Seller-Defined Context in CTV: How SSPs Turn Stream Metadata Into Targetable Supply

Connected TV is finally getting the contextual targeting it deserves. For years, CTV inventory behaved like beautiful yet opaque glass. Titles, genres, and ad breaks existed, but buyers struggled to see them clearly. Player beacons got lost in SSAI, device IDs were sparse, and show metadata did not flow consistently through bidstreams. That opacity depressed relevance, throttled CPMs, and left premium sellers underpaid. Seller-defined context is how the supply side fixes that. By standardizing and packaging stream metadata into interoperable signals that travel in the bid request, SSPs can make CTV supply targetable without user IDs, align to brand suitability expectations, and win more demand with less friction. The payoff is not academic. It is tangible uplift in win rates, fill, and price floors for high quality content. This thought piece lays out how to do it with rigor. We will cover the standards to lean on, the data architecture that works in the real world, code patterns you can adopt today, and the pitfalls to avoid. Most importantly, we will show how seller-defined context becomes a durable asset that compounds across your entire supply footprint. References are included where helpful so your teams can go deeper on specifics, particularly around OpenRTB 2.6 CTV improvements and IAB Tech Lab taxonomies that underpin contextual scale.

What We Mean By Seller-Defined Context

Seller-defined context is the practice of the supply side generating, normalizing, and transmitting contextual signals about content and delivery that help buyers decide where to serve ads. It is adjacent to but distinct from seller-defined audiences.

• Seller-defined audiences describe people in aggregate cohorts without personal identifiers.
• Seller-defined context describes content, placement, and delivery attributes buyers can target and measure against. For CTV, seller-defined context typically includes:
• Content fundamentals such as series, season, episode, title, and long tail metadata like genre, rating, and original air date
• Delivery attributes such as live vs VOD, linear vs FAST, ad pod structure and slot position, and SSAI stitching details
• Brand suitability descriptors aligned to industry frameworks
• Provenance signals such as app, publisher, channel, and supply chain data The intent is to make that context interoperable. That means standard taxonomies, consistent fields, and predictable placement inside the bid request. It also means governance so a buyer can trust “Drama” to mean the same thing from three different apps. Done right, seller-defined context is buyer friendly, verification friendly, and privacy friendly. It is also a major monetization lever for SSPs and CTV publishers, since it finally lets buyers pay for value they understand.

  Why CTV Needs Seller-Defined Context Now

  Three structural realities make this urgent: 1) Signal asymmetry between content value and bidstream signals CTV titles and networks carry strong intent and brand connotations, but too little of that flows into DSPs. The result is buyers over-rely on domain or app-level heuristics and suppress otherwise suitable, premium supply. 2) Privacy and ID scarcity make audience targeting non-universal CTV identifiers are inconsistent. Household identifiers can be suppressed or rotated, and some platforms restrict the identifier for advertising. Context is both privacy safe and always-on, which buyers increasingly prefer for upper and mid-funnel outcomes. 3) CTV standards have matured enough to transmit what matters OpenRTB 2.6 introduced CTV-relevant structures such as pod bidding, slotting, and improved placement metadata. The IAB Tech Lab’s Content Taxonomy 3.0 adds vectorized context that works well for video. Together, these create a practical runway for seller-defined context at scale OpenRTB 2.6 GitHub, IAB Content Taxonomy 3.0 Implementation Guide. As buyers shift toward ID-less and curation workflows, the supply that wins will be the supply that brings its own context to the party in a standard format. IAB Tech Lab’s broader work on ID-less addressability and seller-defined signals underscores this trajectory IAB Tech Lab ID-less Guidance, IAB Tech Lab on Seller-Defined Audience and Context Signaling.

  The Building Blocks: Standards You Should Use

  The supply side does not need to invent new languages. It needs to implement the current ones consistently.

