Preamble Acquisition of MPEG-TS Multicast Sessions - PowerPoint PPT Presentation

Preamble Acquisition of MPEG-TS Multicast Sessions draft-xia-avt-mpeg2ts-preamble-00.txt Frank Xia Xingfen Wu Presented by Peilin Yang

Packetization into MPEG-2 TS Timing Information 27 MHz clock MPEG-2 or H.264 PCRs SDTV or HDTV Video Video Video Video Elementary Stream PES Input Encoder Packetizer MPEG-2 MPEG-1 Level 2 (Musicam) Transport Audio or Dolby AC-3 5.1 Surround Network Stream Audio PES Audio Audio Elementary Stream Packetizer Inputs Encoder Mux Audio PES Additional or alternate audio tracks Optional application data PAT (PID=0) & PMT • Transport Stream defined by ISO/IEC 13818-1 or ITU-T H.222.0 • Preamble is necessary reference information which must be acquired before demux/decoder starts to process any data, e.g PAT, PMT.

Preamble illustration PAT always on PID 0 P Program 2 PID 20 A Program 3 PID 30 T … C CAT always PID 1 P MPEG-2 Video PID 21 H.264 Video PID 31 P A M CA_system_ID MPEG-1 L2 Audio 1 PID 24 Dolby AC3 Audio PID 34 M T EMM_PID 7 T T MPEG-1 L2 Audio 2 PID 25 CA_desc sys_id PID 32 Prog 2 Prog 3 Prog 2 Prog 2 Prog 2 Prog 3 Prog 3 Prog 2 Prog 2 PAT CAT EMM ECM PMT PMT Audio 1 Video Audio 2 Audio Video Video Audio 1 24 ... 0 0 20 30 1 7 24 21 25 32 34 31 21 PID Time Preamble TSes are delivered repeatedly and dispersed among other TSes

Preamble Acquisition and Cache Retransmission Server MPEG2-TS Parser PMT PMT PAT PAT PAT … … MPEG Data Cache for Channel #8 • MPEG2-TS Parser in RS extracts and caches TSes with preamble information • These preamble TSes are packed into new created RTP packets which are sent to a RTP receiver prior to unicast burst

Comparison of the two alternatives begen-avt-rtp-mpeg2ts-preamble xia-avt-mpeg2ts-preamble Format for carry New defined RFC4588 ing preamble Requirement of Post-processing None RR Advantage Flexibility Simplicity The preamble TSes sent from RS are the same as the TSes after RR’s post processing

Mailing list discussion highlights Q: Is it a misuse RFC4588 for carrying preamble? A: RFC4588 reads “ RTP retransmission is an effective packet loss recovery technique for real-time applications with relaxed delay bounds ”. RAMS is not a retransmission solution as specified in RFC4588. This draft shares the same justification as RAMS to use RFC4588 format. Q: How to set OSN field when RFC4588 is used? A: Preamble RTP packet is sent prior to the burst. 1st preamble packet (SN: 2000 - OSN: 99) 1st burst packet (SN: 2001, OSN: 100) 2nd burst packet (SN: 2002, OSN: 101)

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