Video coding

Abstract

A method of encoding a video signal representing a sequence of pictures, the method comprising comparing a first picture with a second picture, calculating a measure of the similarity between the first and the second pictures, comparing the measure of similarity with a predetermined criterion of similarity and, when the measure of similarity does not meet the predetermined criterion of similarity, outputting an indicator indicating that a non-temporally predictive error concealment method should be used by a subsequent decoder and, when the measure of similarity meets the predetermined criterion of similarity, outputting an indicator indicating that a temporally predictive error concealment method should be used by a subsequent decoder.

1 . A method of encoding a video signal representing a sequence of pictures to form an encoded video signal, the method comprising: 
 comparing a first picture of the sequence or a part of the first picture with a second picture of the sequence;    calculating a measure of similarity between said first picture of the sequence or said part of the first picture and the second picture;    comparing the measure of similarity with a predetermined criterion of similarity; and    outputting an error concealment method indicator based on a result of said comparison for indicating a type of error concealment method to be used in a corresponding decoding process for said first picture of the sequence or said part of the first picture.    
   
   
       2 . A method according to  claim 1 , comprising when the measure of similarity does not meet the predetermined criterion of similarity, outputting an error concealment method indicator indicating that a non temporally-predictive error concealment method is to be used in said corresponding decoding process, and when the measure of similarity meets the predetermined criterion of similarity, outputting an error concealment method indicator indicating that a temporally-predictive error concealment method is to be used in said corresponding decoding process.  
   
   
       3 . A method according to  claim 1 , comprising updating the error concealment method indicator when the measure of similarity does not meet the predetermined criterion of similarity and leaving the error concealment method indicator unchanged when the measure of similarity meets the predetermined criterion of similarity.  
   
   
       4 . A method according to  claim 1 , comprising including the error concealment method indicator in a picture header of the encoded video signal.  
   
   
       5 . A method according to  claim 1 , comprising encoding the video signal according to the H.263 video coding standard and including the error concealment method indicator in the Supplemental Enhancement Information of the H.263 video coding standard.  
   
   
       6 . A method according to  claim 1 , comprising using a scene identifier as the error concealment method indicator, the scene identifier having the same value for all pictures of a particular scene, the scene identifier having a different value for each different scene.  
   
   
       7 . A method according to  claim 1 , comprising using a scene identifier as the error concealment method indicator, the scene identifier having one of two values, with pictures from adjacent different scenes having non-identical scene identifier values.  
   
   
       8 . A method according to  claim 1 , comprising including the error concealment method indicator in a picture segment header and/or a macroblock header.  
   
   
       9 . A method according to  claim 1 , comprising using the error concealment method indicator to indicate a type of error concealment method to be applied for a specified rectangular area of a picture.  
   
   
       10 . A method of decoding an encoded video signal representing a sequence of pictures, the method comprising: 
 receiving a part of the encoded video signal representing a picture of said sequence or a part of a picture of said sequence detecting an error during decoding of said picture or said part of a picture from the received part of the encoded video signal and, responsive to detecting said error, examining an error concealment method indicator associated with said picture or said part of a picture, the error concealment method indicator arranged to indicate a type of error concealment method to be used in the decoding process for said picture or said part of a picture when an error occurs; and    using an error concealment method of the type indicated by said error concealment method indicator to conceal said error, irrespective of an encoding mode of the picture.    
   
   
       11 . A method of decoding according to  claim 10 , comprising applying a temporally-predictive error concealment method when the error concealment method indicator is the same as that for a previously received picture, and applying a spatial error concealment method when the error concealment method indicator is different from that of a previously received picture.  
   
   
       12 . A method according to  claim 10 , comprising examining a picture header of the encoded video signal to identify the error concealment method indicator.  
   
   
       13 . A method according to  claim 10 , wherein the encoded video signal is encoded according to the H.263 video coding standard, the method comprising examining the Supplemental Enhancement Information of the H.263 video coding standard to identify the error concealment method indicator.  
   
   
       14 . A method according to  claim 10 , wherein the sequence of pictures includes a number of different scenes and the method comprises using a scene identifier associated with the scenes as the error concealment method indicator, the scene identifier having the same value for all pictures of a scene, the scene identifier having a different value for each different scene.  
   
   
       15 . A method according to  claim 10 , wherein the sequence of pictures includes a number of different scenes, the method comprising using a scene identifier associated with the scenes as the error concealment method indicator, the scene identifier having one of two values with pictures from adjacent different scenes having non-identical scene identifier values.  
   
   
       16 . A method according to  claim 10 , comprising examining a picture segment header and/or a macroblock header to identify the error concealment method indicator.  
   
