Adaptive transform coding system, adaptive transform decoding system and adaptive transform coding/decoding system

Abstract

In an adaptive transform coding system and/or and adaptive transform decoding system, coding efficiency in the case where a small number of quantized values having large absolute value are present, is improved. The adaptive transform coding system codes the small number of quantized values having large absolute values and other quantized values are coded separately. More particularly, the adaptive transform coding system includes a selector ( 6 ) discriminating the small number of quantized value having large absolute value from other quantized value, a pulse coding means for coding the small number of quantized values having large absolute values ( 8 ) and the pulse decoding means ( 16 ) for decoding the same, a coding means ( 7 ) for coding the quantized value other than those having large absolute values and a decoding means ( 15 ) decoding the same, and a synthesis means ( 18 ) for synthesizing the small number of quantized values having large absolute value and other quantized values.

What is claimed is:  
     
       1. An adaptive transform coding system comprising: 
       a transform means for transforming an input signal into a frequency domain signal;  
       an analysis means for analyzing said input signal and said frequency domain signal to derive an allowable quantization error;  
       a quantizing means for quantizing the amplitude value of said frequency domain signal on the basis of a quantization step size to derive a quantized value and a quantization error,  
       a quantization parameter determining means for determining said quantization step size with reference to said allowable quantization error and said quantization error and a total code amount;  
       a selector for analyzing the quantized value of said frequency domain signal to derive a first signal and a second signal;  
       a first coding means for coding said quantized value of said first signal with reference to said second signal to derive a first code and a first code amount;  
       a second coding means for coding said quantized value of said second signal to derive a second code and a second code amount;  
       a parameter coding means for coding said quantization step size to derive a third code and a third code amount;  
       an adder for deriving said total code amount of said first code amount, said second code amount and said third code amount; and  
       a multiplexer for multiplexing said first code, said second code and said third code to generate a bit stream.  
     
     
       2. An adaptive transform coding system as set forth in  claim 1 , wherein said selector divides the quantized value of said frequency domain signal into a first signal and a third signal to generate a fourth signal, in which the absolute value of said quantized value of said first signal is replaced with smaller quantized value, and said second signal is generated by combining said third signal and said fourth signal. 
     
     
       3. An adaptive transform coding system as set forth in  claim 1 , wherein said selector derives said first signal and said second signal so that said total code amount becomes minimum. 
     
     
       4. An adaptive transform coding system as set forth in  claim 1 , wherein said first coding means generates said first code by coding the absolute value of said quantized value of said first signal, the polarity of the quantized value of said first signal and a frequency of said first signal. 
     
     
       5. An adaptive transform coding system as set forth in  claim 4 , wherein said first coding means derives a threshold value for said quantized value of said first signal to code a value derived by subtracting said threshold value from said quantized value of said first signal in place of said absolute value of said quantized value of said first signal. 
     
     
       6. An adaptive transform coding system as set forth in  claim 5 , wherein, in each sample of said first signal, the threshold value is value derived by adding one for the absolute value of the quantized value of a sample of said second signal at the same frequency to the sample of said first signal. 
     
     
       7. An adaptive transform coding system as set forth in  claim 5 , wherein a region of quantized value to be coded in said second coding means is limited, and in each sample of said first signal, said threshold value is a value derived by adding one to a maximum absolute value of an input region of said second coding means upon coding the signal having the same frequency as that of said sample by said second coding means. 
     
     
       8. An adaptive transform coding system as set forth in  claim 4 , wherein said first coding means codes the frequency of each sample of said first signal in sequential ascending order of the frequency, and for the sample other than said sample having the lowest frequency, a difference between the frequency of the sample and the frequency of the sample of the one preceding order are coded. 
     
     
       9. An adaptive transform coding system as set forth in  claim 8 , wherein said frequency signal is divided into a plurality of regions, and in said first coding means, in place of the frequency of the sample having the lowest frequency, the number of boundaries lower than said frequency of the sample having the lowest frequency, and the difference between said frequency of the sample having the lowest frequency and the maximum value in the region boundary frequencies lower than said frequency of the sample having the lowest frequency, are encoded. 
     
     
       10. An adaptive transform decoding system comprising: 
       a demultiplexer for separating an input signal into a first code, a second code and a third code;  
       a first decoding means for decoding said first code with reference to said second code  to derive a first signal;  
       a second decoding means for decoding said second code to derive a second signal;  
       a parameter decoding means for decoding said third signal  code to derive a quantization step size;  
       a synthesis means for synthesizing said first signal and said second signal for deriving  to derive a synthesized signal;  
       an inverse quantizing means for inverse quantizing said quantized value of  said synthesized signal to derive an inverse quantized signal; and  
       an inverse transform means for transforming said inverse quantized signal into a time domain to derive  a time domain signal.  
     
