[Ardour-Users] H2N Google Spatial sound support

[Gunter Königsmann]

Dear all,

I have found a audio format of which I don't know if it will gain
relevance and which currently is only partially supported by ardour:

The long part of the story:
My H2n field recorder contains 5 microphones providing MS Stereo (at the
front of the device) and XY-Stereo (at the back of the device) and was
always able to record both things simultaneously into two separate
stereo files. As Ardour can merge them during import this is no big
problem (that means: If any of you knows how to teach faac to put
information about the right speaker positions into the resulting .m4a
file...). After a firmware update it was able to record surround audio
into a single file. I automatically assumed that it would just put all 4
channels into a single file.

Turns out that the device instead saves surround audio in a somehow
peculiar format instead:
 - The file contains 4 tracks
 - One track is the center Channel
 - One track the difference between Left and Right
 - One track the difference between Back and Front
 - and the waveform of one of the four tracks looks like it is filled
with zeros.

I assume the file will be equipped with special metadata similar to what
can be seen here:
https://github.com/google/spatial-media/blob/master/docs/spatial-audio-rfc.md

As the new format reduces 5 channels to 3 I am convinced using it looses
more information than the 4-track-in-two-files-approach would => I
personally won't use it. But I wanted to inform you that it exists in
case it turns out relevant enough (surround might be part of the future)
that you might want to support it anyway.

If anybody wants to play with the new format I have uploaded a simple	
audio file to www.peterpall.de/fileadmin/peterpall/audio/H2n_Spatial.wav

Kind regards,

 Gunter.