Audio Caption Timing Shifter

Audio Caption Timing Shifter | Online Free Tool | Elysia Tools

Tool usage guide

Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Category: Media
Input types: file, select, number
Output type: file
Sample coverage: 4
API ready: Yes

Overview

The Audio Caption Timing Shifter allows you to easily synchronize SRT or WebVTT subtitle files with your audio tracks. By analyzing the audio, the tool can automatically align the first subtitle cue to the first detected speech segment, or you can apply a precise manual offset in seconds to shift all cues forward or backward while preserving their original durations.

When to use

When your subtitle file is out of sync with the audio track by a constant delay or advance.
When you want to automatically align the start of your subtitles with the first spoken word in an audio recording.
When you need to convert and shift subtitle formats between SRT and WebVTT to match a specific media player requirement.

How it works

1Upload your audio file and the corresponding SRT or WebVTT caption file.
2Choose between 'Auto from first speech onset' to let the tool detect the start of speech, or 'Manual offset' to specify a custom shift in seconds.
3Select your desired output format (SRT or WebVTT) and run the shifter to download the adjusted caption file.

Use cases

Aligning a pre-written SRT script to a newly recorded podcast episode.
Correcting a constant 2.5-second delay in a WebVTT file for an online video lecture.
Converting an SRT file to WebVTT while simultaneously shifting the timing to match an edited audio track.

Examples

1. Aligning Podcast Subtitles Automatically

Podcast Producer

Background

A producer has a fully transcribed SRT file, but the audio recording has an intro silence that makes the subtitles start too early.

Problem

The subtitles need to be shifted forward to match the first spoken word without manually editing timestamps.

How to use

Upload the podcast MP3 file and the SRT caption file. Set the alignment mode to 'Auto from first speech onset' and select SRT as the output format.

alignmentMode: "auto", outputFormat: "srt"

Outcome

The tool detects the first speech onset in the audio and shifts all subtitle cues forward by that exact duration, perfectly aligning the text.

2. Manual Offset for Video Lecture Captions

E-learning Content Creator

Background

An instructor edited a video lecture, adding a 3.5-second intro card at the beginning, which pushed the audio track forward.

Problem

The existing WebVTT captions are now exactly 3.5 seconds ahead of the audio.

How to use

Upload the lecture audio and the WebVTT file. Select 'Manual offset' mode, set the manual offset to 3.5 seconds, and choose WebVTT as the output format.

FAQ

Does this tool transcribe my audio file?

No, it does not transcribe audio or generate new text; it only shifts the timing of your existing caption file.

Can it fix subtitles that drift out of sync over time?

No, it applies a single, uniform time offset to all cues and does not correct progressive drift.

What audio formats are supported?

It supports standard audio files, which are analyzed to detect the initial speech onset.

Can I shift subtitles backward?

Yes, you can enter a negative value in the manual offset field to shift the captions earlier.

Does shifting change the duration of individual subtitles?

No, the duration of each subtitle cue remains exactly the same; only the start and end timestamps are shifted.

alignmentMode: "manual", manualOffsetSeconds: 3.5, outputFormat: "vtt"

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Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Overview

When to use

How it works

Use cases

Examples

1. Aligning Podcast Subtitles Automatically

2. Manual Offset for Video Lecture Captions

FAQ

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