Real-time bidding (RTB) in CTV works on the same OpenRTB protocol as display and mobile programmatic — a bid request sent from an SSP to connected DSPs, bids returned within a fixed timeout, a winning bid determined, and a VAST tag returned to the publisher's ad server. The mechanics are identical to display RTB. The differences are in timing constraints, the signals available in the bid request, the auction structure used by India CTV publishers, and the relationship between RTB and SSAI delivery. Understanding these differences is what separates a buyer who gets CTV RTB right from one who sees unexplained delivery shortfalls.
The CTV RTB auction sequence
Step by step, from ad break trigger to ad delivery:
- Ad break triggered: The CTV publisher's video player or SSAI server detects an upcoming ad break (pre-roll, mid-roll) and initiates an ad request.
- SSP sends bid request: The publisher's SSP (Magnite, PubMatic, SpringServe) constructs an OpenRTB bid request containing inventory signals — app name and bundle ID, content genre and category, device type, IP address, any available audience data — and sends it to connected DSPs simultaneously.
- DSPs evaluate and respond: Each DSP's bidder evaluates the bid request against active campaigns, runs audience matching, applies frequency caps, and returns a bid response with a CPM price and a VAST tag URL. DSPs that don't match any active campaign return a no-bid response.
- SSP runs the auction: The SSP collects all bid responses within the timeout window (typically 200ms for CTV), runs a first-price or second-price auction, and selects the winning bid.
- Winning VAST tag delivered: The SSP returns the winning VAST tag to the publisher's ad server or SSAI system. The ad creative is fetched and delivered to the viewer's device.
How CTV RTB differs from display RTB
The key operational differences:
- Tighter timing tolerance: CTV ad breaks have no tolerance for latency — if the RTB auction doesn't complete before the content gap, the viewer sees a blank screen or the break is skipped. The practical auction window is 150–200ms, same as display, but creative fetch and VAST processing add additional time that display doesn't require. SSAI mitigates this by pre-fetching creatives server-side before the break point.
- No cookies: CTV devices don't have browser cookies. Audience targeting relies on device advertising IDs (Android TV's AAID, Samsung Tizen's TIFA), IP-based household matching, and first-party publisher data passed in the bid request. This reduces the available signal for retargeting and custom audience segments compared to display.
- First-price auctions are standard: India CTV publishers on Magnite and PubMatic transact at first price. There is no second-price discount — buyers pay what they bid. Bidding strategy for CTV therefore requires active bid price optimisation; the DSP's automated bidding algorithms must be configured to account for first-price dynamics.
- Pod bidding complexity: CTV ad pods (3–4 ads in a commercial break) require the SSP to run multiple auctions sequentially and enforce competitive separation (same advertiser can't appear twice in a pod). This adds coordination complexity not present in display RTB.
CTV bid request signals
The OpenRTB bid request for CTV includes signals that display bid requests don't carry, and lacks some that display does:
- Content object: Genre, series, episode, content rating. Allows buyers to target by content type — sports vs drama vs news. JioHotstar and SonyLIV pass rich content metadata; FAST channels often pass minimal content data.
- Device type: CTV device type (7 in OpenRTB), distinguishing from mobile (1) and desktop (2). Essential for CTV-specific targeting.
- App bundle ID: The publisher's app identifier (e.g., com.jiocinema.android). Buyers use app allowlists in DV360 to restrict buys to verified India CTV app IDs, reducing IVT exposure.
- Livestream flag: Whether the content is live (IPL, news) vs on-demand. Livestream inventory commands premium CPMs and has different frequency dynamics.
- No user agent string: Unlike browsers, CTV apps don't pass a user agent. Device identification relies on the device's advertising ID and the app bundle ID.
RTB for India CTV buyers
Practical implications for India programmatic CTV buying:
- Open auction CPMs in India are low but fill rates are uncertain. India CTV open auction CPMs range Rs 150–400. But without app-list filtering, open auction buys include fraudulent and low-quality inventory alongside premium. The fill rate on legitimate premium inventory is lower than the headline impression volume suggests.
- PMP deals provide price certainty and quality control. A PMP deal with JioHotstar or SonyLIV through Magnite guarantees app ID, content category, and floor price. For brand campaigns, PMP is significantly preferable to open auction even at a 30–50% CPM premium.
- Bid timeout management: India broadband variability means SSAI systems and ad servers sometimes miss the 200ms bid window. DSP logs showing high timeout rates on CTV indicate a publisher-side latency issue — raise it with the publisher's ad ops team rather than increasing bid prices.
- First-price bidding strategy: In DV360, set a target CPM below the maximum bid to allow the automated bidder to optimise. Bidding at max CPM on all impressions overpays on impressions that clear at much lower prices — a significant waste in first-price auctions.