  OpenRTB 2.6 for CTV and Pods

  OpenRTB 2.6 reinforced CTV support with enhancements that help buyers reason about pod structures, slot position, frequency per second, and other video-specific mechanics. You can reference the official 2.6 repository for the latest fields and enumerations OpenRTB 2.6. Practically, this gives SSPs structured ways to surface:

• Pod IDs and sequence position
• Ad slot position inside a pod
• Duration and min CPM per second considerations
• Publisher, site, app, and content objects with relevant metadata These fields anchor the delivery context that buyers increasingly require for pacing and suitability.

  IAB Tech Lab Content Taxonomy 3.0

  Content Taxonomy 3.0 gives a common language for describing what a piece of content is about and its format vectors such as Show, Movie, Event, or Clip. The taxonomy is designed to be carried via cat and cattax across AdCOM and OpenRTB IAB Content Taxonomy Guide. The “vectors” concept is particularly helpful in CTV because it lets you express both genre and form factor. That is how a buyer knows they are targeting Episodic Show in Comedy, not a random clip.

  Brand Safety and Suitability Mapping

  Brand suitability categories aligned to the GARM framework are incorporated into the Content Taxonomy so risk can be signaled consistently. Buyers expect alignment with this framework in CTV environments IAB Content Taxonomy Guide, Section 3.

  Seller-Defined Audiences and Context Signaling

  Even though the IAB Tech Lab is evolving naming and guidance around curation and ID-less signals, the core principles remain intact. Sellers define the meaning of their segments and contexts using published taxonomies and standardized bidstream placement. Documentation, transparency, and consistent IDs are essential so buyers and verification partners can validate and activate IAB Tech Lab ID-less Guidance.

  The Metadata You Already Have in CTV

  Most of the context already exists somewhere. The work is to unify it and transmit it predictably. Typical sources include:

  • Content catalogs: Series, season, episode, title, synopsis, genre, rating, production metadata, EIDR or internal IDs
  • Schedule and EPGs: Live program guide, channel lineups, start and end times
  • Player and SSAI beacons: Quartile events, pod start and end, break duration, stitched ad metadata, SCTE-35 markers
  • App and platform data: App bundle IDs, app channels, FAST channel identifiers
  • Network and distributor tags: Network names, channel brands, deal or channel sponsorships
  • Quality and suitability annotations: Internal or third-party brand safety classifications mapped to GARM risk levels
  • Verification and measurement outputs: Viewability, completion rates, invalid traffic flags

  The right architecture turns these disparate datasets into resilient, real-time signals that enrich every eligible impression.

  A Reference Architecture for Seller-Defined Context

  Below is a blueprint you can scale across a multi-seller SSP or a single premium streaming app.

  1) Ingest

• Pull catalog data and schedules from CMS, EPG feeds, and video pipelines.
• Stream player and SSAI events into a log processing system. Maintain break-level and slot-level lineage.
• Normalize app and device metadata so app identifiers and channels are consistent.
• Integrate verification partners to ingest brand safety and suitability scores where contractually permitted.

  2) Normalize and Resolve

• Resolve content to stable IDs. If you have EIDR, ISAN, or TMS-like identifiers, treat them as canonical. If not, generate internal GUIDs and maintain a mapping table. Include aliasing for regional or syndication variants.
• Canonicalize channel and network names. Buyers hate near-duplicates that differ by punctuation or casing.
• Map genres and topics to IAB Content Taxonomy categories and vectors. Maintain a human-in-the-loop process for edge cases.
• Align any brand safety annotations to Content Taxonomy’s suitability vectors so they can be transmitted consistently.

  3) Create Context Packs

  Think of a context pack as a compact, cacheable bundle of everything a buyer needs to know about a piece of content and its delivery conditions. A context pack typically includes:

  • Identity: content_id, series_id, season, episode_number, title
  • Taxonomy: an array of Content Taxonomy category IDs and vectors
  • Suitability annotations: optional per-category suitability or an overall suitability vector
  • Delivery: live_vs_vod, linear_vs_fast, pod structure defaults
  • Provenance: app_id, publisher_id, channel_name
  • Versioning: a hash or ETag so caches and bidding layers can reconcile updates

  Store packs in a low-latency KV store keyed by content_id and channel_id, with TTL policies calibrated to your EPG cadence.

