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MPEG-DASH Conformance and Reference Software


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MPEG-DASH Conformance and Reference Software

  1. 1. MPEG-DASH Conformance and Reference Software ISO/IEC 23009-2 Christian Timmerer Alpen-Adria-Universität Klagenfurt (AAU)  bitmovin GmbH   , 105th MPEG Meeting, Vienna, Austria July 2013
  2. 2. Outline • Introduction and overview • Media presentation conformance • DASH access client reference software: libdash • Sample software – Clients: sample player, GPAC – Segmenter: MP4Box • Summary July 2013 2Christian Timmerer (AAU/bitmovin)
  3. 3. Introduction • Conformance and reference software of MPEG-DASH serves three main purposes: – validation of the written specification; – clarification of the written specification; and – conformance testing for checking interoperability for the various applications against the reference software which aims to be compliant with ISO/IEC 23009 • ISO/IEC 23009-2: media presentation conformance, test vectors, DASH access engine reference software, sample software July 2013 3Christian Timmerer (AAU/bitmovin)
  4. 4. Overview • Media presentation conformance – MPD validator: xlink, schema validation, add’l validation rules – Segment conformance: check ISOBMFF, M2TS against DASH specification – Dynamic service validator: dynamic updates of the MPD • DASH conformance sequences • DASH access client reference software – libdash: access to information contained in the MPD + schedule download of segments • Sample software – Sample player: utilizes libdash, GUI, manual adaptation logic – GPAC player: integrated player or embeddable DASH engine – MP4Box segmenter: create segments + MPD based on encoded content July 2013 4Christian Timmerer (AAU/bitmovin)
  5. 5. MPD Conformance Free online MPD validation service accessible at July 2013 5Christian Timmerer (AAU/bitmovin) Resolves all W3C XLINK attributes as defined in MPEG-DASH Part 1 Performs the XML validation (i.e., well-formed and valid) against the MPD schema as defined in W3C XML and W3C XML SCHEMA Performs the Schematron validation as defined in ISO/IEC 19747-3 according to the rules defined in MPEG-DASH Part 2
  6. 6. libdash • MPEG-DASH Part 1 defines XML-based MPD and segment formats (M2TS, ISOBMFF) – MPD reflects the DASH data model providing HTTP URLs to downloadable segments • Adaptation logic is deliberately excluded from the specification and left open for industry competition • libdash provides the following features: – Object-oriented interface into the MPD – Access information within MPD and schedule download of segments – External interfaces: DASH streaming control (incl. adaptation logic), segment parser, media player – deliberately not implemented: may vary across use cases, deployments, and go beyond what is normatively specified • libdash has full standard support, well-defined interfaces, and enables integration within a media ecosystem ➜ libdash is an enabler! July 2013 7Christian Timmerer (AAU/bitmovin)
  7. 7. Sample Player • Qt-based cross-platform GUI + ffmpeg based on libdash • Works with conformance bitstreams, DASH-IF test vectors, and major DASH datasets July 2013 Christian Timmerer (AAU/bitmovin) 8 Select available MPDs Video content Download MPD, start/stop streaming Interactive seamless switching of AdaptationSets and Representations Segment, frame, audio, video buffer
  8. 8. GPAC Players for DASH • Open Source project • Integrated player or embeddable DASH engine – Multi-platform: desktop, mobile – Playback of a very large subset of DASH conformant content • M2TS and ISOBMFF segments • "static" or "dynamic" presentations • Live, Main, OnDemand and Simple profiles – Support for quality changes • Interactively or automatically (bandwidth estimation and limitation) July 2013 9Christian Timmerer (AAU/bitmovin)
  9. 9. GPAC MP4Box for Segmenting • Conformant generation of – Media files (ISOBMFF, M2TS) – MPD (all profiles) • Support for several MPD syntax options – SegmentList, SegmentTemplate, SegmentTimeline • Automatic mapping of the inputs into adaptation sets, representations, groups, assignment of roles – Based on the content characteristics • Flexible generation of segments and subsegments with possible indexing, RAP alignment, and bitstream switching features • Generation of "dynamic" MPD and segments and updates from pre-recorded content July 2013 10Christian Timmerer (AAU/bitmovin)
  10. 10. Summary • MPEG-DASH conformance and reference software available and accessible via MPEG SVN repository – Includes conformance bitstreams for MPDs, segments, and combinations thereof – libdash + sample player: – GPAC: • Additional useful resources – DASH dataset ( full-length movies w/ different segment sizes, spatial resolutions, bitrates, and genre – Distributed DASH dataset ( one dataset distributed across seven sites (Klagenfurt, Paris, Prague, Torino, Crete, Delft, Taiwan), usage of multiple BaseURL elements – DASH Industry Forum ( DASH-AVC/264 interoperability points, identifier repository, reference client (dash.js,, sample players, clients July 2013 11Christian Timmerer (AAU/bitmovin)