Question: For an MBMS (Multimedia Broadcast/Multicast Service) client receiving an H.264 (AVC) stream without an Instantaneous Decoding Refresh (IDR) access unit at the beginning, when should the decoder start decoding?
Option 1: Only after receiving a recovery point SEI message.
Option 2: Immediately upon receiving data or no later than upon receiving the next IDR access unit or the next recovery point SEI message, whichever is earlier in decoding order.
Option 3: After de-interleaving the packets if interleaved packetization mode is detected, regardless of IDR presence.
Option 4: The decoder should wait for a predefined buffer fill period before initiating the decoding process.
Explanation: This option correctly reflects the requirement for MBMS clients handling H.264 (AVC) streams that do not start with an IDR access unit. It aligns with the specified behavior, allowing for immediate decoding initiation upon data receipt or at the latest when a key point (next IDR or recovery point SEI) is reached in the decoding sequence, ensuring flexibility and efficiency in stream processing.