Video-encoding method, video-decoding method, and apparatus implementing same
The present invention relates to an inter-layer prediction method and to an apparatus implementing the method. The method may comprise the steps of generating a first block constituted by the value obtained by up-sampling the reconstruction value of a reference block of a reference layer corresponding to the current block; generating a second block constituted by a prediction value derived from intra-prediction mode of the current block; and generating a prediction block of the current block by combining sample values of the first block and the second block. Thus, intra-prediction on the current layer can be performed using the intra-prediction mode information of another layer.
1. A video decoding method, performed by a decoding apparatus, comprising:
receiving a bitstream comprising information on a random access point picture, leading pictures and normal pictures, wherein the leading pictures precede the random access point picture in output order and the normal pictures follow the random access point picture in output order;
decoding the random access point picture based on the information;
decoding at least one of the leading pictures or the normal pictures based on the information;
outputting the decoded random access point picture; and
outputting the decoded normal pictures,
wherein the random access point picture is a clean random access (CRA) picture or an instantaneous decoding refresh (IDR) picture,
wherein the leading pictures are not used as reference pictures for the normal pictures,
wherein the leading pictures precede the normal pictures in decoding order,
wherein a first leading picture associated with the CRA picture is not output if the random access point picture is the CRA picture, a random access happens to the CRA picture and flag information indicating whether the first leading picture associated with the CRA picture is not output is set equal to 1, and
wherein a second leading picture associated with the IDR picture is decoded by using at least one of the IDR picture or another leading picture as a reference picture if the random access point picture is the IDR picture and the random access happens to the IDR picture.
2. The method of claim 1 , wherein the first leading picture associated with the CRA picture is discarded from the bitstream when the random access point picture is the CRA picture, the random access happens to the CRA picture and the flag information indicating whether the first leading picture is not output is set equal to 1.
3. The method of claim 1 , wherein the first leading picture associated with CRA picture has a non-decodable or skipped leading picture type and the second leading picture associated with the IDR picture has a decodable leading picture type.
4. The method of claim 1 , wherein the first leading picture associated with the CRA picture contain references to pictures that are not present in the bitstream and the first leading picture associated with the CRA picture is not decodable when the random access point picture is the CRA picture and the random access happens to the CRA picture.
5. The method of claim 4 , wherein normal pictures follows the first leading picture associated with the CRA picture, in decoding order, are decoded after a predetermined delay time.
6. The method of claim 4 , wherein types of leading pictures comprises a non-decodable or skipped leading picture type and a decodable leading picture type, and the first leading picture associated with the CRA picture is the non-decodable or skipped leading picture type.
7. The method of claim 4 , wherein the first leading picture associated with the CRA picture refers to a reference picture that is not present after a random access point in the bitstream.
8. The method of claim 1 , wherein the flag information is obtained from the bitstream.
9. The method of claim 8 , further comprising outputting error information of the bitstream and decoding pictures after the first leading picture associated with the CRA picture when at least one reference picture for the first leading picture associated with the CRA picture is determined to be unavailable through the flag information.
10. The method of claim 1 , wherein the flag information is determined based on a picture type of the random access point picture.
11. A video decoding apparatus, comprising:
a receiver configured to receive a bitstream comprising information on a random access point picture, leading pictures and normal pictures, wherein the leading pictures precede the random access point picture in output order and the normal pictures follow the random access point picture in output order; and
a video processor configured to decode the random access point picture based on the information, to decode at least one of the leading pictures or the normal pictures based on the information, to output the decoded random access point picture, and to output the decoded normal pictures,
wherein the random access point picture is a clean random access (CRA) picture or an instantaneous decoding refresh (IDR) picture,
wherein the leading pictures are not used as reference pictures for the normal pictures,
wherein the leading pictures precede the normal pictures in decoding order,
wherein a first leading picture associated with the CRA picture is not output if the random access point picture is the CRA picture, a random access happens to the CRA picture and flag information indicating whether the first leading picture associated with the CRA picture is not output is set equal to 1, and
wherein a second leading picture associated with the IDR picture is decoded by using at least one of the IDR picture or another leading picture as a reference picture if the random access point picture is the IDR picture and the random access happens to the IDR picture.
12. The apparatus of claim 11 , wherein the first leading picture associated with the CRA picture is discarded from the bitstream when the random access point picture is the CRA picture, the random access happens to the CRA picture and the flag information indicating whether the first leading picture is not output is set equal to 1.
13. The apparatus of claim 11 , wherein the first leading picture associated with CRA picture has a non-decodable or a skipped leading picture type and the second leading picture associated with the IDR picture has a decodable leading picture type.
14. The apparatus of claim 11 , wherein the first leading picture associated with the CRA picture contain references to pictures that are not present in the bitstream and the first leading picture associated with the CRA picture is not decodable when the random access point picture is the CRA picture and the random access happens to the CRA picture.
15. The apparatus of claim 14 , wherein normal pictures follows the first leading picture associated with the CRA picture, in decoding order, are decoded after a predetermined delay time.
16. The apparatus of claim 14 , wherein types of leading pictures comprises a non-decodable or skipped leading picture type and a decodable leading picture type, and the first leading picture associated with the CRA picture is the non-decodable or skipped leading picture type.
17. The apparatus of claim 14 , wherein the first leading picture associated with the CRA picture refers to a reference picture that is not present after a random access point in the bitstream.
18. The apparatus of claim 11 , wherein the flag information is obtained from the bitstream.
19. The apparatus of claim 18 , wherein the video processor outputs error information of the bitstream and decoding pictures after the first leading picture associated with the CRA picture when at least one reference picture for the first leading picture associated with the CRA picture is determined to be unavailable through the flag information.
20. A video encoding method, performed by an encoding apparatus, comprising:
encoding a random access point picture;
encoding at least one of leading pictures or normal pictures, wherein the leading pictures precede the random access point picture in output order and the normal pictures follow the random access point picture in output order; and
outputting a bitstream comprising information on the random access point picture, the leading pictures and the normal pictures,
wherein the random access point picture is a clean random access (CRA) picture or an instantaneous decoding refresh (IDR) picture,
wherein the leading pictures are not used as reference pictures for the normal pictures,
wherein the leading pictures precede the normal pictures in decoding order,
wherein a first leading picture associated with the CRA picture is configured to be not output, by a decoding apparatus, if the random access point picture is the CRA picture, a random access happens to the CRA picture and flag information indicating whether the first leading picture associated with the CRA picture is not output is set equal to 1, and
wherein a second leading picture associated with the IDR picture is configured to be decoded, by the decoding apparatus, by using at least one of the IDR picture or another leading picture as a reference picture if the random access point picture is the IDR picture and the random access happens to the IDR picture.