Coding apparatus, decoding apparatus, and methods

• US 9,741,356 B2
• Filed: 05/31/2016
• Issued: 08/22/2017
• Est. Priority Date: 09/09/2011
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Inventors: Kawashima, Takuya, Daimou, Katsunori, Oshikiri, Masahiro
• Primary Examiner(s): Siddo, Ibrahim
• Application Number:
  US15/168,805
• Publication Number:
  US 20160293178A1
• Time in Patent Office: 448 Days
• CPC Class Codes: G10L 19/0204 using subband decomposition
• CPC Class Codes: G10L 19/265 Pre-filtering, e.g. high frequency emphasis prior to encoding
• CPC Class Codes: G10L 21/0388 Details of processing therefor

Abstract

A coding apparatus normalizes a low-frequency spectrum included in each of sub-bands obtained from dividing a low band part, using a largest amplitude value among the low-frequency spectrum included in each sub-band, obtains a normalized low-frequency spectrum by decoding the first encoded data, and calculates a correlation between each divided band of a high-frequency spectrum and a plurality of candidate bands of the normalized low-frequency spectrum. The best bands of a plurality of candidate bands are identified, each candidate band having a starting frequency position with non-zero amplitude in the normalized low-frequency spectrum, the high-frequency spectrum being in a high band part of the input audio signal that is higher than the predetermined frequency, and the high-frequency spectrum is encoded using lag information identifying the best band for transmitting the lag information to a decoder.

Claims

1. A coding apparatus, comprising:

a processor; and

a memory that stores instructions which, when executed by the processor, cause the processor to perform operations comprising;

encoding a first band of an input audio signal;

normalizing a first spectrum included in each of sub-bands obtained by dividing the first band;

calculating a correlation between each divided band of a second band spectrum and a plurality of candidate bands of the normalized first spectrum, the second spectrum being higher than a predetermined frequency;

identifying best bands of the plurality of candidate bands, each candidate band having a starting frequency position with non-zero amplitude in the normalized first spectrum; and

encoding the second spectrum using lag information identifying the best band for transmitting the lag information to a decoder side.

2. The coding apparatus according to claim 1,

wherein a plurality of other bands which have starting frequency positions with zero amplitude in the normalized first spectrum are skipped in calculating the correlation.

3. The coding apparatus according to claim 1,

wherein the lag information indicates a starting frequency position of the best band.

4. The coding apparatus according to claim 1,

wherein a number of the plurality of candidate bands is four.

5. A decoding apparatus, comprising:

a processor; and

a memory that stores instructions which, when executed by the processor, cause the processor to perform operations comprising;

decoding first encoded data, generated by encoding a first band of an input audio signal;

normalizing a first spectrum included in each of sub-bands obtained by dividing the first band;

obtaining a normalized first spectrum, the first spectrum being obtained by decoding the first encoded data;

obtaining lag information identifying the best band; and

generating a second spectrum by using the best band;

wherein the lag information indicating the particular band having a best correlation between each divided band of an encoding-side second spectrum and an encoding-side first spectrum, that results from normalizing a spectrum generated by decoding the first encoded data, the best bands being selected from a plurality of candidate bands, each having a starting frequency position with non-zero amplitude in the normalized first spectrum, the second spectrum is higher than the predetermined frequency in a coding apparatus.

6. The decoding apparatus according to claim 5,

wherein the lag information indicates the starting frequency position of the best band.

7. The decoding apparatus according to claim 5,

further comprising a second decoder that identifies the particular band based on the lag information, and copies the best band to the second spectrum.

8. A coding method, comprising:

encoding, a first band of an input audio signal;

normalizing a first spectrum included in each of sub-bands obtained by dividing the first band;

calculating a correlation between each divided band of a second band spectrum and a plurality of candidate bands of the normalized first spectrum, the second spectrum being higher than a predetermined frequency;

identifying best bands of the plurality of candidate bands, each candidate band having a starting frequency position with non-zero amplitude in the normalized first spectrum; and

encoding the second spectrum using lag information identifying the best band for transmitting the lag information to a decoder side.

9. The coding method according to claim 8,

wherein in calculating the correlation, a plurality of other bands which have starting frequency positions with zero amplitude in the normalized first spectrum are skipped.

10. The coding method according to claim 8,

wherein the lag information indicates a starting frequency position of the best band.

11. The coding method according to claim 8,

wherein a number of the plurality of candidate bands is four.

12. A decoding method, comprising:

decoding first encoded data, generated by encoding a first band of an input audio signal;

normalizing a first spectrum included in each of sub-bands obtained by dividing the first band;

obtaining a normalized first spectrum, the first spectrum being obtained by decoding the first encoded data;

obtaining lag information identifying the best band; and

generating a second spectrum by using the best band;

wherein the second encoded data contains lag information indicating the particular band having a best correlation between each divided band of an encoding-side second spectrum and an encoding-side first spectrum, that results from normalizing a spectrum generated by decoding the first encoded data, the best bands being selected from a plurality of candidate bands, each having a starting frequency position with non-zero amplitude in the normalized first spectrum, the second spectrum is higher than the predetermined frequency in a coding apparatus.

13. The decoding method according to claim 12,

wherein the lag information indicates the starting frequency position of the best band.

14. The decoding method according to claim 12, further comprising

identifying the particular band based on the lag information, and copying the best band to the second spectrum.