Processing and error concealment of digital signals

Abstract

A method for forward error concealment encoding of a digital signal data stream including a sequence of individual digital samples, includes encoding one or more of the individual digital samples according to an encoding mode selected from a number of predetermined encoding modes in accordance with a value of the respective digital sample, wherein encoding includes determining an encoded digital sample as a combination of bits of the respective digital sample and a predetermined number of forward error concealment bits arranged into predetermined bit positions of the encoded digital sample in accordance with the selected encoding mode. A method for forward error concealment decoding of a digital signal data stream including a sequence of encoded individual digital samples is provided, and includes decoding one or more of the individual encoded samples into respective decoded digital samples according to a decoding mode selected from a number of predetermined decoding.

1 . A method for forward error concealment decoding of a digital signal data stream constituted by a sequence of encoded individual digital samples, the method comprising:
 individually decoding one or more of the individual encoded samples into respective decoded digital samples according to a decoding mode selected from a number of predetermined decoding modes in accordance with a detected encoding mode of the respective encoded digital sample, wherein the encoding mode is detected based on a value of one or more bits of the encoded digital sample.   
     
     
         2 . The method according to  claim 1 , further comprising:
 applying, in response to a failure to detect the encoding mode of a given encoded digital sample, a sample value estimation approach to estimate a value of the given decoded digital sample, wherein the sample value estimation approach comprises determining an estimated value of the given decoded digital sample on basis of one or more decoded digital samples preceding and/or following the given digital sample.   
     
     
         3 . The method according to  claim 2 , wherein the one more decoded digital samples preceding and/or following the given digital sample comprise one or more decoded digital samples preceding the given digital sample to minimize latency introduced by the sample value estimation approach. 
     
     
         4 . The method according to  claim 2 , wherein the one more decoded digital samples preceding and/or following the given digital sample comprise one or more decoded digital samples following the given digital sample to improve accuracy of the sample value estimation approach. 
     
     
         5 . The method according to  claim 2 , wherein the sample value estimation approach employs a polynomial. 
     
     
         6 . The method according to  claim 5 , wherein the polynomial is a cubic polynomial having the order of three. 
     
     
         7 . The method according to  claim 5 , wherein the polynomial has the order from three to seven, wherein the order is selected in accordance of the number and the positions of error-free samples preceding and following the given digital sample. 
     
     
         8 . The method according to  claim 2 , further comprising:
 a bit healing process that includes determining the bit positions of erroneous bits within the given encoded digital sample, determining a number of candidate values based on the given encoded digital sample by setting the erroneous bit positions thereof to both values, zero and one, and selecting the candidate value closest to the estimated value of the given encoded digital sample as the new estimated value of the given encoded digital sample.   
     
     
         9 . The method according to  claim 2 , wherein the estimated value of the given decoded sample is further slew rate limited to a value having a difference to the most recent decoded digital sample that does not exceed a predetermined limit. 
     
     
         10 . An apparatus for forward error concealment decoding of a digital signal data stream constituted by a sequence of encoded individual digital samples, the apparatus comprising:
 at least one processor; and   at least one memory having computer program code recorded therein for one or more programs,   the computer program code configured to, upon execution by the at least one processor, cause the apparatus to individually decode one or more of the individual encoded samples into respective decoded digital samples according to a decoding mode selected from a number of predetermined decoding modes in accordance with a detected encoding mode of the respective encoded digital sample, wherein the encoding mode is detected based on a value of one or more bits of the encoded digital sample.   
     
     
         11 . The apparatus according to  claim 10 , wherein said computer program code further causes the apparatus, in response to a failure to detect the encoding mode of a given encoded digital sample, a sample value estimation approach to estimate a value of the given decoded digital sample, wherein the sample value estimation approach comprises determining an estimated value of the given decoded digital sample on basis of one or more decoded digital samples preceding and/or following the given digital sample. 
     
     
         12 . The apparatus according to  claim 11 , wherein the one more decoded digital samples preceding and/or following the given digital sample comprise one or more decoded digital samples preceding the given digital sample to minimize latency introduced by the sample value estimation approach. 
     
     
         13 . The apparatus according to  claim 11 , wherein the one more decoded digital samples preceding and/or following the given digital sample comprise one or more decoded digital samples following the given digital sample to improve accuracy of the sample value estimation approach. 
     
     
         14 . The apparatus according to  claim 11 , wherein the sample value estimation approach employs a polynomial. 
     
     
         15 . The apparatus according to  claim 14 , wherein the polynomial is a cubic polynomial having the order of three. 
     
     
         16 . The apparatus according to  claim 14 , wherein the polynomial has the order from three to seven, wherein the order is selected in accordance of the number and the positions of error-free samples preceding and following the given digital sample. 
     
     
         17 . The apparatus according to  claim 11 , wherein said computer program code further causes the apparatus to carry out a bit healing process, comprising determining the bit positions of erroneous bits within the given encoded digital sample, determining a number of candidate values based on the given encoded digital sample by setting the erroneous bit positions thereof to both values, zero and one, and selecting the candidate value closest to the estimated value of the given encoded digital sample as the new estimated value of the given encoded digital sample. 
     
     
         18 . The apparatus according to  claim 11 , wherein the estimated value of the given decoded sample is further slew rate limited to a value having a difference to the most recent decoded digital sample that does not exceed a predetermined limit. 
     
     
         19 . A system for forward error concealment encoding and decoding of a digital signal data stream constituted by a sequence of individual digital samples, the system comprising a first apparatus storing a sequence of individual digital samples, at least one processor, and at least one memory having stored therein computer program code for one or more programs, the computer program code configured to, upon execution by the at least one processor, cause the first apparatus to individually encode one or more of the individual digital samples according to an encoding mode selected from a number of predetermined encoding modes in accordance with a value of the respective digital sample, wherein the encoding comprises determining an encoded digital sample as a combination of bits of the respective digital sample and a predetermined number of forward error concealment bits arranged into predetermined bit positions of the encoded digital sample in accordance with the selected encoding mode, the system further comprising at least one additional apparatus in accordance with  claim 10 .