Ethernet streaming and occasional white noise on Windows

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@Georgethesixth, I thought Devialet was using unicasting for streaming. AIR does know the exact IP address of the Devialet (and shows it, when it's connected). So, why would AIR need to broadcast messages? Well, that's a topic for a different thread (perhaps, one titled "Know your Devialet"

Based on what I can see by tracing network traffic between my Mac and Devialet 200, it looks as though AIR streams audio data via unicast UDP (host port 45456 -> Dev port 45455). Each UDP frame seems to carry a 962-byte payload when there's music playing at 16-bit/44.1 kHz. The payload size and/or frame rate will no doubt change for different sample sizes and/or rates, but I haven't tried anything other than 16/44.

The broadcast mechanism seems to run continuously whether the Devialet is in standby, powered up, or streaming. I assume this is just used for discovery. As @Georgthesixth found, the Devialet seems to broadcast to port 45454 several times per second from each interface (Ethernet and/or wi-fi).

I wonder what useful info you'd be able to gather with a network tap, even if you catch it at white noise act. How would you know if AIR sends "noise" packets to the Devialet, or if the noise originates in the Devialet itself (needless to say, I suspect the former). Perhaps, the packets would contain only 1's (no 0's) - that's what white noise is, is it not?

With a network tracing tool you could see the payload of the UDP packets which carry the audio data. Whether that would help or not depends on how the data is formatted. I'm guessing that it might be raw, linear PCM but I haven't any good evidence for that other than that the data rate is roughly right. In any case it would probably be quite difficult to distinguish music from noise by looking at the payload. (it could be easier if you were playing a test tone.) I'd expect white noise to be represented by a random-looking payload, not all-ones.

Speculating wildly...a burst of white noise might be caused if the AIR software sent data from a "random" region of memory on the host to the Devialet. Depending on how the AIR software is implemented this could occur due to memory management problems, which I think you've already suggested as a possible cause.

Not sure whether this helps or not…I hope so.