Coded voice signal format converting apparatus

• US 20010018651A1
• Filed: 02/27/2001
• Published: 08/30/2001
• Est. Priority Date: 02/28/2000
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Takamizawa, Yuichiro
• Granted Patent: US 7,099,823 B2
• Time in Patent Office: Days
• US Class Current: 704/230
• CPC Class Codes: G10L 19/173 Transcoding, i.e. converting between two coded representations avoiding cascaded coding-decoding
• CPC Class Codes: G10L 21/0364 for improving intelligibility
• CPC Class Codes: G10L 21/04 Time compression or expansion

Abstract

A coded voice signal format converting apparatus is provided which is capable of converting a signal format of a coded voice signal by computations in reduced amounts. In the coded voice signal format converting apparatus, in a second coding device is employed a quantizing accuracy information converting section to which a first quantizing accuracy information output from a quantizing accuracy information decoding section in a first decoding device is input. Second mapping signal is quantized by a mapped signal coding section to produce a coded voice signal and the first quantizing accuracy information is converted so that it can be used by mapped signal coding section to determine a second quantizing accuracy information.

Claims

1. A coded voice signal format converting apparatus for converting a format of a coded voice signal between two different voice coding/decoding systems comprising:

a first decoding device used to decode said coded voice signal whose format has not been converted and to produce a first voice signal in accordance with a first voice coding/decoding system;

a second coding device used to code said first voice signal and to produce a coded voice signal whose format has been converted in accordance with a second voice coding/decoding system; and

wherein said first decoding device includes a quantizing accuracy information decoding section to decode a first quantizing accuracy information coded into said coded voice signal whose format has not been converted, a mapped signal generating section to decode and inverse-quantize, a quantized value coded into said coded voice signal whose format has not been converted in accordance with said first quantizing accuracy information and to produce a first mapped signal and wherein said second coding device includes a quantizing accuracy information converting section to determine a second quantizing accuracy information and a mapped signal coding section to quantize and code a voice signal output from said first decoding device based on said second quantizing accuracy information and to produce a coded voice signal whose format has been converted.

2. The coded voice signal format converting apparatus according to

claim 1

, wherein said first voice coding/decoding system is configured by any one of an MPEG (Motion Picture Experts Group) Audio, MPEG-2AAC and Dolby AC-3 systems.

3. The coded voice signal format converting apparatus according to

claim 1

, wherein configurations of said second voice coding/decoding system are different from those of said first voice coding/decoding system and said second voice coding/decoding system is configured by any one of said MPEG Audio, MPEG-2AAC, and Dolby AC-3 system.

4. A coded voice signal format converting apparatus for converting a format of a coded voice signal between two different voice coding/decoding systems comprising:

a first decoding device used to decode said coded voice signal whose format has not been converted and to produce a first voice signal in accordance with a first voice coding/decoding system;

a second coding device used to code said first voice signal and to produce a coded voice signal whose format has been converted in accordance with a second voice coding/decoding system; and

wherein said first decoding device includes a quantizing accuracy information decoding section to decode a first quantizing accuracy information coded into said coded voice signal whose format has not been converted, a mapped signal generating section to decode and inverse-quantize, a quantized value coded into said coded voice signal whose format has not been converted in accordance with said first quantizing accuracy information and to produce a first mapped signal and a inverse mapping converting section to make inverse mapping conversions of said first mapped signal and to produce said first voice signal and wherein said second coding device includes a mapping converting section to make mapping conversions of said first voice signal and to produce a second mapped signal, a quantizing accuracy information converting section to determine second quantizing accuracy information and a mapped signal coding section to quantize and code said second mapped signal based on said second quantizing accuracy information and to produce said coded voice signal whose format has been converted and wherein said quantizing accuracy decoding section outputs said first quantizing accuracy information to said quantizing accuracy information converting section and, in said quantizing accuracy information converting section, said second quantizing accuracy information is determined by converting said first quantizing accuracy information so that said first quantizing accuracy information becomes at least one of a time section or frequency resolution required for obtaining said second quantizing accuracy information.

5. The coded voice signal format converting apparatus according to

claim 4

, wherein, in said quantizing accuracy converting section, quantizing accuracy information obtained in a first time section and in a first frequency band provides quantizing accuracy information at a maximum level out of said quantizing accuracy information extracted from said first quantizing accuracy information obtained in overlapping time sections and frequency bands in said first time section and in said first frequency band.

6. The coded voice signal format converting apparatus according to

claim 4

, wherein said inverse mapping converting section makes inverse mapping conversions by using sub-band synthetic filter processing or inverse modified discrete cosine transforming processing.

7. The coded voice signal format converting apparatus according to claims 4, wherein said mapping converting section makes mapping conversions by using sub-band analysis filter processing or modified discrete cosine transforming processing.

8. The coded voice signal format converting apparatus according to

claim 4

, wherein said first voice coding/decoding system is configured by any one of an MPEG (Motion Picture Experts Group) Audio, MPEG-2AAC and Dolby AC-3 systems.

9. The coded voice signal format converting apparatus according to

claim 4

, wherein configurations of said second voice coding/decoding system are different from those of said first voice coding/decoding system and said second voice coding/decoding system is configured by any one of said MPEG Audio, MPEG-2AAC, and Dolby AC-3 system.

10. A coded voice signal format converting apparatus for converting a format of a coded voice signal between two different voice coding/decoding systems comprising:

a first decoding device used to decode said coded voice signal whose format has not been converted and to produce a first voice signal in accordance with a first voice coding/decoding system;

a second coding device used to code said first voice signal and to produce a coded voice signal whose format has been converted in accordance with a second voice coding/decoding system; and

wherein, when said two different voice coding/decoding systems use a same mapping converting method and a same inverse mapping converting method, said first decoding device includes a quantizing accuracy information decoding section to decode first quantizing accuracy information coded into said coded voice signal whose format has not been converted and a mapped signal generating section to decode and inverse-quantize, a quantized value coded into said coded voice signal whose format has not been converted in accordance with said first quantizing accuracy information and to produce a first mapped signal and wherein said second coding device includes a quantizing accuracy information converting section to determine said quantizing accuracy information and a mapped signal coding section to quantize and code said first mapped signal based on said second quantizing accuracy information and to produce said coded voice signal whose format has been converted and wherein said quantizing accuracy decoding section outputs said first quantizing accuracy information to said quantizing accuracy information converting section and, in said quantizing accuracy information converting section, said second quantizing accuracy information is determined by converting said first quantizing accuracy information so that said first quantizing accuracy information becomes at least one of a time section or frequency resolution required for obtaining said second quantizing accuracy information.

11. The coded voice signal format converting apparatus according to

claim 10

, wherein, in said quantizing accuracy converting section, quantizing accuracy information obtained in a first time section and in a first frequency band provides quantizing accuracy information at a maximum level out of said quantizing accuracy information extracted from said first quantizing accuracy information obtained in overlapping time sections and frequency bands in said first time section and in said first frequency band.

12. The coded voice signal format converting apparatus according to

claim 10

, wherein said first voice coding/decoding system is configured by any one of an MPEG (Motion Picture Experts Group) Audio, MPEG-2AAC and Dolby AC-3 systems.

13. The coded voice signal format converting apparatus according to

claim 10

wherein configurations of said second voice coding/decoding system are different from those of said first voice coding/decoding system and said second voice coding/decoding system is configured by any one of said MPEG Audio, MPEG-2AAC, and Dolby AC-3 system.