     
       11. An adaptive transform decoding system as set forth in  claim 10 , wherein said first decoding means derives  signal includes a frequency of the  a quantized value, an absolute value  and an amplitude of the  said quantized value and a sign of the quantized value by decoding said first code to set a frequency of the quantized value, an absolute value of the quantized value and a sign of the quantized value of said first signal, respectively . 
     
     
       12. An adaptive transform decoding system as set forth in  claim 11 , wherein said first decoding means derives a threshold value and takes a value derived by adding said threshold value to the absolute value  amplitude of the quantized value derived by decoding said first code as an absolute value  amplitude of the quantized value of said first signal, in place of the absolute value  amplitude of the quantized value derived by decoding said first code. 
     
     
       13. An adaptive transform decoding system as set forth in  claim 12 , wherein, in each sample of said first signal, the  threshold value is an absolute value  amplitude of the quantized value of the sample  of said second signal of  having the same frequency to said sample  as said first signal. 
     
     
       14. An adaptive transform decoding system as set forth in  claim 12 , wherein said second decoding means has restriction in an inverse  amplitude of a quantized value, and in each sample of said first signal, the  wherein said threshold value is a value  derived by adding one to the maximum absolute  value of said amplitude in said restriction when said second decoding means decodes the signal having the same frequency as said sample . 
     
     
       15. An adaptive transform decoding system as set forth in  claim 11 , wherein said first decoding means derives a difference between the frequency and the frequency of the sample of the lowest frequency by decoding, and derives the frequency of the sample other than said sample having the lowest frequency  frequency is derived by cumulatively adding the difference of said  a predetermined frequency to the frequency of the sample having the lowest low frequency  previously derived frequency. 
     
     
       16. An adaptive transform decoding system as set forth in claim  15 ,   11 , wherein said frequency belongs to one of the predetermined frequency regions, and wherein the  said frequency signal  is divided into a plurality of region, in said first decoding means, the number of region boundaries and the difference between said frequencies are derived by decoding, and a value derived  derived by adding a difference of said frequencies  predetermined frequency which is included in said first signal to a frequency of region boundary  which is indicated by said  the number of region boundary is taken as the frequency of the sample having the lowest frequency  said frequency regions, and wherein said number is included in said first signal. 
     
     
       17. An adaptive transform decoding system as set forth in  claim 10 , wherein said synthesis means generates a signal replacing the  synthesized signal is derived by replacing a quantized value of the sample  said second signal having the same frequency as the frequency of each sample of  said first signal with the  a quantized value of said first signal to take the replaced signal as said synthesized signal . 
     
     
       18. An adaptive transform coding and decoding system comprising: 
       a transform means for transforming an input signal into a frequency domain signal;  
       an analysis means for analyzing said input signal and said frequency domain signal to derive an allowable quantization error;  
       a quantizing means for quantizing amplitude value of said frequency domain signal on the basis of a quantization step size to derive a quantized value and a quantization error,  
       a quantization parameter determining means for determining said quantization step size with reference to said allowable quantization error and said quantization error and a total code amount;  
       a selector for analyzing the quantized value of said frequency domain signal to derive a first signal and a second signal;  
       a first coding means for coding said quantized value of said first signal with reference to said second signal to derive a first code and a first code amount;  
       a second coding means for coding said quantized value of said second signal to derive a second code and a second code amount;  
       a parameter coding means for coding said quantization step size to derive a third code and a third code amount;  
       an adder for deriving said total code amount of said first code amount, said second code amount and said third code amount;  
       a multiplexer for multiplexing said first code, said second code and said third code to generate a bit stream  
       a demultiplexer for separating an input signal into a first code, a second code and a third code;  
       a first decoding means for decoding said first code with reference to said second code to derive a first signal;  
       a second decoding means for decoding said second code to derive a second signal;  
       a parameter decoding means for decoding said third signal to derive a quantization step size;  
       a synthesis means for synthesizing said first signal and said second signal for deriving a synthesized signal;  
       an inverse quantizing means for inverse quantizing said quantized value of said synthesized signal to derive an inverse quantized signal; and  
       an inverse transform means for transforming said inverse quantized signal into a time domain to derive a time domain signal.  
     
