Reduction of timing jitter in audio-video transport streams
US5828414A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 23, 1996 |
| Grant date | Oct 27, 1998 |
| Priority date | — |
| Expiry date | Feb 23, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N21/64307
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for reducing program clock reference (PCR) jitter in transport packets of a transport stream compliant with MPEG-2 or another suitable audio-video encoding standard. The PCRs from a given single program transport stream (SPTS) of a multi-program transport stream are processed in a phase-locked loop (PLL) to generate dejittered PCRs for that SPTS. The PLL for a given SPTS receives as inputs the PCRs from that SPTS and a cycle count for each PCR indicative of the number of asynchronous clock cycles counted since the previous PCR. The PLL generates a given dejittered PCR as a function of the previous dejittered PCR, the cycle count for the given PCR, and a clock frequency mismatch estimate for the given program clock. The clock frequency mismatch estimate is generated by filtering a sequence of jitter estimates, each corresponding to the difference between a previous PCR and its corresponding dejittered PCR. The SPTS transport packets may then be restamped with the dejittered PCRs from the PLL to provide a dejittered multi-program transport stream.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.