The CTV supply chain explained: from content owner to advertiser impression

Step 1: The viewer presses play

A viewer opens JioCinema on their Android TV and starts watching an IPL match. The JioCinema app on the TV device begins streaming video to the screen. The content is delivered from JioCinema's content delivery network (CDN) — a distributed network of servers that caches video content close to the viewer to minimise buffering.

At the same time, JioCinema's ad server is aware that this viewing session has started and begins preparing for the first ad break. The viewer's session metadata — device type (Android TV), location (city-level at minimum), viewing context (live sport), account tier (free or paid) — is available to inform the ad auction.

Step 2: The publisher creates an ad opportunity

When an ad break is approaching — in live content, this is often a scheduled break; in VOD content, it may be a pre-roll before the programme starts or mid-rolls at defined intervals — JioCinema's ad server generates a bid request.

The bid request is a packet of information sent to the demand side describing the available ad opportunity. It typically includes:

• Impression details: video player size, ad slot position (pre-roll, mid-roll), required ad duration (15s, 30s)
• Content context: content category, programme type, live vs VOD
• Audience signals: device ID (anonymised), location (city/state level), device type (CTV), viewing history signals (where available)
• Floor price: the minimum CPM the publisher will accept for this impression
• Deal IDs: if the publisher has private marketplace (PMP) deals with specific buyers, those deal IDs are included so eligible DSPs can participate

For JioCinema and other premium India CTV publishers using server-side ad insertion (SSAI), this bid request is generated at the ad stitching server level — not by the app on the viewer's device. This is an important technical distinction that affects third-party measurement.

Step 3: The auction runs

The bid request is passed to the publisher's SSP (supply-side platform). The SSP broadcasts the bid request to connected DSPs — potentially dozens simultaneously — and collects bids. This entire process happens in real time, typically within 100–200 milliseconds, before the ad break begins.

DSP bidding

Each connected DSP receives the bid request and evaluates it against active campaigns. For a given bid request, the DSP asks:

• Does any active campaign target this impression type (CTV, JioCinema, India, relevant audience segment)?
• What is the maximum CPM this campaign should bid for this impression?
• Has this device ID been seen recently — should frequency capping prevent another impression?
• Are there any brand safety restrictions that exclude this content type?

If an active campaign matches, the DSP submits a bid with the CPM it is willing to pay. If no campaign matches, the DSP returns a no-bid.

Auction mechanics

Most programmatic CTV auctions run on a second-price model (the winner pays the second-highest bid plus one cent) or a first-price model (the winner pays their actual bid). The industry has largely shifted to first-price auctions in recent years. The SSP collects all bids from connected DSPs, identifies the highest bid above the floor price, and declares a winner.

For JioCinema and other India walled gardens, the auction may be a private marketplace (PMP) or programmatic guaranteed (PG) deal rather than open auction — meaning only pre-approved buyers participate, often at negotiated prices.

Step 4: Ad delivery

The winning DSP's ad creative is retrieved and delivered to the viewer. How this happens depends on whether the publisher uses client-side ad insertion (CSAI) or server-side ad insertion (SSAI).

Client-side ad insertion (CSAI)

In CSAI, the video player on the viewer's device makes a separate request to the ad server to fetch and play the ad. The ad loads from a different CDN than the content, and the viewer's device assembles the content and ad streams together. CSAI allows the ad server to be called directly by the device, enabling standard VAST tracking and third-party measurement pixels to fire. However, it can cause buffering between content and ad (the black-frame pause before the ad starts) and is vulnerable to client-side ad blocking.

Server-side ad insertion (SSAI)

In SSAI, the ad is stitched into the video stream at the server — before it is delivered to the viewer's device. The viewer's TV receives a single, continuous video stream that includes both content and ads seamlessly. From the device's perspective, there is no separate ad request — the entire stream looks like content. This eliminates buffering between content and ads and removes client-side ad blocking as a risk.

The tradeoff: with SSAI, third-party measurement pixels cannot be fired by the viewer's device in the same way as CSAI. Ad verification and viewability measurement vendors have developed SSAI-compatible measurement methods, but coverage is less complete than for client-side delivery. This is a known measurement gap in India CTV — JioCinema and Hotstar use SSAI, which limits what third-party measurement can verify directly.

Step 5: Impression tracking and measurement

Once the ad plays, the impression needs to be counted, tracked, and attributed. This involves multiple systems:

VAST tracking

CTV video ads use the VAST standard (Video Ad Serving Template) — an XML specification that defines how ads are requested, delivered, and tracked. VAST includes tracking events: impression (ad starts playing), first quartile (25% viewed), midpoint (50%), third quartile (75%), complete (100%), and click. These tracking pixels are fired by either the device (CSAI) or the SSAI stitching server (SSAI) at each event.

Campaign ad server measurement

The buying DSP's campaign ad server (e.g., Campaign Manager 360 for DV360 buyers) records the impression and tracking events for campaign measurement — reach, frequency, video completion rate (VCR), and where applicable, conversion events.

Third-party verification

For campaigns with brand safety, viewability, or invalid traffic measurement requirements, third-party verification vendors (DoubleVerify, IAS) are integrated into the delivery chain. Their tracking pixels fire alongside the VAST events. In SSAI environments, this requires the publisher to explicitly support the verification vendor's tracking method — not all India CTV publishers do.

Publisher-reported metrics

In parallel, the publisher (JioCinema, Hotstar) records the impression in its own reporting system. Advertisers in India typically receive two sets of numbers: the DSP's count and the platform's count. Discrepancies between these counts are common — typically 5–15% — and reconciling them is a standard part of India CTV campaign management.

The India supply chain: key differences

• Walled garden access: For JioCinema and Hotstar, the supply chain described above is partially accessible through programmatic channels but much of the premium inventory — live sport, prime-time VOD — is sold direct or through PMP deals, not open auction.
• SSAI dominance: Both major India CTV publishers use SSAI. Third-party measurement is limited by design. Advertisers must rely more heavily on platform-reported metrics than in markets where CSAI is more prevalent.
• Inventory bundling: India CTV platforms frequently bundle mobile and desktop inventory into CTV deals. Advertisers who want pure CTV (TV screen only) need to specify this explicitly and verify device-type reporting in campaign data.
• No universal currency: There is no cross-platform impression measurement currency in India CTV. Each platform counts differently. Advertisers building cross-platform reach curves for CTV campaigns in India are working with imperfect data.