     
       19. A decoding system comprising: 
       
         first decoding means for decoding a first code which relates to the number of a replaced element;  
       
       
         second decoding means for decoding a second code relating to an amplitude of said replaced element and a third code relating to a frequency of said replaced element if said number of said replaced element satisfies a predetermined condition; and  
       
       
         reconstructing means for reconstructing a pulse on the basis of the decoded second and third codes. 
       
     
     
       20. A decoding system as set forth in  claim 19 , further comprising: 
       
         synthesis means for synthesizing said pulse and a Huffman decoded signal to derive a synthesized signal. 
       
     
     
       21. A decoding system as set forth in  claim 20 , wherein said frequency belongs to one of a plurality of predetermined frequency regions, and wherein said frequency is derived by adding a predetermined frequency which is included in the first signal to a frequency which is indicated by the number of said plurality of predetermined frequency regions, and wherein the number is included in said first signal which is derived by decoding said first code. 
     
     
       22. A decoding system comprising: 
       
         first decoding means for decoding a first code which relates to the number of replaced elements;  
       
       
         second decoding means for decoding a second code relating to amplitudes of said replaced elements and a third code relating to frequencies of said replaced elements if said number of said replaced elements satisfies a predetermined condition; and  
       
       
         reconstructing means for reconstructing pulses on the basis of the decoded second and third codes. 
       
     
     
       23. A decoding system as set forth in  claim 22 , further comprising: 
       
         synthesis means for synthesizing said pulses and a Huffman decoded signal to derive a synthesized signal. 
       
     
     
       24. A decoding system as set forth in  claim 22 , wherein said frequencies and said amplitudes are included in a first signal which is derived by decoding said first code. 
     
     
       25. A decoding system as set forth in  claim 24 , wherein at least one of said frequencies are derived by cumulatively adding a predetermined frequency to the previously derived frequency. 
     
     
       26. A decoding system as set forth in  claim 24 , wherein said Huffman decoded signal is divided into a plurality of regions, wherein at least one of said frequencies are derived by adding a predetermined frequency which is included in said first signal to a frequency which is indicated by the number of said plurality of regions, and wherein the number is included in said first signal. 
     
     
       27. An adaptive transform decoding system comprising: 
       
         a demultiplexer for separating an input signal into a first code, a second code and a third code;  
       
       
         a first decoder for decoding said first code to derive a first signal;  
       
       
         a second decoder for decoding said second code to derive a second signal;  
       
       
         a parameter decoder for decoding said third code to derive a quantization step size;  
       
       
         a synthesizer for synthesizing said first signal and said second signal to derive a synthesized signal;  
       
       
         an inverse quantizing circuit for inverse quantizing said synthesized signal based on said quantization step size to derive an inverse quantized signal; and  
       
       
         an inverse transforming circuit for transforming said inverse quantized signal into a time domain signal. 
       
     
     
       28. An adaptive transform decoding system as set forth in  claim 27 , wherein said first signal includes a frequency of a quantized value and an amplitude of said quantized value. 
     
     
       29. An adaptive transform decoding system as set forth in  claim 28 , wherein said first decoder derives a threshold value and takes a value derived by adding said threshold value to the amplitude of the quantized value derived by decoding said first code as an amplitude of the quantized value of said first signal, in place of the amplitude of the quantized value derived by decoding said first code. 
     
     
       30. An adaptive transform decoding system as set forth in  claim 29 , wherein said threshold value is an amplitude of the quantized value of said second signal having the same frequency as said first signal. 
     
     
       31. An adaptive transform decoding system as set forth in  claim 29 , wherein said second decoder has restriction in an amplitude of a quantized value, and wherein said threshold value is derived by adding one to the maximum value of said amplitude in said restriction. 
     
     
       32. An adaptive transform decoding system as set forth in  claim 28 , wherein said frequency is derived by cumulatively adding a predetermined frequency to the previously derived frequency. 
     
     
       33. An adaptive transform decoding system as set forth in  claim 28 , wherein said frequency belongs to one of a plurality of predetermined frequency regions, and wherein said frequency is derived by adding a predetermined frequency which is included in said first signal to a frequency which is indicated by the number of said plurality of predetermined frequency regions, and wherein the number is included in said first signal. 
     
     
       34. An adaptive transform decoding system as set forth in  claim 27 , wherein said synthesized signal is derived by replacing a quantized value of said second signal having the same frequency as said first signal with a quantized value of said first signal. 
     
