Method and apparatus for selectible quantization in an encoder

• US 7,058,677 B1
• Filed: 07/17/2001
• Issued: 06/06/2006
• Est. Priority Date: 07/17/2001
• Status: Expired due to Term

• Current Assignee: VIXS Systems Incorporated (Pixelworks Incorporated), VIXS Incorporated
• Original Assignee: VIXS Incorporated
• Inventors: Chan, Jason, Laksono, Indra
• Primary Examiner(s): Chaki, Kakali
• Assistant Examiner(s): Do, Chat C.
• Application Number:
  US09/906,908
• Time in Patent Office: 1,785 Days
• Field of Search: 708400-404, 375/240.2, 375/240.03, 382/250
• US Class Current: 708/402
• CPC Class Codes: G06F 17/147 Discrete orthonormal transforms, e.g. discrete cosine transform, discrete sine transform, and variations therefrom, e.g. modified discrete cosine transform, integer transforms approximating the discrete cosine transform G06F17/145 takes precedence
• CPC Class Codes: H04N 19/126 Details of normalisation or weighting functions, e.g. normalisation matrices or variable uniform quantisers
• CPC Class Codes: H04N 19/134 characterised by the element, parameter or criterion affecting or controlling the adaptive coding
• CPC Class Codes: H04N 19/146 Data rate or code amount at the encoder output
• CPC Class Codes: H04N 19/147 according to rate distortion criteria rate-distortion as a criterion for motion estimation H04N19/567
• CPC Class Codes: H04N 19/17 the unit being an image region, e.g. an object
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/192 the adaptation method, adaptation tool or adaptation type being iterative or recursive
• CPC Class Codes: H04N 19/60 using transform coding
• CPC Class Codes: H04N 19/61 in combination with predictive coding

Abstract

A method for selectable quantization for use in an encoder for compressing video and/or audio data includes processing that begins by receiving discrete cosine transform data of an encoded signal. The processing continues by obtaining a quantization table. The processing then continues by obtaining a plurality of scaling factors. The process then continues by generating a plurality of quantized value sets of the discrete cosine transform data based on the quantization table and the plurality of quantization scaling factors. The resulting data is then multiplied separately by each of the quantization scaling factors to produce the plurality of quantized values sets. The process then continues by selecting one of the plurality of quantized value sets based on quantization selection criteria.

Claims

1. A method for selectable quantization, the method comprises:

performing a discrete cosine transform function upon a macroblock of Motion Picture Expert Group (MPEG) encoded data of an encoded signal to produce discrete cosine transform data, wherein the discrete cosine transform data includes a matrix of data values;

receiving discrete the cosine transform data of the encoded signal;

obtaining a quantization table;

obtaining a plurality of quantization scaling factors;

generating a plurality of quantized value sets of the discrete cosine transform data based on the quantization table and plurality of quantization scaling factors;

determining quantization selection criteria based on complexity of the matrix of data values, wherein greater complexity of the matrix of data values results in a lower level of desired quantization and wherein lesser complexity of the matrix of data values results in a higher level of desire quantization; and

selecting one of the plurality of quantized value sets based on the quantization selection criteria to produce quantized data.

2. The method of claim 1, wherein the generating the plurality of quantization value sets further comprises:

performing t(i,j)=D(i,j)/[Q(i,j)]*Qs, where i represents a row number of the matrix, j represents a column number of the matrix, t(i,j) represents a quantized value set of the plurality of quantized value sets, D(i,j) represents the matrix of discrete cosine transform data, Q(i,j) represents the quantization table, and Qs represents one of the plurality of quantization scaling factors.

3. The method of claim 1, wherein the selecting the one of the plurality of quantized value sets further comprises:

for each of the plurality of quantized value sets, determining number of insubstantial data values in the quantized value set;

determining an acceptable level of insubstantial data values; and

selecting the one of the plurality of quantized value sets based on the acceptable level of insubstantial data values and the number of insubstantial data values in each of the plurality of quantized value sets.

4. The method of claim 3, wherein the determining an acceptable level of insubstantial data values further comprises:

establishing a video quality threshold; and

determining the acceptable level of insubstantial data values based on the video quality threshold.

5. An apparatus for selectable quantization, the apparatus comprises:

processing module; and

memory operably coupled to the processing module, wherein the memory includes operational instructions that cause the processing module to;

perform a discrete cosine transform function upon a macroblock of Motion Picture Expert Group (MPEG) encoded data of an encoded signal to produce the discrete cosine transform data, wherein the discrete cosine transform data includes a matrix of data values receive the discrete cosine transform data of the encoded signal;

obtain a quantization table;

obtain a plurality of quantization scaling factors;

generate a plurality of quantized value sets of the discrete cosine transform based on the quantization table and plurality of quantization scaling factors;

determining quantization selection criteria based on complexity of the matrix of data values, wherein greater complexity of the matrix of data values results in a lower level of desired quantization and wherein lesser complexity of the matrix of data values results in a higher level of desire quantization; and

select one of the plurality of quantized value sets based on the quantization selection criteria to produce quantized data.

