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 12 days 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.