Session Description Protocol • Essential for SMPTE ST 2110
An SDP file is a plain-text file that uses the Session Description Protocol (SDP). It is a standardized format (originally defined in IETF RFC 4566) that describes the parameters needed to set up and participate in multimedia communication sessions.
SDP does not carry the actual media (audio, video, or data). Instead, it acts like a blueprint that tells devices exactly how to interpret and connect to a media stream.
SDP files are simple text with one parameter per line in the format x=value:
v=0
o=- 3826217993 3826217993 IN IP4 10.10.10.10
s=ST 2110 Example Stream
t=0 0
m=video 50000 RTP/AVP 96
c=IN IP4 239.1.1.1
a=rtpmap:96 H.265/90000
a=fmtp:96 sampling=YCbCr-4:2:2; width=1920; height=1080
m=audio 50004 RTP/AVP 97
c=IN IP4 239.1.1.2
a=rtpmap:97 L24/48000/2
In professional broadcast and media production, SDP files are a core component of SMPTE ST 2110 — the standard for transporting uncompressed (or lightly compressed) video, audio, and ancillary data over IP networks.
Each media essence (video, audio, or data) is sent as a separate IP flow. An SDP file tells receiving devices exactly how to decode and synchronize these flows using precise timing (often with PTP).
By the year 2110, SDP (or its evolved versions) is expected to remain the lightweight, reliable way to describe professional media sessions in broadcast facilities, live production, and advanced IP-based media infrastructure.
SDP files usually have the .sdp extension. They can be opened in any text editor, shared via HTTP, embedded in SIP messages, or used by media infrastructure controllers.
Tools like Wireshark can analyze them easily, and most modern broadcast equipment can generate or consume them automatically.
