| 摘要 |
Variable rate multiplexer devices have, by definition, a variable output rate for bits of information encoded therein. As a result necessary time sync information such as program clock reference information cannot be guaranteed to be delivered within the time interval thresholds mandated by certain industry broadcast standards, such as MPEG-2 and digital video broadcast (DVB). Transmission of reference signals, such as PCR information, may be assured by inserting detection means to detect the time interval between occurrences of the reference signal. If the interval between occurrences of the reference signal exceeds a predetermined time interval threshold, the detection means will instruct a memory device to provide a reference signal, which is then imprinted with reference signal information and inserted into the stream of information being output by the multiplexer. Alternatively, the multiplexer may simply provide an output signal at a preset predetermined time intervals, regardless of whether or not a reference signal is being provided by the input stream. In this embodiment, the output signal may occur substantially more frequently than is required by the time interval threshold of the relevant broadcast standard.1015 |
