Encoder and decoder and methods thereof for encoding/decoding a picture of a video sequence
View Patent ↗An object of the embodiments is to achieve an improved reference picture handling. That is achieved by taking into account whether the reference pictures in the decoded picture buffer are long-term reference pictures or short-term reference pictures when determining how they should be marked when the information of the reference picture set is received. The reference pictures are marked as “used for short-term reference” or “used for long-term reference” in the Decoded Picture Buffer (DPB) depending on whether they are included as short-term pictures or long-term pictures in the RPS of a current picture.
1. A decoder for managing reference pictures to be used for decoding an encoded representation of a picture of a video sequence, the decoder configured to:
decode, from a slice header, a plurality of Picture Order Count (POC) values;
for each POC value of the plurality of POC values:
i) if the POC value indicates a long-term reference picture and there is a reference picture in a decoded picture buffer (DPB) with a POC value that matches the POC value:
if the matching reference picture in the DPB is marked as a long-term reference picture, then include the matching reference picture in the DPB in a long-term reference picture set; and
if the matching reference picture in the DPB is marked as a short-term reference picture, then mark the matching reference picture in the DPB as a long-term reference picture, and include the matching reference picture in the DPB in the long-term reference picture set; and
ii) otherwise, if the POC value indicates a short-term reference picture and there is a reference picture in the DPB with a POC value that matches the POC value:
include the matching short-term reference picture in the DPB in a short-term reference picture set; and
mark all pictures in the DPB that are not included in either the long-term reference picture set or the short-term reference picture set as unused for reference.
2. The decoder of claim 1 , wherein the decoder is configured to determine if the POC value indicates a short-term reference picture or a long-term reference picture by determining if the POC value is included in one of the lists:
PocLtCurr or PocLtFoll, in which case the POC value indicates a long-term reference picture; or
PocStCurrBefore, PocStCurrAfter, or PocStFoll, in which case the POC value indicates a short-term reference picture.
3. The decoder of claim 1 , wherein the decoder is configured to, if the POC value indicates a long-term reference picture, determine if the matching reference picture in the DPB is a long-term reference picture before determining if the matching reference picture in the DPB is a short-term reference picture.
4. A method for managing reference pictures to be used for decoding an encoded representation of a picture of a video sequence, comprising:
decoding, from a slice header, a plurality of Picture Order Count (POC) values;
for each POC value X of the plurality of POC values:
i) if the POC value indicates a long-term reference picture and there is a reference picture in a decoded picture buffer (DPB) with a POC value that matches the POC value:
if the matching reference picture in the DPB is marked as a long-term reference picture, then include the matching reference picture in the DPB in a long-term reference picture set; and
if the matching reference picture in the DPB is marked as a short-term reference picture, then mark the matching reference picture in the DPB as a long-term reference picture, and include the matching reference picture in the DPB in a long-term reference picture set; and
ii) if the POC value indicates a short-term reference picture and there is a reference picture in the DPB with a POC value that matches the POC value:
include the matching short-term reference picture in the DPB in a short-term reference picture set; and
marking all pictures in the DPB that are not included in either the long-term reference picture set or the short-term reference picture set as unused for reference.
5. The method of claim 4 , further comprising:
determining if the POC value indicates a short-term reference picture or a long-term reference picture by determining if the POC value is included in one of the lists:
PocLtCurr or PocLtFoll, in which case the POC value indicates a long-term reference picture; or
PocStCurrBefore, PocStCurrAfter, or PocStFoll, in which case the POC value indicates a short-term reference picture.
6. The method of claim 4 , further comprising:
if the POC value indicates a long-term reference picture, determining if the matching reference picture in the DPB is a long-term reference picture before determining if the matching reference picture in the DPB is a short-term reference picture.
7. A non-transitory computer readable medium storing instructions that, when executed by a processor, cause the processor to perform operations comprising:
decoding, from a slice header, a plurality of Picture Order Count (POC) values;
for each POC value X of the plurality of POC values:
i) if the POC value indicates a long-term reference picture and there is a reference picture in a decoded picture buffer (DPB) with a POC value that matches the POC value:
if the matching reference picture in the DPB is marked as a long-term reference picture, then including the matching reference picture in the DPB in a long-term reference picture set; and
if the matching reference picture in the DPB is marked as a short-term reference picture, then marking the matching reference picture in the DPB as a long-term reference picture, and including the matching reference picture in the DPB in a long-term reference picture set; and
ii) if the POC value indicates a short-term reference picture and there is a reference picture in the DPB with a POC value that matches the POC value:
including the matching short-term reference picture in the DPB in a short-term reference picture set; and
marking all pictures in the DPB that are not included in either the long-term reference picture set or the short-term reference picture set as unused for reference.
8. The non-transitory computer readable medium of claim 7 , wherein the instructions that, when executed by a processor, cause the processor to perform operations further comprising:
determining if the POC value indicates a short-term reference picture or a long-term reference picture by determining if the POC value is included in one of the lists:
PocLtCurr or PocLtFoll, in which case the POC value indicates a long-term reference picture; or
PocStCurrBefore, PocStCurrAfter, or PocStFoll, in which case the POC value indicates a short-term reference picture.
9. The non-transitory computer readable medium of claim 7 , wherein the instructions that, when executed by a processor, cause the processor to perform operations further comprising:
if the POC value indicates a long-term reference picture, determining if the matching reference picture in the DPB is a long-term reference picture before determining if the matching reference picture in the DPB is a short-term reference picture.