Hi,
is there any possibility to adjust the Audio Levels of the NDI Outputs?

We have the effect that a -18dBfs Test Signal is much quieter on the NDI Output. We had a look at the Signal by

1. recording the NDI Signal in Newteks NDI Monitor and added the Videofile as a new Input in vMix
2. sent the NDI to a Birddog NDI to SDI Converter

The effect is the same. The Signal Audio Level is around -30dBfs, so it's about 12dB quieter than the original.

Any ideas?

It would be nice if vMix at least introduced an NDI Audio Conversion setting in the master settings, to include the SMPTE standard of +4dBu(NDI) = -20dBFS, and the EBU version 0dBu(NDI) = -18dBFS, as alternative options to the existing conversion method where +4dBu(NDI) = 0dBFS. It wasn't so important when NDI connections were mainly between software applications (many of which also used this same convention), but with the growth of hardware encoders/decoders which wish to maintain compatibility with the way the Tricaster works (using SMPTE +4dBu(NDI) = -20dBFS, and a maximum NDI level of +24dBu for 0dBFS), the incompatibility with vMix is starting to show up more and causing confusion amongst some users who have only ever know integer-based digital audio with 0dBFS being the maximum before clipping occurs.

Of course some of the blame for all this has to lie with NewTek for coming up with their own standard for NDI audio levels which, I dare say, would never had been adopted had they approached a body like the AES (Audio Engineering Society) and discussed it with their Standards Officer. (This is the organisation that helps get manufacturers together and arbitrate on creating standards like the Broadcast WAV file format, amongst others.)