Side-by-Side / Double Box — Creative Specs

Layout overview

StreamLayer's Double Box unit is a CTV/web/mobile interactive ad surface that uses a squeezeback model:

Left box: the publisher's live video, squeezed in place during the ad opportunity. No asset required from the demand partner — this is the publisher's broadcast.
Right box: the ad creative — video or static image, supplied by the demand partner.
Backdrop: a full-bleed background image (landscape + portrait variants).
Header: brand logo + title text.
Footer: description + CTA button.

The end user is never blocked from the underlying broadcast — they continue watching while the ad is on screen.

┌───────────────────────────────────────────────────────────────┐
│                        [Header Logo]                          │
│                            Title                              │
│  ┌─────────────────────────┐  ┌─────────────────────────┐     │
│  │                         │  │                         │     │
│  │   Publisher live video  │  │     Ad creative         │     │
│  │     (squeezed)          │  │     (Media — 16:9)      │     │
│  │                         │  │                         │     │
│  └─────────────────────────┘  └─────────────────────────┘     │
│  Description                              [ CTA Button ]     │
│                                                               │
│                    (Background image fills behind)            │
└───────────────────────────────────────────────────────────────┘

Asset checklist

#	Asset	Required	Format	Dimensions
1	Square Logo	Yes	PNG or JPG (1:1)	140 × 140 px
2	Full Transparent Logo	Yes	Transparent PNG	Height 140 px, proportional width
3	Main Media (right box)	Yes	PNG or MP4	1920 × 1080 px (16:9)
4	Background — Landscape	Yes	PNG	2560 × 1440 px (16:9)
5	Background — Portrait	Yes	PNG	1000 × 1500 px (2:3)
6	Advertiser Name	Yes	Text	≤ 30 chars
7	Ad Name	Yes	Text	≤ 30 chars
8	Title	Yes	Text	≤ 30 chars
9	Description	Yes	Text	≤ 80 chars
10	CTA Button text	Yes	Text	≤ 25 chars
11	CTA destination URL	Yes	URL	Standard click-through

Brand logos

Square Logo

Purpose: Used in StreamLayer Studio / ad management lists. Not visible to end users in the rendered ad.
Format: PNG or JPG
Aspect ratio: 1:1 (square)
Recommended dimensions: 140 × 140 px

Full Transparent Logo

Purpose: Rendered inside the ad as the header logo at the top of the unit. Visible to end users.
Format: Transparent PNG
Recommended height: 140 px (width scales proportionally)
Notes: The logo must be legible on a dark backdrop. Avoid hard edges and rely on transparency.

Main Media (right box — ad creative)

Property	Value
Format	PNG (static image) or MP4 (video)
Aspect ratio	16:9 (cropped if not exact)
Recommended dimensions	1920 × 1080 px
Video playback	Auto-plays on render
Audio	Muted by default (TBD — pending confirmation)
Duration (video)	6–30s recommended for CTV

Codec / bitrate guidance for MP4:

Codec: H.264 (baseline or main profile)
Bitrate: 2–5 Mbps for 1080p
Frame rate: 24, 25, or 30 fps
Audio: AAC, 128 kbps stereo (if any)

Background images

The background fills the entire unit behind both boxes. Two variants are required to support both orientations.

Landscape (CTV / tvOS / Android TV / landscape web)

Format: PNG
Recommended dimensions: 2560 × 1440 px (16:9)
Notes: Keep brand-critical elements away from the center, since the two media boxes overlap that area. Brand fades, gradients, or subtle textures work best.

Portrait (mobile portrait)

Format: PNG
Recommended dimensions: 1000 × 1500 px (2:3)

Text fields

Field	Max characters	Where it renders
Advertiser Name	30	Brand attribution metadata
Ad Name	30	Internal campaign identifier (not visible to end users)
Title	30	Headline above the two media boxes
Description	80	Sub-text under the media
CTA Button	25	Action button label (e.g. "Learn More", "Shop Now")

Truncation: Strings exceeding the limit are truncated client-side. Pre-truncate at the source.

Behavior controls (configured on the StreamLayer side — informational only)

These don't require creative assets from the demand partner. They're listed here so designers understand the unit's runtime behavior.

