PLAYING_TO_PAUSED

state change from PLAYING to PAUSED.

* Most elements ignore this state change. * The pipeline calculates the running_time based on the last selected Clock and the base_time. It stores this information to continue playback when going back to the PLAYING state. * Sinks unblock any Clock wait calls. * When a sink does not have a pending buffer to play, it returns ASYNC from this state change and completes the state change when it receives a new buffer or an EOS. * Any queued EOS items are removed since they will be reposted when going back to the PLAYING state. The EOS messages are queued in Bin containers. * Live sources stop generating data and return NO_PREROLL.