Ignore in-bus numbers when reading from sound file. Add comment about this. Other cleanups.
Ignore in-bus numbers when reading from sound file. Add comment about this.
Other cleanups.

RTcmix/RTcmix,RTcmix/RTcmix,RTcmix/RTcmix,RTcmix/RTcmix,RTcmix/RTcmix,RTcmix/RTcmix