An AI clip that comes back shorter than you wanted almost always has one of five causes: the model does not offer the length you had in mind, the tool fell back to its 5-second default, an audio track decided the length, an edit mode followed the length of your input clip, or a lip sync model followed your audio. Each has a specific fix, and none of them is a bug.
TL;DR
- Check the model's length options. Veo 3.1 only makes 4, 6 or 8 seconds; the older Kling models only 5 or 10
- 5 seconds is the default almost everywhere. If you did not set a length, that is what you get
- Your audio can set the length. On Pruna p-video the clip follows your track; on Creatify Boreal the length setting cuts your track
- Edit modes follow the input clip. Gemini Omni Flash's video edit returns the length of the clip you gave it, up to 10 seconds
- For more than 30 seconds, stitch or extend. No model on 8frame generates longer in one pass
1. The model does not make that length
Every model has its own set of lengths, and the picker only offers those:
| Model on 8frame | Lengths |
|---|---|
| Wan 3.0, Wan 3.0 Prime | 2 to 30 s |
| Seedance 2.5 | 4 to 30 s |
| Pruna p-video, p-video Draft, Creatify Boreal | 1 to 20 s |
| Kling v3, Kling O3, Happy Horse | 3 to 15 s |
| Hailuo H3, Pruna p-video 2 Pro | 5 to 15 s |
| Gemini Omni Flash | 3 to 10 s |
| Kling 2.6 Pro and older Kling | 5 or 10 s |
| Veo 3.1, Fast, Lite | 4, 6 or 8 s |
If you need 12 seconds and picked Veo 3.1, the longest you can get is 8. The full list, with prices at each length, is in AI video clip length limits by model.
Fix: pick a model whose range covers the length, or plan the shot as two clips.
2. The default is 5 seconds
Most video tools on 8frame start at 5 seconds. Change the length before you generate; a clip already made cannot be lengthened by changing the setting afterwards.
Fix: set the length on the node first. Longer clips cost proportionally more on per-second models, so check the price shown before you run it.
3. An audio track set the length
Two models treat a track you attach in opposite ways:
- Pruna p-video follows the track. Per the provider's schema, the length setting is "ignored when audio is provided", so a 12-second voiceover gives you about 12 seconds, up to 20. 8frame bills the track's length and refuses a longer track before charging.
- Creatify Boreal follows the length setting, not the track. Per the provider's documentation, "the first
durationseconds of the audio are used; shorter audio is padded with silence." With the default of 5 seconds, a 12-second voiceover is cut to its first 5.
Fix: on Boreal, set the length to your track (up to 20 seconds). On p-video, trim the track to the length you want before you attach it. More detail in how to use Creatify Boreal and how to use Pruna p-video.
4. An edit mode followed your input clip
When you edit a video rather than generate one, the output usually tracks the input. Gemini Omni Flash's video edit mode has no length setting: it returns the length of the clip you gave it, and it works in a 3 to 10 second window, refusing longer input rather than trimming it.
Fix: cut the input clip to the length you want before editing it, and keep it within the model's window.
5. A lip sync model followed your audio
Lip sync tools take their length from the audio, not a setting. Pruna Avatar renders the length of your audio, rounded up to the second, up to 35 seconds. Hailuo H3's lip sync mode clips the audio at about 15 seconds. Prices for each are in AI lip sync price by model.
Fix: check the model's maximum before recording the voiceover, and split longer reads into segments.
When you need longer than any model allows
Nothing on 8frame generates more than 30 seconds in one pass. Past that you stitch clips (cheap and controllable, with a join to hide at each cut) or extend turn by turn where a model supports it; Google documents Gemini Omni extension to 40 seconds in total across turns. The trade-offs are in best AI video generator for long clips.
FAQ
Why did my AI video come out at 5 seconds? 5 seconds is the default length on most video tools. Set the length before generating, within the model's range.
Why was my voiceover cut off? On Creatify Boreal, the length setting decides how much of the audio is used, and it defaults to 5 seconds. Raise it to the length of your track.
Can I make an 8-second Veo clip longer? Not in one generation: Veo 3.1 stops at 8 seconds. Generate a second clip and join them, or use a model with a longer range.
What is the longest AI video I can make in one go? 30 seconds, on Wan 3.0 or Seedance 2.5.
Sources
- Length options, defaults and audio-length billing per model: 8frame tool registry and tool configuration, read 2026-09-30
- Pruna p-video audio rule: the input schema of prunaai/p-video, checked 2026-09-30
- Creatify Boreal audio rule: fal.ai/models/creatify/boreal/api, checked 2026-09-30
- Gemini Omni extension to 40 seconds: ai.google.dev/gemini-api/docs/omni, checked 2026-09-30
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