     
       35. A decoding system comprising: 
       
         a first decoder for decoding a first code which relates to the number of a replaced element;  
       
       
         a second decoder for decoding a second code relating to an amplitude of said replaced element and a third code relating to a frequency of said replaced element if said number of the replaced element satisfies a predetermined condition; and  
       
       
         a reconstructing circuit for reconstructing a pulse on the basis of the decoded second and third codes. 
       
     
     
       36. A decoding system as set forth in  claim 35 , further comprising: 
       
         a synthesizer for synthesizing said pulse and a Huffman decoded signal to derive a synthesized signal. 
       
     
     
       37. A decoding system as set forth in  claim 36 , wherein said frequency belongs to one of a plurality of predetermined frequency regions, and wherein said frequency is derived by adding a predetermined frequency which is included in the first signal to a frequency which is indicated by the number of said plurality of predetermined frequency regions, and wherein the number is included in said first signal which is derived by decoding said first code. 
     
     
       38. A decoding system comprising: 
       
         a first decoder for decoding a first code which relates to the number of replaced elements;  
       
       
         a second decoder for decoding a second code relating to amplitudes of said replaced elements and a third code relating to frequencies of said replaced elements if said number of the replaced elements satisfies a predetermined condition; and  
       
       
         a reconstructing circuit for reconstructing pulses on the basis of the decoded second and third codes. 
       
     
     
       39. A decoding system as set forth in  claim 38 , further comprising: 
       
         a synthesizer for synthesizing said pulses and a Huffman decoded signal to derive a synthesized signal. 
       
     
     
       40. A decoding system as set forth in  claim 38 , wherein said frequencies and said amplitudes are included in a first signal which is derived by decoding said first code. 
     
     
       41. A decoding system as set forth in  claim 40 , wherein at least one of said frequencies are derived by cumulatively adding a predetermined frequency to the previously derived frequency. 
     
     
       42. A decoding system as set forth in  claim 40 , wherein said Huffman decoded signal is divided into a plurality of regions, wherein at least one of said frequencies are derived by adding a predetermined frequency which is included in said first signal to a frequency which is indicated by the number of said plurality of regions, and wherein the number is included in said first signal. 
     
     
       43. A decoding method comprising: 
       
         separating an input signal into a first code, a second code and a third code;  
       
       
         decoding said first code to derive a first signal;  
       
       
         decoding said second code to derive a second signal;  
       
       
         decoding said third code to derive a quantization step size;  
       
       
         synthesizing said first signal and second signal to derive a synthesized signal;  
       
       
         inverse quantizing said synthesized signal based on said quantization step size to derive an inverse quantized signal; and  
       
       
         transforming said inverse quantized signal into a time domain signal. 
       
     
     
       44. A decoding method as set forth in  claim 43 , wherein said first signal includes a frequency of a quantized value and an amplitude of said quantized value. 
     
     
       45. A decoding method as set forth in  claim 44 , wherein said first decoding step derives a threshold value and takes a value derived by adding said threshold value to the amplitude of the quantized value derived by decoding said first code as an amplitude of the quantized value of said first signal, in place of the amplitude of the quantized value derived by decoding said first code. 
     
     
       46. A decoding method as set forth in  claim 45 , wherein said threshold value is an amplitude of the quantized value of said second signal having the same frequency as said first signal. 
     
     
       47. A decoding method as set forth in  claim 45 , wherein said second decoding means has restriction in an amplitude of a quantized value, and wherein said threshold value is derived by adding one to the maximum value of said amplitude in said restriction. 
     
     
       48. A decoding method as set forth in  claim 44 , wherein said frequency is derived by cumulatively adding a predetermined frequency to the previously derived frequency. 
     
     
       49. A decoding method as set forth in  claim 44 , wherein said frequency belongs to one of a plurality of frequency regions, and wherein said frequency is derived by adding a frequency amount which is included in said first signal to a frequency which is indicated by the number of said plurality of frequency regions, and wherein the number is included in said first signal. 
     
     
       50. A decoding method as set forth in  claim 43 , wherein said synthesized signal is derived by replacing a quantized value of said second signal having the same frequency as said first signal with a quantized value of said first signal. 
     
     
       51. A decoding method comprising: 
       
         decoding a first code which relates to the number of a replaced element;  
       
       
         decoding a second code relating to an amplitude of said replaced element and a third code relating to a frequency of said replaced element if said number of the replaced element satisfies a specific condition; and  
       
       
         reconstructing a pulse on the basis of the decoded second and third codes. 
       
