Question: What is the primary condition for removing an original UDP packet from the hypothetical FEC decoding buffer, after the signaled initial buffering delay has expired?
Option 1: When all packets in the same FEC source block have been transmitted and the buffer occupancy level reaches its maximum size.
Option 2: Immediately after the initial buffering delay expires, without considering packet sequence or transmission timing.
Option 3: After a specific time elapsed since the removal of the previous packet, calculated based on the packet size and the stream's bitrate specification.
Option 4: When an FEC repair packet is received for the corresponding FEC source block.
Explanation: According to the hypothetical FEC decoder's operation, after the initial buffering delay expires, original UDP packets are removed and output based on a specific timing condition. This condition involves calculating the elapsed time since the removal of the previous packet, using the size of the previous original UDP packet (including headers) and the stream's bitrate specification. This ensures timely processing, aligned with the stream's specifications.