Methods and apparatus for isochronous data delivery within a network

Abstract

Methods and apparatus for efficiently servicing isochronous streams (such as media data streams) associated with a network. In one embodiment, an Isochronous Cycle Manager (ICM), receives multiple independent streams of packets that include isochronous packets arriving according to different time bases (e.g., where each stream has a different time base). The packets are sorted by the ICM into a buffering mechanism according to their required presentation time. Additionally the ICM calculates a launch time for each packet. The NIC transmits the packets from the queue according to an access scheme, such as a time division multiplexed (TDM) scheme where each of a plurality of cycles is subdivided into time slots. During appropriate time slots, the NIC transmits the packets in chronological order, as read out of the buffering mechanism.

1 . A method of managing a plurality of isochronous processes, the method comprising:
 receiving multiple isochronous data streams, each isochronous data stream comprising a plurality of isochronous data packets, each packet having a presentation time associated therewith;   sorting each isochronous data packet according to the presentation time;   calculating a launch time for each isochronous data packet of the multiple isochronous data streams; and   transmitting the isochronous data packets according to the launch time.   
     
     
         2 . The method of  claim 1 , additionally comprising:
 receiving asynchronous data packets; and   transmitting the asynchronous data packets.   
     
     
         3 . The method of  claim 2 , additionally comprising sorting the asynchronous data packets with the isochronous data packets. 
     
     
         4 . The method of  claim 2 , wherein a first portion of transmission bandwidth is reserved for isochronous data packets, and a second portion of transmission bandwidth is reserved for asynchronous data packets. 
     
     
         5 . The method of  claim 1 , wherein the act of sorting comprises storing the isochronous data packets in a ring buffer according to presentation time. 
     
     
         6 . The method of  claim 1 , wherein at least one of the multiple isochronous data streams comprises video data. 
     
     
         7 . The method of  claim 6 , wherein at least one of the multiple isochronous data streams comprises audio data. 
     
     
         8 . The method of  claim 1 , wherein at least one of the multiple isochronous data streams has a time base that differs from a master time base. 
     
     
         9 . The method of  claim 8 , wherein the act of calculating comprises adjusting the launch time of the isochronous data packets according to the master time base. 
     
     
         10 . A method of reconstructing a plurality of isochronous processes, the method comprising:
 receiving one or more unreserved time slots of packet data, the one or more unreserved time slots comprising a plurality of packets transmitted in chronological order, at least one of the plurality of packets having a presentation time associated therewith;   extracting the at least one packet; and   presenting the at least one packet at the associated presentation time.   
     
     
         11 . The method of  claim 10 , wherein the at least one packet comprises an isochronous data packet. 
     
     
         12 . The method of  claim 10 , where at least one other packet of the plurality of packets comprises an asynchronous data packet. 
     
     
         13 . The method of  claim 10 , wherein only a subset of the plurality of packets have a presentation time associated therewith. 
     
     
         14 . The method of  claim 13 , additionally comprising storing the subset of the plurality of packets in order of arrival into a First-In-First-Out buffer. 
     
     
         15 . The method of  claim 10 , wherein the at least one packet comprises video data. 
     
     
         16 . The method of  claim 10 , wherein the at least one packet comprises one or more subpackets of data. 
     
     
         17 . The method of  claim 16 , wherein the one or more subpackets of data comprise a video subpacket and an audio subpacket. 
     
     
         18 . A network interface apparatus, comprising:
 a transmission queue configured to transmit a plurality of slots of data at a designated time;   a data interface configured to receive a plurality of isochronous data streams, the plurality of isochronous data streams comprising one or more different time references;   a network interface clock, the network interface clock configured to generate a designated time reference; and   at least one controller configured to:
 extract one or more data packets from the plurality of isochronous data streams; 
 sort the one or more data packets based at least in part on a presentation time; 
 calculate a launch time for each of the one or more data packets; and 
 transmit the slots of data at the calculated launch time. 
   
     
     
         19 . The network interface apparatus of  claim 18 , wherein the determined launch time is based at least in part on a difference between the one or more different time references and the designated time reference. 
     
     
         20 . The network interface apparatus of  claim 18 , additionally comprising assigning the sorted one or more data packets to a slot of data. 
     
     
         21 . A method of processing isochronous data streams, the method comprising:
 receiving multiple isochronous data streams, each isochronous data stream comprising a plurality of isochronous data packets;   determining a sorting criterion for the multiple isochronous data streams;   sorting at least a portion of the isochronous data packets in each stream according to the determined sorting criterion to produce a sorted order of data packets; and   transmitting the isochronous data packets according to the sorted order.   
     
     
         22 . The method of  claim 21 , additionally comprising:
 receiving asynchronous data packets;   sorting the asynchronous data packets with the isochronous data packets according to at least one of (i) the sorting criterion; and/or (ii) a second sorting criterion, to produce a sorted order of asynchronous packets; and   transmitting the sorted order of asynchronous data packets.   
     
     
         23 . The method of  claim 21 , wherein the sorting criterion is at least temporally based. 
     
     
         24 . The method of  claim 21 , wherein the sorting criterion is based at least in part on a priority. 
     
     
         25 . The method of  claim 21 , wherein at least one of the multiple isochronous data streams comprises both video and audio data.