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Creative formats in AdCP use standardized asset types with well-defined properties. This ensures consistency across formats and makes it easier for buyers to understand requirements.

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Important: Payload vs Requirements

This document describes format requirements (constraints and specifications defined in format specs). For payload schemas (the structure of actual asset data you send in creative manifests), see:
  • Asset Type Registry - Links to all payload schemas
  • Core Asset Schemas at /schemas/v2/core/assets/ - Individual asset payload definitions
Key distinction:
  • Format requirements (this doc): max_file_size_mb, required: true/false, acceptable_formats, duration constraints
  • Payload schemas (schemas): url, width, height, content, duration_ms, format
Asset requirements belong in the format specification’s requirements field. Asset payloads use the core schemas.

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Asset Type Schema

The official JSON schema for asset types is available at:

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Core Asset Types

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Video Asset

Video assets represent video files with specific technical requirements. 
{
  "asset_type": "video",
  "required": true,
  "duration_seconds": 15,
  "acceptable_formats": ["mp4"],
  "acceptable_codecs": ["h264"],
  "acceptable_resolutions": ["1920x1080", "1280x720"],
  "aspect_ratio": "16:9",
  "max_file_size_mb": 30,
  "min_bitrate_mbps": 8,
  "max_bitrate_mbps": 10
}
Properties:
  • duration_seconds: Expected video duration
  • min_duration_seconds / max_duration_seconds: Duration range (if flexible)
  • acceptable_formats: Container formats (mp4, webm, mov)
  • acceptable_codecs: Video codecs (h264, h265, vp8, vp9, av1)
  • acceptable_resolutions: List of width x height strings
  • aspect_ratio: Required aspect ratio (16:9, 9:16, 1:1, etc.)
  • max_file_size_mb: Maximum file size in megabytes
  • min_bitrate_mbps / max_bitrate_mbps: Bitrate range in Mbps
  • features: Additional requirements (e.g., [“non-skippable”, “sound on”])

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Image Asset

Static image assets for banners, logos, and visual content. 
{
  "asset_type": "image",
  "required": true,
  "width": 300,
  "height": 250,
  "acceptable_formats": ["jpg", "png", "gif"],
  "max_file_size_kb": 200,
  "animation_allowed": true
}
Properties:
  • width / height: Dimensions in pixels
  • min_width / min_height: Minimum dimensions (px; typically used by responsive/sizeless formats)
  • aspect_ratio: Required aspect ratio
  • acceptable_formats: Image formats (jpg, png, gif, webp, svg)
  • max_file_size_kb: Maximum file size in kilobytes
  • transparency: Whether transparency is required/supported
  • animation_allowed: Whether animated GIFs are accepted
  • notes: Additional requirements (e.g., “Must be free of text”)
Use Cases:
  • Fixed layout: provide width and height. Do not include min_width, min_height, or aspect_ratio.
  • Responsive (fixed image aspect ratio): provide min_width, min_height and aspect_ratio. Do not include width or height.
  • Responsive (any image aspect ratio): provide min_width and min_height only. Do not include width, height, or aspect_ratio.
Note: In fixed layouts, the image slot is an exact pixel box, so specify width and height. In responsive layouts, the renderer will resize the image; use min_width/min_height to ensure there are enough pixels for a sharp result after scaling. Use aspect_ratio only when the image asset itself must be a specific shape (e.g., 16:9); omit it if any image aspect ratio is acceptable

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Text Asset

Text content for headlines, descriptions, CTAs, etc. 
{
  "asset_type": "text",
  "required": true,
  "text_type": "headline",
  "max_length": 90,
  "min_length": 10
}
Properties:
  • text_type: Specific type (title, headline, description, body, cta, advertiser_name, disclaimer)
  • max_length: Maximum character count
  • min_length: Minimum character count
  • default: Default value if not provided
  • allowed_characters: Regex pattern for validation
  • format: Expected format (plain, currency, percentage)

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URL Asset

Links for clickthroughs, tracking, and landing pages. 
{
  "asset_type": "url",
  "required": true,
  "url_type": "clickthrough",
  "must_be_https": true,
  "tracking_macros_supported": true
}
Properties:
  • url_type: The purpose of the URL (used only in format requirements):
    • clickthrough - User clicks this URL (may redirect through ad tech platforms before reaching destination)
    • impression_tracker - Fires in background (returns 1x1 pixel, JavaScript snippet, or 204 No Content)
    • video_tracker - Video ad tracking URL (for VAST, video events, etc.)
    • landing_page - Landing page URL
  • must_be_https: Whether HTTPS is required
  • allowed_domains: List of allowed domains (if restricted)
  • tracking_macros_supported: Whether URL macros are supported
Note: The url_type field is only used in format requirements to specify how the URL will be used. When providing URLs in creative manifests, you only need to supply the url value - the asset_id already indicates the semantic purpose (e.g., impression_tracker, video_start_tracker, landing_url).

