Tune Caption Delay, Offsets, Partials, and Clear Timing

Align embedded captions with video and control partial cadence, payloads, placement, and clearing.

Written By 4ALL.LIVE

Last updated About 1 month ago

Balance responsiveness and accuracy while synchronizing caption insertion to the actual program delay.

Best for: Caption engineers and live-production technicians.

Before you start

Included with embedded-caption profiles.

  • Sign in with access to the correct organization, team, and event.
  • Record event, language, workstation, app build, OS, drivers, destination, and operator.
  • Commission with a test pattern and non-public receiver before program video.
  • Prepare a repeatable timing script/recording.
  • Know the intentional video delay.
  • Use an independent CEA decoder.

Step by step

Caption tuning controls in 4All Live Setup
Caption tuning balances responsiveness, deduplication, and final-caption stability.
  1. Start with defaults: program delay 2200 ms, caption offset 0 ms, embedded offset -2200 ms, partial interval 700 ms, delta-append, two roll-up lines, and clear timeout 2000 ms.
  2. Measure speech-to-caption timing at the final receiver.
  3. Set Program delay to intentional video delay.
  4. Use Caption offset for general presentation; use Embedded caption offset within -10000 to 10000 ms for CEA alignment.
  5. Choose Partials and finals or Finals only.
  6. Increase partial minimum interval within 0–3000 ms if the decoder churns.
  7. Keep delta-append for roll-up; test full-state only with compatible decoders.
  8. Use origin row -1 automatic or 0–14 and column 0–31.
  9. Set roll-up timeout within 0–60000 ms and clear timeout; test silence, corrections, long speech, and boundaries.

What success looks like: Captions track the designed delay without duplication, churn, premature clears, or stale text.

Check your setup

  • Recorded reference proves timing.
  • Finals do not duplicate partials.
  • Silence clears as documented.
  • Placement remains readable.

Troubleshooting

  • Text leads: increase effective delay or reduce negative offset.
  • Text lags: reduce delay only after measuring network/recognition.
  • Repeated text: compare delta-append/full-state with decoder behavior.
  • Clear wrong: adjust one timeout at a time.

Security and operational notes

Important: Offsets interact and receivers buffer differently. Change one value, record it, and validate every destination.