Frame error concealment method and apparatus and error concealment scheme construction method and apparatus

Abstract

Provided are a frame error concealment method and apparatus and an error concealment scheme construction method and apparatus. The frame error concealment method includes generating a new signal by synthesizing a plurality of previous signals that are similar to a signal of an error frame and reconstructing the signal of the error frame using the generated signal.

1 . A frame error concealment method comprising:
 (a) extracting a first signal and a second signal that are similar to a signal of a current frame having an error from a previous frame preceding the current frame;   (b) generating a synthetic signal for reconstructing the signal of the current frame using the extracted first signal and second signal; and   (c) reconstructing the signal of the current frame using the generated synthetic signal.   
   
   
       2 . The frame error concealment method of  claim 1 , wherein (a) comprises:
 (a1) searching in the previous frame for a first block and a second block that are similar to a previous block located immediately previous to the current frame; and   (a2) extracting the first signal and the second signal by referring to the positions of the found first block and second block.   
   
   
       3 . The frame error concealment method of  claim 2 , wherein the first block and the second block have the highest correlation with the previous block. 
   
   
       4 . The frame error concealment method of  claim 2 , wherein (a2) comprises:
 extracting the first signal including the first block and a next signal of a predetermined length, which follows the first block; and   extracting the second signal including the second block and a next signal of the predetermined length, which follows the second block.   
   
   
       5 . The frame error concealment method of  claim 2 , wherein (b) comprises:
 (b1) windowing the extracted first signal and second signal; and   (b2) overlapping and adding the windowed first signal and second signal.   
   
   
       6 . The frame error concealment method of  claim 5 , wherein (b1) comprises:
 (b11) determining a first window function for windowing the first signal based on correlation between the first block and the previous block and determining a second window function for windowing the second signal based on correlation between the second block and the previous block; and   (b12) windowing the first signal and the second signal by multiplying the first signal by the determined first window function and multiplying the second signal by the determined second window function.   
   
   
       7 . The frame error concealment method of  claim 6 , wherein (b11) comprises determining the first window function and the second window function so that the first window function and the second window function are summed as 1. 
   
   
       8 . The frame error concealment method of  claim 7 , wherein (b11) comprises determining the first window function based on the correlation between the first block and the previous block and determining the second window function based on the correlation between the second block and the previous block. 
   
   
       9 . The frame error concealment method of  claim 8 , wherein (b11) comprises determining the first window function and the second window function so that the greater weight is applied to one of the first signal and the second signal whose block has the higher correlation with the previous block. 
   
   
       10 . The frame error concealment method of  claim 8 , wherein (b11) comprises determining the first window function and the second window function so that one of the first signal and the second signal whose block has the higher correlation with the previous block is faded out and the other is faded in. 
   
   
       11 . The frame error concealment method of  claim 8 , wherein (b11) comprises determining a window function multiplied by one of the first signal and the second signal whose block has the higher correlation with the previous block as F(x) and determining a window function multiplied by the other as 1−F(x), as follows: 
     
       
         
           
             
               
                 
                   
                     
                       F 
                        
                       
                         ( 
                         x 
                         ) 
                       
                     
                     = 
                     
                       
                         ( 
                         
                           1 
                           - 
                           
                             x 
                             m 
                           
                         
                         ) 
                       
                       k 
                     
                   
                   , 
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
           
         
       
       where m is the length of the time axis of the first signal or the second signal and x is a time-axis coordinate of the window function with respect to the starting point of the first signal or the second signal. 
     
   
   
       12 . The frame error concealment method of  claim 11 , wherein k is determined as follows:
     k= 1 −BC 1 −BC 2/2   (2),   where BC1 is a correlation between the first block and the previous block and BC2 is a correlation between the second block and the previous block.   
   
   
       13 . The frame error concealment method of  claim 1 , wherein (c) comprises repeating the synthetic signal at least once in the current frame. 
   
   
       14 . The frame error concealment method of  claim 13 , wherein (c) further comprises overlapping and adding a portion of a previous signal preceding the synthetic signal and a portion of the synthetic signal to smooth the previous signal and the synthetic signal. 
   
   
       15 . The frame error concealment method of  claim 13 , wherein (c) further comprises overlapping and adding a portion of a next signal following the synthetic signal and a portion of the synthetic signal to smooth the next signal and the synthetic signal. 
   
