Reducing latency in video encoding and decoding

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

• setting one or more syntax elements that indicate a constraint on frame reordering latency;
• outputting, as part of a bitstream, the one or more syntax elements that indicate the constraint on frame reordering latency;
• receiving a frame;
• encoding the frame, thereby producing encoded data for the frame;
• and
• outputting the encoded data for the frame as part of the bitstream, thereby enabling a video decoder to perform operations to decode the encoded data for the frame to reconstruct the frame, store the reconstructed frame in a decoded picture buffer (“DPB”), determine when the reconstructed frame in the DPB is ready for output, and output the reconstructed frame, the reconstructed frame in the DPB being ready for output if latency status of the reconstructed frame in the DPB is equal to the constraint on frame reordering latency upon determining the latency status of the reconstructed frame in the DPB and comparing the latency status of the reconstructed frame in the DPB to the constraint on frame reordering latency.

Computer-readable tangible storage having stored thereon encoded data in a bitstream, the encoded data in the bitstream including one or more syntax elements that indicate a constraint on frame reordering latency, the encoded data in the bitstream further including encoded data for a frame, the encoded data in the bitstream being organized to facilitate playback, in a computer system that implements a video decoder, by operations comprising:

• decoding the encoded data for the frame to reconstruct the frame;
• storing the reconstructed frame in a decoded picture buffer (“DPB”);
• determining when the reconstructed frame in the DPB is ready for output, the reconstructed frame in the DPB being ready for output if latency status of the reconstructed frame in the DPB is equal to the constraint on frame reordering latency upon:
• determining the latency status of the reconstructed frame in the DPB;
• and
• comparing the latency status of the reconstructed frame in the DPB to the constraint on frame reordering latency;
• and
• outputting the reconstructed frame.