Adaptive buffer/quantizer control for transform video coders
First Claim
1. Apparatus for dynamically determining a quantization step size for a video coder wherein said video coder is processing at least a portion of at least one video signal comprised of frames wherein each frame contains at least one image representation, comprising:
- quantizer means for quantizing a digital signal representing said video signal comprised of frames;
means for obtaining an average quantization step size employed by said quantizer means in a previous frame;
buffer means for storing a quantized version of said digital signal representing said video signal comprised of frames;
means for obtaining an indication of fullness from said buffer means; and
means responsive to said average quantization step size and said fullness indication for generating an estimated target quantization step size for said digital signal.
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Abstract
A buffer/quantizer controller in a video coder utilizes the average quantization step size employed for the previous frame, the average number of bits produced per pel by the video coder for the image contained in the previous frame and current frame buffer fullness level to obtain an indication of image complexity. A target current frame quantization step size to be employed by the video coder in encoding a current frame is based on the indication of image complexity. Optionally, the target frame quantization step size is adjusted by a mapping procedure, at a predetermined intervals within each frame period, to account for the current buffer fullness. The map employed by the mapping procedure is adjusted in accordance with the target frame quantization step size.
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Citations
15 Claims
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1. Apparatus for dynamically determining a quantization step size for a video coder wherein said video coder is processing at least a portion of at least one video signal comprised of frames wherein each frame contains at least one image representation, comprising:
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quantizer means for quantizing a digital signal representing said video signal comprised of frames; means for obtaining an average quantization step size employed by said quantizer means in a previous frame; buffer means for storing a quantized version of said digital signal representing said video signal comprised of frames; means for obtaining an indication of fullness from said buffer means; and means responsive to said average quantization step size and said fullness indication for generating an estimated target quantization step size for said digital signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for dynamically determining a quantization step size for a video coder wherein said video coder is processing at least a portion of at least one video signal comprised of frames wherein each frame contains at least one image representation and said video coder includes at least quantizer means for quantizing a digital signal representative of said video signal and buffer means for storing a quantized version of said digital signal representative of said video signal, comprising the steps of:
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obtaining an average quantization step size employed by said quantizer means in a previous frame; receiving an indication of fullness from said buffer means; and generating an estimated target quantization step size, responsive to said average quantization step size and said fullness indication, for said digital signal. - View Dependent Claims (13, 14, 15)
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Specification