   
       16 . A frame error concealment method comprising:
 extracting a plurality of signals that are similar to a signal of a current frame having an error from a previous frame preceding the current frame;   generating a synthetic signal for reconstructing the signal of the current frame using the extracted plurality of signals; and   reconstructing the signal of the current frame using the generated synthetic signal.   
   
   
       17 . An error concealment scheme construction method comprising:
 (a) analyzing error concealment conditions of a previous frame preceding and a next frame following a current frame having an error; and   (b) selecting an error concealment scheme for the current frame from among an overlapping method, a repetition method, and an interpolation method in a time domain based on the analysis result.   
   
   
       18 . The error concealment scheme construction method of  claim 17 , wherein (a) comprises analyzing at least one of whether an error occurs in the previous frame and if so, an error concealment scheme for the previous frame, whether an error occurs in the next frame, and whether the overlapping method has been used continuously over a predetermined number of times to conceal the error of the previous frame. 
   
   
       19 . The error concealment scheme construction method of  claim 18 , wherein (b) comprises selecting the overlapping method as the error concealment scheme for the current frame when the previous frame is a good frame having no error. 
   
   
       20 . The error concealment scheme construction method of  claim 18 , wherein (b) comprises selecting one of the overlapping method and the interpolation method as the error concealment scheme for the current frame when the repetition method has been used for the previous frame. 
   
   
       21 . The error concealment scheme construction method of  claim 18 , wherein (b) comprises selecting one of the repetition method and the interpolation method as the error concealment scheme for the current frame when the repetition method has been used for the previous frame continuously over the predetermined number of times. 
   
   
       22 . The error concealment scheme construction method of  claim 18 , wherein (b) comprises selecting the interpolation method as the error concealment scheme for the current frame when the next frame is a good frame having no error. 
   
   
       23 . An adaptive frame error concealment method comprising:
 selecting one of an overlapping method, a repetition method, and an interpolation method in a time domain as an error concealment scheme for a current frame having an error based on error concealment conditions of a previous frame preceding and a next frame following the current frame; and   concealing the error using the selected error concealment scheme.   
   
   
       24 . A computer-readable medium containing computer-readable codes to perform a frame error method comprising
 (a) extracting a first signal and a second signal that are similar to a signal of a current frame having an error from a previous frame preceding the current frame;   (b) generating a synthetic signal for reconstructing the signal of the current frame using the extracted first signal and second signal; and   (c) reconstructing the signal of the current frame using the generated synthetic signal.   
   
   
       25 . A frame error concealment apparatus comprising:
 a similar signal extraction unit extracting a first signal and a second signal that are similar to a signal of a current frame having an error from a previous frame preceding the current frame;   a synthetic signal generation unit generating a synthetic signal for reconstructing the signal of the current frame using the extracted first signal and second signal; and   a reconstruction unit reconstructing the signal of the current frame using the generated synthetic signal.   
   
   
       26 . The frame error concealment apparatus of  claim 25 , wherein the similar signal extraction unit searches in the previous frame for a first block and a second block that are similar to a previous block located immediately previous to the current frame and extracts the first signal and the second signal by referring to the positions of the found first block and second block. 
   
   
       27 . The frame error concealment apparatus of  claim 26 , wherein the first block and the second block have the highest correlation with the previous block. 
   
   
       28 . The frame error concealment apparatus of  claim 26 , wherein the similar signal extraction unit extracts the first signal including the first block and a next signal of a predetermined length, which follows the first block, and extracts the second signal including the second block and a next signal of the predetermined length, which follows the second block. 
   
   
       29 . The frame error concealment apparatus of  claim 26 , wherein the synthetic signal generation unit comprises:
 a windowing unit windowing the extracted first signal and second signal; and   a synthesis unit overlapping and adding the windowed first signal and second signal.   
   
   
       30 . The frame error concealment apparatus of  claim 29 , wherein the windowing unit comprises:
 a window function determination unit determining a first window function for windowing the first signal based on correlation between the first block and the previous block and determining a second window function for windowing the second signal based on correlation between the second block and the previous block; and   a multiplication unit windowing the first signal and the second signal by multiplying the first signal by the determined first window function and multiplying the second signal by the determined second window function.   
   