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Audio Asset

Audio files for audio ads and podcasts. 
{
  "asset_type": "audio",
  "required": true,
  "duration_seconds": 30,
  "acceptable_formats": ["mp3", "m4a"],
  "min_bitrate_kbps": 128,
  "max_file_size_mb": 5
}
Properties:
  • duration_seconds: Expected duration
  • acceptable_formats: Audio formats (mp3, m4a, aac, ogg)
  • min_bitrate_kbps: Minimum bitrate in kilobits per second
  • max_file_size_mb: Maximum file size in megabytes
  • stereo_required: Whether stereo audio is required

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HTML Asset

HTML5 creative assets for rich media formats and third-party display tags. 
{
  "asset_type": "html",
  "required": true,
  "format": "html5",
  "max_initial_load_kb": 200,
  "max_total_size_kb": 500,
  "restricted_features": ["document.write", "eval"]
}
Properties:
  • content: Inline HTML content
  • url: URL to externally hosted HTML file (alternative to inline content)
  • format: HTML format type (html5, amphtml)
  • max_initial_load_kb: Maximum initial load size
  • max_total_size_kb: Maximum total size including all assets
  • allowed_features: Allowed HTML5 features
  • restricted_features: Features that must not be used

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VAST Asset

VAST (Video Ad Serving Template) tags for third-party video ad serving. URL Delivery: 
{
  "asset_type": "vast",
  "required": true,
  "delivery_type": "url",
  "url": "https://vast.example.com/video/123",
  "vast_version": "4.1",
  "vpaid_enabled": false
}
Inline Delivery: 
{
  "asset_type": "vast",
  "required": true,
  "delivery_type": "inline",
  "content": "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<VAST version=\"4.2\">...</VAST>",
  "vast_version": "4.2",
  "vpaid_enabled": false
}
Properties:
  • delivery_type: “url” or “inline” (required discriminator)
  • url: URL endpoint that returns VAST XML (required when delivery_type is “url”)
  • content: Inline VAST XML content (required when delivery_type is “inline”)
  • vast_version: VAST specification version (2.0, 3.0, 4.0, 4.1, 4.2)
  • vpaid_enabled: Whether VPAID (Video Player-Ad Interface Definition) is supported
  • max_wrapper_depth: Maximum allowed wrapper/redirect depth
  • duration_ms: Expected video duration in milliseconds (if known)
  • tracking_events: Array of supported tracking events
Use Cases:
  • Third-party video ad servers
  • Programmatic video buying
  • Video ad networks
  • VPAID interactive video ads

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DAAST Asset

DAAST (Digital Audio Ad Serving Template) tags for third-party audio ad serving. URL Delivery: 
{
  "asset_type": "daast",
  "required": true,
  "delivery_type": "url",
  "url": "https://daast.example.com/audio/456",
  "daast_version": "1.0"
}
Inline Delivery: 
{
  "asset_type": "daast",
  "required": true,
  "delivery_type": "inline",
  "content": "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<DAAST version=\"1.0\">...</DAAST>",
  "daast_version": "1.0"
}
Properties:
  • delivery_type: “url” or “inline” (required discriminator)
  • url: URL endpoint that returns DAAST XML (required when delivery_type is “url”)
  • content: Inline DAAST XML content (required when delivery_type is “inline”)
  • daast_version: DAAST specification version (1.0, 1.1)
  • duration_ms: Expected audio duration in milliseconds (if known)
  • tracking_events: Array of supported tracking events
  • companion_ads: Whether companion display ads are included
Use Cases:
  • Third-party audio ad servers
  • Podcast advertising networks
  • Streaming audio platforms
  • Radio-style digital audio ads

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Common Properties

All asset types share these common properties:
  • asset_id: Unique identifier for this asset within the format (e.g., “hero_image”, “video_file”, “headline”)
  • asset_type: The type of asset (image, video, audio, text, html, css, javascript, vast, daast, url, promoted_offerings)
  • asset_role: Semantic purpose of the asset (e.g., “hero_video”, “logo”, “cta_button”)
  • required: Boolean indicating if the asset is mandatory