   
       17 . A method according to  claim 10 , comprising using an error concealment method of the type indicated by the error concealment method indicator to conceal an error in a specified rectangular area of a picture.  
   
   
       18 . A method according to  claim 14 , comprising when an error is identified in the encoded video signal for a picture, comparing a scene identifier for the picture with a scene identifier for a temporally neighbouring correctly decoded picture and, if the scene identifier for the picture is the same as the scene identifier for the temporally neighbouring correctly decoded picture, applying a temporally-predictive error concealment algorithm in the decoding process for the picture.  
   
   
       19 . A method according to  claim 14 , comprising when an error is identified in the encoded video signal for a picture, comparing a scene identifier for the picture with a scene identifier for a temporally neighbouring correctly decoded picture and, if the scene identifier for the picture is different from the scene identifier for the temporally neighbouring correctly decoded picture, applying a spatial error concealment method in the decoding process for the picture.  
   
   
       20 . An apparatus for encoding a video signal representing a sequence of pictures to form an encoded video signal, the apparatus being arranged to: 
 compare a first picture of the sequence or a part of the first picture with a second picture of the sequence;    calculate a measure of similarity between said first picture of the sequence or said part of the first picture and the second picture;    compare the measure of similarity with a predetermined criterion of similarity; and    output an error concealment method indicator based on a result of said comparison for indicating a type of error concealment method to be in a corresponding decoding process for said first picture of the sequence or said part of the first picture.    
   
   
       21 . An apparatus according to  claim 20 , wherein the apparatus is arranged to output an error concealment method indicator indicating that a non temporally-predictive error concealment method is to be used in the corresponding decoding process for said first picture of the sequence or said part of the first picture when the measure of similarity does not meet the predetermined criterion of similarity and to output an error concealment method indicator indicating that a temporally-predictive error concealment method is to be used in the corresponding decoding process for said first picture of the sequence or said part of the first picture when the measure of similarity meets the predetermined criterion of similarity.  
   
   
       22 . An apparatus according to  claim 20 , wherein the apparatus is arranged to update the error concealment method indicator when the measure of similarity does not meet the predetermined criterion of similarity and to leave the error concealment method indicator unchanged when the measure of similarity meets the predetermined criterion of similarity.  
   
   
       23 . An apparatus according to  claim 20 , wherein the apparatus is arranged to include the error concealment method indicator in a picture header of the encoded video signal.  
   
   
       24 . An apparatus according to  claim 20 , wherein the apparatus is arranged to encode the video signal according to the H.263 video coding standard and to include the error concealment method indicator in the Supplemental Enhancement Information of the H.263 video coding standard.  
   
   
       25 . An apparatus according to  claim 20 , wherein the apparatus is arranged to use a scene identifier as the error concealment method indicator, the scene identifier having the same value for all pictures of a scene, the scene identifier having a different value for each different scene.  
   
   
       26 . An apparatus according to  claim 20 , wherein the apparatus is arranged to use a scene identifier as the error concealment method indicator, the scene identifier having one of two values with pictures from adjacent different scenes having non-identical scene identifier values.  
   
   
       27 . An apparatus according to  claim 20 , wherein the apparatus is arranged to include the error concealment method indicator in a picture segment header and/or a macroblock header.  
   
   
       28 . An apparatus according to  claim 20 , wherein the error concealment method indicator is arranged to indicate a type of error concealment to be applied for a specified rectangular area of a picture.  
   
   
       29 . An apparatus for decoding an encoded video signal representing a sequence of pictures, the apparatus being arranged to: 
 receive a part of the encoded video signal representing a picture of said sequence or a part of a picture of said sequence;    detect an error during decoding of said picture or said part of a picture from the received part of the encoded video signal and, responsive to detecting said error, to examine an error concealment method indicator associated with said picture or said part of a picture, the error concealment method indicator arranged to indicate a type of error concealment method to be used in the decoding process for said picture or said part of a picture when an error occurs; and    use an error concealment method of the type indicated by said error concealment method indicator to conceal said error, irrespective of an encoding mode of the picture.    
   
   
       30 . An apparatus according to  claim 29 , wherein the apparatus is arranged to apply a temporally-predictive error concealment method when the error concealment method indicator is the same as that for a previously received picture, and to apply a spatial error concealment method when the error concealment method indicator is different from that of a previously received picture.  
   
   
       31 . An apparatus according to  claim 29 , wherein the apparatus is arranged to examine a picture header of the encoded video signal to identify the error concealment method indicator.  
   
   
       32 . An apparatus according to  claim 29 , wherein the encoded video signal is encoded according to the H.263 video coding standard and the apparatus is arranged to examine the Supplemental Enhancement Information of the H.263 video coding standard to identify the error concealment method indicator.  
   
