Ericsson Ericsson Ericsson The Audio-visual Profile with Feedback (AVPF) specification defines a framework and messages for fast feedback and media control over RTCP. The Codec Control Messages (CCM) specification defines an extension to AVPF, by specifying additional messages for codec control and feedback. This specification extends CCM, by specifying messages that let participants dynamically communicate a set of codec configuration parameters, which enables better optimization of resource efficiency and quality of media transmission.