Get multicast IP and RTP payload

[BugProg]

Hi there!

First, thank you for the development. It's a relief to see we can have control over Dante's devices on Linux!

I would like to get the multicast IP and the RTP payload (for devices that send data over the network). I can develop the feature if needed and ask for a PR. My question is, why is the multicast IP not in the JSON output or somewhere else? Is it a lack of time (that I can completely understand) or a technical issue?

Thank you for your help !

[Mo-way]

Hi @BugProg,

Could you explain what you mean by "multicast IP" and "RTP payload"?

Dante by default doesn't use a multicast channel and only uses RTP if you put it into AES67 mode.

Getting the multicast IP in AES67 mode should be possible, but no one implemented it AFAIK.
If you want to have a shot at it, that's great! Note that activating multicast channels is also not implemented on main. I have a fork where it works for my AVIO, but it's not tested much.

"Getting the RTP paylaod" in AES67 mode would mean you want an AES67 receiver, not a controller.
Either use a Ravenna sound card for this: https://www.ravenna-network.com/products/#product-grid+filtered_category:soundcards-physical-virtual+p:1
Or use an open source program:

• Kernel module: https://github.com/bondagit/aes67-linux-daemon
• Javascript with GUI: https://github.com/philhartung/aes67-monitor
• gstreamer: https://superuser.com/questions/1912033/rtp-stream-receiving-with-gstreamer-how-to-reduce-high-latency/1912034#1912034

I'm not the author, so I can't tell you anything about the reasoning.

PS: I also collect above mentioned tools in an awesome list: https://github.com/Mo-way/awesome-aoip/

[BugProg]

Hello @Mo-way !

Thank you for your kind answer!

I have a Dante AVIO 2CH Analog Input Adapter. I would like to play the audio from GStreamer and then do other stuff with it.

As you mention in your message, GStreamer needs address (multicast because it starts with 239) and payload=(int) as parameters.

I'm currently using my GStreamer pipeline through Python with an auto-discover mode to auto-find the right parameters.

As outlined in the screenshot below (from Wireshark) the protocol is RTP over multicast, isn't it ?

I started to auto-fetch those parameters with pyshark, but it's clearly not a good idea since it breaks the code logic and needs advanced permissions.

Thank you for the links; they are very useful :).

[Mo-way]

Your avio is in AES67 mode if it sends RTP packets.

Probably it's possible to get that address from the dante device, do some network traces of Dante controller getting it to find out.
For a quick win, simply get the IP from Netaudio. Then filter the network traffic for multicast addresses, where that IP sends traffic to. scapy, tcpdump should be easily capable of it

Happy to help
Mo

[BugProg]

Yes, I used pyshark to do the job, and it's working great.

I wanted to figure out a new way to retrieve those values in a more “conventional way” to have something cleaner.

Pyshark is good, but you need to be in the same group as Wireshark to launch the program without admin rights. That is a very tricky thing to ask a user.

Finally, I wanted to integrate directly into this project, but if Pyshark is the only solution, I doubt that is a good idea, for the reasons above.