Blackmagic Forum

I have a question that is not clear from the documentation
If I have an existing HD SDI with the "normal" two channels of audio embedded, and I want to add 8 more channels via the Audio-Sdi mini converter using aes/ebu, Do I have to use 8-16 inorder not to overwrite the 1-2, or will it wipe 1-2 out when it adds 9-16.
If I want to just use this a input to the audio mixer in the ATEM (feeding it via a mixer with an aes/ebu output so the audio is properly mixed, ) then 1-8 can be used Or does the Atem ONLY look at inputs 1-2 on the imbedded audio stream via the SDI imput

Second question If I want to add 8 channels to an input on the Atem via sdi, I am assuming that it must contain a video stream?
Thanks
Sharyn

1. I think you will need to set the Audio -> SDI converter to channels 9-16 since in "1 - 8" mode you would only be able to embed 6 channels (because the first TRS jack would be in bypass mode to preserve the already embedded audio.

2. The ATEM only accepts 2 channels of audio, it will ignore the other channels.

3. The Audio -> SDI converter MUST have a corresponding video input to add the audio channels to, otherwise it won't do anything.

Chad wrote:3. The Audio -> SDI converter MUST have a corresponding video input to add the audio channels to, otherwise it won't do anything.

Why do people keep saying this? the audio to sdi converter WILL generate a stream without a video input present...i use these to add intercom to HD-SDI feeds and the intercom audio will pass with no video present. there is a very brief interruption of audio when video is added or removed while the device reclocks

so to further clarify, If I want to have all 16 sdi audio channels embedded I would have to concatenate to audio to sdi bmd converters, selecting 1-8 in one and 9-16 in the other, and if i want to keep the first two already embedded audio channels, just do not connect up the first aex/ebu?

I understand that the Atomos Samurai will only record 12 channels of sdi embedded audio. I see that teh hyperdeck familly will record all 16 but there seemed to be people having an issue with channel 15-16 only have noise?

what I am looking at is being able to have 16 independent audio channels in the sdi feed to be recorded so that when the final video file in brought into the NLE (Sony Vegas) all the audio tracks will be imported at the same time. The Idea is that each of the audio tracks will have been controlled via a digital mixer, but that the final mix can still be done in the NLE,

Sharyn

let's take this explanation further. HD-SDI embedding happens in groups of four. most cameras only add two active channels, but there is bits generated for four channels at a minimum. the BMD Audio to SDI unit will REPLACE a group of four (analog) or eight (AES) channels in the stream as it passes through the box. Any audio that exists before the box will be discarded. This is all configured with the DIP switches on the unit.

If you want to keep your existing 2ch camera audio in your example, you either need to leave the first quad alone and let it pass through, or de-embed it it and add it with other channels back into another embedder. In other words if you embed 1-8 and leave the first pair disconnected on the BMD, the first two channels from your camera will be replaced with silence. Yes, you can combine several of the BMD converters to end up with a full 16 channel audio stream.

That is a ton of effort to do something that you can do in different ways, a lot easier. My question is why? Why go to so much effort to put the audio into the SDI for use in post? If you are going to use it in post, you can get this audio in many ways that do not involve over complicating the SDI signal (and possibly screwing up your entire recoding in the process.)

Buy two of these. You'll be glad you did.
http://www.bhphotovideo.com/c/product/8 ... ORDER.html

Voila! 16 channels of audio for post, no screwed up video, no ton of converters and adapters, no set of 8 wall wart power supplies causing you grief. What is left is 16 good audio channels on an SD card with adjustment levels and time code sync input. It also has mix down outputs you can send over to your ATEM for use like a mixer. Sync up the time code in post, and you are rocking and rolling without all the silly effort of embedding.

This is your audio mixer as well as your 16 channels of separate recorded audio, it is easy to sync up in editing, and gives you much better control over the record levels. If you want to record audio, use audio gear to do it.

You know you are right sometimes the simplest solution works best
I have a HD24 that would probably do the trick also
Thanks
Sharyn