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Report on the implementation of WebVTT in MP4 in GPAC


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This presentation was made during the MPEG 105th meeting reporting on the implementation of the WebVTT in MP4 support in the GPAC project

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Report on the implementation of WebVTT in MP4 in GPAC

  1. 1. Institut Mines-Télécom Report of WebVTT implementation Cyril Concolato m30301
  2. 2. Institut Mines-Télécom Status  Implementation within GPAC • • 14496-12 • 14496-30  Support for WebVTT packaging with MP4Box  Support for WebVTT playback with MP4Client (& others)  Plan to support next • PlainText (SVG, HTML, …) • TTML (with meta box) – test suite available ? 31/07/2013 GPAC & WebVTT - m303012
  3. 3. Institut Mines-Télécom Packaging into WebVTTCueBoxes  Basic usages MP4Box -add file1.vtt:lang=en subtitle1.mp4 MP4Box -add subtitle2.mp4 • More options (layout, edit list, frame rate change…) • More usages: split, concatenate, export (SRT -> WebVTT) • Problem: 3GPP Text Box for WebVTT ? 31/07/2013 GPAC & WebVTT - m303013
  4. 4. Institut Mines-Télécom DASH and WebVTT and others  Basic usage MP4Box -dash 10000 subtitle.mp4:role=subtitle video.mp4 • Other options (fragment duration …) • Use of redundant samples if necessary • Example ─ Possibility to mix 3GPP Timed Text and WebVTT  Problems • Exposing track layout in MPD for WebVTT is not always useful • Missing ability to store the role in the MP4 file format 31/07/2013 GPAC & WebVTT - m303014
  5. 5. Institut Mines-Télécom Example <Period duration="PT0H10M0.00S"> <AdaptationSet segmentAlignment="true" group="1"> <Role schemeIdUri="urn:mpeg:dash:role:2011" value="subtitle"/> <Representation id="1" mimeType="video/mp4" codecs="tx3g" width="1920" height="1080" startWithSAP="1" bandwidth="391"> <SegmentTemplate timescale="1000" duration="10000" media="counter-tx3g_dash$Number$.m4s" startNumber="1" initialization="counter-tx3g_dashinit.mp4"/> </Representation> </AdaptationSet> <AdaptationSet segmentAlignment="true" group="1"> <Role schemeIdUri="urn:mpeg:dash:role:2011" value="subtitle"/> <Representation id="2" mimeType="video/mp4" codecs="wvtt" width="1920" height="1080" startWithSAP="1" bandwidth="606"> <SegmentTemplate timescale="1000" duration="10000" media="counter-vtt_dash$Number$.m4s" startNumber="1" initialization="counter-vtt_dashinit.mp4"/> </Representation> </AdaptationSet> </Period>31/07/2013 GPAC & WebVTT - m303015
  6. 6. Institut Mines-Télécom Playback of WebVTT in MP4 31/07/2013 GPAC & WebVTT - m303016 MP4 Parser MP4 File (WebVTT) WebVTT Cues JavaScript Conversion (configurable) SVG Tiny 1.2 elements Rendering GPAC Player
  7. 7. Institut Mines-Télécom Playback of WebVTT in MP4  Status • Tested in the following configurations ─ Local file, progressive http download, DASH ─ With or without video • Rendering Feature support ─ Top-based line positioning, bottom-based line positioning, explicit positioning ─ Line wrapping ─ Multiline cues ─ Multiple cues simultaneously ─ Basic text styling: italic, bold, underlined  Problems? • Metadata (name,value) pair ─ Regions? ─ Need for a new box • WebVTTCueSourceIdBox 31/07/2013 GPAC & WebVTT - m303017
  8. 8. Institut Mines-Télécom Demonstration 31/07/2013 GPAC & WebVTT - m303018