Sora 2, Runway Gen-4.5, and Veo 3.1 can all turn a brief into moving images. The harder question starts after the first clip: which model keeps the planned beats, preserves the subject, and gives you a usable sound track without making every correction a restart?
This comparison treats a storyboard as a production contract. It looks at shot direction, state carried between shots, native audio, and the cost of fixing a weak take. It is a capability and workflow comparison, not a controlled quality benchmark.
Quick answer: choose the handoff
Choose Sora 2 for migration work, synchronized dialogue and sound effects, or a test of shot blocks and character references. It is not a sensible greenfield default: the web and app experiences ended on April 26, 2026, and the API is scheduled to end on September 24, 2026.
Choose Runway Gen-4.5 for one carefully directed shot. It accepts text or image input, handles sequenced instructions and camera choreography, and exposes a clear 2 to 10 second, 720p contract. Plan audio separately because its current model documentation focuses on visual generation.
Choose Veo 3.1 when the story depends on synchronized sound, reference images, first and last frames, or shot extension. It is the strongest first test for an audio-visual scene that must remain editable after the opening take.
| Production need | First model to test | Why it fits | Main check |
|---|---|---|---|
| Existing Sora assets or an API migration | Sora 2 | Its video, audio, character, edit, and extension surfaces match an inherited workflow | Can the team replace the route before the sunset date? |
| One hero shot with exact camera and action direction | Runway Gen-4.5 | Detailed prompts cover camera choreography, timing, motion, and physical response | Does the take obey the main action without adding a second story? |
| Dialogue or sound-led narrative shots | Veo 3.1 | Native audio combines with reference images, first/last frames, and extension | Does the audio remain synchronized after the visual revision? |
| A sequence with recurring identity and location | Veo 3.1 or Sora 2 | References and shot context make state explicit | Which state survives with fewer manual repairs? |
The current status changes the comparison
The model names look like a normal three-way matchup, but their production contracts are not equal. Sora 2 is now a legacy model in the OpenAI API catalog. Runway Gen-4.5 is a current visual model. Veo 3.1 is a current video-and-audio model exposed through Google's creative and developer surfaces.
| Control surface | Sora 2 | Runway Gen-4.5 | Veo 3.1 |
|---|---|---|---|
| Current status | Legacy; first-party web and app access ended | Current web model | Current model for Flow and developer routes |
| Core input | Text and image; up to two character references in the API guide | Text and image | Text, image direction, references, first/last frames, and extensions depending on route |
| Native audio | Synchronized dialogue and sound effects | Not listed in the current Gen-4.5 model contract | Native synchronized audio and dialogue |
| Useful storyboard primitive | Shot blocks in a detailed prompt, then edit or extend | Precise camera and action language for a focused take | Ingredients, first/last frames, and Extend |
| Published output contract | 720p standard; Pro adds higher sizes; 4 to 20 seconds in the guide | 720p, 24 or 25 fps, 2 to 10 seconds | 16:9 or 9:16; 720p or 1080p on documented routes |
Do not compare Sora 2 with the other two as if all three were equal long-term bets. Use it for migration or capability analysis, then select a current route for new work.
Storyboard control: shot blocks versus reference states
The same storyboard can be represented three ways: Sora 2 as a structured prompt, Runway Gen-4.5 as shot direction, and Veo 3.1 as visual states connected by frames, references, and continuation.
Sora 2: write the beats as separate shot blocks. The current guide recommends framing, action, lighting, and timing. Multiple shots are valid, but each block should have one camera setup and one main action. A four-shot sequence is safer as four deliberate units than as one overloaded generation.
Runway Gen-4.5: direct the camera and the action. Its creation guide emphasizes sequenced instructions, camera choreography, timing, and atmospheric changes. That suits a pan, truck, orbit, reveal, or continuous shot with one dramatic beat. Keep the shot boundary visible so a failure has a clear repair.
Veo 3.1: pin the states that matter. Reference images hold characters, objects, and style; first and last frames define a transition; Extend carries action forward. This is closer to an edit decision list than a single prompt when a wide shot must become a close-up without losing the subject or location.
Narrative coherence: preserve state, not just style
Narrative coherence has four separate tests:
- Identity: the same face, wardrobe, prop, and silhouette remain recognizable.
- Space: the geography, screen direction, light source, and object placement stay plausible.
- Action: the next shot begins from the previous action instead of quietly resetting it.
- Sound: dialogue, ambience, and effects match the visible event and the edit point.
Sora 2 has a strong documented narrative idea: it can follow intricate instructions across multiple shots while persisting world state, and its extension endpoint uses the initial clip as context. The tradeoff is operational: the model is legacy, and the guide still favors concise shots and active iteration.
Runway Gen-4.5 fits coherence inside one take. Weight, momentum, liquids, hair, and material details benefit from specific action direction. For a multi-shot story, build the chain of approved frames and references yourself.
