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POST
cURL
Use gen4.5 to generate a video from a text prompt. Send your CometAPI API key with Bearer authentication and a JSON request body.

Prepare the request

  • Set model to gen4.5.
  • Describe the scene and motion in promptText, using 1 to 1,000 UTF-16 code units.
  • Set ratio to 1280:720 for landscape or 720:1280 for portrait.
  • Set duration to a whole number from 2 through 10 seconds.
All four fields are required. To start from an image, use Create a Runway image-to-video task. Do not include promptImage or an audio toggle in this text-to-video request.

Set optional controls

For an explicit sampling seed, use 1 through 4294967295. Omission or 0 selects a random seed. If you include contentModeration, set its publicFigureThreshold to auto or low; otherwise omit the object. Use outputFormat to select MP4, ProRes, PNG sequences, or one of the HDR formats listed in the request schema. Omit it for H.264 MP4. You can set proresProfile only when outputFormat is prores or hdr_prores. The HDR ProRes format accepts 422, 422 HQ, or 4444.

Retrieve the result

Save the returned id and use Get a Runway task. When status is SUCCEEDED, read the video URLs in output.

Authorizations

Authorization
string
header
required

Use your CometAPI API key.

Body

application/json

Request parameters for gen4.5.

model
enum<string>
required

Model ID for this request variant.

Available options:
gen4.5
Allowed value: "gen4.5"
promptText
string
required

Describe the requested scene or motion in 1 to 1,000 UTF-16 code units.

Required string length: 1 - 1000
ratio
enum<string>
required

Requested output dimensions, expressed as width:height. Choose a value listed for this model and endpoint.

Available options:
1280:720,
720:1280
duration
integer
required

Requested video duration in whole seconds, from 2 through 10.

Required range: 2 <= x <= 10
seed
integer

Optional sampling seed. Use a positive integer for an explicit seed. Omission or 0 selects a random seed.

Required range: 0 <= x <= 4294967295
contentModeration
object

Optional content moderation settings. Omit the object to use standard moderation.

outputFormat
enum<string>

Output encoding. Omit for mp4 (H.264). prores returns MOV; png_sequence returns a PNG ZIP; sdr_rec709_10bit returns 10-bit Rec.709 HEVC. hdr10 and hlg return 10-bit HDR MP4; hdr_pq_12bit_master returns 12-bit HEVC MOV; hdr_prores returns HDR ProRes MOV. The HDR PNG/EXR sequence formats return ZIP archives; the ACEScg variants target the named ACES version.

Available options:
mp4,
prores,
png_sequence,
hdr10,
hlg,
sdr_rec709_10bit,
hdr_pq_12bit_master,
hdr_prores,
hdr_png_sequence,
hdr_exr_sequence,
hdr_exr_acescg_sequence_1_3,
hdr_exr_acescg_sequence_2_0
proresProfile
enum<string>

Profile for outputFormat prores or hdr_prores. Omit for 4444 with prores, or 422 HQ with hdr_prores. hdr_prores accepts only 422, 422 HQ, or 4444. Omit this field for other formats.

Available options:
422,
4444,
422 Proxy,
422 LT,
422 HQ,
4444 XQ

Response

Task submitted. Save its id to retrieve task status.

id
string
required

Task ID for GET /runwayml/v1/tasks/{id}.

status
string

Task state, when returned.

createdAt
string<date-time>

Task submission timestamp, when returned.

output
string<uri>[]

Result URLs, when returned.

failure
string

Failure explanation, when returned.

failureCode
string

Machine-readable failure code, when returned.

estimatedCost
object

Task estimate metadata, when returned.

cost
object

Task cost metadata, when returned.

Last modified on September 21, 2026