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Extensions for Hybrid Delivery using MPEG-2 TS and DASH

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Slides presented during the 102nd MPEG meeting, October 2012, presenting some ideas for the hybrid delivery (DASH over IP/ MPEG-2 TS over non-IP networks) of multimedia content.

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Extensions for Hybrid Delivery using MPEG-2 TS and DASH

  1. 1. m26903Extensions for Hybrid Delivery using MPEG-2 TS and DASH Jean Le Feuvre Cyril Concolato {lefeuvre, concolato} @ telecom-paristech.fr
  2. 2. Context ■ Connected TVs and STBs • But dedicated services: broadcast or broadband ■ Existing broadcast Infrastructure • MPEG-2 TS based ■ New services • 3DHD, UD, UHD, FVP, … • Need more bandwidth • May not target 100% of the deployed TVs/STBs − Broadcasting all data too costly1 1/15/2013
  3. 3. Goals ■ Enhance existing broadcast • Media replacements − Audio, subtitles, … • Scalable enhancements − AVC 1080p broadcast + HEVC Scalable 4K − 3D: AVC 1080p broadcast + MVC or other AVC right view ■ Without impacting existing broadcast infrastructure • StatMux or other equipments ■ Use DASH for delivery of enhancements • MPD covers most of the use cases − Alternative, scalability, BR adaptation, … • But misses − Description of broadcast TS in MPD − Description of TS « MPD timing » – Need frame-accurate timing for scalable-based services2 1/15/2013
  4. 4. Problem #1: Find the MPD ■ Out-of-band (out of TS) signaling • How does a STB locate the MPD? − Likely complex & out of scope: less interoperable • Need identifier for − TS program − Potentially TS Mux ID, tuner params (T or S) … ■ In-band signaling • Send MPD Location (URL) − Lighter than sending the MPD … • OPT1: MPD associated with a mux − Needs program identifier  • OPT1: MPD associated with a program − DONE !3 1/15/2013
  5. 5. Problem #2: Describe in MPD ■ Existing Tools • DVB triplets and co − Hard to use in non-DVB world ■ Define new scheme • pid:// or similar to identify a PID in a program − Scheme pid:// already used in 4on2 • Use scheme in MPD URL describing the TS representation(s) • Maybe not elegant but PIDs are usually static ■ Brodacasted TS not « segmentable » • Can’t use SegmentList or SegmentTemplate • Single segment running « forever » − Use SegmentBase4 1/15/2013
  6. 6. Problem #3: Find the TS « MPD Timing » ■ Using PCR & PTS • How to handle discontinuities? • PCR can be modified by network equipements ■ Fingerprinting & co • Complex • Accuracy ~10ms − Not for scalable-based services… ■ Recovery from UTC info in TS • TDT, … − From other SBOs … • Table insertions not accurate enough − Up to 2s drift on french DVB-T networks ■ Send the media time • PES data streaming • Associate media timeline to PES PTS5 1/15/2013
  7. 7. Problem #4: Latencies ■ Classic Hybrid Delivery issues • Broadcast is real-time live − Pausing live for buffering not desired • Broadband is onDemand − Latency in delivery ■ Provide some hints • Enable prefetching of broadband media for each new event − Period anouncements6 1/15/2013
  8. 8. Proposal Overview7 1/15/2013
  9. 9. Proposal ■ MPD URL in PMT through Descriptor ■ URL scheme PID:// to identify PIDs in MPD ■ TS « MPD Timeline » PES data streaming • Presentation time: media timeline associated to PES MPT (in seconds) = (PTS - PTS0 )/90000 + (MPT0 - @presentationTimeOffset)/SegmentBase.timescale • PeriodID: indicate the ID of the current period or the following period • Period_switch_time: indicate time when this periodID becomes the current one − Allows prefetch8 1/15/2013
  10. 10. Example <Period> <AdaptationSet …> <Representation id="R1" codecs="avc1.4D401F" mimeType="video/mp2t" > <SegmentBase media="pid://110" timescale=”25000”/> </Representation> <Representation id="R11" dependencyId="R1" > </Representation> </AdaptationSet> <AdaptationSet mimeType="video/mp2t" codecs="mp4a" …> <Representation id="R2"> <SegmentBase media="pid://120" timescale=”25000”/> </Representation> </AdaptationSet> </Period>9 1/15/2013
  11. 11. Questions ?

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