2) United States Patent Reducing Latency in Video Encoding and Decoding I Start

(74) Attorney, Agent, or Firm * Aaron Chatterjee; Andrew Sanders; Micky Minhas (57) ABSTRACT Techniques and tools for reducing latency in video encoding and decoding by constraining latency due to reordering of video frames, and by indicating the constraint on frame reor dering latency with one or more syntax elements that accom pany encoded data for the video frames. For example, a real time communication tool with a video encoder sets a syntax element that indicates a constraint on frame reordering latency, which is consistent with inter-frame dependencies between multiple frames of a video sequence, then outputs the syntax element. A corresponding real-time communica tion tool with a video decoder receives the syntax element that indicates the constraint on frame reordering latency, deter mines the constraint on frame reordering latency based on the syntax element, and uses the constraint on frame reordering latency to determine when a reconstructed frame is ready for output (in terms of output order).