Mitigating Impairments in Redundant Streams

Abstract

In one embodiment, a method comprises receiving a primary stream of encoded frames and a separate stream of redundant frames. The method further comprises decoding and reconstructing in parallel the frames in the primary stream and the separate stream of redundant frames, on a real-time basis, in accordance with a specified common clock reference. The method further comprises, upon determining that a frame in the primary stream exhibits an error or impairment, determining a decoded redundant frame in the separate stream that corresponds to the impaired frame, and substituting at least a portion of the information in the decoded redundant frame for a corresponding decoded version of the impaired frame.

We claim: 
     
         1 . A method comprising:
 receiving a primary stream of encoded frames and a separate stream of frames selected from frames in the primary stream based on a combination of: 1) a minimum number of other frames depending on each frame in relation to reference frames, 2) a level of information propagation via indirect dependence, and 3) a longevity of the information propagation.   
     
     
         2 . The method of  claim 1 , further comprising:
 decoding and reconstructing in parallel the frames in the primary stream and the separate stream of redundant frames.   
     
     
         3 . The method of  claim 2 , wherein decoding and reconstruction in parallel occurs on a real-time basis, in accordance with a specified common clock reference: 
     
     
         4 . The method of  claim 2 , further comprising: determining that a frame in the primary stream exhibits an error or impairment. 
     
     
         5 . The method of  claim 4 , further comprising: determining a decoded redundant frame in the separate stream that corresponds to the determined frame in the primary stream exhibiting an error or impairment. 
     
     
         6 . The method of  claim 5 , further comprising: substituting at least a portion of the decoded redundant frame for a corresponding decoded version of the impaired frame. 
     
     
         7 . The method of  claim 6 , further comprising: determining whether a forward error correction (FEC) frame associated with the frame in the primary stream has been received; and if the FEC frame has been received, using the FEC frame to correct the frame in the primary stream. 
     
     
         8 . The method of  claim 6 , further comprising:
 determining whether a forward error correction (FEC) frame associated with the frame in the primary stream has been received;   if the FEC frame has not been received, evaluating whether decoding with the frame in the primary stream will produce a picture of acceptable quality; and   if the evaluation determines that the decoding will produce unacceptable quality, requesting retransmission of the frame in the primary stream.   
     
     
         9 . The method of  claim 6 , further comprising:
 determining whether a forward error correction (FEC) frame associated with the frame in the primary stream has been received;   if the FEC frame has not been received, evaluating whether decoding with the frame in the primary stream will produce a picture of acceptable quality; and   if the evaluation determines decoding will produce acceptable quality, supplying the frame in the primary stream for decoding.   
     
     
         10 . A system comprising:
 means for receiving a primary stream of encoded frames and a separate stream of frames redundant of frames in the primary stream, wherein frames are selected for the separate stream based on a combination of: 1) a minimum number of other frames depending on each frame in relation to reference frames, 2) a level of information propagation via indirect dependence, and 3) a longevity of the information propagation.   
     
     
         11 . The system of  claim 10 , further comprising:
 means for determining if a frame in the primary stream exceeds an error criterion.   
     
     
         12 . The system of  claim 11 , further comprising:
 means for determining a decoded corresponding frame in the separate stream corresponds to a frame in the primary stream.   
     
     
         13 . The system of  claim 12 , further comprising:
 means for supplying the corresponding frame responsive to the frame in the primary stream exceeding the error criterion.   
     
     
         14 . The system of  claim 12 , further comprising:
 means for determining the decoded corresponding frame in the separate stream based on a picture or slice type.   
     
     
         15 . The system of  claim 12 , further comprising:
 means for determining the decoded corresponding frame in the separate stream based on a frame number that is relative to a sequence parameter set.   
     
     
         16 . The system of  claim 12 , further comprising:
 means for determining the decoded corresponding frame in the separate stream based on matching a presentation time stamp in a frame in the primary stream with a presentation time stamp in the frame in the separate stream.   
     
     
         17 . The system of  claim 11 , further comprising:
 means for determining whether a forward error correction (FEC) frame associated with the frame in the primary stream has been received, responsive to the frame in the primary stream exceeding the error criterion; and   means for using the FEC frame to correct the frame in the primary stream, responsive to determining the FEC frame has been received.   
     
     
         18 . The system of  claim 11 , further comprising:
 means for determining whether a forward error correction (FEC) frame associated with the frame in the primary stream has been received, responsive to the frame in the primary stream exceeding the error criterion; and   means for requesting retransmission of the frame in the primary stream, responsive to determining the FEC frame has not been received.   
     
     
         19 . The system of  claim 11 , further comprising:
 means for determining whether a forward error correction (FEC) frame associated with the frame in the primary stream has been received, responsive to the frame in the primary stream exceeding the error criterion;   means for evaluating whether decoding with the frame in the primary stream will produce a picture of acceptable quality, responsive to determining that the FEC frame has not been received; and   means for requesting retransmission of the frame in the primary stream, responsive to the evaluation that decoding will produce unacceptable quality.   
     
     
         20 . An apparatus comprising:
 an encoder; and   a multiplexer configured to combine a primary stream of encoded frames and a separate stream of frames redundant of frames in the primary stream, wherein frames are selected for the separate stream based on a combination of: 1) a minimum number of other frames depending on each frame in relation to reference frames, 2) a level of information propagation via indirect dependence, and 3) a longevity of the information propagation.