Abstract
Methods and apparatus for post-processing a decoded sound signal in order to enhance the perceived quality of the signal are disclosed. The decoded signal is divided into a number of frequency sub-band signals and post-processing is applied to at least one but not all of the sub-band signals. The sub-bands may then be added to produce an output signal that has had post-processing localised to a desired sub-band or sub-bands with the remaining sub-bands remaining unaltered.
Technologies
Signal Processing
Product
Use Cases
Network Optimization
Services
Claim
1. A method for post-processing a decoded sound signal in view of 5 enhancing a perceived quality of said decoded sound signal, comprising:
', 'dividing the decoded sound signal into a plurality of frequency sub-band signals; and applying post-processing to at least one of the frequency sub-band signals, but not all the frequency sub-band signals.
10
2FES 2007 28
', 'RECEIVED
', 'upper-band signal;
', '- low-pass filtering the decoded sound signal to produce a frequency lower-band signal; and applying post-processing to at least one of the frequency sub-band 5 signals comprises:
', 'applying post-processing to the decoded sound signal prior to low-pass filtering the decoded sound signal to produce the frequency lower-band signal.
11. A post-processing method as defined in claim 10, wherein applying 10 post-processing to the frequency lower-band signal comprises pitch enhancing the decoded sound signal prior to low-pass filtering the decoded sound signal.
12. A post-processing method as defined in claim 10, further comprising summing the frequency upper-band and lower-band signals to
15 produce an output post-processed decoded sound signal.
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13. A post-processing method as defined in claim 1, wherein:
', 'dividing the decoded sound signal into a plurality of frequency sub-
', 'band signals comprises:
2 S FEE 2C37
', 'R E c E i V F n processor further comprises a second low-pass filter supplied with the decoded sound signal to produce a low-pass filtered decoded sound signal supplied to the pitch enhancer."
2. A post-processing method as defined in claim 1, further comprising summing the frequency sub-band signals, after post-processing of said at least one frequency sub-band signal, to produce an output post-processed decoded sound signal.
15
2 , FSB 2G37
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', 'jW=(i-§ K"J1_4'W"_:r H«+r I
', 'where xn is the decoded sound signal, yn is the pitch enhanced decoded 5 sound signal in a given sub-band, T is a pitch delay of the decoded sound signal, and a is a coefficient varying between 0 and 1 to control an amount of inter-harmonic attenuation of the decoded sound signal.
3. A post-processing method as defined in claim 1, wherein applying post-processing to at least one of the frequency sub-band signals comprises adaptively filtering said at least one frequency sub-band signal.
5
', '45. A post-processing device as defined in claim 44, wherein the postprocessor comprises an inter-harmonic filter supplied with the decoded sound signal to produce an inter-harmonic, attenuated decoded sound signal.
10 46. A post-processing device as defined in claim 45, wherein the post processor comprises a multiplier for multiplying the inter-harmonic, attenuated decoded sound signal by an adaptive pitch enhancement gain.
', '47. A post-processing device as defined in claim 45, further comprising 15 a low-pass filter supplied with the decoded sound signal to produce a low-pass filtered decoded sound signal supplied to the inter-harmonic filter.
', '48. A post-processing device as defined in claim 44, further comprising an adder for summing the decoded sound signal and the frequency low-band
5 sound signal, and wherein the up-sampling means is combined with the sub-band filter means.
5 40. A post-processing device as defined in claim 37, further comprising an adder for summing the frequency high-band and low-band signals to produce an output post-processed decoded sound signal.
', '41. A post-processing device as defined in claim 32, wherein: 10 the dividing means comprises:
', '- a band-pass filter supplied with the decoded sound signal to produce a frequency upper-band signal; and
', '- a low-pass filter supplied with the decoded sound signal to produce a frequency lower-band signal; and
15 the post-processing means comprises:
', '- a post-processor for post-processing the decoded sound signal prior to low-pass filtering the decoded sound signal through the low-pass filter to produce the frequency lower-band signal.
5 16. A post-processing method as defined in claim 14, further comprising low-pass filtering the decoded sound signal prior to processing the decoded sound signal through the inter-harmonic filter.
17. A post-processing method as defined in claim 13, further ^ 10 comprising summing the decoded sound signal and the frequency low-band signal to produce an output post-processed decoded sound signal.
