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

Video PES PCRs Audio PES MPEG-1 Level 2 (Musicam)

• r Dolby AC-3 5.1 Surround

Audio Elementary Stream

Packetization into MPEG-2 TS

• 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.

MPEG-2 Transport Stream Mux Video Encoder Audio Encoder

MPEG-2 or H.264 SDTV or HDTV Video Elementary Stream

Packetizer

Video Input Audio Inputs

Packetizer

Audio PES Network

Additional or alternate audio tracks Optional application data PAT (PID=0) & PMT

27 MHz clock Timing Information

Preamble illustration

Program 2 PID 20 Program 3 PID 30 … P A T

MPEG-2 Video PID 21 MPEG-1 L2 Audio 1 PID 24 MPEG-1 L2 Audio 2 PID 25

P M T

H.264 Video PID 31 Dolby AC3 Audio PID 34 CA_desc sys_id PID 32

P M T C A T

PAT Prog 2 PMT Prog 3 PMT CAT EMM Prog 2 Video Prog 3 Video Prog 2 Audio 2 Prog 3 Audio Prog 2 Audio 1 CA_system_ID EMM_PID 7 Prog 2 Video Prog 2 Audio 1

PID 1 7 32 30 24 21 25 34 31 21 24 ...

CAT always PID 1 PAT always on PID 0 ECM

20 Time

Preamble TSes are delivered repeatedly and dispersed among

• ther TSes

Preamble Acquisition and Cache

PMT PMT PAT PAT PAT

Retransmission Server

MPEG2-TS Parser … …

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 ing preamble New defined RFC4588 Requirement of RR Post-processing None 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)

Thank You