Reducing latency in video encoding and decoding

A computer system comprising one or more processing units and memory, wherein the computer system implements a video encoder configured to perform operations comprising:

• setting one or more syntax elements that indicate a constraint on frame reordering latency, wherein the constraint on frame reordering latency is expressed in terms of a maximum count of frames that can precede any frame of a video sequence in output order but follow that frame in coded order;
• outputting the one or more syntax elements, thereby facilitating determination of when reconstructed frames are ready for output;
• encoding a given frame of the video sequence, thereby producing encoded data for the given frame, wherein the encoding uses inter-frame dependencies, within the video sequence, that are consistent with the constraint on frame reordering latency;
• and
• outputting the encoded data for the given frame.

Computer-readable tangible storage having stored thereon, in a bitstream, one or more syntax elements that indicate a constraint on frame reordering latency, wherein the constraint on frame reordering latency is expressed in terms of a maximum count of frames that can precede any frame of a video sequence in output order but follow that frame in coded order, the computer-readable tangible storage further having stored thereon, in the bitstream, encoded data for a given frame of the video sequence, the bitstream having been produced, with a computer system that implements a video encoder, by operations comprising:

• setting the one or more syntax elements that indicate the constraint on frame reordering latency;
• outputting the one or more syntax elements, thereby facilitating determination of when reconstructed frames are ready for output;
• encoding the given frame of the video sequence, thereby producing the encoded data for the given frame, wherein the encoding uses inter-frame dependencies, within the video sequence, that are consistent with the constraint on frame reordering latency;
• and
• outputting the encoded data for the given frame.