18. A post-processing method as defined in claim 13, wherein applying post-processing to the frequency low-band signal comprises processing the
15 decoded sound signal through an inter-harmonic filter having the following transfer function:
', 'y M=\xln\~ ^ {*» - T\+ *"+7*1
5 where xn is the decoded sound signal, yn is the pitch enhanced decoded sound signal in a given sub-band, T is a pitch delay of the decoded sound signal, and a is a coefficient varying between 0 and 1 to control an amount of inter-harmonic attenuation of the decoded sound signal.
10 21. A post-processing method as defined in claim 20, comprising receiving the pitch delay T through a bitstream.
5 35. A post-processing device as defined in claim 32, wherein the dividing means comprises sub-band filter means supplied with the decoded sound signal.
6. A post-processing method as defined in claim 1, wherein:
', 'dividing the decoded sound signal into a plurality of frequency sub-band signals comprises:
', '- a high-pass filtering of the decoded sound signal to produce a frequency 5 high-band signal; and
', '- a first low-pass filtering the decoded sound signal to produce a frequency low-band signal; and applying post-processing to at least one of the frequency sub-band signals comprises:
10 - applying post-processing to the decoded sound signal prior to the first low-pass filtering of the decoded sound signal to produce the frequency low-band signal.
7. A post-processing method as defined in claim 6, wherein applying 15 post-processing to the decoded sound signal comprises pitch enhancing said decoded sound signal to reduce an inter-harmonic noise in the decoded sound signal.
8. A post-processing method as defined in claim 7, wherein applying 20 post-processing to the decoded sound signal further comprises a second low-
', 'pass filtering of the decoded sound signal prior to pitch enhancing said decoded sound signal.
9. A post-processing method as defined in claim 6, further comprising 25 summing the frequency high-band and low-band signals to produce an output post-processed decoded sound signal.
10. A post-processing method as defined in claim 1, wherein:
', 'dividing the decoded sound signal into a plurality of frequency sub-
20. A post-processing method as defined in claim 1, wherein applying post-processing to at least one of the frequency sub-band signals comprises
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20 4. A post-processing method as defined in claim 1, wherein dividing the decoded sound signal into a plurality of frequency sub-band signals comprises sub-band filtering the decoded sound signal to produce the plurality of frequency sub-band signals.
20 - low-pass filtering the decoded sound signal to produce a frequency low-band signal; and applying post-processing to at least one of the frequency sub-band signals comprises:
', '- applying post-processing to the frequency low-band signal.
20 42. A post-processing device as defined in claim 41, wherein the post processor comprises a pitch filter supplied with the decoded sound signal to produce a pitch enhanced decoded sound signal supplied to the low-pass filter.
20 24. A post-processing method as defined in claim 1, wherein, during encoding, the sound signal is down-sampled from a higher sampling frequency to a lower sampling frequency, and wherein dividing the decoded sound signal into a plurality of frequency sub-band signals comprises up-sampling the decoded sound signal from the lower sampling frequency to the higher
20 pass filter with a cut-off frequency below a fundamental frequency of the decoded sound signal; and means for processing the decoded sound signal through the calculated high-pass filter.
20 32. A device for post-processing a decoded sound signal in view of enhancing a perceived quality of said decoded sound signal, comprising:
', 'means for dividing the decoded sound signal into a plurality of frequency sub-band signals; and means for post-processing at least one of the frequency sub-band 25 signals, but not all the frequency sub-band signals.
20 for inter-harmonic attenuation of the decoded sound signal, where xrt is the decoded sound signal, yn is the inter-harmonic filtered decoded sound signal in a given sub-band, and lis a pitch delay of the decoded sound signal.
19. A post-processing method as defined in claim 18, further 25 comprising summing the unprocessed decoded sound signal and the inter-harmonic filtered frequency low-band signal to produce an output post-processed decoded sound signal.
20 decoded sound signal to reduce an inter-harmonic noise in the decoded sound signal.
20 signal to produce an output post-processed decoded sound signal.
', '49. A post-processing device as defined in claim 44, wherein the postprocessor comprises an inter-harmonic filter having the following transfer function:
22. A post-processing method as defined in claim 20, comprising decoding the pitch delay Tfrom a received, encoded bitstream.
15
23. A post-processing method as defined in claim 20, comprising calculating the pitch delay T in response to the decoded sound signal for an improved pitch tracking.
25 63. A sound signal decoder comprising:
', 'an input for receiving an encoded sound signal;
', 'a parameter decoder supplied with the encoded sound signal for decoding sound signal encoding parameters;
', 'a sound signal decoder supplied with the decoded sound signal
25 5. A post-processing method as defined in claim 1, wherein, for said at least one of the frequency sub-band signals:
', 'applying post-processing comprises adaptively filtering the decoded sound signal; and dividing the decoded sound signal comprises sub-band filtering the
25
14. A post-processing method as defined in claim 13, wherein applying post-processing to the frequency low-band signal comprises processing the decoded sound signal through an inter-harmonic filter for inter-harmonic attenuation of the decoded sound signal.
