Question: In a 3GPP Transparent end-to-end Packet-switched Streaming Service (PSS), what is a requirement for a video stream delivered after content rate adaptation through transmission rate adaptation?
Option 1: The video stream must belong to the SDP announced profile and be consistent with any configuration.
Option 2: The video stream can switch to any alternative encoding without adhering to the initial SDP description.
Option 3: The server must notify the client of a new SDP description before adapting the transmission rate.
Option 4: Content rate adaptation is not applicable for video streams in PSS.
Explanation: This is correct because, according to the transmission adaptation guidelines in PSS, even after content rate adaptation, the delivered media (e.g., a video stream) must still conform to the original Session Description Protocol (SDP) description. This ensures consistency and compatibility with the initially agreed-upon media profiles and configurations, potentially limiting the alternatives or necessitating the declaration of multiple payload types or media encodings upfront.