Veo 3.1 gives the sequence more explicit state controls. Ingredients can anchor the character and setting, first and last frames define a transition, and Extend continues from the final second. That makes it a practical first test when the story is built from visual anchors rather than long prose.
Use this audit after every generation. A take that preserves the face but breaks screen direction is not coherent; one that drops the line of dialogue is not ready for delivery.
Native audio changes the production test
Native audio changes what counts as a keeper. A silent visual take can pass a frame review and fail once dialogue, footsteps, or room tone are added.
| Audio requirement | Sora 2 | Runway Gen-4.5 | Veo 3.1 |
|---|---|---|---|
| Synchronized dialogue | Core documented capability | Add in a separate audio pass | Core documented capability |
| Sound effects and ambience | Generated with the scene | Separate from the model contract | Generated with the scene and available across key Flow features |
| Main risk | First-party availability and migration deadline | Audio drift between picture and post-production layers | Audio may still need repair after a visual extension or edit |
Veo 3.1 is the cleanest route when sound belongs to the shot itself. A character opening a metal door, saying one line, and stepping into a tunnel can be evaluated as one audio-visual event. Sora 2 can do the same for an inherited workflow; Runway remains useful when voice, music, or foley are already handled separately.
For a fair comparison, use the same audio brief in every route:
- one line of dialogue with a clear speaker;
- one physical sound tied to an on-screen action;
- one persistent ambience;
- no music unless music is part of the deliverable.
Judge sync at the edit point, not from an impressive still frame.
Run one storyboard brief through all three
Use a small sequence that exposes continuity without requiring a feature film:
Four-shot scene, one traveler and one yellow case.
Shot 1: wide shot, the traveler enters a rain-soaked station.
Shot 2: medium tracking shot, the traveler checks a paper ticket under a flickering light.
Shot 3: close-up, a train door opens and the traveler says, "Last train to North?"
Shot 4: wide hold, the train leaves and the empty platform keeps the same direction and rain.
Must hold: traveler identity, yellow case, station geography, screen direction, rain, and dialogue timing.
Reject: wardrobe changes, teleporting props, reversed movement, silent dialogue, and a new location.Adapt the same brief to each control surface:
- Give Sora 2 distinct shot blocks and short durations. Record the character reference, extension, and edit operation.
- Give Runway Gen-4.5 one shot at a time. Make the camera move, action, and physical consequence explicit, then carry the approved frame forward.
- Give Veo 3.1 a compact reference set, transition frames where needed, and audio direction for dialogue, ambience, and physical sound.
| Acceptance check | What to inspect | Failure cost |
|---|---|---|
| Beat order | Each shot starts and ends on the planned action | The editor rebuilds the sequence around accidental motion |
| Subject state | Face, wardrobe, prop, and scale remain stable | New references or manual compositing are required |
| Spatial state | Screen direction, geography, and light remain plausible | Continuity repair can cost more than another generation |
| Audio state | Dialogue, effects, and ambience land on the visible action | Re-recording or replacement audio breaks the original timing |
| Revision | One weak shot can change without losing approved shots | The entire sequence becomes disposable |
The useful result is not a score out of ten. It is the route that produces the smallest reliable handoff for this brief.
Revision cost is the real decision
The first pass is easy to show. The second pass reveals production value. Count five costs:
- Prompt cost: how many words or structural changes fix a missed beat?
- Reference cost: do you need a new image, character clip, or first frame to recover identity?
- Sequence cost: can you repair one shot, or must you regenerate the whole chain?
- Audio cost: is the sound still usable after a visual revision?
- Delivery cost: can the team repeat the keeper with the same settings and source assets?
Run the comparison in a shared workspace such as Seavid AI. Start with the same brief in text-to-video, move an approved frame into image-to-video, and use reference-to-video when identity or style is the bottleneck. The existing Runway Gen-4.5 vs Luma Ray3.2 vs Veo 3.1 comparison covers motion and physical realism; this article focuses on story state and sound.
Which one should you use?
There is no universal winner. Sora 2 is a migration reference with a hard availability boundary. Runway Gen-4.5 is the focused shot director. Veo 3.1 is the strongest first route when storyboard states and native sound must travel together.
FAQ
Is Sora 2 still a good choice for a new project?
Not as a long-term first choice. It remains useful for existing outputs or inherited workflows, but the first-party app is gone and the API has a published September 24, 2026 end date. Build a replacement path while testing it.
Which model generates native audio?
Sora 2 and Veo 3.1 have documented synchronized audio output. Gen-4.5's current contract is visual, so plan dialogue, ambience, and effects as a separate Runway pass.
How should I compare the three fairly?
Use one brief, one reference set, and one acceptance checklist. Record input shape, duration, resolution, audio setting, retries, failed state, and repair action. Compare the keeper and the next edit, not the prettiest first frame.