Low delay concept in multi-layered video coding
An interleaved multi-layered video data stream with interleaved decoding units of different layers is provided with further timing control information in addition to the timing control information reflecting the interleaved decoding unit arrangement. The additional timing control information pertains to either a fallback position according to which all decoding units of an access unit are treated at the decoded buffer access unit-wise, or a fallback position according to which an intermediate procedure is used: the interleaving of the DUs of different layers is reversed according to the additionally sent timing control information, thereby enabling a DU-wise treatment at the decoder's buffer, however, with no interleaving of decoding units relating to different layers. Both fallback positions may be present concurrently. Various advantageous embodiments and alternatives are the subject of the various claims attached herewith.
1. A decoder comprising a processor configured to decode a multi-layered video data stream that includes encoded video content represented in a plurality of layers, the multi-layered video data stream including a sequence of network abstraction layer (NAL) units, which are divided into a sequence of access units,
wherein each access unit includes a plurality of decoding units, with each decoding unit of the plurality of decoding units having at least one NAL unit corresponding to one layer of the plurality of layers, and
wherein the multi-layered video data stream includes:
first timing control information in the multi-layered video data stream signaling a first decoder buffer retrieval time for an access unit from the sequence of access units, and
second timing control information in the multi-layered video data stream, separate from the first timing control information, the second timing control information signaling a second decoder buffer retrieval time for each decoding unit of a particular access unit according to a sequential order of the respective decoding unit in the multi-layered video data stream.
2. The decoder of claim 1 , wherein the multi-layered video data stream includes third timing control information signaling a third decoder buffer retrieval time for each decoding unit of a particular access unit according to a layer order defined for the plurality of layers, wherein in accordance with the layer order, within an access unit, a first decoding unit associated with a first layer precedes a second decoding unit associated with a second layer that succeeds the first layer based on the layer order.
3. The decoder of claim 2 , wherein decoding units associated with different layers of the plurality of layers are interleaved in the multi-layered video data stream.
4. The decoder of claim 3 , wherein the processor is configured to, in emptying a decoder's buffer in units of access units, remove the access units' decoding units, by de-interleaving, in accordance with the layer order.
5. The decoder of claim 1 , further comprising a plurality of buffers, each buffer of the plurality of buffers for storing decoding units of one layer of the plurality of layers, and the processor is configured to, for each layer, buffer the decoding units including NAL units associated with the respective layer in the corresponding buffer for the respective layer.
6. The decoder of claim 1 , further comprising a plurality of buffers, each buffer of the plurality of buffers for storing decoding units of a subset of layers of the plurality of layers, and the processor is configured to, for each layer, buffer the decoding units including NAL units associated with the respective layer in the corresponding buffer for the subset of layers to which the respective layer belongs.
7. The decoder of claim 1 , wherein the processor is configured to:
empty a decoder's buffer for buffering the multi-layered data stream in units of access units based on the first timing control information,
responsive to the second timing control information, empty a decoder's buffer for buffering the multi-layered data stream in units of the decoding units according to the sequential order based on the second decoder buffer retrieval time, and
responsive to the third timing control information, empty a decoder's buffer for buffering the multi-layered data stream in units of the decoding units according to the layer order based on the third decoder buffer retrieval time.
8. An encoder comprising a processor configured to encode video content into a plurality of layers of a multi-layered video data stream, the multi-layered video data stream including a sequence of network abstraction layer (NAL) units, which are divided into a sequence of access units,
wherein each access unit includes a plurality of decoding units, with each decoding unit of the plurality of decoding units having at least one NAL unit corresponding to one layer of the plurality of layers, and
wherein the encoder is configured to encode first timing control information and second timing control information into the multi-layered video data stream,
the first timing control information signaling a first decoder buffer retrieval time for an access unit from the sequence of access units, and
the second timing control information, separate from the first timing control information, signaling a second decoder buffer retrieval time for each decoding unit of a particular access unit according to a sequential order of the respective decoding unit in the multi-layered video data stream.
