AdCP — Asset Types

Creative formats in AdCP use standardized asset types with well-defined properties. Assets are the discrete, typed building blocks used by formats to define requirements and by manifests to supply concrete values. Standardizing asset types ensures consistency across formats and makes requirements easier for buyers and systems to understand.

Important: Payload vs Requirements

For payload schemas (the structure of the actual asset data supplied in creative manifests), see:

Asset Type Registry - Links to all payload schemas
Core Asset Schemas at /schemas/v3/core/assets/ - Individual asset payload definitions

Key distinction: Format requirements (this document) define constraints such as:

Whether an asset is required or optional
Acceptable file or container formats
Duration, dimension, or aspect ratio limits
File size and bitrate limits
Allowed or restricted features (for tag-based assets)

Payload schemas (core schemas) define the supplied values, such as:

url
content (for inline text or inline tag markup)
width / height (when declared)
duration_ms (when applicable)
format (declared container type)

Asset Type Schema

The official JSON schema for asset types is available at:

Production: https://adcontextprotocol.org/schemas/asset-types-v1.json
GitHub: https://github.com/adcontextprotocol/adcp/blob/main/static/schemas/asset-types-v1.json

Core Asset Types

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”])

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

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)

URL Asset

Links for clickthroughs, tracking, and landing pages. Two related but distinct fields describe a URL asset:

url_type (on the manifest asset) — the mechanism the receiver uses to invoke this URL.
url-asset-requirements.role (on the format) — the purpose this URL slot serves in the creative.

A slot can be click_tracker (purpose) and accept a tracker_pixel (mechanism) URL — those describe different things.

Manifest-side: `url_type` (mechanism)

Senders SHOULD include url_type on every URL asset. The valid values are:

Value	Mechanism
`clickthrough`	User-click destination (landing page or ad-tech redirector)
`tracker_pixel`	Fires HTTP GET, expects 1×1 pixel or 204 response (impression / event / 3P trackers)
`tracker_script`	Loads as a `<script>` tag — measurement SDKs (OMID verification, native event trackers using `method: 2`)

{
  "asset_type": "url",
  "url_type": "tracker_pixel",
  "url": "https://track.brand.com/imp?cb={CACHEBUSTER}"
}

If url_type is absent, receivers SHOULD fall back to the format’s url-asset-requirements.role:

`role` (format)	Fallback `url_type` (mechanism)
`clickthrough`, `landing_page`	`clickthrough`
`impression_tracker`, `click_tracker`	`tracker_pixel`
`viewability_tracker`	`tracker_script` — OMID and equivalent verification SDKs require a `<script>` tag; firing them as a pixel produces no measurement
`third_party_tracker`	No safe fallback. Mechanism is integration-specific (DV/IAS ship both pixel and script forms). Receivers MAY reject or warn.

If neither url_type nor a format-side role is available, receivers MUST NOT silently pick a mechanism — firing a clickthrough URL as a pixel (or vice versa) silently corrupts measurement and breaks the user flow. Receivers SHOULD reject the manifest.

VAST/DAAST URLs are not URL assets. A URL pointing to ad-server XML markup is parsed, not GET-fired. Use asset_type: "vast" with delivery_type: "url" for VAST tags, and the dedicated tracker types (vast_tracker / daast_tracker) once those land per RFC #2915. A VAST tag declared as asset_type: "url" with url_type: "tracker_pixel" is non-conformant under these mechanism semantics.

Migration cue for sellers. If your tooling previously emitted only {asset_type: "url", url: ...} (per the older docs), you can keep doing so through 3.x — but plan to add url_type before 4.0, when this field becomes required.

Format-side: `role` (purpose)

In format requirements, role declares what the URL slot is for:

{
  "asset_type": "url",
  "asset_id": "impression_tracker",
  "required": true,
  "requirements": {
    "role": "impression_tracker",
    "protocols": ["https"]
  }
}

role enum: clickthrough, landing_page, impression_tracker, click_tracker, viewability_tracker, third_party_tracker.