   
       33 . An apparatus according to  claim 29 , wherein the sequence of pictures includes a number of different scenes and the apparatus is arranged to use a scene identifier associated with the scenes as the error correction method indicator, the scene identifier having the same value for all pictures of a scene, the scene identifier having a different value for each different scene.  
   
   
       34 . An apparatus according to  claim 29 , wherein the sequence of pictures includes a number of different scenes and the apparatus is arranged to use a scene identifier associated with the scenes as the error concealment method indicator, the scene identifier having one of two values with pictures from adjacent different scenes having non-identical scene identifier values.  
   
   
       35 . An apparatus according to  claim 29 , wherein the apparatus is arranged to examine a picture segment header and/or a macroblock header to identify the error concealment method indicator.  
   
   
       36 . An apparatus according to  claim 29 , wherein the apparatus is arranged to use an error concealment method of the type indicated by the error concealment method indicator to conceal an error in a specified rectangular area of a picture.  
   
   
       37 . An apparatus according to  claim 33 , wherein the apparatus is arranged to compare a scene identifier for a picture with a scene identifier for a temporally neighbouring correctly decoded picture when an error is identified in the encoded video signal for the picture and to apply a temporally-predictive error concealment algorithm in the decoding process for the picture if the scene identifier for the picture is the same as the scene identifier for the temporally neighbouring correctly decoded picture.  
   
   
       38 . An apparatus according to  claim 33 , wherein the apparatus is arranged to compare a scene identifier for a picture with a scene identifier for a temporally neighbouring correctly decoded picture when an error is identified in the encoded video signal for the picture and to apply a spatial error concealment method in the decoding process for the picture if the scene identifier for the picture is different from the scene identifier for the temporally neighbouring correctly decoded picture.  
   
   
       39 . A portable radio communications device including of an apparatus for encoding according to  claim 20 .  
   
   
       40 . An apparatus for video encoding according to  claim 20 , wherein the apparatus is a circuit for video encoding.  
   
   
       41 . An apparatus for video decoding according to  claim 29 , wherein the apparatus is a circuit for video decoding.  
   
   
       42 . A computer program comprising computer readable code arranged to perform a method of encoding a video signal representing a sequence of pictures to form an encoded video signal, the computer program comprising: 
 computer readable code for comparing a first picture of the sequence or a part of the first picture with a second picture of the sequence;    computer readable code for calculating a measure of similarity between said first picture of the sequence or said part of the first picture and the second picture;    computer readable code for comparing the measure of similarity with a predetermined criterion of similarity; and    computer readable code for outputting an error concealment method indicator based on a result of said comparison for indicating a type of error concealment method to be used in a corresponding decoding process for said first picture of the sequence or said part of the first picture.    
   
   
       43 . A computer program comprising computer readable code arranged to perform a method of decoding an encoded video signal representing a sequence of pictures, the computer program comprising: 
 computer readable code for receiving a part of the encoded video signal representing a picture of said sequence or a part of a picture of said sequence;    computer readable code for detecting an error during decoding of said picture or said part of a picture from the received part of the encoded video signal and, responsive to detecting said error, examining an error concealment method indicator associated with said picture or said part of a picture, the error concealment method indicator arranged to indicate a type of error concealment method to be used in the decoding process for said picture or said part of a picture when an error occurs; and    computer readable code for using an error concealment method of the type indicated by said error concealment method indicator to conceal said error, irrespective of an encoding mode of the picture.    
   
   
       44 . A video encoder for encoding a video signal representing a sequence of pictures to form an encoded video signal, the video encoder comprising: 
 means for comparing a first picture of the sequence or a part of the first picture with a second picture of the sequence;    means for calculating a measure of similarity between said first picture of the sequence or said part of the first picture and the second picture;    means for comparing the measure of similarity with a predetermined criterion of similarity; and    means for outputting an error concealment method indicator based on a result of said comparison for indicating a type of error concealment method to be in a corresponding decoding process for said first picture of the sequence or said part of the first picture.    
   
   
       45 . A video decoder for decoding an encoded video signal representing a sequence of pictures, the video decoder comprising: 
 means for receiving a part of the encoded video signal representing a picture of said sequence or a part of a picture of said sequence;    means for detecting an error during decoding of said picture or said part of a picture from the received part of the encoded video signal and, means responsive to said means for detecting said error, for examining an error concealment method indicator associated with said picture or said part of a picture, the error concealment method indicator arranged to indicate a type of error concealment method to be used in the decoding process for said picture or said part of a picture when an error occurs; and    means for using an error concealment method of the type indicated by said error concealment method indicator to conceal said error, irrespective of an encoding mode of the picture.