CreateBufferGroup
void CreateBufferGroup(MediaOutputInfo * output_info);
status_t status = CreateBufferGroup(); // also initializes buffer period
virtual status_t CreateBufferGroup();
status = CreateBufferGroup(&group);
status_t status = CreateBufferGroup(&newGroup);
if (CreateBufferGroup(&group) != B_OK)
status_t CreateBufferGroup(BBufferGroup** buffer) const;