Other URL-asset-requirements properties

protocols: Allowed schemes (https, http)
allowed_domains: List of allowed hostnames
max_length: Maximum URL length
macro_support: Whether macro substitution is permitted

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

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

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. Valid values are defined by the VAST Tracking Event enum. Aligned to the IAB VAST 4.2 XSD TrackingEvents_type/Tracking/@event enumeration (vast_4.2.xsd lines 112–136), plus AdCP-flattened representations of Impression, Error, VideoClicks, and ViewableImpression elements:
- Playback: impression (billing event), creativeView, loaded, start, firstQuartile, midpoint, thirdQuartile, complete
- Interaction: mute, unmute, pause, resume, rewind, skip, playerExpand, playerCollapse, fullscreen (VAST 2.x/3.x compat), exitFullscreen (VAST 2.x/3.x compat), otherAdInteraction, interactiveStart (SIMID)
- Non-linear / companion: acceptInvitation, adExpand, adCollapse, minimize, overlayViewDuration
- Progress: progress (for custom progress points via VAST offset attribute)
- Click & close: clickTracking, customClick, close, closeLinear
- Verification: viewable, notViewable, viewUndetermined, measurableImpression (AdCP extension), viewableImpression
- Errors: error

Use Cases:

Third-party video ad servers
Programmatic video buying
Video ad networks
VPAID interactive video ads

VAST Tracker Asset

A single URL bound to a VAST TrackingEvents event. Use this when the creative agent emits decomposed per-event URLs and the sales agent is responsible for assembling the VAST TrackingEvents block at serve time — as an alternative to shipping a complete VAST tag. Example:

{
  "asset_type": "vast_tracker",
  "vast_event": "start",
  "url": "https://tracker.example.com/start?cid={CREATIVE_ID}&mb={MEDIA_BUY_ID}"
}

Progress with offset:

{
  "asset_type": "vast_tracker",
  "vast_event": "progress",
  "offset": "00:00:15.000",
  "url": "https://tracker.example.com/15s"
}

Properties:

vast_event: The event this URL fires on. Any VAST tracking-event enum value except impression, clickTracking, customClick, error, or any of viewable / notViewable / viewUndetermined / measurableImpression / viewableImpression — those live in dedicated VAST elements (Impression, VideoClicks, Error, ViewableImpression), not under TrackingEvents (see Tracker routing normative rule below). Common values: start, firstQuartile, midpoint, thirdQuartile, complete, pause, resume, mute, unmute, skip, progress.
url: Tracker URL. Supports AdCP universal macros.
offset: Required for vast_event: "progress". VAST 4.2 offset format (Tracking@offset): HH:MM:SS or HH:MM:SS.mmm (two-digit hours, minutes 00–59, seconds 00–59, exactly 3 fractional digits when present) for absolute time, or an integer percentage 0–100 suffixed with %. Negative offsets are NOT permitted — the VAST 4.2 XSD pattern does not allow a leading minus.
target: Which VAST creative element scopes this tracker — linear (default), non_linear, or companion. VAST 4.2 places <TrackingEvents> under three different parents (<Linear>, <NonLinearAds>, <CompanionAds>/<Companion>) with different valid event sets — e.g., acceptInvitation is meaningful on non_linear/companion, closeLinear only on linear. Sales agents read this to place the tracker correctly during VAST assembly.

