Error resilient video transmission using instantaneous receiver feedback and channel quality adaptive packet retransmission

A method for delivering real-time video imagery to a receiver over a channel, comprising:

• capturing a current video frame;
• encoding the current video frame by dividing the current video frame into a plurality of macroblocks and determining, for each macroblock, as a coding mode, whether to (1) skip the macroblock and copy the macroblock from a same location from a previous video frame, (2) intra code the macroblock without reference to a previous frame, or (3) inter code the macroblock using motion compensation based on a reference frame;
• determining a state of the channel over which the real-time video imagery is to be sent by monitoring feedback received from a receiver regarding video packets that have been successfully received, wherein the state of the channel is calculated based on a packet error rate for a frame of video prior to the current video frame;
• based on the state of the channel, controlling a quantization parameter for each macroblock to be quantized and encoding each macroblock in accordance with the coding mode;
• and
• packetizing the macroblocks so encoded and transmitting resulting video packets to the receiver;
• and
• calculating a residual packet error rate (RPER) and, if the RPER is greater than a predetermined value, skipping a next video frame and any subsequent video frames as long as the RPER remains greater than the predetermined value, and using respective time slots for such skipped video frames for retransmission of lost packets until such time that the RPER falls below the predetermined value.

A system for transmitting real-time digital video, comprising:

• an encoder/transmitter configured to encode a current video frame by dividing the current video frame into a plurality of macroblocks and determining, for each macroblock, as a coding mode, whether to (1) skip the macroblock and copy the macroblock from a same location from a previous video frame, (2) intra code the macroblock without reference to a previous frame, or (3) inter code the macroblock using motion compensation based on a reference frame;
• and
• a receiver/decoder configured to send to the encoder/transmitter feedback regarding video packets that have been successfully received over a wireless channel by the receiver/decoder,
• wherein based on a state of the wireless channel, the encoder/transmitter is configured to control a quantization parameter for each macroblock to be quantized and is configured to encode each macroblock in accordance with the coding mode, and is further configured to packetize the macroblocks so encoded and transmit resulting video packets to the receiver/decoder,
• wherein the state of the channel is calculated based on a packet error rate for a frame of video prior to the current video frame;
• and
• wherein the encoder/transmitter is configured to calculate a residual packet error rate (RPER) and, if the RPER is greater than a predetermined value, to skip a next video frame and any subsequent video frames as long as the RPER remains greater than the predetermined value, and to use respective time slots for such skipped video frames for retransmission of lost packets until such time that the RPER falls below the predetermined value.