speed

The playback rate as a multiplier of real time. Frame durations and sync corrections are computed in media time and divided by the rate into wall time, and the video clock extrapolates at the same rate, so a video-only file paces correctly with no audio to follow.

Applies from the schedule's next step, with no flush. When audio is the master the schedule paces at the rate the audio clock reports instead, which is the rate the listener hears: the audio already buffered still plays the old rate for a moment after a change.