Hello,
I took some foogates with Theta V with TA-1 mic.
I want to downmix ambisonic B-format to surround audio format.
After converting in Movie converter app, Imported the movie footages to Reaper where I can see 4 audio channel(Ambisonic B-format).
Is there simple solution that I can extract surround format from it?
Thanks for reading.
Self answer 
Soundfiled by Rode convert Ambisonic A&B format to mono~surround 7.1. It’s working as a plug in with Logic, Reaper, Protools & Nuendo. Very easy to use and accurate. I also tried Blue Ripple core vst and ETC but Soundfiled was most easy and suitable with simple conversion.
Also VLC Player support realtime conversion of B-format to surround. So if you set up surround system in your place, you can listen to spatial sound in surround system. It’s really useful and interesting when you watch your footages with someone else. Although It might not be as accurate as Binaural sound with headphone.