OTT glossary: DRM, SSAI, SVOD, CENC, SCTE-35 & more

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Origin

The authoritative source the CDN pulls content from when a segment is not already cached at the edge.

Origin shield

A mid-tier cache in front of the origin that absorbs edge misses, so a live premiere cannot overwhelm the origin.

OTT (over-the-top)

Delivering video over the open internet, bypassing traditional cable or satellite TV; the umbrella term for streaming services.

Output protection

License rules controlling which outputs and capture paths are allowed, to stop the decrypted picture leaking.

Packager

The component that wraps encoded video into segments and manifests for HLS/DASH and applies encryption.

Paywall

The gate in front of content that requires payment or registration before a viewer can watch.

Per-title encoding

Tuning the encoding ladder to each piece of content instead of using a fixed ladder, to save bitrate and improve quality.

Playout

Assembling content into a continuous, scheduled linear stream - the engine behind a 24/7 channel.

PlayReady

Microsoft's DRM system, used on Windows, Edge, Xbox, and many smart TVs and set-top boxes.

PoP (point of presence)

A physical CDN location full of edge servers, placed near viewers to shorten the path to content.

PPV (pay-per-view)

Paying once to watch a specific live event, such as a boxing match or concert.

Programmatic advertising

Automated, auction-based buying and selling of ad impressions in real time.

PSSH box

Metadata in an encrypted file that tells each DRM system how to obtain the key for the content.

QoE (quality of experience)

How good playback feels to the viewer, measured by startup time, rebuffering, bitrate, and play-failure rate.

Rebuffering

When playback stalls to refill the buffer; the QoE problem most strongly tied to viewer abandonment and churn.

Recommendation system

The engine that predicts what each viewer wants to watch next and orders the catalog around them.

Registration wall

A gate that asks for an account (but not payment) before watching, capturing identity and data.

Rendition

A single rung of the encoding ladder — one resolution and bitrate combination the player can choose.

Request coalescing

Collapsing many simultaneous misses for the same object into a single origin fetch.

Retention

The share of users who keep coming back over time; the inverse of churn and the goal of most analytics.

SCTE-35

The standard for signaling ad-break opportunities inside a stream, telling the system where an ad can be inserted.

Segment

A short slice of the stream, a few seconds long, that the player downloads one at a time over HTTP.

Shaka Player

Google's open-source web player built on MSE and EME, supporting DASH and HLS with DRM.

SSAI (server-side ad insertion)

Stitching ads into the video stream at the server or edge, so ads arrive as part of the stream and resist ad-blockers.

Startup time

How long from press-play to the first frame appearing; a top driver of viewer satisfaction and abandonment.

Subscriber

A viewer with an active recurring payment for access to the catalog; the core unit of an SVOD business.

SVOD (subscription VOD)

The subscription model: viewers pay a recurring fee for unlimited access to the catalog, Netflix-style.

Takedown

The process of getting an infringing stream or copy removed by the host, platform, or network.

Tizen (Samsung TV)

Samsung's smart-TV operating system, a key target platform for OTT apps in the living room.

Tokenized URL

A time-limited, signed link that authorizes a specific viewer to fetch content from the CDN.

Transcoding

Converting a source video into the multiple renditions and codecs the platform needs to deliver to viewers.

TTL (time to live)

How long a CDN may serve a cached object before revalidating it; balances freshness against offload.

TVOD (transactional VOD)

The pay-per-title model: viewers rent or buy individual titles or pay-per-view events.

VAST

The IAB standard an ad server uses to describe a video ad to a player or stitcher (VMAP describes the ad schedule).

Video player

The client software that downloads segments, manages the buffer, switches bitrates, and renders the video.

Video start failure (VSF)

When a requested playback never starts at all; the most severe QoE failure because nothing plays.

VMAF

A perceptual video-quality metric from Netflix that predicts how good an encode looks to human viewers.

VMAP

The IAB standard that describes the ad schedule for a video - which breaks exist and what plays in each.

VOD (video on demand)

A catalog of pre-recorded titles a viewer can start at any time, encoded once and served on request.