Interlaced video coding with leading pictures
A video coding mechanism is disclosed. The mechanism includes receiving a bitstream comprising a flag and a plurality of coded pictures including an intra random access point (IRAP) picture and one or more non-leading pictures associated with the IRAP picture. When the flag is set to a first value any leading pictures associated with the IRAP picture precede, in decoding order, all non-leading pictures associated with the IRAP picture. When the flag is set to a second value a non-leading picture precedes, in decoding order, an initial leading picture associated with the IRAP picture. The IRAP picture, any leading pictures associated with the IRAP picture, and the one or more non-leading pictures associated with the IRAP picture are decoded in decoding order based on the flag.
1 . A method for storing an encoded bitstream of video data, wherein the method comprises:
receiving the bitstream, wherein the bitstream comprises a sequential field flag (field_seq_flag) and a plurality of coded pictures including an intra random access point (IRAP) picture and one or more non-leading pictures associated with the IRAP picture, wherein any leading pictures associated with the IRAP picture precede, in decoding order, all non-leading pictures associated with the IRAP picture when the flag is set to zero, wherein at most one non-leading picture precedes, in decoding order, an initial leading picture associated with the IRAP picture, wherein no non-leading pictures are positioned between the initial leading picture and a final leading picture in decoding order when the flag is set to one, wherein the field_seq_flag is set to one when a coded video sequence includes pictures that represent fields, and wherein the field_seq_flag is set to zero when the coded video sequence includes pictures that represent frames; and
storing the bitstream into a storage medium.
2 . The method of claim 1 , wherein the bitstream includes a sequence parameter set (SPS), and wherein the flag is obtained from the SPS.
3 . The method of claim 1 , wherein the IRAP picture includes a first field of a frame, and wherein the non-leading picture preceding the initial leading picture includes a second field of the frame.
4 . A method for transmitting an encoded bitstream of video data, wherein the method comprises:
obtaining a bitstream from a storage medium, wherein the bitstream comprises a sequential field flag (field_seq_flag) and a plurality of coded pictures including an intra random access point (IRAP) picture and one or more non-leading pictures associated with the IRAP picture, wherein any leading pictures associated with the IRAP picture precede, in decoding order, all non-leading pictures associated with the IRAP picture when the flag is set to zero, wherein at most one non-leading picture precedes, in decoding order, an initial leading picture associated with the IRAP picture, wherein no non-leading pictures are positioned between the initial leading picture and a final leading picture in decoding order when the flag is set to one, wherein the field_seq_flag is set to one when a coded video sequence includes pictures that represent fields, wherein the field_seq_flag is set to zero when the coded video sequence includes pictures that represent frames, and wherein the bitstream is stored in the storage medium; and
sending the bitstream.
5 . The method of claim 4 , wherein the bitstream includes a sequence parameter set (SPS), and wherein the flag is obtained from the SPS.
6 . The method of claim 5 , wherein the IRAP picture includes a first field of a frame, and wherein the non-leading picture preceding the initial leading picture includes a second field of the frame.
7 . A non-transitory computer-readable storage medium storing a bitstream that, when decoded by a coding device, is used by the coding device to generate a video, the bitstream comprising:
a sequential field flag (field_seq_flag) and a plurality of coded pictures including an intra random access point (IRAP) picture and one or more non-leading pictures associated with the IRAP picture, wherein any leading pictures associated with the IRAP picture precede, in decoding order, all non-leading pictures associated with the IRAP picture when the flag is set to zero, wherein at most one non-leading picture precedes, in decoding order, an initial leading picture associated with the IRAP picture, wherein no non-leading pictures are positioned between the initial leading picture and a final leading picture in decoding order when the flag is set to one, wherein the field_seq_flag is set to one when a coded video sequence includes pictures that represent fields, and wherein the field_seq_flag is set to zero when the coded video sequence includes pictures that represent frames.
8 . The storage medium of claim 7 , wherein the bitstream includes a sequence parameter set, SPS, and wherein the flag is obtained from the SPS.
9 . The storage medium of claim 8 , wherein the IRAP picture includes a first field of a frame, and wherein the non-leading picture preceding the initial leading picture includes a second field of the frame.