Add Audio to Video
「Add Audio to Video」は画像とデザインに使えるブラウザツールです。入力内容と結果は通常この端末内で処理され、登録は必要ありません。
LOCAL WEBM EXPORT
Give a video a new audio track
This browser renders the selected video frames with the selected audio, then records a new WebM video on your device. It does not relabel either source file.
Privacy: source files, rendering, recording, previewing, and downloading stay in this browser tab. Temporary file URLs are released when you clear the tool or leave the page.
使い方
使い方
- Choose a browser-decodable MP4, WebM, Ogg video, or MOV file, plus a browser-decodable audio file. Each source can be up to 50 MB.
- Review the source duration and estimated recording. The video duration defines the download; the replacement audio begins at the start and ends when either track ends.
- Create the WebM, preview the newly recorded video, and download it when the recording completes.
A real video recording, not a renamed file
This tool uses the browser’s Canvas, Web Audio, and MediaRecorder APIs to create a new video stream and audio stream, then records them into WebM. The download is a genuine video/audio container whose MIME type is checked before recording. It never changes a filename extension to simulate a conversion.
Defined local limits
Each source file is limited to 50 MB and 10 minutes. The video duration controls the result, and the tool records at up to 30 frames per second. To avoid excessive tab memory, source dimensions are capped at 3840 × 2160 and generated WebM output at 250 MB. Audio starts at 0:00 and ends when its file or the video ends.
Browser support and privacy
Export depends on a browser that can decode both inputs and record WebM with MediaRecorder. Current Chromium and Firefox browsers commonly support this path; a browser without a supported recorder will explain that it cannot export. Files stay in the current browser tab and are never uploaded by this tool.
よくある質問
あわせて知りたいこと
What video format will I download?
A real WebM video. The page checks the recorder MIME type before it enables export and names the download with a .webm extension.
What happens if my audio is shorter or longer than the video?
Both tracks start together. The output keeps the video duration; if the audio ends first, the rest of the video is silent. Audio after the video ends is not included.
Will every MP4, MOV, or audio file work?
No. The browser must be able to decode the source codecs, even when the file extension is accepted. A file that cannot be decoded is reported before recording.
Do my source files leave my device?
No. File decoding, canvas rendering, recording, previewing, and downloading occur in your current browser session only.