Methods, Apparatuses and System for Encoding and Decoding Signal

• US 20110194598A1
• Filed: 05/03/2011
• Published: 08/11/2011
• Est. Priority Date: 12/10/2008
• Status: Active Grant

• Current Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Inventors: Liu, Zexin, Taddei, Herve Marcel, Xiao, Wei, Chen, Longyin, Zhang, Qing, Miao, Lei, Hu, Chen
• Granted Patent: US 8,135,593 B2
• Time in Patent Office: Days
• US Class Current: 375/240
• CPC Class Codes: G10L 19/002 Dynamic bit allocation for perceptual audio coders G10L19/032
• CPC Class Codes: G10L 19/025 Detection of transients or attacks for time/frequency resolution switching
• CPC Class Codes: G10L 21/038 using band spreading techniques
• CPC Class Codes: G10L 25/93 Discriminating between voiced and unvoiced parts of speech signals G10L25/90 takes precedence

Abstract

Methods and apparatuses for encoding a signal and decoding a signal and a system for encoding and decoding are provided. The method for encoding a signal includes performing a classification decision process on high frequency signals of input signals, adaptively encoding the high frequency signals according to the result of the classification decision process, and outputting a bitstream including codes of low frequency signals of the input signals, adaptive codes of the high frequency signals, and the result of the classification decision process. The classification decision process is performed on the high frequency signals, and adaptive encoding or adaptive decoding is performed according to the result of the classification decision process, so the quality of voice and audio output signals is improved.

Claims

1. A method for encoding a signal, the method comprising:

performing a classification decision process on high frequency signals of input signals;

adaptively encoding the high frequency signals according to a result of the classification decision process, wherein the classification decision process is used to determine a type of the high frequency signals, wherein the type of the high frequency signals comprises a transient signal or a non-transient signal;

encoding low frequency signals of the input signals; and

outputting an encoded bitstream of the low frequency signals, an adaptively encoded bitstream of the high frequency signals, and the result of the classification decision process.

2. The method according to claim 1, wherein adaptively encoding the high frequency signals comprises:

encoding four time envelopes and four spectral envelopes for a transient signal;

or

encoding eight spectral envelopes for a non-transient signal, wherein no time envelope is encoded for the non-transient signal.

3. The method according to claim 1, wherein performing the classification decision process on the high frequency signals of the input signals comprises:

calculating parameters of the high frequency signals; and

determining a current frame type of the high frequency signals according to the parameters and a decision mechanism.

4. The method according to claim 3, wherein the decision mechanism is dynamically adjusted according to a previous frame type of the high frequency signals and a weighted value of several previous frame types.

5. The method according to claim 3, wherein adaptively encoding the high frequency signals according to the result of the classification decision process comprises:

allocating bits according to the current frame type of the high frequency signals; and

adaptively encoding a time envelope and a spectral envelope of the current frame of the high frequency signals by using the allocated bits.

6. The method according to claim 5, wherein:

if the current frame type of the high frequency signals is a transient signal, B1 represents all bits occupied by the transient signal, M1 represents bits occupied by the time envelope of the transient signal, N1 represents bits occupied by the spectral envelope of the transient signal, B1=M1+N1, and M1 is greater than or equal to N1; and

if the current frame type of the high frequency signals is a non-transient signal, B2 represents all bits occupied by the non-transient signal, M2 represents bits occupied by the spectral envelope of the non-transient signal, N2 represents bits occupied by the time envelope of the non-transient signal, B2=M2+N2, and M2 is greater than or equal to N2.

7. The method according to claim 6, wherein B represents allocated bits, and B=B1=B2.

8. The method according to claim 6, wherein B represents allocated bits, B>

B1, and B>

B2.

9. The method according to claim 8, wherein:

a difference between B and B1 is used for performing fine quantizing encoding on the time envelope and/or the spectral envelope of the high frequency signals, or is used for performing fine quantizing encoding on the low frequency signals; and

a difference between B and B2 is used for performing fine quantizing encoding on the spectral envelope and/or the time envelope of the high frequency signals, or is used for performing fine quantizing encoding on the low frequency signals.

10. A method for decoding a signal, the method comprising:

receiving an encoded bitstream of low frequency signals, an adaptive encoded bitstream of high frequency signals, and a result of a classification decision process;

adaptively decoding the high frequency signals according to the result of the classification decision process and a determined excitation signal, wherein the classification decision process is used to determine a type of the high frequency signals, wherein the type of the high frequency signals comprises a transient signal or a non-transient signal;

decoding the encoded bitstream of low frequency signals; and

obtaining output signals comprising the decoded low frequency signals and the adaptively decoded high frequency signals.

11. The method according to claim 10, wherein the result of the classification decision process comprises a type of a current frame of the high frequency signals, and the adaptively decoding the high frequency signals comprises:

allocating bits according to the current frame type of the high frequency signals; and

adaptively decoding a time envelope and a spectral envelope of the current frame of the high frequency signals according to the determined excitation signal by using the allocated bits.

12. The method according to claim 11, further comprising:

determining the excitation signal according to the result of the classification decision process and the decoded low frequency signals.

13. The method according to claim 11, further comprising:

performing fine quantizing and decoding on the time envelope and/or the spectral envelope of the high frequency signals;

or

performing fine quantizing and decoding on the low frequency signals by using bits remaining after the allocation.

14. A system for encoding and decoding, comprising:

a signal encoding apparatus adapted to perform a classification decision process on high frequency signals of input signals, to adaptively encode the high frequency signals according to a result of the classification decision process, and to output an encoded bitstream of low frequency signals of the input signals, an adaptive encoded bitstream of the high frequency signals, and the result of the classification decision process, wherein the classification decision process is used to determine a type of the high frequency signals, the type of the high frequency signals comprising at least one of a transient signal and a non-transient signal; and

a signal decoding apparatus adapted to receive the encoded bitstream of the low frequency signals, the adaptive encoded bitstream of the high frequency signals, and the result of the classification decision process, to adaptively decode the high frequency signals according to the result of the classification decision process and a determined excitation signal, and to obtain output signals including the decoded low frequency signals and the adaptively decoded high frequency signals.