Information Technology - Generic Coding of Moving Pictures and Associated Audio Information - Part 9: Extension for Real Time Interface for Systems Decoders

This part of ISO/IEC 13818 does not change or supersede any of the requirements in ISO/IEC 13818-1. All Transport Streams, whether or not they are delivered in accordance with the RTI shall comply with ISO/IEC 13818-1. In particular, the accuracy requirement in ISO/IEC 13818-1 for PCRs in Transport Streams is not changed by the requirements of this part of ISO/IEC 13818. Compliance with this part of ISO/IEC 13818 is not required for compliance with ISO/IEC 13818-1.
 
This part of ISO/IEC 13818 does not address decoder requirements related to clock acquisition and slew rate constraints. For example, suppose a system utilizes the 27 MHz system clock to derive an ITU-R PAL chroma clock of 4.434 MHz, with a 0.1 Hz/sec slew rate limitation. With a source clock of 0.1 ppm accuracy, a decoder clock of 30 ppm accuracy, and straightforward phase-lo cked loop clock recovery circuitry, a decoder could require about 305,000 bits to prevent buffer under/overflow during frequency acquisition, even with low-jitter delivery. The actual number of bits a decoder requires for this purpose could be higher or lower, depending on the implementation.
 
Figure 1 provides a simplified view of the scope of this part of ISO/IEC 13818. This figure shows a Data Link Interface Adaptor, a Real-Time Interface Decoder (RTD), and the location of the Transport Stream which complies with the RTI Specification. It should be noted that the Data Link Interface Adaptor is responsible for removing any data link protocol or data structures, as well as any timing variations (i.e. jitter) in order to produce a compliant RTI Transport Stream