Name: HeyGen Avatar IV Talking Avatar Video API
Brand: magicapi
SKU: api-magicapi-realistic-talking-avatar-videos-heygen-avatar-iv
Availability: InStock
Author: API Market

Shashank Agarwal

# 🗣️ Talking Avatar Video API - Text to Speaking Presenter (HeyGen Avatar IV)

## Overview
Avatar IV is HeyGen's avatar engine. Its developer describes it as creating realistic talking avatar videos from text: you choose an avatar and a voice, and the avatar speaks your script.

Send an `avatar_id`, a `voice_id` and the script as `input_text` (less than 5000 characters). Optional fields set the avatar style, voice speed and emotion, captions and the video size. Each request returns the URL of one MP4 video.

`avatar_id` and `voice_id` are HeyGen ids. The example on this page uses `Abigail_standing_office_front` and `KQkyHvsV1wdsvvqTolHK`, which work as shown. Other avatar and voice ids come from HeyGen's own catalog and are not listed on api.market.

## Features
- **Text to talking video**: the avatar speaks `input_text`, up to 5000 characters.
- **Avatar style**: `normal` (default), `closeUp` or `circle`.
- **Voice control**: `voice_speed` from 0.5 to 1.5 (default 1), and `voice_emotion` (`Excited`, `Friendly`, `Serious`, `Soothing`, `Broadcaster`, or `none`) when the selected voice supports it.
- **Captions**: set `caption` to `true` to enable captions in the video.
- **Video size**: `width` 100 to 3840 pixels (default 1920) and `height` 100 to 2160 pixels (default 1080).

## Use Cases
1. **Product walkthroughs**: a presenter that explains a feature or a pricing page from a written script.
2. **Onboarding and training**: turn written lessons or help articles into short presenter videos.
3. **Personalized messages**: generate one video per customer by changing the script for each request.
4. **Vertical social clips**: set `width` to 1080 and `height` to 1920 for a portrait video.

## Visual Examples
### Example Input
- **avatar_id**: `Abigail_standing_office_front`
- **voice_id**: `KQkyHvsV1wdsvvqTolHK`
- **input_text**: "Hi there! I'm your guide to api.market. Pick any AI model, grab a single API key, and start building in minutes."

All other fields were left at their defaults (`avatar_style` `normal`, `voice_speed` `1`, no emotion, no captions, 1920 x 1080).

### Example Output
[Watch the example output](https://blog.api.market/wp-content/uploads/2026/10/avatar-iv-output-api-market.mp4)

## Input Parameters
| Field | Type | Required | Default | Allowed values | Description |
| --- | --- | --- | --- | --- | --- |
| `avatar_id` | string | Yes |  |  | HeyGen avatar id. The example id `Abigail_standing_office_front` works; other ids come from HeyGen's avatar catalog, which is not listed on api.market. |
| `input_text` | string | Yes |  |  | Text that the avatar will speak. Must be less than 5000 characters. |
| `voice_id` | string | Yes |  |  | HeyGen voice id. The example id `KQkyHvsV1wdsvvqTolHK` works; other ids come from HeyGen's voice catalog, which is not listed on api.market. |
| `title` | string | No | `""` |  | Title of the video. |
| `avatar_style` | string | No | `normal` | `normal`, `closeUp`, `circle` | Visual style of the avatar. |
| `voice_speed` | number | No | `1` | 0.5 to 1.5 | Voice speed. Value ranges from 0.5 to 1.5. |
| `voice_emotion` | string | No | `none` | `none`, `Excited`, `Friendly`, `Serious`, `Soothing`, `Broadcaster` | Adds emotion to the voice, if supported by the selected voice. Set to `none` for no emotion. |
| `caption` | boolean | No | `false` |  | Whether to enable captions in the video. |
| `width` | integer | No | `1920` | 100 to 3840 | Width of the output video in pixels. |
| `height` | integer | No | `1080` | 100 to 2160 | Height of the output video in pixels. |

## Pricing
- **Pay As You Go (PAYG) pricing**: you only pay for what you use.
- **Price**: $0.094 per API unit.
- **1 API unit = 1 second of output video, rounded up per request.** There is no duration field: the length of the video follows the spoken script, so a longer `input_text` or a slower `voice_speed` makes a longer, more expensive video. The charge is based on the length of the output video.
- **Worked examples**: a 10 second video is 10 units = $0.94; a 30 second video is 30 units = $2.82; a 60 second video is 60 units = $5.64.
- Avatar style, captions, emotion and video size do not change the per-second price.
- **The example request above** (a 21-word script) returned a 9.12 second video, billed as 10 units = $0.94. The exact charge follows the length of the returned video.
- **Failed or cancelled predictions are not billed.**
- **GET requests to check prediction status** are free and don't count toward API unit usage.
- **No monthly subscription fee.**

