Constraints and unit types to simplify video random access
Disclosed herein are innovations for bitstreams having clean random access (CRA) pictures and/or other types of random access point (RAP) pictures. New type definitions and strategic constraints on types of RAP pictures can simplify mapping of units of elementary video stream data to a container format. Such innovations can help improve the ability for video coding systems to more flexibly perform adaptive video delivery, production editing, commercial insertion, and the like.
1 . In a computer system that implements a video encoder, a method comprising:
encoding a broken link access (BLA) picture, thereby generating encoded data for the BLA picture;
outputting, as part of encoded data in a bitstream, the encoded data for the BLA picture;
encoding a leading picture associated with the BLA picture, thereby generating encoded data for the leading picture, including generating an explicit indication for the leading picture indicating whether the leading picture is decodable or not decodable when pictures from before the BLA picture in decoding order are unavailable to a decoder; and
outputting, as part of the encoded data in the bitstream, the encoded data for the leading picture, the encoded data for the leading picture including the explicit indication for the leading picture.
2 . The method of claim 1 , wherein the explicit indication for the leading picture is part of network abstraction layer (“NAL”) unit type.
3 . The method of claim 1 , wherein the explicit indication for the leading picture indicates the leading picture is decodable when pictures from before the BLA picture in decoding order are unavailable to a decoder.
4 . The method of claim 1 , wherein the explicit indication for the leading picture indicates the leading picture is not decodable when pictures from before the BLA picture in decoding order are unavailable to a decoder.
5 . The method of claim 1 , wherein the leading picture is a first leading picture associated with the BLA picture, the method further comprising:
encoding a second leading picture associated with the BLA picture, thereby generating encoded data for the second leading picture, including generating an explicit indication for the second leading picture indicating whether the second leading picture is decodable or not decodable when pictures from before the BLA picture in decoding order are unavailable to a decoder; and
outputting, as part of the encoded data in the bitstream, the encoded data for the second leading picture, the encoded data for the second leading picture including the explicit indication for the second leading picture.
6 . The method of claim 1 , wherein the encoding the BLA picture includes generating an explicit indication for the BLA picture indicating that the BLA picture is one of a plurality of available types of BLA pictures.
7 . The method of claim 6 , wherein the explicit indication for the BLA picture is part of network abstraction layer (“NAL”) unit type.
8 . The method of claim 6 , wherein one of the plurality of available types of BLA pictures is a BLA type that may have one or more associated decodable or non-decodable leading pictures.
9 . One or more non-transitory computer-readable media having stored thereon computer-executable instructions for causing one or more processing units, when programmed thereby, to perform operations comprising:
receiving, as part of encoded data in a bitstream, encoded data for a broken link access (BLA) picture;
decoding the BLA picture;
receiving, as part of the encoded data in the bitstream, encoded data for a leading picture associated with the BLA picture, the encoded data for the leading picture including an explicit indication for the leading picture indicating whether the leading picture is decodable or not decodable when pictures from before the BLA picture in decoding order are unavailable to a decoder; and
decoding the leading picture in accordance with the explicit indication for the leading picture.
10 . The one or more computer-readable media of claim 9 , wherein the explicit indication for the leading picture is part of network abstraction layer (“NAL”) unit type.
11 . The one or more computer-readable media of claim 9 , wherein the explicit indication for the leading picture indicates the leading picture is decodable when pictures from before the BLA picture in decoding order are unavailable to a decoder.
12 . The one or more computer-readable media of claim 9 , wherein the explicit indication for the leading picture indicates the leading picture is not decodable when pictures from before the BLA picture in decoding order are unavailable to a decoder.
13 . The one or more computer-readable media of claim 9 , wherein the leading picture is a first leading picture associated with the BLA picture, the operations further comprising:
receiving, as part of the encoded data in the bitstream, encoded data for a second leading picture associated with the BLA picture, the encoded data for the second leading picture including an explicit indication for the second leading picture indicating whether the second leading picture is decodable or not decodable when pictures from before the BLA picture in decoding order are unavailable to a decoder; and
decoding the second leading picture in accordance with the explicit indication for the second leading picture.
14 . The one or more computer-readable media of claim 9 , wherein the encoded data for the BLA picture includes an explicit indication for the BLA picture indicating that the BLA picture is one of a plurality of available types of BLA pictures.
15 . The one or more computer-readable media of claim 14 , wherein the explicit indication for the BLA picture is part of network abstraction layer (“NAL”) unit type.
16 . The one or more computer-readable media of claim 14 , wherein one of the plurality of available types of BLA pictures is a BLA type that may have one or more associated decodable or non-decodable leading pictures.
17 . The one or more computer-readable media of claim 9 , wherein the decoding the leading picture in accordance with the explicit indication for the leading picture includes:
determining that the leading picture is decodable; and
decoding the leading picture.
18 . The one or more computer-readable media of claim 9 , wherein the decoding the leading picture in accordance with the explicit indication for the leading picture includes:
determining that the leading picture is not decodable; and
skipping the decoding the leading picture.
19 . One or more non-transitory computer-readable media having stored thereon encoded data in a bitstream, the encoded data in the bitstream including encoded data for a broken link access (BLA) picture and encoded data for a leading picture associated with the BLA picture, the encoded data for the leading picture including an explicit indication for the leading picture indicating whether the leading picture is decodable or not decodable when pictures from before the BLA picture in decoding order are unavailable to a decoder, the encoded data in the bitstream resulting from encoding, in a computer system that implements a video encoder, by operations that include:
encoding the BLA picture, thereby generating the encoded data for the BLA picture; and
encoding the leading picture, thereby generating encoded data for the leading picture.
20 . The one or more computer-readable media of claim 19 , wherein the explicit indication for the leading picture is part of network abstraction layer (“NAL”) unit type.