Efficient Temporal Envelope Coding Approach by Prediction Between Low Band Signal and High Band Signal

• US 20100063812A1
• Filed: 09/04/2009
• Published: 03/11/2010
• Est. Priority Date: 09/06/2008
• 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: Gao, Yang
• Granted Patent: US 8,352,279 B2
• Time in Patent Office: Days
• US Class Current: 704/230
• CPC Class Codes: G10L 19/002 Dynamic bit allocation for perceptual audio coders G10L19/032
• CPC Class Codes: G10L 19/0204 using subband decomposition
• CPC Class Codes: G10L 19/025 Detection of transients or attacks for time/frequency resolution switching
• CPC Class Codes: G10L 19/04 using predictive techniques

Abstract

This invention proposes a more efficient way to quantize temporal envelope shaping of high band signal by benefiting from energy relationship between low band signal and high band signal; if low band signal is well coded or it is coded with time domain codec such as CELP, temporal envelope shaping information of low band signal can be used to predict temporal envelope shaping of high band signal; the temporal envelope shaping prediction can bring significant saving of bits to precisely quantize temporal envelope shaping of high band signal. This prediction approach can be combined with other specific approach to further increase the efficiency and save mores bits.

Claims

1. A encoding method, comprising the steps of:

obtaining temporal envelope shaping from a low band signal;

calculating an energy ratio between a high band signal and the low band signal, and quantizing the energy ratio; and

sending the quantized low band signal and the quantized energy ratio to decoder.

2. The method according to claim 1, further comprising:

obtaining the high band signal and the low band signal from splitting a signal.

3. The method according to claim 1, wherein the low band signal has a plurality of frames, each of the plurality of frames having a plurality of sub-segments;

the process of obtaining temporal envelope shaping from a low band signal comprises;

calculating square root of average energy of the each sub-segment in Linear domain or Log domain, to obtain a plurality of energy magnitudes; and

applying the plurality of energy magnitudes to form the temporal envelope shaping.

4. The method according to claim 1, wherein duration of each sub-segment size is 1.25 ms.

5. The method according to claim 1, wherein the high band signal and the low band signal respectively have a plurality of frames, each of the plurality of frames having a plurality of sub-segments;

the energy ratio between high band signal and low band signal is estimated at least once per frame.

6. The method according to claim 1, wherein some of the energy ratios between current frame and previous frame can be interpolated in Log domain or Linear domain.

7. The method according to claim 1, further comprising the steps of:

multiplying the temporal envelope shaping of low band signal with the energy ratio to obtain a predicted temporal envelope shaping of the high band signal;

estimating correction errors of the predicted temporal envelope shaping compared to the ideal temporal envelope shaping; and

sending the quantized correction errors to decoder.

8. A decoding method, comprising the steps of receiving low band signal from a coder;

estimating temporal envelope shaping from the received low band signal;

obtaining an energy ratio between high band signal and low band signal;

multiplying the temporal envelope shaping of low band signal with the energy ratio(s) to obtain a predicted temporal envelope shaping of the high band signal;

obtaining the high band signal according to the temporal envelope shaping of the high band signal.

9. The method according to claim 8, further comprising:

decoding the low band signal according to transmitted information.

10. The method according to claim 8, wherein obtaining an energy ratio between high band signal and low band signal comprises:

receiving a quantized energy ratio from a coder; and

evaluating the energy ratio.

11. The method according to claim 8, wherein obtaining an energy ratio between high band signal and low band signal comprises:

estimating average energy ratios between decoded high band signal and decoded low band signal.

12. The method according to claim 8, wherein some of the energy ratios between current frame and previous frame can be interpolated in Log domain or Linear domain.

13. The method according to claim 8, further comprising:

estimating correction errors of the predicted temporal envelope shaping according to received information from encoder; and

the high band signal is obtained according to the predicted and corrected temporal envelope shaping of the high band signal.

14. The system of claim 8, wherein the system is configured to operate over a voice over internet protocol (VOIP) system.

15. The system of claim 8, wherein the system is configured to operate over a cellular telephone network.

16. The system of claim 8, further comprising a receiver, the receiver comprising an audio decoder configured to receive the audio parameters and produce an output audio signal based on the received audio parameters, wherein the output audio signal comprises an improved temporal envelope shape.