After a stream transition event such as a channel change, a drift between audio and video presentation time stamps in an audio/video stream is determined. The thus determined drift serves to compute a duration of a slow video motion start sequence with a given slow video rate, so that video can be shown early without yet being synchronized with audio. The slow video motion start enables the audio to catch up with the video and allows to ensure a synchronization of audio with video after the duration of the slow video motion start sequence, where after video and audio are synchronized and evolve normally. The present principles use a single decoder clock that is fed to the audio and video decoders, the decoder clock fed to the video decoder being offset with a decreasing value during the period of slow video motion.