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DVB AL-FEC Hybrid FEC Protection draft-begen-fecframe-dvb-al-fec-00 IETF 72 – July 2008

DVB AL-FEC Hybrid FEC Protection draft-begen-fecframe-dvb-al-fec-00 IETF 72 – July 2008. Ali C. Begen and Thomas Stockhammer abegen@cisco.com, stockhammer@digitalfountain.com. Introduction. DVB AL-FEC protocol uses two layers of protection: Base layer: 1-D Interleaved Parity FEC Code

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DVB AL-FEC Hybrid FEC Protection draft-begen-fecframe-dvb-al-fec-00 IETF 72 – July 2008

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  1. DVB AL-FEC Hybrid FEC Protectiondraft-begen-fecframe-dvb-al-fec-00IETF 72 – July 2008 Ali C. Begen and Thomas Stockhammer abegen@cisco.com, stockhammer@digitalfountain.com

  2. Introduction • DVB AL-FEC protocol uses two layers of protection: • Base layer: 1-D Interleaved Parity FEC Code  draft-begen-fecframe-interleaved-fec-scheme • Enhancement layer: Raptor Code  draft-watson-fecframe-raptor • Both layers are systematic codes • The target source can be audio, video, text or application • The spec is available in ETSI TS 102 034 (Annex E)

  3. DVB AL-FEC Encoder +--------------+ +--+ +--+ +--+ +--+ --> | Systematic | -> +--+ +--+ +--+ +--+ +--+ +--+ +--+ +--+ |FEC Protection| +--+ +--+ +--+ +--+ +--------------+ | Parity | -> +==+ +==+ +==+ | Encoder | +==+ +==+ +==+ +--------------+ | Raptor | -> +~~+ +~~+ | Encoder | +~~+ +~~+ +--------------+ Source Packet: +--+ +--+ Base-layer Repair Packet: +==+ +==+ Enhancement-layer Repair Packet: +~~+ +~~+

  4. DVB AL-FEC Decoders Minimum Performance Decoder: +--------------+ +--+ X X +--+ --> | Systematic | -> +--+ +--+ +--+ +--+ +--+ +--+ |FEC Protection| +--+ +--+ +--+ +--+ +--------------+ +==+ +==+ +==+ --> | Parity | +==+ +==+ +==+ | Decoder | +--------------+ Enhanced Decoder: +--------------+ +--+ X X +--+ --> | Systematic | -> +--+ +--+ +--+ +--+ +--+ +--+ |FEC Protection| +--+ +--+ +--+ +--+ +--------------+ +==+ +==+ +==+ --> | Parity | +==+ +==+ +==+ | Decoder | +--------------+ +~~+ +~~+ --> | Raptor | +~~+ +~~+ | Decoder | +--------------+ Lost Packet: X

  5. Hybrid Decoding • Perform parity decoding • Are all missing packets recovered? • Yes  Done • No  Go to step 2 • Perform Raptor decoding • Are all missing packets recovered? • Yes  Done • No  Go to step 3 • Convert the unprocessed parity repair packets to a form in which they can be added to the Raptor decoding process and continue decoding

  6. SDP Example v=0 o=ali 1122334455 1122334466 IN IP4 fec.rocks.com s=DVB AL-FEC Example t=0 0 a=group:FEC S1 R1 R2 m=video 30000 RTP/AVP 100 c=IN IP4 224.1.1.1/127 a=rtpmap:100 MP2T/90000 a=fec-source-flow: id=0 a=mid:S1 m=application 30000 RTP/AVP 110 c=IN IP4 224.1.2.1/127 a=rtpmap:110 1d-interleaved-parityfec/90000 a=fec-repair-flow: encoding-id=10; ss-fssi=L:5 D:10 a=repair-window: 200 a=mid:R1 m=application 30000 RTP/AVP 111 c=IN IP4 224.1.3.1/127 a=rtpmap:111 raptor-fec/90000 a=fec-repair-flow: encoding-id=11; ss-fssi=qwe123 a=repair-window: 200 a=mid:R2

  7. Next Steps • Shall we make this draft a WG item?

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