SDP ensures that receivers know the nature of all flows arriving through the IP port.
SDP is a protocol that describes communications parameters for streaming media for the purpose of session announcement, session invitation, and parameter negotiation.
Allows end points to negotiate media type, format, and all associated properties, which is called a session profile. SDP provides the information between senders and receivers in multiple applications, and primarily for media applications, including mobile networks.
SAP protocol is found on the Application Layer
SDP protocol is found on the Application Layer
Video, audio and metadata flows are located on the Transport Layer.
SDP is communicated within the SIP framework and, as an application, configures flows on the transport layer.
Streams contain intrinsic information such as video format, frame rate, colorimetry, etc.
The control application acquires the desired stream’s SDP file in order to read the provided information description. The control system acquires the SDP file from the sender and sends it to the receiver. One SDP file is present for each flow. Typically the sender will have six (6) SDP files: one (1) for the video flow, four (4) for the audio flows and one (1) for the metadata flow.
To acquire the SDP file, the control system can use the UID to obtain the associated SDP files from the flows. The control system will then build the SDP table (which will include the SDP file information for each device) for each sender. Optionally the files for the receiver can be obtained also.
Video/audio/medatada are typically transported on the same physical network called the media network. Control can also be transported inside the media network -as in-band network- or it can be sent over a different network typically called control network.
It is the control system’s responsibility to maintain an up-to-date SDP. For example, if the format of the source of the encapsulator changes, the control system should implement a mechanism to obtain the new SDP from the encapsulator. Some senders will send a SAP message automatically if something has changed on the sender in order to readapt in consequence. SAP allows a constant update process between the two.
