METHOD AND SYSTEM FOR PROVIDING INSTANT REVERSE PLAY

摘要

A method for displaying video data instantly in reverse order is disclosed. According to the method, a compressed audio and video (AfV) stream is received from a source. The compressed A/V stream is demultiplexed into an audio stream and a video stream. The video stream has a number of compressed video frames which include a number of key frames. Each key frame is followed by one or more associated frames. Each of the compressed video frames is tagged with a tag. The tag associated with each key frame and file position of each key frame is stored in a table. The compressed video frames are decoded to generate a number of decoded video frames while maintaining their corresponding tags. During normal play, the decoded video frames are stored in a forward queue, and the decoded video frames in the forward queue are then outputted in a FIFO (first-in-first-out) order to a reverse queue and a display device for display. The reverse queue operates in a FIFO manner by discarding the oldest decoded video frame stored in the reverse queue when the reverse queue is full. During reverse play, the tag of the oldest decoded video frame in the reverse queue is recorded when a reverse play command is received, and the decoded video frames in the reverse queue are outputted in a LIFO (last-in- first-out) order to the forward queue and the display device for display. At the start of the reverse play, the forward queue operates in a LIFO manner until the most recently decoded video frames stored in the forward queue are discarded. Thereafter, the forward queue and the reverse queue operate in a FIFO manner. The recorded tag is used to retrieve one or more compressed video frames from the source. The retrieved one or more compressed video frames are tagged and decoded to generate one or more newly decoded video frames. The one or more newly decoded video frames are forwarded to the reverse queue.