9. The encoder of claim 8 , wherein the multi-layered video data stream includes third timing control information signaling a third decoder buffer retrieval time for each decoding unit of a particular access unit according to a layer order defined for the plurality of layers, wherein in accordance with the layer order, within an access unit, a first decoding unit associated with a first layer precedes a second decoding unit associated with a second layer that succeeds the first layer based on the layer order.
10. The encoder of claim 9 , wherein decoding units associated with different layers of the plurality of layers are interleaved in the multi-layered video data stream.
11. The encoder of claim 10 , wherein the processor is configured to, in emptying a decoder's buffer in units of access units, remove the access units' decoding units, by de-interleaving, in accordance with the layer order.
12. The encoder of claim 8 , further comprising a plurality of buffers, each buffer of the plurality of buffers for storing decoding units of one layer of the plurality of layers, and the processor is configured to, for each layer, buffer the decoding units including NAL units associated with the respective layer in the corresponding buffer for the respective layer.
13. The encoder of claim 8 , further comprising a plurality of buffers, each buffer of the plurality of buffers for storing decoding units of a subset of layers of the plurality of layers, and the processor is configured to, for each layer, buffer the decoding units including NAL units associated with the respective layer in the corresponding buffer for the subset of layers to which the respective layer belongs.
14. The encoder of claim 8 , wherein the processor is configured to:
empty a decoder's buffer for buffering the multi-layered data stream in units of access units based on the first timing control information,
responsive to the second timing control information, empty a decoder's buffer for buffering the multi-layered data stream in units of the decoding units according to the sequential order based on the second decoder buffer retrieval time, and
responsive to the third timing control information, empty a decoder's buffer for buffering the multi-layered data stream in units of the decoding units according to the layer order based on the third decoder buffer retrieval time.
15. A non-transitory computer-readable medium for storing data associated with a video, comprising:
a multi-layered data stream stored in the non-transitory computer-readable medium, the multi-layered data stream comprising video content encoded therein as a plurality of layers, the multi-layered video data stream including a sequence of network abstraction layer (NAL) units, which are divided into a sequence of access units,
wherein each access unit includes a plurality of decoding units, with each decoding unit of the plurality of decoding units having at least one NAL unit corresponding to one layer of the plurality of layers, and
wherein the multi-layered video data stream includes:
first timing control information in the multi-layered video data stream signaling a first decoder buffer retrieval time for an access unit from the sequence of access units, and
second timing control information in the multi-layered video data stream, separate from of the first timing control information, the second timing control information signaling a second decoder buffer retrieval time for each decoding unit of a particular access unit according to a sequential order of the respective decoding unit in the multi-layered video data stream.
16. The non-transitory computer-readable medium of claim 15 , wherein the multi-layered video data stream includes third timing control information signaling a third decoder buffer retrieval time for each decoding unit of a particular access unit according to a layer order defined for the plurality of layers, wherein in accordance with the layer order, within an access unit, a first decoding unit associated with a first layer precedes a second decoding unit associated with a second layer that succeeds the first layer based on the layer order.
17. The non-transitory computer-readable medium of claim 16 , wherein decoding units associated with different layers of the plurality of layers are interleaved in the multi-layered video data stream.
18. The non-transitory computer-readable medium of claim 17 , in emptying a decoder's buffer in units of access units, the access units' decoding units are removed by de-interleaving in accordance with the layer order.
19. The non-transitory computer-readable medium of claim 15 , wherein each buffer of a plurality of buffers stores decoding units of one layer of the plurality of layers, and for each layer, the decoding units including NAL units associated with the respective layer are buffered in the corresponding buffer for the respective layer.
20. The non-transitory computer-readable medium of claim 15 , wherein each buffer of a plurality of buffers stores decoding units of a subset of layers of the plurality of layers, and for each layer, the decoding units including NAL units associated with the respective layer are buffered in the corresponding buffer for the subset of layers to which the respective layer belongs.