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📈 PCR Monotonicity

The Program Clock Reference (PCR) is the 27 MHz timing reference carried in MPEG-TS adaptation fields for the PMT-declared PCR PID.

PCR values are expected to move forward monotonically so decoders can maintain a stable encoder clock timeline.

What This Test Does​

The PCR Monotonicity test scans PCR-bearing packets on the selected PCR PID and records an error when PCR moves backward without a valid wraparound case.

The checker resets its PCR baseline when the transport packet sets the adaptation-field discontinuity indicator.

✅ Pass Criteria​

The test passes when no backward PCR values are detected.

Application result message:

No backward PCR values were detected.

❌ Fail Criteria​

The test fails when one or more backward PCR values are detected.

Typical causes include:

  • Encoder clock instability
  • Timestamp rewrite or remux defects
  • Incorrect wrap handling

Application result message:

<n> PCR monotonicity errors were detected.

Example​

Here a chart that shows a PMT referencing non-existing klv stream.

Missing PID chart

Test file​

  • klv-missing-pid.ts

PCR backward at packet 247: 72900000 -> 70200000 PCR backward at packet 499: 126900000 -> 124200000 PCR backward at packet 762: 180900000 -> 178200000 PCR backward at packet 1033: 234900000 -> 232200000