Skip to main content

📉 Stream vs KLV Drift

Purpose​

The Stream vs KLV Drift test checks whether the MPEG-TS timing domains and the metadata timing domain stay aligned over time.

It compares:

  • PCR timing
  • PES PTS timing when present
  • Normalized MISB ST 0601 Tag 2: Precision Time Stamp

✅ Pass Criteria​

The test passes when the PCR clock, the PTS timeline when present, and the normalized KLV Tag 2 time remain within the configured drift threshold across the inspected period.

❌ Fail Criteria​

The test fails when PCR drift or PTS drift against normalized KLV Tag 2 time exceeds the configured threshold, indicating sustained timing divergence or a timestamp alignment problem.

Chart​

The chart shows drift between the stream clocks and normalized KLV Tag 2 time over the file so the operator can see whether loss of alignment is isolated or sustained.

PCR drift is always shown when samples are available. A second series is shown when the source KLV packets also carry PTS.

Passing sample result​

Passing MISB ST 0601 Stream vs KLV Drift chart showing PCR and PTS drift staying near zero

In this passing example, PCR drift and PTS drift stay near 0 ms relative to normalized MISB ST 0601 Tag 2 time. Both series remain inside the configured threshold, so the MPEG-TS timing domains and metadata timestamp domain stay aligned.

This is the expected shape when metadata and video timing are synchronized: small variation around zero is acceptable, but there is no sustained slope and no threshold crossing.

Failing sample result​

Stream vs KLV drift chart

In this failing example, one timing domain drifts steadily away from normalized KLV Tag 2 time. Sustained drift means the stream clock and metadata clock are no longer advancing together, which can lead to overlay mismatch, incorrect metadata-to-frame correlation, or late/early metadata display.