Alias cancelling during audio coding mode transitions

Abstract

An apparatus for processing an audio signal and method thereof are disclosed. The present invention includes receiving, by an audio processing apparatus, an audio signal including a first data of a first block encoded with rectangular coding scheme and a second data of a second block encoded with non-rectangular coding scheme; receiving a compensation signal corresponding to the second block; estimating a prediction of an aliasing part using the first data; and, obtaining a reconstructed signal for the second block based on the second data, the compensation signal and the prediction of aliasing part.

What is claimed is: 
     
       1. A method for processing an audio signal, comprising:
 receiving, by an audio processing apparatus, an audio signal including a first data of a first block encoded with a rectangular coding scheme and a second data of a second block encoded with a non-rectangular coding scheme;   generating an output signal for the first block using the first data of the first block based on the rectangular coding scheme;   receiving a compensation signal corresponding to the second block;   obtaining a prediction of an aliasing part by applying a window of the second block to the output signal for the first block; and   obtaining a reconstructed signal for the second block based on the second data, the compensation signal and the prediction of the aliasing part,   wherein, when the first data is encoded with a LPD (Linear Prediction Domain) coding scheme and the window of the second block belongs to a transition window class, the window of the second block has an ascending line with a first slope,   wherein the first slope is gentler than a second slope.   
     
     
       2. The method of  claim 1 , wherein, when the first data is encoded with a FD (Frequency Domain) coding scheme and the window of the second block belongs to the transition window class, the window of the second block has an ascending line with the second slope. 
     
     
       3. The method of  claim 1 , wherein, when the transition window class comprises a long_stop window and a stop_start window, and
 the long_stop window and the stop_start window have horizontal-asymmetry, and have a zero part in a left half.   
     
     
       4. The method of  claim 1 , wherein the compensation signal is received, when the first data is encoded with the rectangular coding scheme. 
     
     
       5. The method of  claim 1 , wherein the compensation signal is generated based on at least one of a difference related to asymmetry between a rectangular window and a non-rectangular window, and a difference between the aliasing part and a prediction of the aliasing part. 
     
     
       6. An apparatus for processing an audio signal, comprising:
 a de-multiplexer receiving an audio signal including a first data of a first block encoded with a rectangular coding scheme and a second data of a second block encoded with a non-rectangular coding scheme, and receiving a compensation signal corresponding to the second block;   a rectangular decoding unit generating an output signal for the first block using the first data of the first block based on the rectangular coding scheme, and obtaining a prediction of an aliasing part by applying a window of the second block to the output signal for the first block; and   a non-rectangular decoding unit obtaining a reconstructed signal for the second block based on the second data, the compensation signal and the prediction of the aliasing part,   wherein, when the first data is encoded with a LPD (Linear Prediction Domain) coding scheme and the window of the second block belongs to a transition window class, the window of the second block has an ascending line with a first slope,   wherein the first slope is gentler than a second slope.    
     
     
       7. The apparatus of  claim 6 , wherein, when the first data is encoded with a FD (Frequency Domain) coding scheme and the window of the second block belongs to the transition window class, the window of the second block has an ascending line with the second slope.  
     
     
       8. The apparatus of  claim 6 , wherein, when the transition window class comprises a long_stop window and a stop_start window, and
 the long_stop window and the stop_start window have horizontal-asymmetry, and have a zero part in a left half.    
     
     
       9. The apparatus of  claim 6 , wherein the compensation signal is received, when the first data is encoded with the rectangular coding scheme. 
     
     
       10. The apparatus of  claim 6 , wherein the compensation signal is generated based on at least one of a difference related to asymmetry between a rectangular window and a non-rectangular window, and a difference between the aliasing part and a prediction of the aliasing part. 
     
     
       11. A method for processing an audio signal including a first data of a first block encoded with a first coding scheme using a rectangular window and a second data of a second block encoded with a second coding scheme using a non-rectangular window, the method comprising:
 generating, by an audio processing apparatus, an output signal for the first block using the first data of the first block based on the first coding scheme;   receiving a compensation signal corresponding to the second block;   obtaining a prediction of an aliasing part by applying a window of the second block to the output signal for the first block; and   obtaining a reconstructed signal for the second block based on the second data, the compensation signal and the prediction of the aliasing part, wherein, the first data is encoded with a LPD (Linear Prediction Domain) coding scheme and the window of the second block belongs to a transition window class.   
     
     
       12. The method of claim 11, wherein, when the transition window class comprises a long_stop window and a stop_start window, and the long_stop window and the stop_start window have horizontal-asymmetry, and have a zero part in a left half. 
     
     
       13. The method of claim 11, wherein the compensation signal is received, when the first data is encoded with the first coding scheme. 
     
     
       14. An apparatus for processing an audio signal that includes (i) a first data of a first block encoded with a first coding scheme using a rectangular window, (ii) a second data of a second block encoded with a second coding scheme using a non-rectangular window, and (iii) a compensation signal corresponding to the second block, the apparatus comprising::
 a de-multiplexer configured to receive the audio signal;   a rectangular decoding unit configured to generate an output signal for the first block using the first data of the first block based on the first coding scheme, and to obtain a prediction of an aliasing part by applying a window of the second block to the output signal for the first block; and   a non-rectangular decoding unit configured to obtain a reconstructed signal for the second block based on the second data, the compensation signal and the prediction of the aliasing part, wherein, the first data is encoded with a LPD (Linear Prediction Domain) coding scheme and the window of the second block belongs to a transition window class.   
     
     
       15. The apparatus of claim 14, wherein the compensation signal is received, when the first data is encoded with the first coding scheme. 
     
     
       16. The apparatus of claim 14, wherein the compensation signal is generated based on at least one of a difference related to asymmetry between a rectangular window and a non-rectangular window, and a difference between the aliasing part and a prediction of the aliasing part.