Configure Audio Encoding and Lip-Sync Offset

Configure AAC or Opus, 48 kHz, channels, bitrate, and measured audio timing.

Written By 4ALL.LIVE

Last updated 12 days ago

Deliver clean program audio using the destination-required codec with controlled video synchronization.

Best for: Audio engineers and streaming operators.

Before you start

AAC is the interoperability default; Opus requires explicit receiver support.

  • 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.
  • Know the input channel layout and receiver specification.
  • Prepare a slate, clap, or flash/beep reference.
  • Monitor the final receiver.

Configuration

  1. Choose AAC unless the receiver explicitly supports and requires Opus.
  2. Keep sample rate at 48 kHz.
  3. Choose mono or stereo and confirm any multichannel downmix/mapping.
  4. Start with 160 Kbps stereo AAC and adjust to contract.
  5. Leave Audio offset at 0 ms initially.
  6. Send a timing reference through the complete chain and measure whether audio leads or lags video.
  7. Adjust in small increments and repeat after any encoder, buffer, or destination change.

What success looks like: Audio decodes on intended channels without clipping, silence, or unacceptable lip-sync error.

Check your setup

  • Receiver reports 48 kHz and correct channels.
  • No swap or phase cancellation.
  • Lip sync is within tolerance.
  • Caption timing remains separately controlled.

Troubleshooting

  • Silence: verify capture audio device, mapping, and receiver selection.
  • Distortion: correct input level and avoid double gain.
  • Opus rejected: switch to AAC.
  • Drift: investigate clocks/discontinuities instead of a static offset.

Security and operational notes

Important: Audio offset moves the entire program. Do not use it to hide unstable clocks or caption timing.