align_audio: Locate a clip's audio within a longer narration

In compost: Video Compositing via 'FFmpeg'

Locate a clip's audio within a longer narration

Description

Normalized cross-correlation of amplitude envelopes (10ms resolution by default): returns the offset in seconds at which clip's audio best matches narration. Works on video files (their audio stream) and plain audio files alike.

Usage

align_audio(clip, narration, sr = 8000L, hop = 80L)

Arguments

clip	Media file whose audio to place.
narration	The continuous reference audio (e.g. the track's audio.mp3).
sr	Decode sample rate (default 8000).
hop	Envelope hop in samples (default 80 = 10ms at 8kHz).

Value

Offset in seconds (numeric), with attributes correlation (peak normalized correlation, 0-1ish) and curve (correlation per candidate lag).

Examples

## Not run: 
align_audio("media/chunk02.mp4", "audio.mp3")

## End(Not run)

compost documentation built on Aug. 4, 2026, 5:11 p.m.