Molmo2 Video Captioner
Playground
Try it on WavespeedAI!Molmo2-4B Video Captioner: Generate detailed, accurate captions for videos with customizable detail levels (low, medium, high). Open-source vision-language model with temporal understanding capabilities. Ready-to-use REST API, no cold starts, duration-based pricing.
Features
Molmo2 Video Captioner
Molmo2 Video Captioner is an intelligent video understanding model that generates detailed captions and descriptions for video content. Upload a video and receive natural-language descriptions of scenes, actions, objects, and events — with adjustable detail levels to match your workflow needs.
Perfect for content creators, accessibility teams, and developers building video understanding pipelines.
Why Choose This?
-
Adjustable detail levels Choose from low, medium, or high detail to control caption depth — from quick summaries to comprehensive scene breakdowns.
-
Scene-aware captioning Understands context, actions, objects, environments, and temporal flow to produce coherent, meaningful descriptions.
-
Flexible video input Accepts video uploads or public URLs for seamless integration into existing workflows.
-
Fast processing Optimized for quick turnaround while maintaining caption accuracy and coherence.
-
Production-ready API Ready-to-use REST endpoint with predictable per-second pricing and no cold starts.
Parameters
| Parameter | Required | Description |
|---|---|---|
| video | Yes | Input video (upload or public URL) |
| detail_level | No | Caption detail: low, medium (default), or high |
Detail Level Options
- Low — Brief, high-level summary of the video content
- Medium — Balanced description with key scenes and actions (default)
- High — Comprehensive breakdown with fine-grained details
How to Use
- Upload your video — drag and drop a file or paste a public video URL.
- Select detail level — choose low, medium, or high based on your needs.
- Submit — the model processes the video and returns a caption.
- Use the output — integrate captions into your content, accessibility tools, or data pipelines.
Pricing
Per-5-second billing with a 5-second minimum.
| Video Duration | Cost |
|---|---|
| Up to 5s | $0.005 |
| 10s | $0.01 |
| 30s | $0.03 |
| 60s | $0.06 |
| 120s (max) | $0.12 |
Billing Rules
- Minimum charge: 5 seconds ($0.005)
- Rate: $0.001 per second ($0.005 per 5 seconds)
- Maximum video length: 120 seconds (2 minutes)
Best Use Cases
- Accessibility — Generate video descriptions for visually impaired users and screen readers.
- Content indexing — Create searchable metadata for video libraries and archives.
- Social media — Auto-generate captions for posts, reels, and stories.
- Video SEO — Improve discoverability with rich text descriptions for video content.
- Surveillance and monitoring — Summarize footage for quick review and logging.
- Education — Describe instructional videos for enhanced learning materials.
Notes
- If using a URL, ensure it is publicly accessible. A preview thumbnail in the interface confirms successful access.
- For videos longer than 2 minutes, split into segments and process separately.
- Clear, well-lit footage yields the most accurate captions.
- Use high detail level for complex scenes; low detail for quick overviews.
Authentication
For authentication details, please refer to the Authentication Guide.
API Endpoints
Submit Task & Query Result
# Submit the task
curl --location --request POST "https://api.wavespeed.ai/api/v3/wavespeed-ai/molmo2/video-captioner" \
--header "Content-Type: application/json" \
--header "Authorization: Bearer ${WAVESPEED_API_KEY}" \
--data-raw '{
"detail_level": "medium"
}'
# Get the result
curl --location --request GET "https://api.wavespeed.ai/api/v3/predictions/${requestId}/result" \
--header "Authorization: Bearer ${WAVESPEED_API_KEY}"
Parameters
Task Submission Parameters
Request Parameters
| Parameter | Type | Required | Default | Range | Description |
|---|---|---|---|---|---|
| video | string | Yes | - | Input video URL for captioning. Supports common video formats (MP4, MOV, WebM). Maximum 2 minutes. | |
| detail_level | string | No | medium | low, medium, high | Level of detail in the generated caption. Low: brief summary. Medium: balanced description. High: comprehensive, detailed analysis with temporal dynamics. |
Response Parameters
| Parameter | Type | Description |
|---|---|---|
| code | integer | HTTP status code (e.g., 200 for success) |
| message | string | Status message (e.g., “success”) |
| data.id | string | Unique identifier for the prediction, Task Id |
| data.model | string | Model ID used for the prediction |
| data.outputs | array | Array of URLs to the generated content (empty when status is not completed) |
| data.urls | object | Object containing related API endpoints |
| data.urls.get | string | URL to retrieve the prediction result |
| data.has_nsfw_contents | array | Array of boolean values indicating NSFW detection for each output |
| data.status | string | Status of the task: created, processing, completed, or failed |
| data.created_at | string | ISO timestamp of when the request was created (e.g., “2023-04-01T12:34:56.789Z”) |
| data.error | string | Error message (empty if no error occurred) |
| data.timings | object | Object containing timing details |
| data.timings.inference | integer | Inference time in milliseconds |
Result Request Parameters
| Parameter | Type | Required | Default | Description |
|---|---|---|---|---|
| id | string | Yes | - | Task ID |
Result Response Parameters
| Parameter | Type | Description |
|---|---|---|
| code | integer | HTTP status code (e.g., 200 for success) |
| message | string | Status message (e.g., “success”) |
| data | object | The prediction data object containing all details |
| data.id | string | Unique identifier for the prediction, the ID of the prediction to get |
| data.model | string | Model ID used for the prediction |
| data.outputs | string | Array of URLs to the generated content (empty when status is not completed). |
| data.urls | object | Object containing related API endpoints |
| data.urls.get | string | URL to retrieve the prediction result |
| data.status | string | Status of the task: created, processing, completed, or failed |
| data.created_at | string | ISO timestamp of when the request was created (e.g., “2023-04-01T12:34:56.789Z”) |
| data.error | string | Error message (empty if no error occurred) |
| data.timings | object | Object containing timing details |
| data.timings.inference | integer | Inference time in milliseconds |