Method and apparatus for providing rate control in a video encoder
First Claim
1. A method for controlling the quantization in a digital video encoder that comprises a plurality of parallel compression engines, comprising the steps of:
- determining a target quantization level for a video frame;
wherein the video frame is represented by a plurality of panels, each panel comprises a plurality of slices, and each panel is processed in parallel by a respective one of the compression engines;
encoding the first slice of each panel in accordance with said target quantization level; and
encoding subsequent slices in each panel in accordance with a quantization level that is allowed to vary from said target quantization level until the last slice of each panel is reached;
wherein the quantization level used for encoding the last slice of each panel is driven toward said target quantization level.
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Abstract
A method and apparatus are provided for controlling the quantization level in a digital video encoder that comprises a plurality of parallel compression engines (12). The input picture is partitioned into a number of panels (10) and each panel is processed by a distinct compression engine (12). A reference quantizer scale is determined before encoding a frame of video. The reference quantizer scale is used at the first slice of every video image panel being processed by the video encoder. The quantizer scale at the last slice of the image panel is then forced to be the same as the first slice. The forcing step can use a piecewise-linear feedback formula. A group of pictures (GOP) target bit rate is adjusted based on the number of film pictures and non-film pictures currently in the processing pipeline of at least one of the compression engines. A higher target bit rate is provided for non-film pictures. A buffer (16) level of the video encoder is used to control the start of a new group of pictures (GOP). The start of a new GOP is delayed if the buffer (16) does not have sufficient space to accommodate an intra-coded (I) frame for the new GOP.
131 Citations
33 Claims
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1. A method for controlling the quantization in a digital video encoder that comprises a plurality of parallel compression engines, comprising the steps of:
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determining a target quantization level for a video frame; wherein the video frame is represented by a plurality of panels, each panel comprises a plurality of slices, and each panel is processed in parallel by a respective one of the compression engines; encoding the first slice of each panel in accordance with said target quantization level; and encoding subsequent slices in each panel in accordance with a quantization level that is allowed to vary from said target quantization level until the last slice of each panel is reached; wherein the quantization level used for encoding the last slice of each panel is driven toward said target quantization level. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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16. Apparatus for controlling the quantization in a digital video encoder that comprises a plurality of parallel compression engines, comprising:
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means for determining a target quantization level for a video frame; wherein the video frame is represented by a plurality of panels, each panel comprises a plurality of slices, and each panel is processed in parallel by a respective one of the compression engines; means for encoding the first slice of each panel in accordance with said target quantization level; and means for encoding subsequent slices in each panel in accordance with a quantization level that is allowed to vary from said target quantization level until the last slice of each panel is reached; and means for driving the quantization level at the last slice of each of said image panels toward said target quantization level.
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Specification