Start the sound at a specific second
For example, start an MP3 at second 3 of your finished video, use second 1 of the audio as its starting point, and play it for 2 seconds. All times can be adjusted in the editor.
Add audio to video at the right second
Place an MP3 exactly where your edit needs it. Add music, a sound bite or your own recorded voice, then mix it with the original sound or replace one section.
- Up to 3 minutes
- 100 MB per video
- MP4 with a timed MP3 insert
0 s3 s6 s9 s12 s
Video
Selected footage
MP3
Audio at 3 s
Example timing. Add your own audio or text in the editor.
Self-made sample with synthetic audio and hand-written captions. Use a video with speech to try automatic transcription.
How to add an MP3 to a video
Load your video and MP3
Open the editor to upload a video, or begin with a public TikTok link. In Timed inserts, upload your MP3 or extract audio from the current video.
Set the insertion time
Enter the start second on the finished video, the starting point within the MP3 and the playback length. Choose Mix to keep the original sound, or Replace to mute it during that section.
Listen to the exported result
Export the creation pack and play the completed MP4 to check the timing and volume. Audio is mixed into the existing timeline; the video length stays the same.
Control what plays and when
Mix or replace the original soundtrack
Layer an MP3 over the existing audio, or replace only its selected time window. Adjust the inserted track from zero to twice its original volume and listen to the finished export.
Pair an audio insert with text
Add a caption on the same finished-video timeline, such as a short explanation during a voice recording. You can arrange up to five audio inserts in one edit.
Before you start
The current editor accepts videos up to 180 seconds and 100 MB. Cloud imports, AI processing and exports require sign-in. Portrait video exports use a 720 × 1280 canvas. Only upload material that can be public: the current demo uses a public asset bucket.
Frequently asked questions
Can I add audio at a specific time in the video?
Yes. Enter the insertion second in Timed inserts. These times refer to your finished video after cutting and joining sections, rather than the positions in the original source.
Can I replace the original audio for just a few seconds?
Yes. Choose Replace for the inserted MP3. The original audio is muted during that insert and remains audible outside its time window.
Which audio files can I upload?
The insert uploader currently accepts MP3 files up to 20 MB and 180 seconds. The inserted section must fit inside both the MP3 and the finished video.
Will the MP3 extend the video length?
No. The audio is mixed into the existing timeline. Its end must fit within the finished video, and it does not shift later footage or extend the duration.
Can I add a voiceover?
Yes, if you already have the recording as an MP3. Upload it, set its timing and choose mix or replace. This feature does not generate a voice recording from text.
