Temporal envelope coding of energy attack signal by using attack point location

1. A method of transceiving an audio signal, the method comprising:

providing an input audio signal;

determining whether an energy attack signal exists within the input audio signal;

setting a decision flag if the energy attack signal exists;

detecting a temporal location of the energy attack point in the input audio signal;

determining energy variations before and after the temporal location of an energy attack point;

quantizing the energy variations to produce quantized energy variations;

quantizing a peak area energy of the input audio signal to produce a quantized peak area energy; and

transmitting the decision flag, the temporal location of the energy attack point, the quantized energy variations and the quantized peak energy.

2. The method of claim 1 , further comprising:

determining energy variations before and after the temporal location of an energy attack point;

quantizing the energy variations to produce quantized energy variations;

transmitting the quantized energy variations.

3. The method of claim 1 , further comprising:

receiving the transmitted decision flag, temporal location of the energy attack point, and quantized peak energy; and

rebuilding a temporal envelope shape of the energy attack signal based on the received decision flag, temporal location of the energy attack point, and quantized peak energy.

4. The method of claim 3 , further comprising:

receiving quantized energy variations; and

rebuilding a temporal envelope shape of the energy attack signal based on the received decision flag, temporal location of the energy attack point, quantized energy variations and quantized peak energy.

5. The method of claim 3 , wherein rebuilding comprises estimating the temporal envelope by assuming that signal energy after the peak area decays.

6. The method of claim 3 , further comprising, converting the temporal envelope shape into an output audio signal based on the rebuilding.

7. The method of claim 6 , further comprising driving a loudspeaker with the output audio signal.

8. The method of claim 1 , wherein transmitting comprises transmitting over a voice over interne protocol (VOIP) network.

9. The method of claim 1 , wherein transmitting comprises transmitting over a cellular telephone network.

10. The method of claim 1 , wherein determining whether the energy attack signal exists comprises:

determining one or more ratios between a peak magnitude and average magnitudes of the input audio signal; and

determining a ratio between two magnitudes of said adjacent small segments within the input audio signal.

11. The method of claim 1 , wherein determining whether the energy attack signal exists comprises determining a voicing parameter that represents signal periodicity.

12. The method of claim 1 , wherein determining whether the energy attack signal exists comprises determining pitch correlation or pitch gain within the input audio signal.

13. The method of claim 1 , wherein determining whether the energy attack signal exists comprises searching for maximum energy area and/or said maximum energy increasing area from one small segment of the input audio signal to a next segment of the input audio signal.

14. The method of claim 1 , further comprising shaping energy variations before the temporal location of an energy attack point, shaping comprising interpolating between a beginning level of a segment at the beginning of the frame and an ending level of the segment just before the attack point.

15. The method of claim 1 , further comprising shaping energy variations after the temporal location of an energy attack point, shaping comprising interpolating between a beginning level of a segment just after the peak and an ending level of the segment at the end of the frame.

16. The method of claim 1 , further comprising:

determining an average energy before the temporal location of an energy attack point;

quantizing the average energy before the temporal location of an energy attack point to produces a quantized average energy;

determining an energy variation after the temporal location of an energy attack point;

quantizing the energy variation after the temporal location of an energy attack point to produces a quantized energy variation; and

transmitting the quantized average energy and the quantized energy variation.

17. The method of claim 16 , wherein rebuilding further comprising improving the temporal envelope shape based on the received temporal location of the energy attack point, the quantized average energy and the quantized energy variation.

18. The method of claim 1 , further comprising:

determining average energies before and after the temporal location of an energy attack point;

quantizing the average energies to produce quantized average energies; and

transmitting the quantized average energies.

19. The method of claim 18 , further rebuilding further comprising:

improving the temporal envelope shape based on the received temporal location of the energy attack point and the quantized average energies.