25
', 'ynh\ An\ ~{xn-T + xn + Tl for inter-harmonic attenuating the decoded sound signal, where xn is the decoded sound signal, yn is the inter-harmonic filtered decoded sound signal 30 in a given sub-band, and T is a pitch delay of the decoded sound signal.
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25 sound signal by means of the following equation:
', '\y^n+T J
', 'where xn is the decoded sound signal, yn is the pitch enhanced decoded 30 sound signal in a given sub-band, T is a pitch delay of the decoded sound signal, and or is a coefficient varying between 0 and 1 to control an amount of
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25 43. A post-processing device as defined in claim 41, further comprising an adder for summing the frequency upper-band and lower-band signals to produce an output post-processed decoded sound signal.
', '44. A post-processing device as defined in claim 32, wherein: 30 the dividing means comprises:
', '- a low-pass filter supplied with the decoded sound signal to produce a
', 'frequency low-band signal; and the post-processing means comprises:
', '- a post-processor for post-processing the decoded sound signal to produce a post-processed decoded sound signal supplied to the low-pass filter.
25
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25. A post-processing method as defined in claim 24, wherein dividing the decoded sound signal into a plurality of frequency sub-band signals comprises sub-band filtering the decoded sound signal, and wherein the up-
26. A post-processing method as defined in claim 24, comprising: band-pass filtering the decoded sound signal to produce a frequency upper-band signal, said band-pass filtering of the decoded sound signal being 5 combined with up-sampling of the decoded sound signal from the lower sampling frequency to the higher sampling frequency; and post-processing the decoded sound signal and low-pass filtering the post-processed decoded sound signal to produce a frequency lower-band signal, said low-pass filtering of the post-processed decoded sound signal 10 being combined with up-sampling of the post-processed decoded sound signal from the lower sampling frequency to the higher sampling frequency.
27. A post-processing method as defined in claim 26, further comprising adding the frequency upper-band signal with the frequency lower-
15 band signal to form an output post-processed and up-sampled decoded sound signal.
28. A post-processing method as defined in claim 26, wherein postprocessing of the decoded sound signal comprises pitch enhancing the
29
', 'iRE.CE H/ £ r post-processing to the frequency low-band signal comprises multiplying the inter-harmonic filtered decoded sound signal by an adaptive pitch enhancement gain.
29. A post-processing method as defined in claim 28, wherein pitch enhancing the decoded sound signal comprises processing the decoded
30
', 'pitch enhancing the decoded sound signal using the following equation:
', '>|n=(l-|)c«}f^-{x«-r +o{n+T J
30 adaptively filtered decoded sound signal.
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30 encoding parameters for producing a decoded sound signal; and a post processing device as recited in any of claims 32 to 62 for post-
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15. A post-processing method as defined in claim 14, wherein applying
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30 band signals comprises:
', '- band-pass filtering the decoded sound signal to produce a frequency
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30. A post-processing method as defined in claim 1, wherein:
', 'dividing the decoded sound signal into a plurality of frequency sub-band 5 signals comprises dividing the decoded sound signal into a frequency upper-band signal and a frequency lower-band signal; and applying post-processing to at least one of the frequency sub-band signals comprises post-processing the frequency lower-band signal.
10 31. A post-processing method as defined in claim 1, wherein applying post-processing to said at least one of the frequency sub-band signals comprises:
', 'determining a pitch value of the decoded sound signal;
', 'calculating, in relation to the determined pitch value, a high-pass filter 15 with a cut-off frequency below a fundamental frequency of the decoded sound signal; and t
', 'processing the decoded sound signal through the calculated high-pass filter.
30 sampling of the decoded sound signal from the lower sampling frequency to the higher sampling frequency is combined to the sub-band filtering.
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32
', 'inter-harmonic attenuation of the decoded sound signal.
33. A post-processing device as defined in claim 32, further comprising adder means for summing the frequency sub-band signals, after postprocessing of said at least one frequency sub-band signal, to produce an 30 output post-processed decoded sound signal.
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34. A post-processing device as defined in claim 32, wherein the postprocessing means comprises adaptive filter means supplied with the decoded sound signal.
