I work for the IT department of my school and I am currently re-doing the IP audio system that is used for announcements or the school bell. My school uses devices from the company "2N" for this. The audio transmission is done via multicast.
Until now, all devices used the same multicast address, which made it impossible to address only one building. So, in order to be able to address the buildings independently, I use different multicast addresses for each building.
For example:
- Building A: 224.0.0.5:8910
- Building B: 224.0.0.6:8910
Until now, one device was the "master" sending the school chime via the single multicast address. Unfortunately, the device is not able to address more than four multicast addresses simultaneously. Therefore I thought I could use GStreamer for this.
However, I do not manage to address the 2N devices via GStreamer. The devices are configured to a specific multicast address as shown in the example above and all use UDP port 8910. As codec I am offered PCMU, PCMA, L16 / 16kHz, G.729, G.722 in the interface. Unfortunately, the manufacturer does not publish more information.
I currently use the codec "L16 / 16kHz", because it provides the best audio quality. I can also send sounds over it via the master, but not with GStreamer.
I have tried these commands without success:
# Using "L16 / 16kHz"
gst-launch-1.0.exe -v audiotestsrc ! audioconvert ! rtpL16pay ! udpsink host=224.0.0.8 port=8910
# Using PCMU
gst-launch-1.0.exe -v filesrc location=Pausengong.wav ! decodebin ! audioconvert ! audioresample ! mulawenc ! rtppcmupay ! udpsink host=224.0.0.8 port=8910
Another complicating factor is that the 2N devices are completely silent when they receive "false data" - no crackling or noise.
I'm sorry I can't contribute more information. To be honest, I'm a bit out of my depth and can't work well with the small amount of information and the insufficient support from the manufacturer. Maybe someone here has a bright idea!
Thanks in advance!
With kind regards
Linus