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View Full Version : NDI, Dante, an long-distance audio



JGale
02-16-2018, 07:57 PM
Hi guys,

Here's a crazy idea I've been thinking about for a while. Is is realistic to mix the broadcast audio 100 miles away from a concert?

Dante is good for audio over a network, but doesn't like the Internet. NDI is good for video over network, and can handle video over the Internet. As far as Google and I can tell, it also has a high limit to the number of audio channels it can send in a single video feed. Here's the signal flow that I'm contemplating, for running gigs in the next state/province over:

Video feed is mixed for broadcast, encoded, and sent to the broadcast server. No NDI involved, and the upload speed needed is under 10Mbps; completely doable in most places
Audio inputs are split from the band/FOH, and sent over Dante. All the channels are patched from Dante to an NDI output, sending the smallest video resolution NDI possible (144p24, or something smaller) and just a black screen. The NDI feed is sent over the Internet back to home base, and NDI is used exclusively to send all the audio channels, where they're used to mix the broadcast audio output. The audio is sent to the same broadcast server, merged with the encoded video, and sent to the live audience.

Questions:
Is this a good idea?
How many audio channels can NDI support?
What's the smallest resolution video that can be sent?

PIZAZZ
02-19-2018, 08:31 AM
Hi guys,

Here's a crazy idea I've been thinking about for a while. Is is realistic to mix the broadcast audio 100 miles away from a concert?

Dante is good for audio over a network, but doesn't like the Internet. NDI is good for video over network, and can handle video over the Internet. As far as Google and I can tell, it also has a high limit to the number of audio channels it can send in a single video feed. Here's the signal flow that I'm contemplating, for running gigs in the next state/province over:

Video feed is mixed for broadcast, encoded, and sent to the broadcast server. No NDI involved, and the upload speed needed is under 10Mbps; completely doable in most places
Audio inputs are split from the band/FOH, and sent over Dante. All the channels are patched from Dante to an NDI output, sending the smallest video resolution NDI possible (144p24, or something smaller) and just a black screen. The NDI feed is sent over the Internet back to home base, and NDI is used exclusively to send all the audio channels, where they're used to mix the broadcast audio output. The audio is sent to the same broadcast server, merged with the encoded video, and sent to the live audience.

Questions:
Is this a good idea?
How many audio channels can NDI support?
What's the smallest resolution video that can be sent?

As someone that has been doing quite a bit of mixed remote production the last few years, there are some small details that you are looking over.

I will try to answer your questions and add a little context too.

1. Is this a good idea?? Great idea but it will not work well as you described it. NDIHX will need 20mbps to give you both full quality HX video and audio. Latency is going to be a killer in the scenario you described. Syncing the audio and video back together will be a complete crap shoot. Best to always keep them in sync from the get go.

2. NDI can support up to 16 channels of audio

3. From my understanding, smaller video resolution also means dropping the audio quality bitrate too.



You mentioned Dante... I speak Dante. Dante is NOT designed as a WAN audio solution. It is designed to be run on a LOCAL LAN only. NDI is much more bandwidth than DANTE and definitely would not consider it "can handle video over internet" Well not right out of the box. Though with enough bandwidth, anything is possible though.

What we do in our production division to remote audio is to remotely control the digital audio mixer from a PC located at the Network Ops Center. We are just virtually controlling the mix according to how the master output audio sounds to us here at the NOC. We are not mixing the elements here but are remotely controlling the audio mixer to give us the desired output mix. We normally do not have more than 6-8 channels of audio currently so it is just easier for us to remotely control our Yamaha mixers.

That is one way to do it. The other way is to use a bridge software to bring the audio channels from the remote site to the NOC and do the mix there.
We have successfully used this UNITY Connect software to bridge local DANTE audio into another site's COMM and DANTE audio network.
http://www.unityintercom.com/unity-connect/
With Unity Connect you can bridge up to 64x64 audio channels from Point A to Point B. That is pretty powerful stuff. Only Mac based though so keep that in mind. What you are asking for is definitely possible but it is not as simple as you laid out. Especially combining the audio and video and keeping them in sync.

livepad
02-21-2018, 10:11 AM
Hi guys,

Here's a crazy idea I've been thinking about for a while. Is is realistic to mix the broadcast audio 100 miles away from a concert?

Dante is good for audio over a network, but doesn't like the Internet. NDI is good for video over network, and can handle video over the Internet. As far as Google and I can tell, it also has a high limit to the number of audio channels it can send in a single video feed. Here's the signal flow that I'm contemplating, for running gigs in the next state/province over:

Video feed is mixed for broadcast, encoded, and sent to the broadcast server. No NDI involved, and the upload speed needed is under 10Mbps; completely doable in most places
Audio inputs are split from the band/FOH, and sent over Dante. All the channels are patched from Dante to an NDI output, sending the smallest video resolution NDI possible (144p24, or something smaller) and just a black screen. The NDI feed is sent over the Internet back to home base, and NDI is used exclusively to send all the audio channels, where they're used to mix the broadcast audio output. The audio is sent to the same broadcast server, merged with the encoded video, and sent to the live audience.

Questions:
Is this a good idea?
How many audio channels can NDI support?
What's the smallest resolution video that can be sent?

Sienna.Cloud for NDI (http://sienna.cloud) might be what you are looking for. You could set the data rate very low, and enable 'proxy' on the sender and it will give a low quality video, with full uncompressed audio up to 16 channels. If you feed black into the video it will keep things smooth

The 16 audio channels will remain in sync. If you feed multiple cloud streams, they will be resynchronised at the receiver, if they share a common source clock. This will be frame accurate, but not sample accurate sync so phase sync audio should be kept within the same 16 channel streams.

There are probably lots of other ways to do this, more focussed on audio, but Sienna.Cloud has a lot of cool things which might be handy. Not least the fact that its NDI in NDI out.

JGale
02-22-2018, 09:28 PM
Terrific replies, I appreciate them! I'd been thinking about using Sienna.Cloud as the bridge, but want to make sure this is doable from the 10,00ft level, before thinking deeper. Where can I find the specs on how NDI handles audio?

@PIZAZZ What distances are you using Unity to control audio? That might be a realistic solution for us.

PIZAZZ
03-01-2018, 02:01 PM
Terrific replies, I appreciate them! I'd been thinking about using Sienna.Cloud as the bridge, but want to make sure this is doable from the 10,00ft level, before thinking deeper. Where can I find the specs on how NDI handles audio?

@PIZAZZ What distances are you using Unity to control audio? That might be a realistic solution for us.

Few thousand miles. Is that far enough for your purposes?