RTSP in Stagefright (1)

RTSP support was added into Stagefright on GingerBread release:

• A preliminary foundation module, provides a generic way to asynchronously handle commands and events/messages sequentially in the schedule thread. Each message has a target id, indicating its corresponding handler, which is then registered in a looper. A looper spawns a thread, and schedules registered handlers to process any messages posted to it.
• ARTSPController acts as MediaExtractor for RTSP playback, which then delegates RTSP related stuff to ARTSPConnection, and payload parsing related to ARTPConnection/ARTPSource. ARTPSource leverages ARTPAssembler to re-assemble RTP packets to frames. AAMRAssembler, AH263Assembler, etc. all inherit from ARTPAssember according to the corresponding protocols. Buffers parsed are sent back via AMessage and queued in APacketSource, which acts as the MediaSource for downstream components.
• There is also ARTPSession and ARTPWriter which re-uses the existing RTP protocol for VOIP(Gtalk?) solution.