## API Documentation

### Base URL
All API requests go to: `https://prod.api.market/api/v1/magicapi/realistic-talking-avatar-videos-heygen-avatar-iv`

### Authentication
Send your api.market API key in the `x-api-market-key` header:
```
x-api-market-key: YOUR_API_MARKET_KEY
```

### Asynchronous Processing
**IMPORTANT**: This API is asynchronous. The flow is:
1. Send a POST request to `/predictions`. A successful request returns **201 Created** with a prediction `id` and a `status` of `starting` or `processing`.
2. Poll GET `/predictions/{id}` with that ID.
3. Keep polling while `status` is `starting` or `processing`.
4. Stop when `status` is `succeeded` (read `output`), `failed` or `canceled` (read `error`).

Rendering a talking avatar video takes longer than an image. A polling interval of 5 seconds and an overall timeout of 1800 seconds (30 minutes) work well.

### Endpoints

#### Create a Prediction
```bash
curl -X POST "https://prod.api.market/api/v1/magicapi/realistic-talking-avatar-videos-heygen-avatar-iv/predictions" \
  -H "Content-Type: application/json" \
  -H "x-api-market-key: YOUR_API_MARKET_KEY" \
  -d '{
    "version": "47140d7dd37b83a583d0279e2875987b9be1dff97bf3e2a051cc2a78a68df6eb",
    "input": {
      "avatar_id": "Abigail_standing_office_front",
      "voice_id": "KQkyHvsV1wdsvvqTolHK",
      "input_text": "Hi there! I'\''m your guide to api.market. Pick any AI model, grab a single API key, and start building in minutes."
    }
  }'
```

Response (201 Created):
```json
{
  "id": "een7h2zhz1rmt0d17g2s1ppya8",
  "version": "47140d7dd37b83a583d0279e2875987b9be1dff97bf3e2a051cc2a78a68df6eb",
  "status": "starting",
  "created_at": "2026-10-14T20:06:25.149Z"
}
```

#### Check Prediction Status
```bash
curl -X GET "https://prod.api.market/api/v1/magicapi/realistic-talking-avatar-videos-heygen-avatar-iv/predictions/{id}" \
  -H "x-api-market-key: YOUR_API_MARKET_KEY"
```

Response when the prediction has finished (200 OK):
```json
{
  "id": "een7h2zhz1rmt0d17g2s1ppya8",
  "status": "succeeded",
  "output": "https://blog.api.market/wp-content/uploads/2026/10/avatar-iv-output-api-market.mp4",
  "error": null,
  "created_at": "2026-10-14T20:06:25.149Z",
  "started_at": "2026-10-14T20:06:26.149Z",
  "completed_at": "2026-10-14T20:08:25.149Z"
}
```

`output` is a single URL string pointing to the generated MP4 video.

### Status Codes
- **201 Created**: prediction created (POST `/predictions`). This is the normal success response.
- **200 OK**: prediction details returned (GET `/predictions/{id}`).
- **400 Bad Request**: invalid input, for example a missing `avatar_id`, `voice_id` or `input_text`, or a `voice_speed` outside 0.5 to 1.5.
- **401 Unauthorized**: missing or invalid API key.
- **404 Not Found**: no prediction with that ID.
- **429 Too Many Requests**: rate limit exceeded.
- **500 Internal Server Error** or **503 Service Unavailable**: temporary server problem; retry later.

## Rate Limits

All plans allow 10 requests per second. Requests above that return `429 Too Many Requests`; back off before retrying and honour any `Retry-After` header. Polling a prediction with GET is free but still counts toward the per-second limit, so poll every 1 to 5 seconds rather than in a tight loop.

## Error Handling
- Check the HTTP status code of every request and read the response body for the error message.
- A prediction can also end with `status` set to `failed`; the `error` field then explains why. Failed predictions are not billed.
- An `avatar_id` or `voice_id` that HeyGen does not recognize can make the prediction end as `failed`. Check the id and try again.
- Retry 429, 500 and 503 responses with exponential backoff. Fix the input before retrying a 400.

