Efficient transcoding device and method
AssigneeMotorola, Inc.
InventorsM. Vedat Eyuboglu, Mei Yong
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Abstract
The present invention provides a transcoder for transcoding of digitally encoded bit streams produced by predictive encoders. The transcoder of this invention is less complex than previously known transcoders in terms of both computational and storage requirements. This efficiency is achieved by combining decoding and re-encoding steps into one step. This one-step transcoding is accomplished by modifying the originally quantized vectors and then requantizing and noiseless encoding these vectors into a bit stream in accordance with a predetermined objective.
Claims36
A device for transcoding a sequence of quantized vectors Y.sub.i generated by a predictive waveform encoder utilizing modified quantization error vectors S.sub.i, comprising:
- (A) an adder, operably coupled to receive at least a first quantized vector Y.sub.i and at least a first modified quantization error vector S.sub.i, for generating a difference vector E.sub.i '=Y.sub.i -S.sub.i between the quantized vector Y.sub.i and the modified quantization error vector S.sub.i ;
- (B) a quantizer, operably coupled to the adder, for quantizing the difference vector E.sub.i ' to obtain a transcoded vector Y.sub.i ';
- (C) a quantization error vector calculator (QEVC), operably coupled to receive at least two of the vectors Y.sub.i, E.sub.i ' and Y.sub.i ', for generating an inverse-transformed error vector d.sub.i '=A.sub.i.sup.-1 [D.sub.i '], where D.sub.i ' is a quantization error vector and A.sub.i.sup.-1 is an inverse transformation;
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- (D) modifying circuitry, operably coupled to the QEVC, for generating a modified quantization error vector S.sub.i based on past values of the vector d.sub.i ', where S.sub.i is input to the adder.
A method for transcoding a sequence of quantized vectors Yi generated by a predictive waveform encoder utilizing modified quantization error vectors S.sub.i, comprising the steps of:
- (A) generating a difference vector E.sub.i '=Y.sub.i -S.sub.i between at least a first quantized vector Y.sub.i and a modified quantization error vector S.sub.i ;
- (B) quantizing the difference vector E.sub.i ' to obtain a transcoded vector Y.sub.i ';
- (C) receiving at least two of the vectors Y.sub.i, E.sub.i ' and Y.sub.i ' and generating an inverse-transformed error vector d.sub.i '=A.sub.i.sup.-1 [D.sub.i '], where D.sub.i ' is a quantization error vector and A.sub.i.sup.-1 is an inverse transformation;
- and
- (D) generating the modified quantization error vector S.sub.i based on past values of the vector d.sub.i '.
A transcoding device for converting a sequence of quantized vectors Y.sub.i generated by a predictive waveform encoder utilizing modified quantization error vectors S.sub.i, comprising:
- (A) an adder, operably coupled to receive at least a first quantized vector Y.sub.i and at least a first modified quantization error vector S.sub.i, for generating a difference vector E.sub.i '=Y.sub.i -S.sub.i between the quantized vector Y.sub.i and the modified quantization error vector S.sub.i ;
- (B) a generalized quantizer, operably coupled to the adder and having a quantization error vector calculator, for quantizing the difference vector E.sub.i ' to obtain a transcoded vector Y.sub.i ', receiving at least one of the vectors Y.sub.i and E.sub.i ', for generating an inverse-transformed error vector d.sub.i '=A.sub.i.sup.-1 [D.sub.i '], where D.sub.i ' is a quantization error vector and A.sub.i.sup.-1 is an inverse transformation;
- and
- (C) modifying circuitry, operably coupling the quantization error vector calculator to the adder, for generating the modified quantization error vector S.sub.i based on past values of the vector d.sub.i '.
Dependencies are inferred from the claim text.