Error detection and recovery for high rate isochronous data in MPEG-2 data streams

A method for managing errors in isochronous data ("isodata") received in bursts from a packetized data stream carrying isodata presentation units in fixed length isodata transport packets, each of said transport packets including a packet identifier (PIP) and at least some of said packets containing a presentation time stamp (PTS) indicative of a time for commencing the fixed rate presentation of isodata presentation units from a buffer into which they are temporarily stored upon receipt, said method comprising the steps

• monitoring said data stream to detect PIDs identifying said isodata transport packets;
• monitoring the isodata transport packets identified by said PIPs to locate isodata PTSs;
• synchronizing the presentation of said presentation units from said buffer no a system time clock (STC) using timing information derived from the located isodata PTSs, said synchronization step comparing the STC to the timing information derived from the PTSs;
• and
• providing fill bits as output until it is time to present said presentation units if said comparison determines that said presentation units are too early to be presented.

A method for managing errors in isochronous data ("isodata") received in bursts from a packetized data stream carrying isodata presentation units in fixed length isodata transport packets, each of said transport packets including a packet identifier (PID) and at least some of said packets containing a presentation time stamp (PTS) indicative of a time for commencing the fixed rate presentation of isodata presentation units from a buffer into which they are temporarily stored upon receipt, said method comprising the steps of:

• monitoring said data stream to detect PIDs identifying said isodata transport packets;
• monitoring the isodata transport packets identified by said PIDs to locate isodata PTSs;
• synchronizing the presentation of said presentation units from said buffer to a system time clock (STC) using timing information derived from the located isodata PTSs, said synchronization step comparing the STC to the timing information derived from the PTSs;
• monitoring said isodata transport packets identified by said PIDs to determine if any of them are designated as being encrypted after any encryption should have been removed;
• and
• if a single packet only is designated as being encrypted after any encryption should have been removed, advancing a write pointer of said buffer by a suitable number of bits to ignore the single packet, while maintaining the synchronization of said presentation with respect to said STC.

A decoder for receiving and managing errors in isochronous data ("isodata") received in bursts from a packetized data stream carrying isodata presentation units in fixed length isodata transport packets, each of said transport packets including a packet identifier (PID) and at least some of said packets containing a presentation time stamp (PTS) indicative of a time for commencing the fixed rate presentation of isodata presentation units from a buffer into which they are temporarily stored upon receipt, said decoder comprising:

• means for monitoring said data stream to detect PIDs identifying said isodata transport packets;
• means for monitoring the isodata transport packets identified by said PIDs to locate isodata PTSs;
• means for synchronizing the presentation of said presentation units from said buffer to a system time clock (STC) using timing information derived from the located isodata PTSs;
• means for identifying discontinuity errors between successive ones of said isodata transport packets and, if a discontinuity of no more than one packet is identified, advancing a write pointer of said buffer by a suitable number of bits to compensate for the discontinuity, while maintaining the synchronization of said presentation with respect to said STC.

A decoder for receiving and managing errors in isochronous data ("isodata") received in bursts from a packetized data stream carrying isodata presentation units in fixed length isodata transport packets, each of said transport packets including a packet identifier (PID) and at least some of said packets containing a presentation time stamp (PTS) indicative of a time for commencing the fixed rate presentation of isodata presentation units from a buffer into which they are temporarily stored upon receipt, said decoder comprising:

• means for monitoring said data stream to detect PIDs identifying said isodata transport packets;
• means for monitoring the isodata transport packets identified by said PIDs to locate isodata PTSs;
• means for synchronizing the presentation of said presentation units from said buffer to a system time clock (STC) using timing information derived from the located isodata PTSs;
• and
• means for providing fill bits as output until it is time to present said presentation units if said comparison determines that said presentation units are too early to be presented.

A decoder for receiving and managing errors in isochronous data ("isodata") received in bursts from a packetized data stream carrying isodata presentation units in fixed length isodata transport packets, each of said transport packets including a packet identifier (PID) and at least some of said packets containing a presentation time stamp (PTS) indicative of a time for commencing the fixed rate presentation of isodata presentation units from a buffer into which they are temporarily stored upon receipt, said decoder comprising:

• means for monitoring said data stream to detect PIDs identifying said isodata transport packets;
• means for monitoring the isodata transport packets identified by said PIDs to locate isodata PTSs;
• means for synchronizing the presentation of said presentation units from said buffer to a system time clock (STC) using timing information derived from the located isodata PTSs, said synchronization step comparing the STC to the timing information derived from the PTSs;
• means for determining if any of the isodata transport packets identified by said PIDs are identified as being encrypted after any encryption should have been removed;
• and
• means responsive to said determining means when a single packet only is designated as being encrypted after any encryption should have been removed, for advancing a write pointer of said buffer by a suitable number of bits to ignore the single packet while maintaining the synchronization of said presentation with respect to said STC.