DLNA & Streaming Glossary — UPnP, SSDP, HEVC and More

Protocols & UPnP

DLNA: Digital Living Network Alliance — a legacy set of interoperability guidelines for sharing media over a local network. Its last guidelines (HNv2, 2014) constrained UPnP AV, HTTP and codecs. The organisation dissolved in 2017, but DLNA-compatible TVs still implement the same UPnP substrate today.
UPnP: Universal Plug and Play — the protocol suite DLNA profiles build on. It defines how devices discover each other (SSDP), describe themselves, and issue control actions over HTTP.
SSDP: Simple Service Discovery Protocol — the multicast UDP discovery layer of UPnP. A server advertises itself with NOTIFY messages, and clients search with M-SEARCH. If a TV cannot find a server, SSDP multicast is usually the reason.
DIDL-Lite: Digital Item Declaration Language, Lite — the XML format a UPnP ContentDirectory server returns in a Browse response. It describes each media item and folder (container) the client can select.
SOAP: Simple Object Access Protocol — the XML-over-HTTP envelope used for UPnP control actions such as Browse. Zee Cast answers these on /ContentDirectory/control.
ContentDirectory Service (CDS): The UPnP AV service that exposes a media library as a browsable tree of containers and items. This is what a TV reads when it lists your Zee Cast collections.
AVTransport: The UPnP AV service that controls playback on a renderer — play, pause, stop and seek. It is what makes remote-control scrubbing possible.
HTTP byte-range request: An HTTP/1.1 feature (RFC 7233 / RFC 9110) that lets a client request just the bytes it needs from a file. It is why a TV can start playing instantly and seek anywhere without downloading the whole video.
Direct Play: Serving the original media file to the renderer with no transcoding. Zee Cast Direct Plays by default, so the TV's own hardware decoder does the work at full quality.

Media & codecs

H.264 (AVC): The near-universal video codec. Every smart TV and phone decodes it, so it is the safest fallback — but it needs the most bitrate for a given quality.
HEVC (H.265): High Efficiency Video Coding — roughly 50% more efficient than H.264 at the same quality. Hardware decode is common on TVs from 2016 onward. iPhone and Android HDR video is typically HEVC.
AV1: A royalty-free codec that compresses better than HEVC, but hardware decode is still inconsistent on smart TVs in 2026. Useful for streaming services; not yet a safe bet for local playback on every TV.
Dolby Vision: A dynamic HDR format that carries per-scene brightness metadata. iPhones record it as Profile 8.4, which includes a backwards-compatible HLG base layer so non-Dolby TVs still show HDR.
HDR10+: A dynamic HDR format layered on the static HDR10 base. Used by Samsung and some others; not the same as Dolby Vision.
HLG: Hybrid Log-Gamma — an HDR format with an SDR-compatible base layer. It is the fallback layer inside iPhone Dolby Vision Profile 8.4.
HEIC: High Efficiency Image Container — Apple's default photo format. Many DLNA TVs cannot decode it, so Zee Cast's iOS build serves a JPEG compatibility stream.
Bitrate: How much data a video uses per second (Mbps). A 4K HDR stream typically needs only 15–25 Mbps; phone-captured 4K 60fps can peak above 100 Mbps.
Rec. 2020 / Rec. 709: The colour spaces for HDR (Rec. 2020, 10-bit, wide gamut) and SDR (Rec. 709, 8-bit). Screen mirroring often truncates Rec. 2020 to Rec. 709, causing colour banding.

Networking

AP isolation: Also called client isolation. A router setting that blocks devices on the same Wi-Fi from reaching each other. It is a frequent cause of a TV never seeing a media server — common on guest and hotel networks.
Multicast: One-to-many delivery where a single packet reaches a group of devices. SSDP discovery depends on it, and some networks filter multicast traffic.
Personal Hotspot: The phone's own Wi-Fi network. It creates a local network with no AP isolation, so a TV can join it and reach Zee Cast even with no internet — ideal for hotels and travel.
Captive portal: The sign-in web page a hotel or café network shows before granting internet. TVs often cannot complete it, which is why a Personal Hotspot bypasses the problem entirely.
MLO (Wi-Fi 7): Multi-Link Operation — Wi-Fi 7's ability to use several bands at once for stability. It helps in busy homes, but needs a Wi-Fi 7 router and Wi-Fi 7 client to matter.
Wi-Fi 6 / 6E / 7: Successive Wi-Fi generations. Wi-Fi 6 adds efficiency; 6E opens the 6 GHz band; 7 adds 320 MHz channels and MLO. For a single 4K stream, Wi-Fi 5 or 6 is already enough.
Band steering: A router feature that pushes devices between 2.4 GHz and 5 GHz. If it moves a phone and a TV to different bands, discovery between them can fail.

Put it into practice

These terms all describe one idea: your phone can serve the original file to a TV over your own network, with no cloud and no re-encoding. See the setup guides for the TV you own, or readhow we test the claims on this site.