Target with non-linear event:

{
  "asset_type": "vast_tracker",
  "vast_event": "acceptInvitation",
  "target": "non_linear",
  "url": "https://tracker.example.com/accept"
}

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. Valid values are defined by the DAAST Tracking Event enum. Aligned to DAAST 1.1 §3.2.1.7 <Tracking event="…"> values (the audio-applicable subset of VAST), plus close (DAAST 1.1 §3.2.4.2) and AdCP-flattened representations of Impression, Error, and the click children of <AdInteractions>:
- Playback: impression (billing event), creativeView (also used for companion display per DAAST 1.1 §3.2.2.7), start, firstQuartile, midpoint, thirdQuartile, complete
- Interaction: mute, unmute, pause, resume, rewind, skip
- Progress: progress (with offset attribute, DAAST 1.1 §3.2.4.3)
- Click & close: clickTracking, customClick, close
- Verification (AdCP extensions, OM-SDK Audio): viewable, notViewable, viewUndetermined, measurableImpression, viewableImpression
- Errors: error

Video-only VAST events (loaded, playerExpand/playerCollapse, fullscreen/exitFullscreen, acceptInvitation, adExpand/adCollapse, minimize, overlayViewDuration, interactiveStart) are deliberately excluded — they have no defined audio semantics in DAAST 1.1.

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

DAAST Tracker Asset

Audio-side analogue of vast_tracker: a single URL bound to a DAAST TrackingEvents event. Example:

{
  "asset_type": "daast_tracker",
  "daast_event": "complete",
  "url": "https://tracker.example.com/complete?cid={CREATIVE_ID}"
}

Properties:

daast_event: Any DAAST tracking-event enum value except impression, clickTracking, customClick, error, or any of viewable / notViewable / viewUndetermined / measurableImpression / viewableImpression (same element-routing rule as vast_tracker — those values belong in Impression / <AdInteractions> / Error / AdCP-extension verification slots, not TrackingEvents). Common values: start, firstQuartile, midpoint, thirdQuartile, complete, pause, resume, mute, unmute, rewind, skip, progress.
url: Tracker URL. Supports AdCP universal macros.
offset: Required for daast_event: "progress" (DAAST 1.1 §3.2.4.3). Same format as VAST 4.2 Tracking@offset. Negative offsets are NOT permitted.
target: Which DAAST creative element scopes this tracker — linear (default, DAAST 1.1 §3.2.1.7) or companion (DAAST 1.1 §3.2.2.7, where the only valid event is creativeView). DAAST has no <NonLinearAds> element — audio is linear or accompanied by a visual companion.

Creative / Sales Agent Boundary (VAST Assembly)

AdCP separates creative agents (produce the assets a creative is made of) from sales agents (assemble those assets into the serving format the ad server expects). For VAST and DAAST, the boundary is normative:

Complete tag vs decomposed trackers

A creative manifest MAY emit VAST trackers in one of two shapes. The creative agent chooses; the sales agent handles either. Complete tag — the creative agent hands off a hosted or inline VAST tag and the sales agent wraps it:

{
  "asset_type": "vast",
  "delivery_type": "url",
  "url": "https://adserver.example.com/vast.xml",
  "vast_version": "4.2"
}

Decomposed trackers — the creative agent emits per-event URLs; the sales agent assembles the TrackingEvents block:

[
  { "asset_type": "vast_tracker", "vast_event": "start",         "url": "..." },
  { "asset_type": "vast_tracker", "vast_event": "firstQuartile", "url": "..." },
  { "asset_type": "vast_tracker", "vast_event": "midpoint",      "url": "..." },
  { "asset_type": "vast_tracker", "vast_event": "thirdQuartile", "url": "..." },
  { "asset_type": "vast_tracker", "vast_event": "complete",      "url": "..." }
]