  4) Real-time Enrichment

  At request time, your bid adapter enriches the OpenRTB request using the relevant pack:

• Populate content.cat with taxonomy IDs and set cattax to 2 per the spec.
• Set content.title or content.series where appropriate if allowed by business rules.
• Describe pod structure and slot position via OpenRTB 2.6 video and pod fields.
• Attach supply chain and app identifiers consistently. You also attach any publisher-declared context segments using a documented schema buyers can audit.

  5) Governance and Transparency

• Publish context catalog documentation and segment dictionaries. Include definitions, taxonomies used, and update cadence.
• Maintain test endpoints and sample requests that DSP partners can validate against.
• Monitor for drift. If a show’s genre classification changes, record why and when so buyer-facing reconciliation is easy.
• Honor privacy. No user or household identifiers are created or inferred as part of this context pipeline. The point is to transform context into a reliable product. That product then fuels yield strategies, curation, and private marketplace packaging.

  Code Patterns You Can Use Today

  Below are illustrative snippets to show how to package, enrich, and transmit context. Adapt them to your stack and your commercial guardrails.

  1) Context Pack Definition

  A simple schema to store a normalized context pack for a program or channel.

  {
  "content_id": "eidr:10.5240/ABCD-1234-EFGH-5678-IJKL-M",
  "series_id": "series:Friends",
  "season": 4,
  "episode": 12,
  "title": "The One With The Embryos",
  "vectors": {
  "form_factor": ["Video", "Show", "Episodic Show"],
  "aboutness_cat_ids": ["1001", "1021", "1215"],
  "genres_cat_ids": ["Drama", "Comedy"]
  },
  "iab_cat": ["1001", "1021", "1215", "Comedy"],
  "cattax": 2,
  "brand_suitability": {
  "framework": "GARM",
  "risk": "Low"
  },
  "delivery": {
  "live": false,
  "linear": false,
  "fast_channel": null,
  "default_pod": {
  "slots": 4,
  "durations_sec": [15, 15, 30, 15]
  }
  },
  "provenance": {
  "publisher_id": "pub_9832",
  "app_bundle": "com.streamer.app",
  "channel_name": null
  },
  "version": "d41d8cd98f00b204e9800998ecf8427e",
  "updated_at": "2025-08-10T12:34:56Z"
  }

  Notes:

• iab_cat carries the category IDs you will put into content.cat.
• cattax should be set to 2 to indicate Content Taxonomy 2.x and higher per IAB guidance IAB Content Taxonomy Implementation.
• brand_suitability is declared for buyers who negotiate for publisher-provided suitability, but you should expect buy-side verification to make its own determinations.

  2) SQL-like Mapping Logic

  A straightforward mapping from internal genre labels to IAB taxonomy IDs. This runs in your metadata ETL.

  INSERT INTO ctx_taxonomy_map (content_id, cat_id)
  SELECT c.content_id,
  CASE
  WHEN LOWER(c.genre) IN ('sitcom', 'comedy') THEN 'Comedy'
  WHEN LOWER(c.genre) IN ('documentary') THEN 'Documentary'
  WHEN LOWER(c.genre) IN ('sports', 'football', 'soccer') THEN 'Sports'
  ELSE 'Entertainment'
  END AS cat_id
  FROM raw_catalog c
  WHERE c.platform = 'CTV';

  In production, maintain a dedicated mapping table with coverage reports and human QA queues for edge cases.

  3) OpenRTB 2.6 Bid Request Enrichment

  An illustrative fragment for a video impression inside an OpenRTB 2.6 request. Exact enumerations vary by implementation, so align to your integration guide and the official spec.