6. The apparatus of claim 5, wherein the memory further comprises operational instructions that cause the processing module to generate the plurality of quantization value sets by:

performing t(i,j)=D(i,j)/[Q(i,j)]*Qs, where i represents a row number of a matrix, j represents a column number of a matrix, t(i,j) represents a quantized value set of the plurality of quantized value sets, D(i,j) represents the matrix of discrete cosine transform data, Q(i,j) represents the quantization table, and Qs represents one of the plurality of quantization scaling factors.

7. The apparatus of claim 5, wherein the memory further comprises operational instructions that cause the processing module to select the one of the plurality of quantized value sets by:

for each of the plurality of quantized value sets, determining number of insubstantial data values in the quantized value set;

determining an acceptable level of insubstantial data values; and

selecting the one of the plurality of quantized value sets based on the acceptable level of insubstantial data values and the number of insubstantial data values in each of the plurality of quantized value sets.

8. The apparatus of claim 7, wherein the memory further comprises operational instructions that cause the processing module to determine an acceptable level of insubstantial data values by:

establishing a video quality threshold; and

determining the acceptable level of insubstantial data values based on the video quality threshold.

9. A method for selectable quantization, the method comprises:

receiving discrete cosine transform data of an encoded signal;

obtaining a quantization table;

obtaining a plurality of quantization scaling factors;

generating a plurality of quantized value sets of the discrete cosine transform data based on the quantization table and plurality of quantization scaling factors; and

selecting one of the plurality of quantized value sets based on quantization selection criteria to produce quantized data by;

determining number of insubstantial data values in the quantized value set, for each of the plurality of quantized value sets;

determining an acceptable level of insubstantial data values; and

selecting the one of the plurality of quantized value sets based on the acceptable level of insubstantial data values and the number of insubstantial data values in each of the plurality of quantized value sets.

10. The method of claim 9, wherein the receiving the discrete cosine transform data further comprises:

performing a discrete cosine transform function upon a macroblock of Motion Picture Expert Group (MPEG) encoded data to produce the discrete cosine transform data, wherein the discrete cosine transform data includes a matrix of data values.

11. The method of claim 10, wherein the generating the plurality of quantization value sets further comprises:

performing t(i,j)=D(i,j)/[Q(i,j)]*Qs, where i represents a row number of the matrix, j represents a column number of the matrix, t(i,j) represents a quantized value set of the plurality of quantized value sets, D(i,j) represents the matrix of discrete cosine transform data, Q(i,j) represents the quantization table, and Qs represents one of the plurality of quantization scaling factors.

12. The method of claim 9, wherein the determining an acceptable level of insubstantial data values further comprises:

establishing a video quality threshold; and

determining the acceptable level of insubstantial data values based on the video quality threshold.

13. An apparatus for selectable quantization, the apparatus comprises:

processing module; and

memory operably coupled to the processing module, wherein the memory includes operational instructions that cause the processing module to;

receive discrete cosine transform data of an encoded signal;

obtain a quantization table;

obtain a plurality of quantization scaling factors;

generate a plurality of quantized value sets of the discrete cosine transform based on the quantization table and plurality of quantization scaling factors; and

select one of the plurality of quantized value sets based on quantization selection criteria to produce quantized data by;

determining number of insubstantial data values in the quantized value set, for each of the plurality of quantized value sets;

determining an acceptable level of insubstantial data values; and

selecting the one of the plurality of quantized value sets based on the acceptable level of insubstantial data values and the number of insubstantial data values in each of the plurality of quantized value sets.

14. The apparatus of claim 13, wherein the memory further comprises operational instructions that cause the processing module to receive the discrete cosine transform data by:

performing a discrete cosine transform function upon a macroblock of Motion Picture Expert Group (MPEG) encoded data to produce the discrete cosine transform data, wherein the discrete cosine transform data includes a matrix of data values.

15. The apparatus of claim 14, wherein the memory further comprises operational instructions that cause the processing module to generate the plurality of quantization value sets by:

performing t(i,j)=D(i,j)/[Q(i,j)]*Qs, where i represents a row number of a matrix, j represents a column number of a matrix, t(i,j) represents a quantized value set of the plurality of quantized value sets, D(i,j) represents the matrix of discrete cosine transform data, Q(i,j) represents the quantization table, and Qs represents one of the plurality of quantization scaling factors.

16. The apparatus of claim 13, wherein the memory further comprises operational instructions that cause the processing module to determine an acceptable level of insubstantial data values by:

establishing a video quality threshold; and

determining the acceptable level of insubstantial data values based on the video quality threshold.