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.

1. m26903
Extensions for Hybrid Delivery using
MPEG-2 TS and DASH
Jean Le Feuvre
Cyril Concolato
{lefeuvre, concolato} @ telecom-paristech.fr

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 costly
1 1/15/2013

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 services
2 1/15/2013

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. 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 SegmentBase
4 1/15/2013

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 PTS
5 1/15/2013

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 anouncements
6 1/15/2013

8. Proposal Overview
7 1/15/2013

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 prefetch
8 1/15/2013

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. Questions ?