  {
  "id": "req-9f83",
  "source": {
  "tid": "txn-5835",
  "ext": {
  "schain": {
  "ver": "1.0",
  "complete": 1,
  "nodes": [
  {
  "asi": "ssp.example.com",
  "sid": "pub_9832",
  "hp": 1
  }
  ]
  }
  }
  },
  "app": {
  "bundle": "com.streamer.app",
  "publisher": {
  "id": "pub_9832",
  "name": "StreamerCo"
  },
  "name": "Streamer App"
  },
  "device": {
  "ua": "Mozilla/5.0",
  "ip": "2406:da1:abcd::",
  "ifa": "AEBE52E7-03EE-455A-B3C4-E57283966239",
  "lmt": 1
  },
  "user": {
  "consent": "CPXxRfAPXxRfAAHABBENBRCgAAAAAAAAAAYgAAAAAAAA"
  },
  "imp": [
  {
  "id": "1",
  "video": {
  "w": 1920,
  "h": 1080,
  "mimes": ["video/mp4", "video/x-m4v"],
  "minduration": 5,
  "maxduration": 60,
  "podid": 3,
  "podseq": 2,
  "slotinpod": 2,
  "linearity": 1,
  "placement": 1,
  "plcmt": 1
  },
  "tagid": "channel-47",
  "bidfloor": 18.50,
  "bidfloorcur": "USD"
  }
  ],
  "content": {
  "id": "eidr:10.5240/ABCD-1234-EFGH-5678-IJKL-M",
  "title": "The One With The Embryos",
  "series": "Friends",
  "season": "4",
  "episode": 12,
  "livestream": 0,
  "cat": ["1001", "1021", "1215", "Comedy"],
  "cattax": 2,
  "producer": {
  "name": "Warner Bros.",
  "domain": "warnerbros.com"
  }
  }
  }

  Notes:

• podid, podseq, and slotinpod help buyers manage frequency and pacing strategies in CTV OpenRTB 2.6 overview.
• content.cat and cattax carry Content Taxonomy 3.0 aligned vectors for interoperable contextual targeting IAB Taxonomy Guide.
• Verify field support with each DSP. Some will accept episode-level richness, others rely on title and network-level fields. Provide what is allowed and documented.

  4) Seller-Defined Context Segment Catalog

  Publish a human and machine readable catalog that describes the context segments you may also transmit via deal targeting or extensions.

  {
  "seller": "StreamerCo",
  "updated": "2025-08-10T12:34:56Z",
  "taxonomies": [
  {
  "name": "IAB Content Taxonomy",
  "version": "3.0",
  "reference": "https://iabtechlab.com/standards/content-taxonomy"
  }
  ],
  "segments": [
  {
  "id": "ctx.show.top_comedy",
  "name": "Top Comedy Episodic",
  "definition": "Episodic shows classified as Comedy with top 20 percent completion rates.",
  "rules": {
  "cattax": 2,
  "cat": ["Comedy", "Video", "Show", "Episodic Show"],
  "kpi": {"vcr_percentile": ">=80"}
  }
  },
  {
  "id": "ctx.live.sports.preroll_high_attn",
  "name": "Live Sports Pre-roll High Attention",
  "definition": "First slot in pod for live sports events where pods are <= 90s.",
  "rules": {
  "delivery": {"live": true, "event": "Sports"},
  "pod": {"slotinpod": 1, "pod_duration_sec_max": 90}
  }
  }
  ]
  }

  This catalog helps buyers, curation partners, and verification vendors understand what your segments mean. It also creates internal discipline so different supply endpoints produce consistent signals.

  Packaging Context for Buyers That Care

  Buyers have converged on several high-value use cases in CTV. Your packaging should map to these behaviors so your context is monetizable from day one.

  • Brand suitability: Buyers want supply aligned to GARM risk thresholds at the program or channel level, not just app-level. Package deals for Low and Medium risk across specific genres and dayparts.
  • Pod and slot preference: Some buyers will pay uplifts for first-in-pod or last-in-pod depending on creative goals. Use OpenRTB 2.6 to describe and enforce these positions in deals and auctions.
  • Live vs VOD bifurcation: Many campaigns separate live sports or news from VOD because of pacing and budget controls. Make this flag trivially targetable.
  • Premium comedy or drama clusters: Provide curated lists of episodic shows by genre and completion-rate percentile to help buyers find quality at scale.
  • Channel and network constructs: FAST buyers think in channels. Provide channel names and stable IDs so they can build channel packs with confidence.

