Rate control for stereoscopic digital video encoding
First Claim
1. A rate control method for a stereoscopic digital data signal having a base layer and an enhancement layer, wherein first and second reference pictures are available for use in coding at least a portion of a current picture of the enhancement layer, comprising the steps of:
- selecting one of said first and second reference pictures for use in coding said at least a portion of said current picture according to a selection criteria;
wherein the first reference picture precedes the current picture in the enhancement layer and the second reference picture is concurrent with the current picture in the base layer;
calculating a first number of bits to allocate in coding said at least a portion of said current picture according to whether said first or second reference picture is selected in said selecting step;
calculating a quantization step size for coding said at least a portion of said current picture according to said first number of bits;
and coding said current picture as a disparity-predicted P-picture when said second reference picture is a first picture of a group of pictures of said base layer.
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Accused Products
Abstract
Rate control in a stereoscopic digital video communication system is accomplished by modifying the quantization level of P or B-frame data in the enhancement layer depending on whether the frame is temporally predicted (from the same layer) or disparity predicted (from the opposite layer). The invention can maintain a consistent image quality by providing additional quantization bits for disparity-predicted P-pictures, for example, where a P-frame may be encoded from a B-frame in the enhancement layer. The selected quantization level corresponds to an overall bit rate requirement of the enhancement layer. For disparity predicted P-frames, the quantization step size is modified according to the activity level of the frame being encoded in the enhancement layer, or of the reference frame, whichever is greater. Also, image quality is improved and frame freeze up is prevented during editing modes such as fast forward and fast rewind which require random access to the picture data. When the reference frame in the base layer is the first frame of a group of pictures (GOP), the corresponding enhancement layer frame will be encoded as an I or P frame instead of as a B frame to improve image quality and eliminate or reduce error propagation during random access.
199 Citations
24 Claims
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1. A rate control method for a stereoscopic digital data signal having a base layer and an enhancement layer, wherein first and second reference pictures are available for use in coding at least a portion of a current picture of the enhancement layer, comprising the steps of:
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selecting one of said first and second reference pictures for use in coding said at least a portion of said current picture according to a selection criteria; wherein the first reference picture precedes the current picture in the enhancement layer and the second reference picture is concurrent with the current picture in the base layer; calculating a first number of bits to allocate in coding said at least a portion of said current picture according to whether said first or second reference picture is selected in said selecting step; calculating a quantization step size for coding said at least a portion of said current picture according to said first number of bits; and coding said current picture as a disparity-predicted P-picture when said second reference picture is a first picture of a group of pictures of said base layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An apparatus for rate control of a stereoscopic digital data signal having a base layer and an enhancement layer, wherein first and second reference pictures are available for use in coding at least a portion of a current picture of the enhancement layer, comprising:
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means for selecting one of said first and second reference for use in coding said at least a portion of said current picture according to a selection criteria; wherein the first reference picture precedes the current picture in the enhancement layer and the second reference picture is concurrent with the current picture in the base layer; means for calculating a first number of bits to allocate in coding said at least a portion of said current picture according to whether said first or second reference picture is selected by said selecting means; means for calculating a quantization step size for coding said at least a portion of said current picture according to said first number of bits; and means for coding said current picture as a disparity-predicted P-picture when said second reference picture is a first picture of a group of pictures of said base layer. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification