> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.reka.ai/vision/video-chat/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.reka.ai/_mcp/server.

# Video Chat

> Ask questions about one or more videos

> **Info**
>
> For chat over text, images and short videos, use the OpenAI-compatible [Chat Completions API](/chat/overview).

`POST /v2/chat` answers natural language questions about up to five of your videos at once. Answers draw on each video's transcript and captions, and can also look at the frames of a specific time range.

> **Info**
>
> To ask about a short clip without uploading it first, send the video inline with the [Chat Completions API with a video input](/chat/multimodal#video).

## Prerequisites

Every video in the request needs the `captions` [feature](/vision/video-features) to be `ready`. If it is not, the API returns an error listing the missing features. To prepare a video, call [Plan Features](/vision/video-features#plan-features) with `{"desired": ["captions"]}` and trigger what it returns.

## Ask a question

#### Bash

```bash
curl -X POST https://vision-agent.api.reka.ai/v2/chat \
  -H "X-Api-Key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "messages": [
      {"role": "user", "content": "What is happening in this video?"}
    ],
    "context": [
      {"video_id": "550e8400-e29b-41d4-a716-446655440000"}
    ]
  }'
```

#### Python

```python
import requests

BASE_URL = "https://vision-agent.api.reka.ai"
headers = {"X-Api-Key": REKA_API_KEY}

payload = {
    "messages": [
        {"role": "user", "content": "What is happening in this video?"}
    ],
    "context": [
        {"video_id": "550e8400-e29b-41d4-a716-446655440000"}
    ],
}
response = requests.post(f"{BASE_URL}/v2/chat", json=payload, headers=headers)
response.raise_for_status()
print(response.json()["response"])
```

### Response

```json
{
  "response": "A presenter walks through a slide deck, pausing on a bar chart of quarterly revenue.",
  "model": "MODEL_NAME"
}
```

* **`response`**: The answer to the question.
* **`model`**: The model that generated the answer.

## Request parameters

* **`messages`** (required): The conversation so far, 1 to 20 messages. Each message has a `role` (`user` or `assistant`) and a non-empty `content` string. The last message must be from the user.
* **`context`** (required): The videos to analyze, 1 to 5 entries. Each entry has:
  * **`video_id`** (required): The video to analyze.
  * **`start`** (optional): Start of a time range in seconds. Setting it turns on visual analysis, which extracts and looks at frames from that range. The video's upload must be complete.
  * **`end`** (optional): End of the time range in seconds. Defaults to `start` plus 10 seconds, clamped to the video's duration.

## Multi-turn conversations

Send earlier answers back as `assistant` messages to ask follow-up questions.

```bash
curl -X POST https://vision-agent.api.reka.ai/v2/chat \
  -H "X-Api-Key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "messages": [
      {"role": "user", "content": "What is happening in this video?"},
      {"role": "assistant", "content": "The video shows a person walking on the beach during sunset."},
      {"role": "user", "content": "What color is the car in the background?"}
    ],
    "context": [
      {"video_id": "550e8400-e29b-41d4-a716-446655440000"}
    ]
  }'
```

## Ask about a specific moment

Pair chat with [video search](/vision/video-search): take the `video_id`, `start`, and `end` of a search result and pass them as context, so the answer looks at the frames of that moment.

```python
search = requests.post(
    f"{BASE_URL}/v2/search",
    json={"query": "person unboxing a laptop", "page_limit": 3},
    headers=headers,
).json()

context = [
    {"video_id": r["video_id"], "start": r["start"], "end": r["end"]}
    for r in search["data"]
]

answer = requests.post(
    f"{BASE_URL}/v2/chat",
    json={
        "messages": [{"role": "user", "content": "Which laptop brand is being unboxed in each clip?"}],
        "context": context,
    },
    headers=headers,
).json()
print(answer["response"])
```

## Question examples

* **General**: "What is happening in this video?"
* **Specific**: "What color is the car in the video?"
* **Temporal**: "What happens at the beginning of the video?"
* **Comparative**: "How do the two product demos differ?"
* **Descriptive**: "Describe the setting and atmosphere."

## Error handling

* **Video not found**: Check that each `video_id` in `context` exists and belongs to you.
* **Video not ready**: Trigger the `captions` feature and wait for it to be `ready`.
* **Upload not complete**: Wait for the upload to finish before sending a `start` time.

> One OpenAI-compatible API for Reka models and a curated selection of open models.