Adaptive video quality
A method for encoding a first stream of video data comprising a plurality of frames of video, the method, for one or more of the plurality of frames of video, comprising the steps of: encoding in a hierarchical arrangement a frame of the video data, the hierarchical arrangement comprising a base layer of video data and a first enhancement layer of video data, said first enhancement layer of video data comprising a plurality of sub-layers of enhancement data, such that when encoded: the base layer of video data comprises data which when decoded renders the frame at a first, base, level of quality; and each sub-layer of enhancement data comprises data which, when decoded with the base layer, render the frame at a higher level of quality than the base level of quality; and wherein the steps of encoding the sub-layers of enhancement data comprises: quantizing the enhancement data at a determined initial level of quantization thereby creating a set of quantized enhancement data; associating to each of the plurality of sub-layers a respective notional quantization level and allocating, for each of the plurality of sub-layers, a sub-set of the set of quantized enhancement data based on the respective notional quantization level.
1. A method for encoding a first stream of video data comprising a plurality of frames of video, the method, for one or more of the plurality of frames of video, comprising the steps of:
encoding an enhancement layer for a frame of the video data, the enhancement layer enhancing a base layer of video data, said enhancement layer of video data comprising a plurality of sub-layers of enhancement data,
such that when encoded:
each sub-layer of enhancement data comprises data which, when decoded with the base layer, render the frame at a higher level of quality than a base level of quality, the base layer of video data comprising data which when decoded renders the frame at the base level of quality;
and wherein the steps of encoding the sub-layers of enhancement data comprises:
encoding the sub-layers as sub-layers of residual data;
defining a deadzone around a zero value for the residual data, a width of the deadzone being determined at least in part by a quantization factor and such that a size of the each sub-layer enhancement data is at or below a maximum allowable size; and
removing residual values for pixels that fall within the deadzone for the plurality of sub-layers.
2. The method of claim 1 , wherein the steps of encoding the sub-layers of enhancement data comprise:
determining an available data rate for the enhancement layer; and
setting the width of the deadzone based on the available data rate.
3. The method of claim 2 , wherein the width of the deadzone is different for each of the different sub-layers of enhancement data.
4. The method of claim 3 , wherein the steps of encoding the sub-layers of enhancement data comprise:
defining a number of bins, each bin defining a range of residual values; and
assigning a different number of bits to each bin for the encoding of the residual data.
5. The method of claim 2 , wherein determining an available data rate for the enhancement layer comprises:
determining a total data rate available for transmission;
determining a data rate required for the base layer of video data; and
subtracting the data rate required for the base layer from the total data rate to determine the available data rate for the enhancement layer.
6. The method of claim 1 , wherein the base layer is encoded using an MPEG standard based encoding algorithm.
7. The method of claim 6 , wherein the base layer when decoded renders the frame at SD resolution, and the enhancement layer of video data when decoded renders the frame at HD or higher resolution.
8. The method of claim 1 , wherein the encoded video stream is broadcast to a plurality of client devices.
9. The method of claim 8 , wherein the base layer is selected as a standard which each of the plurality of client devices is able to decode.
10. The method of claim 9 , wherein the client device is configured to decode the base layer plus one or more sub-layers of enhancement data to produce a video with a higher level of quality of the base layer, wherein the number of sub-layers of enhancement decoded by the client device is dependent on the capability of the decoding client device.
11. The method of claim 1 , wherein the sub-layers of enhancement data are encoded in a hierarchical fashion with a lowest sub-layer having the lowest notional quantization level and each subsequent sub-layer having a higher quantization level than the preceding sub-layer.
12. An apparatus for encoding a first stream of video data comprising a plurality of frames of video, the apparatus comprising a video streaming server, said video stream configured, for one or more of the plurality of frames of video, to:
encode an enhancement layer for a frame of the video data, the enhancement layer enhancing a base layer of video data, said enhancement layer of video data comprising a plurality of sub-layers of enhancement data,
such that when encoded:
each sub-layer of enhancement data comprises data which, when decoded with the base layer, render the frame at a higher level of quality than a base level of quality, the base layer of video data comprising data which when decoded renders the frame at the base level of quality;
and wherein the apparatus is configured to encode the sub-layers of enhancement data by:
encoding the sub-layers as sub-layers of residual data;
defining a deadzone around a zero value for the residual data, a width of the deadzone being determined at least in part by a quantization factor and such that a size of the each sub-layer enhancement data is at or below a maximum allowable size; and
removing residual values for pixels that fall within the deadzone for the plurality of sub-layers.
13. The apparatus of claim 12 , wherein the width of the deadzone is set based on an available data rate for the enhancement layer and wherein the width of the deadzone is different for each of the different sub-layers of enhancement data.
14. A non-transitory computer-readable medium comprising an encoded stream of video data, the encoded stream of video data comprising an enhancement layer for a frame of the video data, the enhancement layer enhancing a base layer of video data, said enhancement layer of video data comprising a plurality of sub-layers of enhancement data, wherein each sub-layer of enhancement data comprises data which, when decoded with the base layer, render the frame at a higher level of quality than a base level of quality, the base layer of video data comprising data which when decoded renders the frame at the base level of quality, wherein the plurality of sub-layers of enhancement data are encoded as sub-layers of residual data, and wherein residual values for pixels that fall within a deadzone defined around a zero value for the plurality of sub-layers are removed, a width of the deadzone being determined at least in part by a quantization factor and such that a size of the each sub-layer enhancement data is at or below a maximum allowable size.
15. The medium of claim 14 , wherein the width of the deadzone is set based on a data rate for the enhancement layer and wherein the width of the deadzone is different for each of the different sub-layers of enhancement data.