Control	Options
Close Timer	No Timer / 5s / 10s / 15s / 30s / 60s
CTA Button Type	Basic (URL click-through) / Add to Wallet / Return to Video / Send to User (QR code) / No Button

Sample VAST response

<?xml version="1.0" encoding="UTF-8"?>
<VAST version="4.2" xmlns="http://www.iab.com/VAST">
  <Ad id="ad-12345" sequence="1">
    <InLine>

      <AdSystem version="1.0">ExampleDSP</AdSystem>
      <AdTitle><![CDATA[Discover the Collection]]></AdTitle>
      <Description><![CDATA[New season. Now available.]]></Description>
      <Advertiser><![CDATA[Example Brand]]></Advertiser>
      <Pricing model="CPM" currency="USD">25.00</Pricing>

      <Impression id="imp-1"><![CDATA[https://impressions.example-dsp.com/imp?id=12345&cb=[CACHEBUSTING]]]></Impression>

      <Creatives>
        <Creative id="creative-1" sequence="1">
          <Linear>
            <Duration>00:00:15</Duration>

            <TrackingEvents>
              <Tracking event="start"><![CDATA[https://t.example-dsp.com/start?id=12345]]></Tracking>
              <Tracking event="firstQuartile"><![CDATA[https://t.example-dsp.com/q1?id=12345]]></Tracking>
              <Tracking event="midpoint"><![CDATA[https://t.example-dsp.com/mid?id=12345]]></Tracking>
              <Tracking event="thirdQuartile"><![CDATA[https://t.example-dsp.com/q3?id=12345]]></Tracking>
              <Tracking event="complete"><![CDATA[https://t.example-dsp.com/complete?id=12345]]></Tracking>
              <Tracking event="mute"><![CDATA[https://t.example-dsp.com/mute?id=12345]]></Tracking>
              <Tracking event="unmute"><![CDATA[https://t.example-dsp.com/unmute?id=12345]]></Tracking>
            </TrackingEvents>

            <VideoClicks>
              <ClickThrough id="ct-1"><![CDATA[https://example-brand.com/spring-collection]]></ClickThrough>
              <ClickTracking id="clk-1"><![CDATA[https://t.example-dsp.com/click?id=12345]]></ClickTracking>
            </VideoClicks>

            <MediaFiles>
              <MediaFile id="hd"
                         delivery="progressive"
                         type="video/mp4"
                         width="1920" height="1080"
                         bitrate="3500"
                         codec="avc1.4d401f">
                <![CDATA[https://cdn.example-dsp.com/creatives/12345/1080p.mp4]]>
              </MediaFile>
            </MediaFiles>
          </Linear>
        </Creative>
      </Creatives>

      <Extensions>
        <Extension type="streamlayer/double-box/v1">
          <DoubleBox>
            <AdName><![CDATA[Spring 2026 — Double Box]]></AdName>

            <Backgrounds>
              <Background orientation="landscape" width="2560" height="1440" type="image/png">
                <Url><![CDATA[https://cdn.example-dsp.com/creatives/12345/bg-landscape.png]]></Url>
              </Background>
              <Background orientation="portrait" width="1000" height="1500" type="image/png">
                <Url><![CDATA[https://cdn.example-dsp.com/creatives/12345/bg-portrait.png]]></Url>
              </Background>
            </Backgrounds>

            <Logos>
              <Logo role="header" width="140" height="140" type="image/png">
                <Url><![CDATA[https://cdn.example-dsp.com/brand/logo-transparent.png]]></Url>
              </Logo>
              <Logo role="square" width="140" height="140" type="image/png">
                <Url><![CDATA[https://cdn.example-dsp.com/brand/logo-square-140.png]]></Url>
              </Logo>
            </Logos>

            <CTA>
              <Label><![CDATA[Shop Now]]></Label>
              <Type>basic</Type>
            </CTA>
          </DoubleBox>
        </Extension>
      </Extensions>

    </InLine>
  </Ad>
</VAST>

Notes:

Standard VAST 4.2. Video, impression, tracking, and click-through all live in spec nodes. Nothing custom inside <Linear>.
All StreamLayer-specific fields go in a single <Extension type="streamlayer/double-box/v1">. The type attribute versions the contract.
Dimensions are attributes (width / height) on the element, not nested.
Enums:
- Background.orientation: landscape | portrait
- Logo.role: header | square
- CTA.Type: basic | add_to_wallet | return_to_video | send_to_user | none
The type (MIME) attribute on backgrounds and logos is optional but recommended for pre-validation.
Do not put video, tracking, impression, or click-through inside the Extension — they belong in the standard nodes.
Macros substituted in URLs: [CACHEBUSTING], [TIMESTAMP], [CONTENTPLAYHEAD].
Character limits: AdTitle ≤ 30, Description ≤ 80, Advertiser ≤ 30, AdName ≤ 30, CTA.Label ≤ 25.
VAST wrappers (VASTAdTagURI) are supported (rolling out). Please fire <Error> pixels per-layer on failure, per spec.