   
       31 . The frame error concealment apparatus of  claim 30 , wherein the window function determination unit determines the first window function and the second window function so that the first window function and the second window function are summed as 1. 
   
   
       32 . The frame error concealment apparatus of  claim 31 , wherein the window function determination unit determines the first window function based on the correlation between the first block and the previous block and determines the second window function based on the correlation between the second block and the previous block. 
   
   
       33 . The frame error concealment apparatus of  claim 32 , wherein the window function determination unit determines the first window function and the second window function so that the greater weight is applied to one of the first signal and the second signal whose block has the higher correlation with the previous block. 
   
   
       34 . The frame error concealment apparatus of  claim 32 , wherein the window function determination unit determines the first window function and the second window function so that one of the first signal and the second signal whose block has the higher correlation with the previous block is faded out and the other is faded in. 
   
   
       35 . The frame error concealment apparatus of  claim 32 , wherein the window function determination unit determines a window function multiplied by one of the first signal and the second signal whose block has the higher correlation with the previous block as F(x) and determines a window function multiplied by the other as 1−F(x), as follows: 
     
       
         
           
             
               
                 
                   
                     
                       F 
                        
                       
                         ( 
                         x 
                         ) 
                       
                     
                     = 
                     
                       
                         ( 
                         
                           1 
                           - 
                           
                             x 
                             m 
                           
                         
                         ) 
                       
                       k 
                     
                   
                   , 
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
           
         
       
       where m is the length of the time axis of the first signal or the second signal and x is a time-axis coordinate of the window function with respect to the starting point of the first signal or the second signal. 
     
   
   
       36 . The frame error concealment apparatus of  claim 35 , wherein k is determined as follows:
     k= 1 −BC 1 −BC 2/2   (2),   where BC1 is a correlation between the first block and the previous block and BC2 is a correlation between the second block and the previous block.   
   
   
       37 . The frame error concealment apparatus of  claim 25 , wherein the reconstruction unit repeats the synthetic signal at least once in the current frame. 
   
   
       38 . A frame error concealment apparatus comprising:
 a similar signal extraction unit extracting a plurality of signals that are similar to a signal of a current frame having an error from a previous frame preceding the current frame;   a synthetic signal generation unit generating a synthetic signal for reconstructing the signal of the current frame using the extracted plurality of signals; and   a reconstruction unit reconstructing the signal of the current frame using the generated synthetic signal.   
   
   
       39 . An error concealment scheme construction apparatus comprising:
 an analysis unit analyzing error concealment conditions of a previous frame preceding and a next frame following a current frame having an error; and   a selection unit selecting an error concealment scheme for the current frame from among an overlapping method, a repetition method, and an interpolation method in a time domain based on the analysis result.   
   
   
       40 . The error concealment scheme construction apparatus of  claim 39 , wherein the analysis unit analyzes at least one of whether an error occurs in the previous frame and if so, an error concealment scheme for the previous frame, whether an error occurs in the next frame, and whether the overlapping method has been used continuously over a predetermined number of times to conceal the error of the previous frame. 
   
   
       41 . The error concealment scheme construction apparatus of  claim 39 , wherein the selection unit selects the overlapping method as the error concealment scheme for the current frame when the previous frame is a good frame having no error. 
   
   
       42 . The error concealment scheme construction apparatus of  claim 39 , wherein the selection unit selects one of the overlapping method and the interpolation method as the error concealment scheme for the current frame when the repetition method has been used for the previous frame. 
   
   
       43 . The error concealment scheme construction apparatus of  claim 39 , wherein the selection unit selects one of the repetition method and the interpolation method as the error concealment scheme for the current frame when the repetition method has been used for the previous frame continuously over the predetermined number of times. 
   
   
       44 . The error concealment scheme construction apparatus of  claim 39 , wherein the selection unit selects the interpolation method as the error concealment scheme for the current frame when the next frame is a good frame having no error. 
   
   
       45 . An adaptive frame error concealment apparatus comprising:
 an error concealment scheme selection unit selecting one of an overlapping method, a repetition method, and an interpolation method in a time domain as an error concealment scheme for a current frame having an error based on error concealment conditions of a previous frame preceding and a next frame following the current frame; and   an error concealment unit concealing the error using the selected error concealment scheme.