| 摘要 |
<p>A redundant remultiplexer (500) is described which is capable of remultiplexing fixed length transport stream packets. Illustratively, at least some of the packets contain program data, i.e., data with a sensitive delivery schedule, such as variably compressed audio-video data. An example of such variably compressed data is MPEG-2 encoded video. The redundant remultiplexer has a chassis architecture with input modules (521) that receive externally originating transport packets, output modules (521) that output externally selected transport stream packets and switch modules (531, 532). The switch modules perform a packet switch function, i.e., they switch selected packet received by the input modules to respective output modules on a packet by packet basis, e.g., based on address information in each respective switched packet. The switch modules can also receive externally supplied packets and output externally respective packets. Each, module has a backup module (522) that assumes the role of the modules for which it is a backup in the event of failure. In the case of input and output modules, the backup module is actually running, even while standby mode, but otherwise disables its output. The reason is that packets must be processed as a preliminary step to outputting them (e.g., to ensure that the strict delivery schedule is maintained). This manner of operation enables quicker recovery and fewer lost packets, especially where retransmission of lost packets (e.g., program bearing packets) to an ultimate receiver is not possible.</p> |