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Asset ID vs Asset Role

asset_id: A unique identifier for this asset within the format specification. Used as the key when constructing manifests. asset_role: Describes the semantic purpose or function of the asset in the creative. Helps buyers, AI systems, and publishers understand what the asset is for. Example: 
{
  "asset_id": "main_video",
  "asset_type": "video",
  "asset_role": "hero_video",
  "required": true
}
In this example:
  • asset_id = “main_video” (the unique identifier for manifests)
  • asset_role = “hero_video” (indicates this is the primary video content)
Common asset roles:
  • hero_image / hero_video - Primary visual content
  • logo - Brand logo
  • headline - Main headline text
  • description - Body copy or description text
  • cta_button - Call-to-action button
  • background_image - Background visual
  • thumbnail - Preview image
  • companion_banner - Secondary display ad
Asset roles enable AI systems to generate appropriate content and help publishers understand how to render each asset in the creative.

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Asset ID Usage

The asset_id field is crucial for orchestrators and creative management systems. It provides a stable identifier for mapping uploaded assets to their correct positions in the creative format.

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Example: Uploading Assets

When submitting creative assets, the orchestrator uses asset_id to map files: 
{
  "format_id": {
    "agent_url": "https://creative.adcontextprotocol.org",
    "id": "foundational_immersive_canvas"
  },
  "assets": {
    "hero_image": "https://cdn.example.com/campaign123/hero.jpg",
    "brand_logo": "https://cdn.example.com/brand/logo.png",
    "headline": "Discover Our New Collection",
    "description": "Experience premium quality with our latest products",
    "video_content": "https://cdn.example.com/campaign123/video.mp4"
  }
}
The keys in the assets object correspond to the asset_id values defined in the format.

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Usage in Creative Formats

Creative formats specify their assets using the assets array. Each asset has a required boolean:
  • required: true - Asset MUST be provided for a valid creative
  • required: false - Asset is optional, enhances the creative (e.g., companion banners, third-party tracking pixels)
{
  "format_id": {
    "agent_url": "https://creative.adcontextprotocol.org",
    "id": "video_15s_hosted"
  },
  "assets": [
    {
      "item_type": "individual",
      "asset_id": "video_file",
      "asset_type": "video",
      "required": true,
      "requirements": {
        "duration_seconds": 15,
        "acceptable_formats": ["mp4"],
        "acceptable_codecs": ["h264"],
        "acceptable_resolutions": ["1920x1080", "1280x720"],
        "max_file_size_mb": 30
      }
    },
    {
      "item_type": "individual",
      "asset_id": "impression_tracker",
      "asset_type": "url",
      "required": false,
      "requirements": {
        "format": ["url"],
        "description": "Third-party impression tracking pixel URL"
      }
    }
  ],

  // DEPRECATED: Use "assets" above instead. Kept for backward compatibility.
  "assets_required": [
    {
      "item_type": "individual",
      "asset_id": "video_file",
      "asset_type": "video",
      "requirements": {
        "duration_seconds": 15,
        "acceptable_formats": ["mp4"],
        "acceptable_codecs": ["h264"],
        "acceptable_resolutions": ["1920x1080", "1280x720"],
        "max_file_size_mb": 30
      }
    }
  ]
}
Backward Compatibility: The assets_required field is deprecated but still supported. Existing implementations can continue using assets_required for required assets only. New implementations should use assets with the required boolean for full asset discovery.

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Repeatable Asset Groups

For formats with asset sequences (like carousels, slideshows, stories), see the Carousel & Multi-Asset Formats guide for complete documentation on repeatable asset group patterns.

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Validation

Implementations should validate assets against these schemas to ensure compatibility. The JSON schema can be used for automated validation: 
// Example validation (pseudocode)
const assetSchema = await fetch('https://adcontextprotocol.org/schemas/asset-types-v1.json');
const validator = new JsonSchemaValidator(assetSchema);

const videoAsset = {
  asset_type: "video",
  required: true,
  duration_seconds: 15,
  // ... other properties
};

const isValid = validator.validate(videoAsset, 'video');

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Best Practices

  1. Be Specific: Use exact values rather than ranges when possible
  2. Include All Constraints: Document all technical requirements upfront
  3. Use Standard Units:
    • File sizes: MB for video/audio, KB for images
    • Bitrates: Mbps for video, Kbps for audio
    • Durations: seconds
    • Dimensions: pixels
  4. Provide Reasonable Limits: Balance quality with file size constraints
  5. Document Edge Cases: Use the notes field for special requirements