Normative rules

Wrapper is a sales-agent concern. The creative agent MUST NOT emit a VAST Wrapper element. Wrapper is a multi-hop chaining construct — if the served VAST needs to be wrapped (for macro signing, SSAI-compatible envelope, or ad-server redirection), the sales agent constructs the wrapper at serve time around the creative agent’s output. Emitting an inline VAST document with Ad > InLine > Creatives content (the pattern shown in Universal Macros) is permitted and unchanged.
Assembly responsibilities. The sales agent is responsible for constructing VAST envelope elements that assemble resources from the creative agent: TrackingEvents (from vast_tracker assets), AdVerifications (from OMID verification resources), and Wrapper / VASTAdTagURI (if chaining). The creative agent supplies the resources; the sales agent places them in the correct element. A dedicated omid_verification asset type for decomposing OMID resources is a planned follow-up.
Tracker routing by element. VAST’s tracker URLs live in three different elements and AdCP models them with three different asset shapes — don’t cross the streams:
- Impression URL → url asset with url_type: "tracker_pixel" (not a vast_tracker).
- TrackingEvents events (start, quartiles, complete, pause, etc.) → vast_tracker asset with vast_event.
- VideoClicks URLs (ClickThrough, ClickTracking, CustomClick) → url asset (url_type: "clickthrough" for ClickThrough; click-tracker URLs use url_type: "tracker_pixel").
The vast_tracker schema enforces this split: vast_event MUST NOT be impression, clickTracking, customClick, or error. The same rule applies to DAAST.
Mixing allowed. A creative manifest MAY mix a complete vast tag with additional vast_tracker and url (impression / click) assets — the sales agent merges them into one VAST document at serve time.

SSAI caveat

In server-side ad insertion (SSAI) environments — Yospace, AWS Elemental, MediaTailor — the stream-stitcher rewrites and re-signs the VAST XML before it reaches the player. Trackers that must survive SSAI need to be in the VAST document before stitching. AdCP does not today specify an SSAI-specific manifest shape; this is a known gap and a follow-on RFC topic.

Common Properties

All asset types share these common fields:

asset_id: Unique identifier within the format
asset_type: The asset’s type (image, video, text, url, etc.)
asset_role: Semantic purpose (hero_video, logo, cta_button)
required: Whether the asset is mandatory

Asset ID vs Asset Role

asset_id: A stable identifier used by manifests to supply values. asset_role: A semantic label describing the asset’s purpose. Example:

{
  "asset_id": "main_video",
  "asset_type": "video",
  "asset_role": "hero_video",
  "required": true
}

Asset roles enable consistent rendering, validation, and AI-assisted generation without hard-coding layout assumptions. 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 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.

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.

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": [
    {
      "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
      }
    }
  ]
}

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.

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');

Best Practices

Be specific where possible
Declare all constraints explicitly
Use standard units:
- File size: MB (video/audio), KB (images)
- Duration: seconds
- Bitrate: Mbps (video), Kbps (audio)
- Dimensions: pixels
Balance quality with performance
Document edge cases using notes

Documentation

Documentation Index

​Important: Payload vs Requirements

​Asset Type Schema

​Core Asset Types

​Video Asset

​Image Asset

​Text Asset

​URL Asset

​Manifest-side: url_type (mechanism)

​Format-side: role (purpose)

​Other URL-asset-requirements properties

​Audio Asset

​HTML Asset

​VAST Asset

​VAST Tracker Asset

​DAAST Asset

​DAAST Tracker Asset

​Creative / Sales Agent Boundary (VAST Assembly)

​Complete tag vs decomposed trackers

​Normative rules

​SSAI caveat

​Common Properties

​Asset ID vs Asset Role

​Asset ID Usage

​Example: Uploading Assets

​Usage in Creative Formats

​Repeatable Asset Groups

​Validation

​Best Practices

Important: Payload vs Requirements

Asset Type Schema

Core Asset Types

Video Asset

Image Asset

Text Asset

URL Asset

Manifest-side: `url_type` (mechanism)

Format-side: `role` (purpose)

Other URL-asset-requirements properties

Audio Asset

HTML Asset

VAST Asset

VAST Tracker Asset

DAAST Asset

DAAST Tracker Asset

Creative / Sales Agent Boundary (VAST Assembly)

Complete tag vs decomposed trackers

Normative rules

SSAI caveat

Common Properties

Asset ID vs Asset Role

Asset ID Usage

Example: Uploading Assets

Usage in Creative Formats

Repeatable Asset Groups

Validation

Best Practices