ENCODING APPARATUS AND DECODING APPARATUS FOR TRANSFORMING BETWEEN MODIFIED DISCRETE COSINE TRANSFORM-BASED CODER AND HETERO CODER

• US 20110137663A1
• Filed: 09/18/2009
• Published: 06/09/2011
• Est. Priority Date: 09/18/2008
• Status: Active Grant

• Current Assignee: Electronics and Telecommunications Research Institute, Kwangwoon University Industry
• Original Assignee: Electronics and Telecommunications Research Institute, Kwangwoon University Industry
• Inventors: Park, Ho Chong, Park, Young-cheol, Kang, Kyeongok, Hong, Jin Woo, Lee, Tae Jin, Kim, Min Je, Jang, Dae Young, Beack, Seung Kwon
• Granted Patent: US 9,773,505 B2
• Time in Patent Office: Days
• US Class Current: 704/501
• CPC Class Codes: G10L 19/0212 using orthogonal transformation

Abstract

An encoding apparatus and a decoding apparatus in a transform between a Modified Discrete Cosine Transform (MDCT)-based coder and a hetero coder are provided. The encoding apparatus may encode additional information to restore an input signal encoded according to the MDCT-based coding scheme, when switching occurs between the MDCT-based coder and the hetero coder. Accordingly, an unnecessary bitstream may be prevented from being generated, and minimum additional information may be encoded.

Claims

1. An encoding apparatus, comprising:

a first encoding unit to encode a speech characteristic signal of an input signal according to a hetero coding scheme different from a Modified Discrete Cosine Transform (MDCT)-based coding scheme; and

a second encoding unit to encode an audio characteristic signal of the input signal according to the MDCT-based coding scheme,

wherein the second encoding unit performs encoding by applying an analysis window which does not exceed a folding point, when the folding point where switching occurs between the speech characteristic signal and the audio characteristic signal exists in a current frame of the input signal.

2. The encoding apparatus of claim 1, wherein the second encoding unit applies the analysis window, the analysis window being configured as a window which has a value of 0 and corresponds to a first sub-block, a window corresponding to an additional information area of a second sub-block, and a window which has a value of 1 and corresponds to a remaining area of the second sub-block based on the folding point, the first sub-block indicating the speech characteristic signal, and the second sub-block indicating the audio characteristic signal.

3. The encoding apparatus of claim 1, wherein the folding point is set at a point of N/4 or 3N/4, when the current frame is configured as sub-blocks having a size of N/4.

4. The encoding apparatus of claim 2, wherein the first encoding unit encodes a portion corresponding to the additional information area in the first sub-block for overlapping among blocks based on the folding point.

5. An encoding apparatus, comprising:

a window processing unit to apply an analysis window to a current frame of an input signal;

an MDCT unit to perform an MDCT with respect to the current frame where the analysis window is applied;

a bitstream generation unit to encode the current frame and to generate a bitstream of the input signal,

wherein the window processing unit applies an analysis window which does not exceed a folding point, when the folding point where switching occurs between a speech characteristic signal and an audio characteristic signal exists in the current frame of the input signal.

6. The encoding apparatus of claim 5, wherein the window processing unit applies the analysis window, the analysis window being configured as a window which has a value of 0 and corresponds to a first sub-block, a window corresponding to an additional information area of a second sub-block, and a window which has a value of 1 and corresponds to a remaining area of the second sub-block based on the folding point, the first sub-block indicating the speech characteristic signal, and the second sub-block indicating the audio characteristic signal.

7. The encoding apparatus of claim 5, wherein the folding point is set at a point of N/4 or 3N/4, when the current frame is configured as sub-blocks having a size of N/4.

8. The encoding apparatus of claim 6, wherein the additional information area in the first sub-block is encoded according to a hetero coding scheme different from an MDCT coding scheme for overlapping among blocks based on the folding point.

9. A decoding apparatus, comprising:

a first decoding unit to decode a speech characteristic signal of an input signal encoded according to a hetero coding scheme different from an MDCT-based coding scheme;

a second decoding unit to decode an audio characteristic signal of the input signal encoded according to the MDCT-based coding scheme; and

a block compensation unit to perform block compensation with respect to a result of the first decoding unit and a result of the second decoding unit, and to restore the input signal,

wherein the block compensation unit applies a synthesis window which does not exceed a folding point, when the folding point where switching occurs between the speech characteristic signal and the audio characteristic signal exists in a current frame of the input signal.

10. The decoding apparatus of claim 9, wherein the block compensation unit applies a first synthesis window to additional information, and applies a second synthesis window to the current frame to perform an overlap-add operation, the additional information being extracted by the first decoding unit, and the current frame being extracted by the second decoding unit.

11. The decoding apparatus of claim 10, wherein the block compensation unit applies the second synthesis window, the second synthesis window being configured as a window which has a value of 0 and corresponds to a first sub-block, a window corresponding to an additional information area of a second sub-block, and a window which has a value of 1 and corresponds to a remaining area of the second sub-block based on the folding point, the first sub-block indicating the speech characteristic signal, and the second sub-block indicating the audio characteristic signal.

12. The decoding apparatus of claim 9, wherein the second decoding unit decodes a block which is not adjacent to the folding point in the current frame of the input signal, and the block compensation unit applies the second synthesis window to a sub-block adjacent to the folding point in the current frame of the input signal.

13. The decoding apparatus of claim 9, wherein the first decoding unit decodes additional information encoded according to the hetero coding scheme to restore the audio characteristic signal in the current frame of the input signal.

14. The decoding apparatus of claim 9, wherein the folding point is set at a point of N/4 or 3N/4, when the current frame is configured as sub-blocks having a size of N/4.

15. A decoding apparatus, comprising:

a block compensation unit to apply a synthesis window to additional information extracted from a speech characteristic signal and a current frame and to restore an input signal, when a folding point where switching occurs between the speech characteristic signal and the audio characteristic signal exists in the current frame of the input signal.

16. The decoding apparatus of claim 15, wherein the block compensation unit performs an overlap-add operation by applying the synthesis window which does not exceed the folding point to the current frame and the additional information.

17. The decoding apparatus of claim 15, wherein the block compensation unit applies the synthesis window, the synthesis window being configured as a window which has a value of 0 and corresponds to a first sub-block, a window corresponding to an additional information area of a second sub-block, and a window which has a value of 1 and corresponds to a remaining area of the second sub-block based on the folding point, the first sub-block indicating the speech characteristic signal, and the second sub-block indicating the audio characteristic signal.

18. The decoding apparatus of claim 17, wherein the block compensation unit applies the synthesis window to a sub-block adjacent to the folding point in the current frame of the input signal.

19. The decoding apparatus of claim 15, wherein the folding point is set at a point of N/4 or 3N/4, when the current frame is configured as sub-blocks having a size of N/4.