36. A post-processing device as defined in claim 32, wherein, for said at least one of the frequency sub-band signals:
', 'the post-processing means comprises an adaptive filter supplied with the decoded sound signal to produce an adaptively filtered decoded sound signal; and the dividing means comprises a sub-band filter supplied with the adaptively filtered decoded sound signal.
37. A post-processing device as defined in claim 32, wherein: the dividing means comprises:
', '- a high-pass filter supplied with the decoded sound signal to produce a frequency high-band signal; and
', '- a first low-pass filter supplied with the decoded sound signal to produce a frequency low-band signal; and the post-processing means comprises:
', '- a post-processor for post-processing the decoded sound signal prior to low-pass filtering the decoded sound signal through the first low-pass filter.
38. A post-processing device as defined in claim 37, wherein the post processor comprises a pitch enhancer supplied with the decoded sound signal to produce a pitch enhanced decoded sound signal.
39. A post-processing device as defined in claim 38, wherein the post-
39
', 'processing the decoded sound signal in view of enhancing a perceived quality of said decoded sound signal.
', 'END OF CLAIMS
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50. A post-processing device as defined in claim 49, further comprising an adder for summing the unprocessed decoded sound signal and the inter-harmonic filtered frequency low-band signal to produce an output post-processed decoded sound signal.
51. A post-processing device as defined in claim 32, wherein the postprocessing means comprises a pitch enhancer of the decoded sound signal using the following equation:
', 'jtof? W"-7, Mw+rI
', 'where xn is the decoded sound signal, yn is the pitch enhanced decoded sound signal in a given sub-band, T is a pitch delay of the decoded sound 15 signal, and a is a coefficient varying between 0 and 1 to control an amount of inter-harmonic attenuation of the decoded sound signal.
52. A post-processing device as defined in claim 51, comprising means for receiving the pitch delay Tthrough a bitstream.
53. A post-processing device as defined in claim 51, comprising means for decoding the pitch delay Tfrom a received, encoded bitstream.
54. A post-processing device as defined in claim 51, comprising means 25 for calculating the pitch delay T in response to the decoded sound signal for an improved pitch tracking.
55. A post-processing device as defined in claim 32, wherein, during encoding, the sound signal is down-sampled from a higher sampling frequency 30 to a lower sampling frequency, and wherein the dividing means comprises means for up-sampling the decoded sound signal from the lower sampling
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56. A post-processing device as defined in claim 55, wherein the dividing means comprises sub-band filter means supplied with the decoded
57. A post-processing device as defined in claim 55, wherein:
', '- the post-processing means comprises:
10 means for post-processing the decoded sound signal; and
', '- the dividing means comprises:
', 'a band-pass filter supplied with the decoded sound signal to produce a frequency upper-band signal, said band-pass filter being combined with the up-sampling means; and 15 a low-pass filter supplied with the post-processed decoded sound signal to produce a frequency lower-band signal, said low-pass filter being combined with the up-sampling means.
58. A post-processing device as defined in claim 57, further comprising 20 an adder for summing the frequency upper-band signal with the frequency lower-band signal to form an output post-processed and up-sampled decoded sound signal.
59. A post-processing device as defined in claim 57, wherein the 25 means for post-processing the decoded sound signal comprises means for pitch enhancing the decoded sound signal to reduce an inter-harmonic noise in the decoded sound signal.
60. A post-processing device as defined in claim 59, wherein the pitch 30 enhancing means comprises means for processing the decoded sound signal by means of the following equation:
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61. A post-processing device as defined in claim 32, wherein:
10 the dividing means comprises means for dividing the decoded sound signal into a frequency upper-band signal and a frequency lower-band signal; and the post-processing means comprises means for post-processing the frequency lower-band signal.
15
62. A post-processing device as defined in claim 32, wherein the postprocessing means comprises:
', 'means for determining a pitch value of the decoded sound signal;
', 'means for calculating, in relation to the determined pitch value, a high-
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SUMMARY
ClaimChart-NZ536237A-STO
Patent number:NZ536237A
Claim Chart Type : SEP Claim Chart
Price: 200 €
Note:
The information in blue was extracted from the third parties (Standard Setting Organisation, Espacenet)
The information in grey was provided by the patent holder
The information in purple was extracted from the FrandAvenue
Explicitly disclosed patent:openly and comprehensibly describes all details of the invention in the patent document.
Implicitly disclosed patent:does not explicitly state certain aspects of the invention, but still allows for these to be inferred from the information provided.
Basis patent:The core patent in a family, outlining the fundamental invention from which related patents or applications originate.
Family member:related patents or applications that share a common priority or original filing.