  The goal is to make it easier for DSP traders to allocate budget to supply you can actually deliver consistently, with signals they can optimize on programmatically.

  Verification, Measurement, and Trust

  Context is only as valuable as buyers’ trust in the signals. Three things matter. 1) Documentation and transparency Publish your segment dictionaries, taxonomy usage, and examples. Point to the IAB standards you implement and how your values map. Keep it updated with versioning so integrations are auditable. 2) Compatibility with verification Verification partners use their own classifiers and site scans. Context you send should not contradict those determinations at scale. That does not mean you cannot be more granular. It means drift should be explainable. 3) Governance and controls Operate a QA loop. Sample content across partners weekly. Spot check genre accuracy and suitability mappings. Create clear escalation paths with content partners for misclassification. Maintain rollbacks if an update increases mismatch rates beyond a threshold. When in doubt, align with the Content Taxonomy guidance and recognize that GARM-aligned suitability is a floor signal. Buyers will add their own checks IAB Content Taxonomy 3.0, Section 5–7.

  Monetization Impact: What Uplift to Expect

  Every supply footprint is different, but consistent patterns emerge when seller-defined context is implemented.

  • Bid density increases: More qualified bidders enter the auction when signals match their contextual and suitability preferences. Expect measurable rises in number of bids per impression opportunity.
  • Price floors hold: Enriched impressions maintain higher floors with fewer markdowns because buyers can suppress unsuitable supply early. This reduces bid shading variance.
  • Fill stabilizes on premium: Live sports and top episodic shows gain consistent demand in the dayparts buyers care about. Clearance improves under constrained budgets.
  • Deal performance improves: Seller-defined context segments power PMPs and curated packages that outperform generic app-level contextual. DSP-side reports show healthier completion rates and lower waste.

  The key is predictability. Once traders see that your “Top Comedy Episodic” actually means something repeatable, budgets return with fewer conditional caveats.

  Pitfalls to Avoid

  Seller-defined context can go sideways if the basics are ignored.

  • Inconsistent taxonomy application: If the same title flips between Comedy and Romance week to week, traders lose trust. Use QA dashboards and locking rules for canonical series mappings.
  • Leaky signals: Passing too much free-form text in title fields can trigger mismatches or disapprovals. Use structured fields and enumerations. Protect licensing constraints with clear business rules.
  • SSAI opacity: If SSAI strips or obscures in-stream signals, rebuild the context at the SSP and pass it in OpenRTB. Do not assume player beacons will survive downstream hops.
  • Over-fitting to one DSP: Build to standards first, custom per-DSP mappings second. You want scale across platforms, not brittle one-offs.
  • No feedback loop: Without buyer and verification feedback, drift accumulates. Establish monthly context reviews with top DSPs and third-party partners.

  How Red Volcano Helps

  Red Volcano focuses on the supply side intelligence that makes seller-defined context actionable.

• Discovery and mapping We continuously map web, app, and CTV publishers, their technology stacks, and their identifiers. That means you start with clean app bundles, channel-level mappings, and publisher lineage instead of raw strings.
• Taxonomy alignment at scale We monitor Content Taxonomy usage in the wild and provide playbooks and templates to normalize your genre and vector assignments across partners. That reduces reconciliation overhead with DSPs.
• Ads.txt, app-ads.txt, and sellers.json monitoring Supply chain hygiene and provenance are prerequisites for trust. We track and alert on configuration drift so your context signals sit on a solid trust foundation.
• CTV pod and slot intelligence We capture and model pod practices across streaming partners. That informs your deal packaging and helps your team set realistic promises for slot-in-pod delivery, aligned to OpenRTB 2.6 expectations.
• Outreach and enablement Our publisher outreach services help your teams align with best practices and connect with buy-side activation teams to test and certify seller-defined context packages. All of this supports a simple goal. Make the supply you have both discoverable and desirable to the buyers who need it most.

