Method and apparatus for processing audio signals

An audio signal processing apparatus comprising:

• a long term prediction unit configured to perform long term prediction on a time domain using a source audio signal of a preceding frame to generate a temporary residual of a current frame;
• a frequency transforming unit configured to frequency transform the temporary residual using the preceding frame and the current frame;
• an inverse transforming unit configured to inversely frequency transform the frequency transformed temporary residual to generate a synthesized residual of the preceding frame;
• a long term synthesis unit configured to perform long term synthesis using the temporary prediction gain, the temporary pitch lag, and the synthesized residual of the preceding frame to generate a synthesized audio signal of the preceding frame;
• and
• a prediction information decision unit configured to decide long term prediction information using the synthesized audio signal of the preceding frame, the long term prediction information including a final prediction gain and a final pitch lag,
• wherein the final prediction gain, the final pitch lag and the frequency transformed temporary residual are included in a bitstream, and
• wherein the synthesized residual of the preceding frame is generated by inverse transforming two consecutive and partially overlapping current and preceding frames and then adding the inverse transformed two frames.

A non-transitory computer-readable storage medium for storing instructions that, when executed by a computer, perform the steps of:

• performing long term prediction on a time domain using a source audio signal of a preceding frame to generate a temporary prediction gain, a temporary pitch lag, and a temporary residual of a current frame;
• frequency transforming the temporary residual using the preceding frame and the current frame;
• inversely frequency transforming the frequency transformed temporary residual to generate a synthesized residual of the preceding frame;
• performing, in a mobile terminal, long term synthesis using the temporary prediction gain, the temporary pitch lag, and the synthesized residual of the preceding frame to generate a synthesized audio signal of the preceding frame;
• deciding long term prediction information using the synthesized audio signal of the preceding frame, the long term prediction information including a final prediction gain and a final pitch lag;
• and
• generating a bitstream including the final prediction gain, the final pitch lag and the frequency transformed temporary residual,
• wherein the synthesized residual of the preceding frame is generated by inverse transforming two consecutive and partially overlapping current and preceding frames and then adding the inverse transformed two frames.