## Implementation Guide
### Example Code

#### JavaScript
```javascript
const apiKey = "YOUR_API_MARKET_KEY";
const baseUrl = "https://prod.api.market/api/v1/magicapi/realistic-talking-avatar-videos-heygen-avatar-iv";

async function createAndWaitForPrediction(input) {
  const response = await fetch(`${baseUrl}/predictions`, {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
      "x-api-market-key": apiKey
    },
    body: JSON.stringify({ version: "47140d7dd37b83a583d0279e2875987b9be1dff97bf3e2a051cc2a78a68df6eb", input })
  });

  if (response.status !== 201) {
    throw new Error(`API error: ${response.status} ${await response.text()}`);
  }

  const prediction = await response.json();
  return pollForResults(prediction.id);
}

const delay = (ms) => new Promise((resolve) => setTimeout(resolve, ms));

async function pollForResults(predictionId) {
  const maxTimeout = 1800000;
  const pollInterval = 5000;
  const startTime = Date.now();

  while (Date.now() - startTime < maxTimeout) {
    const response = await fetch(`${baseUrl}/predictions/${predictionId}`, {
      headers: { "x-api-market-key": apiKey }
    });

    if (!response.ok) {
      throw new Error(`API error: ${response.status} ${await response.text()}`);
    }

    const prediction = await response.json();

    if (prediction.status === "succeeded") {
      return prediction.output;
    }

    if (prediction.status === "failed" || prediction.status === "canceled") {
      throw new Error(`Prediction ${prediction.status}: ${prediction.error || "Unknown error"}`);
    }

    await delay(pollInterval);
  }

  throw new Error("Prediction timed out after 30 minutes");
}

createAndWaitForPrediction({
  "avatar_id": "Abigail_standing_office_front",
  "voice_id": "KQkyHvsV1wdsvvqTolHK",
  "input_text": "Hi there! I'm your guide to api.market. Pick any AI model, grab a single API key, and start building in minutes."
}).then((output) => console.log(output));
```

#### Python
```python
import time
import requests

API_KEY = "YOUR_API_MARKET_KEY"
BASE_URL = "https://prod.api.market/api/v1/magicapi/realistic-talking-avatar-videos-heygen-avatar-iv"

def create_and_wait_for_prediction(input_data):
    headers = {"Content-Type": "application/json", "x-api-market-key": API_KEY}
    response = requests.post(
        f"{BASE_URL}/predictions",
        headers=headers,
        json={"version": "47140d7dd37b83a583d0279e2875987b9be1dff97bf3e2a051cc2a78a68df6eb", "input": input_data},
    )

    if response.status_code != 201:
        raise Exception(f"API error: {response.status_code} {response.text}")

    return poll_for_results(response.json()["id"])

def poll_for_results(prediction_id):
    max_timeout = 1800
    poll_interval = 5
    headers = {"x-api-market-key": API_KEY}
    start_time = time.time()

    while time.time() - start_time < max_timeout:
        response = requests.get(f"{BASE_URL}/predictions/{prediction_id}", headers=headers)

        if response.status_code != 200:
            raise Exception(f"API error: {response.status_code} {response.text}")

        prediction = response.json()

        if prediction["status"] == "succeeded":
            return prediction["output"]

        if prediction["status"] in ("failed", "canceled"):
            raise Exception(f"Prediction {prediction['status']}: {prediction.get('error') or 'Unknown error'}")

        time.sleep(poll_interval)

    raise Exception("Prediction timed out after 30 minutes")

print(create_and_wait_for_prediction({
  "avatar_id": "Abigail_standing_office_front",
  "voice_id": "KQkyHvsV1wdsvvqTolHK",
  "input_text": "Hi there! I'm your guide to api.market. Pick any AI model, grab a single API key, and start building in minutes."
}))
```

## FAQ
- **Where do I get avatar and voice ids?**
  - The ids in the example (`Abigail_standing_office_front` and `KQkyHvsV1wdsvvqTolHK`) work as shown. Other ids come from HeyGen's avatar and voice catalog, which is not listed on api.market.
- **How long will my video be, and what will it cost?**
  - The length follows your script and `voice_speed`. You pay $0.094 per second of the returned video, rounded up per request. A script of about 20 words gives a video of roughly 9 seconds.
- **Can I make a vertical video?**
  - Yes. Set `width` to 1080 and `height` to 1920. Width can be 100 to 3840 pixels and height 100 to 2160 pixels.
- **Does `voice_emotion` work with every voice?**
  - No. It adds emotion only when the selected voice supports it. Leave it at `none` for no emotion.
- **Is the 201 response from POST an error?**
  - No. 201 Created means the prediction was accepted. Use the returned `id` to poll GET `/predictions/{id}` until `status` is `succeeded`, `failed` or `canceled`.
- **What if my prediction fails?**
  - Failed predictions are not billed. Read the `error` field, check the avatar and voice ids, and try again.

## Contact Us

If you have any questions or need assistance, you can reach out to us through the embedded chat on the bottom right corner of the page or send an email to hello@magicapi.com.


Create talking avatar videos from text with HeyGen Avatar IV: pick an avatar and a voice, send a script, get an MP4. $0.094 per second of video, pay as you go.