Data packet processing

Abstract

Data packet processing is described. A set of first data packets comprising hierarchically encoded data is accessed. A number of the first data packets are identified as candidate data packets to be potentially transmitted over a network to a receiver based at least in part on the hierarchically encoded data. The number of candidate data packets is then reduced based at least in part on the hierarchically encoded data so that a number of second data packets comprising error correction information for one or more of the first data packets can be increased.

1 . A method of processing data packets, said method comprising:
 accessing a plurality of first data packets comprising hierarchically encoded data;   identifying a first number of said first data packets as candidate data packets to be potentially transmitted to a receiver over a period of time, wherein said identifying said first number is based at least in part on said hierarchically encoded data of said plurality of first data packets; and   reducing said first number of candidate data packets so that a second number of second data packets comprising error correction information for selected said candidate data packets is increased, wherein candidate data packets removed in order to reduce said first number are not sent to said receiver during said period of time and are removed based at least in part of said hierarchically encoded data of said plurality of first data packets.   
   
   
       2 . The method of  claim 1  wherein said hierarchically encoded data is encoded using MPEG and comprises I-frame data packets, P-frame data packets and B-frame data packets, said reducing said first number of candidate data packets comprising:
 evaluating said B-frame data packets as said candidate data packets;   provided said evaluating said B-frame data packets does not reduce said first number sufficiently, evaluating said P-frame data packets as said candidate data packets; and   provided said evaluating said P-frame data packets does not reduce said first number sufficiently, evaluating said I-frame data packets as said candidate data packets.   
   
   
       3 . The method of  claim 1  wherein said hierarchically encoded data comprises scalably coded data comprising a base layer data packets and enhancement layer data packets, said reducing said first number of candidate data packets comprising:
 evaluating said enhancement layer data packets as said candidate data packets; and   provided said evaluating said enhancement layer data packets does not reduce said first number sufficiently, evaluating said base layer data packets as said candidate data packets.   
   
   
       4 . The method of  claim 3  wherein said scalably coded data is selected from a list consisting essentially of: scalably coded video data, scalably coded audio data, scalably coded speech data, scalably coded graphics data, and scalably coded image data. 
   
   
       5 . The method of  claim 1  wherein said reducing said first number of candidate data packets comprises:
 reducing said first number of candidate packets based at least in part on evaluating packet importance information for said plurality of first data packets.   
   
   
       6 . The method of  claim 1  wherein said second data packets comprises error correction information for a portion of said plurality of first data packets sent to said receiver. 
   
   
       7 . The method of  claim 1  wherein said reducing said first number of candidate data packets comprises:
 reducing said first number of candidate data packets such that said first number of candidate data packets and said second number of second data packets satisfy transmission bandwidth constraints.   
   
   
       8 . The method of  claim 1  further comprising:
 discarding candidate data packets in order to reduce said first number; and   increasing said second number by a corresponding amount, wherein said discarding and increasing are performed until there are enough of said second data packets to compensate for a data packet loss rate.   
   
   
       9 . The method of  claim 1  wherein said plurality of first data packets comprises first subset data packets comprising said hierarchically encoded data and second subset data packets comprising error correction information for said first subset data packets. 
   
   
       10 . The method of  claim 9  further comprising:
 selectively reducing said second subset data packets so that said second number of second data packets comprising error correction information for selected said candidate data packets is increased.   
   
   
       11 . A computer-usable medium having computer-readable code stored thereon for causing a device to perform a method of processing data packets, said method comprising:
 accessing a set of first data packets comprising data to be potentially included in an output stream, said first data packets comprising importance information;   applying an error correcting technique to one or more first data packets in said set to produce second data packets comprising error correction information; and   iteratively removing selected first data packets from said set based at least in part on said importance information until a number of first data packets in said set and a number of said second data packets is less than or equal to a specified limit, wherein said selected first data packets are not included in said output stream.   
   
   
       12 . The computer-usable medium of  claim 11  wherein said first data packets are encoded using MPEG and comprises I-frame data packets, P-frame data packets and B-frame data packets, wherein said importance information comprises coding information identifying said I-frame data packets, said P-frame data packets and said B-frame data packets, said iteratively removing selected first data packets comprising:
 iteratively removing selected B-frames data packets from said set;   provided said number of first data packets in said set and said number of said second data packets in said set is greater than said specified limit, iteratively removing selected P-frames data packets from said set; and   provided said number of first data packets in said set and said number of said second data packets in said set is greater than said specified limit, iteratively removing selected I-frames data packets from said set.   
   
   
       13 . The computer-usable medium of  claim 12  wherein said first data packets comprises scalably coded data comprising a base layer data packets and enhancement layer data packets, wherein said importance information comprises coding information identifying said base layer data packets and said enhancement layer data packets, said iteratively removing selected first data packets comprising:
 iteratively removing selected enhancement layer data packets from said set; and   provided said number of first data packets in said set and said number of said second data packets in said set is greater than said specified limit, iteratively removing selected base layer data packets from said set.   
   
   
       14 . The computer-usable medium of  claim 13  wherein said scalably coded data is selected from a list consisting essentially of: scalably coded video data, scalably coded audio data, scalably coded speech data, scalably coded graphics data, and scalably coded image data. 
   
   
       15 . The computer-usable medium of  claim 11  wherein said method further comprises:
 discarding said selected first data packets from said set to reduce said first number by an amount; and   increasing said second number by said amount, wherein said discarding and increasing are performed until there are enough of said second data packets to compensate for a data packet loss rate.   
   
   
       16 . A device for processing data packets, said device comprising:
 a transmitter operable for transmitting hierarchically encoded data over a link between said device and a receiving device, said link having a bandwidth;   a memory coupled to said transmitter and operable for storing a plurality of first data packets comprising said hierarchically encoded data; and   a processor coupled to said memory and operable for processing said first data packets, said processor for selecting a first number of said first data packets as candidate data packets to be potentially transmitted via said link and then reducing said first number of candidate data packets so that a second number of second data packets comprising error correction information for selected said candidate data packets can be increased, wherein said selecting and reducing are based at least in part on said hierarchically encoded data, wherein said first number plus said second number is constrained by a limit corresponding to said bandwidth;   wherein candidate data packets that are removed by said reducing are not transmitted via said link.   
   
   
       17 . The device of  claim 16  wherein said hierarchically encoded data is encoded using MPEG and comprises I-frames, P-frames and B-frames, wherein said processor is for reducing said first number of candidate data packets by evaluating said B-frames as said candidate data packets, evaluating said P-frames as said candidate data packets if said evaluating said B-frames does not reduce said first number sufficiently, and evaluating said I-frames as said candidate data packets if said evaluating said P-frames does not reduce said first number sufficiently. 
   
   
       18 . The device of  claim 16  wherein said hierarchically encoded data comprises scalably coded data comprising a base layer and at least one enhancement layer, wherein said processor is for reducing said first number of candidate data packets by evaluating said enhancement layer as said candidate data packets, and evaluating said base layer as said candidate data packets if said evaluating said enhancement layer does not reduce said first number sufficiently. 
   
   
       19 . The device of  claim 18  wherein said scalably coded data is selected from a list consisting essentially of: scalably coded video data, scalably coded audio data, scalably coded speech data, scalably coded graphics data, and scalably coded image data. 
   
   
       20 . The device of  claim 16  wherein said plurality of first data packets comprises first subset data packets comprising said hierarchically encoded data and second subset data packets comprising error correction information for said first subset data packets, and wherein said processor is for selectively reducing said second subset data packets so that said second number of second data packets comprising error correction information for selected said candidate data packets is increased.