     
     
       52. A decoding method as set forth in  claim 51 , further comprising: 
       
         synthesizing said pulse and a Huffman decoded signal to derive a synthesized signal. 
       
     
     
       53. A decoding method as set forth in  claim 52 , wherein said frequency belongs to one of a plurality of frequency regions, and wherein said frequency is derived by adding a frequency amount which is included in the first signal to a frequency which is indicated by a number of said plurality of frequency regions, and wherein the number is included in said first signal which is derived by decoding said first code. 
     
     
       54. A decoding method comprising: 
       
         decoding a first code which relates to the number of replaced elements;  
       
       
         decoding a second code relating to amplitudes of said replaced elements and a third code relating to frequencies of said replaced elements if said number of the replaced elements satisfies specific condition; and  
       
       
         reconstructing pulses on the basis of the decoded second and third codes. 
       
     
     
       55. A decoding method as set forth in  claim 54 , further comprising: 
       
         synthesizing said pulses and a Huffman decoded signal to derive a synthesized signal. 
       
     
     
       56. A decoding method as set forth in  claim 54 , wherein said frequencies and said amplitudes are included in a first signal which is derived by decoding said first code. 
     
     
       57. A decoding method as set forth in  claim 56 , wherein at least one of said frequencies are derived by cumulatively adding a predetermined frequency to the previously derived frequency. 
     
     
       58. A decoding method as set forth in  claim 56 , wherein said Huffman decoded signal is divided into a plurality of regions, wherein at least one of said frequencies are derived by adding a frequency amount which is included in said first signal to a frequency which is indicated by the number of said plurality of regions, and wherein the number is included in said first signal. 
     
     
       59. An adaptive transform decoding system, comprising: 
       
         a demultiplexer for separating an input signal into a first code, a second code and a third code;  
       
       
         a first decoding means for decoding said first code with reference to said second code to derive a first signal;  
       
       
         a second decoding means for decoding said second code to derive a second signal;  
       
       
         a parameter decoding means for decoding said third signal to derive a quantization step size;  
       
       
         a synthesis means for synthesizing said first signal and said second signal for deriving a synthesized signal;  
       
       
         an inverse quantizing means for inverse quantizing said quantized value of said synthesized signal to derive an inverse quantized signal; and  
       
       
         an inverse transform means for transforming said inverse quantized signal into a time domain to derive a time domain signal. 
       
     
     
       60. An adaptive transform decoding system as set forth in  claim 59 , wherein said first decoding means derives a frequency of the quantized value, an absolute value of the quantized value and a sign of the quantized value by decoding said first code to set a frequency of the quantized value, an absolute value of the quantized value and a sign of the quantized value of said first signal, respectively. 
     
     
       61. An adaptive transform decoding system as set forth in  claim 60 , wherein said first decoding means derives a threshold value and takes a value derived by adding said threshold value to the absolute value of the quantized value derived by decoding said first code as an absolute value of the quantized value of said first signal, in place of the absolute value of the quantized value derived by decoding said first code. 
     
     
       62. An adaptive transform decoding system as set forth in  claim 61 , wherein, in each sample of said first signal, the threshold value is an absolute value of the quantized value of the sample of said second signal of the same frequency to said sample. 
     
     
       63. An adaptive transform decoding system as set forth in  claim 61 , wherein said second decoding means has restriction in an inverse quantized value, and in each sample of said first signal, the threshold value is a value derived by adding one to the maximum absolute value of said restriction when said second decoding means decodes the signal having the same frequency as said sample. 
     
     
       64. An adaptive transform decoding system as set forth in  claim 60 , wherein said first decoding means derives a difference between the frequency and the frequency of the sample of the lowest frequency by decoding, and derives the frequency of the sample other than said sample having the lowest frequency by cumulatively adding the difference of said frequency to the frequency of the sample having the lowest frequency. 
     
     
       65. An adaptive transform decoding system as set forth in  claim 64 , wherein the frequency signal is divided into a plurality of region, in said first decoding means, the number of region boundaries and the difference between said frequencies are derived by decoding, and a value derived by adding a difference of said frequencies to a frequency of region boundary indicated by said number of region boundary is taken as the frequency of the sample having the lowest frequency. 
     
     
       66. An adaptive transform decoding system as set forth in  claim 59 , wherein said synthesis means generates a signal replacing the quantized value of the sample having the same frequency as the frequency of each sample of said first signal with the quantized value of said first signal to take the replaced signal as said synthesized signal.