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Blackmagic HDMI to SDI for audio

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Camden Bucey
Blackmagic HDMI to SDI for audio
on Jan 16, 2012 at 5:16:54 pm

I'm trying to convert analog audio to AES/EBU over SDI output. I have an ATEM TV Production studio and would like to get the audio from my mixer into the switcher. Is this possible with the Blackmagic HDMI to SDI miniconverter? I cannot seem to get it to work with a variety of settings.


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Jeff Hartman
Re: Blackmagic HDMI to SDI for audio
on Jan 16, 2012 at 9:39:15 pm

[Camden Bucey] "I'm trying to convert analog audio to AES/EBU over SDI output. I have an ATEM TV Production studio and would like to get the audio from my mixer into the switcher. Is this possible with the Blackmagic HDMI to SDI miniconverter? I cannot seem to get it to work with a variety of settings."

That's not going to work for a number of reasons. For one thing, the ATEM doesn't pass audio from the SDI inputs through to the output; its internal embedder replaces whatever would have come from the selected input. Second, you can't connect the SDI-to-HDMI converter to the ATEM's AES input, because AES audio is a totally different sort of data from SDI video.

The most straightforward solution is to use a Blackmagic Audio-to-SDI miniconverter to take in the analog audio from your mixer and the program video from the ATEM; the miniconverter's output will contain the embedded audio. The converter doesn't care about the video format, and requires little to no setup to make it happen seamlessly.

Regards,

Jeff Hartman
Engineering Project Manager
Newport Television, Northeast


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Camden Bucey
Re: Blackmagic HDMI to SDI for audio
on Jan 17, 2012 at 12:26:53 am

Jeff,

Thanks for the reply. After further research, I've since purchased a Behringer SRC2496 24-Bit/96 kHz A/D-D/A & Sample Rate Converter. From what I read, this should allow me to get my analog audio into the ATEM TV Production Studio. I also ordered the Behringer Shark FBQ100 as a delay line to fix any audio/video sync issues. Should this do the trick?


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Jeff Hartman
Re: Blackmagic HDMI to SDI for audio
on Jan 17, 2012 at 2:19:10 pm

[Camden Bucey] "Thanks for the reply. After further research, I've since purchased a Behringer SRC2496 24-Bit/96 kHz A/D-D/A & Sample Rate Converter. From what I read, this should allow me to get my analog audio into the ATEM TV Production Studio. I also ordered the Behringer Shark FBQ100 as a delay line to fix any audio/video sync issues. Should this do the trick?"

Sorry... I reflexively cringe when I see "Behringer" -- much of it is essentially musical instrument store grade stuff, and there are other issues with the company that don't really bear on your question. But we'll set that aside.

I still think that the Blackmagic Audio-to-SDI MiniConverter is a better solution: it integrates the analog to digital converter and embedder into a single small package; you don't need to worry about sample clocks, because the ADC is automatically locked to the video. This eliminates a whole host of problems right there. You also don't need to worry so much about gain structure, and the system complexity is vastly lower.

Delay shouldn't be a terribly serious issue, especially if you can genlock your cameras and the ATEM to the same reference; if you do, the video delay will be on the order of tenths of milliseconds; worst case without shared reference is about 33 milliseconds, which is essentially imperceptible. If you still need delay, there are better units -- Rane, for example, makes several -- that aren't coupled with the sorts of aggressive filtering that are intrinsic to a feedback processor like what you bought.

One minor point: the equipment you mention handles the AES audio as a balanced signal with an XLR connector, but the ATEM's AES input expects an unbalanced feed on BNC. You should have a matching transformer to make the necessary physical and electrical changes -- something like a Canare BJC-XJ-TRB or Neutrik NADITBNC-F would be appropriate.

Still, I am a fan of simplicity... the fewer active devices you have, the more likely the system is to work reliably, and take less time and effort to troubleshoot.

Regards,

Jeff Hartman
Engineering Project Manager
Newport Television, Northeast


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Camden Bucey
Re: Blackmagic HDMI to SDI for audio
on Jan 20, 2012 at 7:11:58 pm

I have all my gear connected, but I'm still not getting an audio signal in Blackmagic Media Express. I have the balanced XLR outputs of my mixer going into the Behringer SRC2496. I'm getting levels on the Behringer. I have the AD/DA conversion turned on and set to AES/EBU output. I'm running the device's digital XLR output to a Canare BCJ-XJ-TRB impedance transformer. From there I run BNC into the AES/EBU input on the ATEM TV Production studio. What am I missing?


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Jeff Hartman
Re: Blackmagic HDMI to SDI for audio
on Jan 23, 2012 at 3:39:29 pm

[Camden Bucey] "I have all my gear connected, but I'm still not getting an audio signal in Blackmagic Media Express. I have the balanced XLR outputs of my mixer going into the Behringer SRC2496. I'm getting levels on the Behringer. I have the AD/DA conversion turned on and set to AES/EBU output. I'm running the device's digital XLR output to a Canare BCJ-XJ-TRB impedance transformer. From there I run BNC into the AES/EBU input on the ATEM TV Production studio. What am I missing?"

Is the Behringer set for 48kHz sample rate? That's what the ATEM is going to expect.

Jeff Hartman
Engineering Project Manager
Newport Television, Northeast


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Camden Bucey
Re: Blackmagic HDMI to SDI for audio
on Jan 24, 2012 at 9:39:22 pm

It turned out my Behringer SRC2496 was defective. I received a replacement unit and it working exactly as I expected.


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Jeff Hartman
Re: Blackmagic HDMI to SDI for audio
on Jan 25, 2012 at 1:34:56 pm

[Camden Bucey] "It turned out my Behringer SRC2496 was defective. I received a replacement unit and it working exactly as I expected."

Good for you!

(Defective Behringer product... working as expected... I won't go there. Evil grin...)

-- Jeff


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