I have some questions with Bus and channelGroup SoundGroup

when i start a event, i print the curent channelNumber. it is not zero. so i want know which channel group it is in. i get the masterChannelGroup and print all channel:
nGroupNum 1 curChannelGroup Name FMOD master curGroupHaveChannelCount 0
nGroupNum 1 curChannelGroup Name Master Bus curGroupHaveChannelCount 0
nGroupNum 1 curChannelGroup Name Group Bus curGroupHaveChannelCount 0
nGroupNum 1 curChannelGroup Name Input Bus curGroupHaveChannelCount 0
nGroupNum 1 curChannelGroup Name Master Bus curGroupHaveChannelCount 0
nGroupNum 0 curChannelGroup Name Group Bus curGroupHaveChannelCount 1

i do not konw when i use evnet to play a sound , the sound soundgroup channel channel group how to use and change.

and i do not konw that when i use fmod studio api , if i want to change some sound volume, i must use bus not the channelGroup or soundGroup?

thank you~~

The number of channels playing in a channelgroup are channels that belong directly to that channelgroup alone, and not the children.
Im assuming you’re using EventInstance or BusInstance and then calling getChannelGroup and ChannelGroup::getNumChannels? This does not tell you how many channels are playing below a parent channelgroup.
You would have to recurse through the child channelgroups and find all children channelgroups and how many channels they have. Do you need to do this though? What is the purpose?