ADAPTIVE TEMPORAL FILTER FOR AN UNAVAILABLE REFERENCE PICTURE

1 . A decoder, the decoder comprising circuitry configured to:

receive a bitstream;

decode a plurality of video frames from the bitstream;

determine for a current block of a current frame that a unavailable reference block update mode is enabled;

determine an unavailable reference block update including pixel values and using the plurality of video frames; and

update a portion of an unavailable frame with the unavailable reference block update.

2 . The decoder of claim 1 , wherein determining the unavailable reference block update includes computing a statistic of collocated pixels for the plurality of video frames.

3 . The decoder of claim 2 , wherein the statistic includes a mean, a median, and/or a mode.

4 . The decoder of claim 1 , wherein determining the unavailable reference block update includes applying a temporal filter operation to the plurality of video frames.

5 . The decoder of claim 1 , further configured to determine a unavailable reference buffer including the plurality of frames, decode a new frame, and add the new frame to the unavailable reference buffer.

6 . The decoder of claim 5 , further configured to determine that a reset mode is enabled, receive a scene change signal, and clear the long term frame buffer.

7 . The decoder of claim 5 , further configured to determine that a reset mode is enabled, detect a scene change, and clear the unavailable reference frame buffer.

8 . The decoder of claim 5 , further configured to determine that the unavailable reference buffer has met or exceeds a predefined maximum allowed buffer size, and remove a frame from the unavailable reference buffer.

9 . The decoder of claim 1 , further configured to segment each video frame into blocks, and apply a temporal filter to the blocks of the video frames to compute the unavailable reference block update.

10 . The decoder of claim 1 , further configured to decode a new frame, wherein the determining the unavailable reference block update includes using the unavailable reference frame and the new frame.

11 . The decoder of claim 1 , further comprising:

an entropy decoder processor configured to receive the bit stream and decode the bitstream into quantized coefficients;

an inverse quantization and inverse transformation processor configured to process the quantized coefficients including performing an inverse discrete cosine;

a deblocking filter;

a frame buffer; and

an intra prediction processor.

12 . A method comprising:

receiving a bitstream;

decoding a plurality of video frames from the bitstream;

determining for a current block of a current frame that an unavailable reference block update mode is enabled;

determining an unavailable reference block update including pixel values and using the plurality of video frames; and

updating a portion of an unavailable reference frame with the unavailable reference block update.

13 . The method of claim 12 , wherein determining the unavailable reference block update includes computing a statistic of collocated pixels for the plurality of video frames.

14 . The method of claim 13 , wherein the statistic includes a mean, a median, and/or a mode.

15 . The method of claim 12 , wherein determining the unavailable reference block update includes applying a temporal filter operation to the plurality of video frames.

16 . The method of claim 12 , further comprising:

determining an unavailable reference buffer including the plurality of frames;

decoding a new frame; and

adding the new frame to the unavailable reference buffer.

17 . The method of claim 16 , further comprising:

determining that a reset mode is enabled;

receiving a scene change signal; and

clearing the unavailable reference buffer.

18 . The method of claim 16 , further comprising:

determining that a reset mode is enabled;

detecting a scene change; and

clearing the unavailable reference buffer.

19 . The method of claim 16 , further comprising:

determining that the unavailable reference buffer has met or exceeds a predefined maximum allowed buffer size; and

removing a frame from the unavailable reference buffer.

20 . The method of claim 12 , further comprising:

segmenting each video frame into blocks; and

applying a temporal filter to the blocks of the video frames to compute the unavailable reference block update.

21 . The method of claim 12 , further comprising decoding a new frame, wherein the determining the unavailable reference block update includes using the unavailable reference frame and the new frame.

22 . The method of claim 12 , the decoder further comprising:

an entropy decoder processor configured to receive the bit stream and decode the bitstream into quantized coefficients;

an inverse quantization and inverse transformation processor configured to process the quantized coefficients including performing an inverse discrete cosine;

a deblocking filter;

a frame buffer; and

an intra prediction processor.