludovic Chale
Re: Several audio feeds with ATEM 1 or 2 - how to?
on Mar 2, 2012 at 9:29:02 am

Thanks Justin & Mike, after a little bit of investigation I know now what we will be provided with: 4 HD SDI cables with 4 embedded audio channels in each. I will not need an ATEM in fact since the switch will be handled beforehand.

From your posts I understand that I will need to get a sound mixer if I want to split these 4 audio channels into 2+2. Basically 2 sources will be original + 2 translations and basically I need to setup two different streams per SDI (one with the original, one with translations).

I hope it makes sense, in any case I am thinking of - as you suggest - de-embedding into a mixer with 2 outputs to leave me with these channels separated.


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