  A Quick Buyer-aligned Packaging Playbook

  Three packages that are easy to explain, simple to deliver, and hard to commoditize.

  • Brand-safe Prime Comedy Episodic: Low risk per GARM suitability, Episodic Show vector, Comedy genre, evenings and weekends, first or last slot preference optional. Clear definitions, clear outcomes.
  • Live Sports Pod Starters: Live flag, Event vector set to Sports, slotinpod equals 1, maximum pod duration 90 seconds. Buyers love attention and recall associated with early pod positions.
  • FAST News Essentials: FAST channel identifier list, News vector, Medium risk tolerance with specific exclusions. Buyers pacing daily budgets in news environments get predictable channel coverage.

  You can express each package via standard OpenRTB fields and provide curated allowlists that traders can audit. Keep the documentation public and versioned.

  Implementation Checklist

  A crisp checklist for your product and engineering teams.

  • Adopt OpenRTB 2.6: Confirm pod-related fields and content object support with top DSPs. Publish an integration guide.
  • Map to IAB Content Taxonomy 3.0: Use cat and cattax consistently. Document your genre to taxonomy mappings.
  • Publish a context catalog: Human and machine readable, with segment IDs, definitions, and update cadence.
  • Instrument QA and drift alerts: Weekly classification audits, verification partner comparisons, and rollback procedures.
  • Pilot with two DSPs: Run A/B tests on enriched vs baseline signals. Share lift metrics and adjust packaging.
  • Align commercial terms: Clearly state what signals are guaranteed and what are best-effort. Avoid over-promising on slot delivery where SSAI constraints apply.

  Advanced Topics

  If your program is maturing, consider these.

  • Attention-informed slot pricing: Use completion and viewability data to price first-in-pod vs mid-pod slots differentially where supported. Be transparent about methodology.
  • Contextual curation for marketplace distribution: Package seller-defined context segments as PMPs across multiple DSPs. Maintain consistent IDs and meanings, even if destination-specific translation is needed.
  • Automated content ID resolution: Invest in fuzzy matching and vendor integrations to link titles to canonical IDs. Reduce manual overhead while improving precision.
  • Suitability variance reporting: Report when publisher-declared suitability diverges from buy-side verification by category. Use it as a process improvement KPI.
  • FAST-first design: FAST channels behave like linear TV. Build channel-level context that travels well, including show blocks and dayparting cues.

  Evidence and Standards You Can Cite Internally

• OpenRTB 2.6 explicitly improved CTV signal handling, including pod constructs and placement details. This is the base for slot targeting in CTV programmatic OpenRTB 2.6 GitHub, Index Exchange explainer.
• IAB Tech Lab’s Content Taxonomy 3.0 shows how to place categories in content.cat with cattax set to 2 and how to use vectors for form factor and suitability alignment Taxonomy Implementation Guide PDF.
• IAB Tech Lab continues to steer ID-less addressability and seller-defined signals, now under broader curation and transparency guidance. The direction favors standardized context and audience signaling without IDs IAB ID-less Guidance, Predictable Privacy.
• Market education around pod structures and slotting in CTV underscores buyer demand for more expressive supply. Regional bodies have published helpful handbooks that align with these practices IAB Australia CTV Handbook 2024.

  Conclusion

  CTV is premium because of context. But premium only monetizes when context travels with the impression. Seller-defined context is the practical path for the supply side to surface what buyers need in a privacy-safe, interoperable way. Use OpenRTB 2.6 to express placement. Use Content Taxonomy 3.0 to express aboutness and vectors. Align to GARM suitability so brand expectations are met. Then package and document your segments so traders can buy with confidence. Do this with discipline and you will see bid density rise, deal performance improve, and floor integrity strengthen across your CTV footprint. The best part is that seller-defined context compounds. Every new program or channel you normalize drops into a well-understood framework, which makes the next integration faster and the next deal simpler. When the signals are clear, the market rewards the supply that made them that way. Red Volcano is here to help you get there faster, with the discovery, taxonomies, and monitoring that keep your seller-defined context both accurate and actionable.