An ASS subtitle file holds timed caption lines and styling. Prepare the song, check the words, time each line against the recording, save the file and review the final render.
ASS, or Advanced SubStation Alpha, is a subtitle format that can store caption timing and styling. A lyric-video workflow can use an approved ASS file to place words over a song; the file itself is not an MP4.
A subtitle editor such as Aegisub can help you time lines against audio. The exact result depends on the file, fonts, settings and renderer, so review the exported video rather than assuming every styling effect will behave identically.
Prepare the final recording and approved words
Work from the mix you intend to release. Use a written lyric sheet as a reference, then listen through the recording and confirm changed lines, featured artists, names, ad-libs and repeated hooks.
A transcript or automatic timing suggestion is a draft. Correct the words first so you are not spending time synchronizing lyrics the singer did not actually perform.
Enter lines and set their timing
Open the audio in a subtitle editor and create lines that can be read comfortably while the vocal plays. Set each line’s start and end around the phrase, then listen to the transition into the next one. Aegisub documents both an audio timing view and a subtitle grid for editing lines.
Do not assume that every line has the same rhythm or duration. Review fast passages in shorter sections and check the full song again at normal speed. Word-by-word karaoke effects require additional timing and renderer support; they are not promised by this product guide.
Save an ASS file and inspect it
Save the subtitle project in ASS format. Reopen it in your editor, make sure it contains nonempty timed lyric lines, and check the opening, chorus, bridge and ending against the recording. Review the style and position using a representative video or image when your editor supports a preview.
For the current Lyric Video Forge browser renderer, the product page specifies a finished audio file under 25 MB and an approved ASS subtitle file under 2 MB. Keep the source and approved versions together; do not overwrite the artist’s lyric sheet with an unreviewed transcript.
Understand burned-in captions
Lyric Video Forge describes its output as an MP4 with ASS captions burned into the picture. Those visible words are part of the video image. If the lyric text or timing is wrong after export, correct the source captions and make a new render rather than expecting a viewer to edit the visible text.
Platforms can also provide separate caption tracks. For YouTube, review its supported caption formats and its instructions for uploading or editing a track; do not assume the rendered ASS styling will transfer to a separate platform caption file.
Check the actual MP4 before release
Play the full export with sound. Confirm the audio starts and ends cleanly, the first and final lyrics appear, captions do not cover important artwork and fast lines remain readable. Test playback on the device where you will review or publish it.
The current product record describes a 720p landscape MP4 and a still or plain-color background. Timing and transcription should be reviewed before rendering, and broader full-song and mobile testing remains pending in the product record.
- Finished audio and approved words
- Nonempty ASS file, under the stated limit
- Every section timed against the final recording
- Permissions for the song and optional artwork
- Full exported MP4 watched with sound
Frequently asked questions
What is an ASS file?
ASS is a subtitle file format that can contain timed caption lines and style information. It is not itself a finished video.
Does a lyric video need word-by-word highlighting?
No. A readable, timed line-level lyric video can be useful. Word-level highlighting requires extra timing and support from the renderer and is not part of the current self-service promise.
Can I upload the ASS file directly as YouTube captions?
Check YouTube’s current supported subtitle formats. A separate SRT or a YouTube caption track may be needed; keep it synchronized with the published video.
What if a lyric is wrong after rendering?
Edit and review the original caption file, then render a corrected video. Check the product’s current credit terms before another render.
About this guide
This guide was drafted with AI assistance for iLLCo AI. Product and third-party details were checked against the linked public sources on October 28, 2026. The tool comparison is based on provider descriptions, not an independent hands-on test.