TimedText/IMSC1 Implementation Report

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IMSC 1 Implementation Report

Introduction

This implementation report is now frozen and closed.

Please refer to the IMSC1 Test suite and implementation page for current information.

The following is the implementation report for the IMSC 1 specification based on the IMSC 1 test suite.

This implementation report is used to demonstrate implementation experience for IMSC 1 transition to Proposed Recommendation.

IMSC1 introduces extensions to TTML1, as well as incorporates extensions specified in ST2052-1 and EBU-TT-D. Tests cover every feature defined in IMSC1 not already present in TTML1. Refer to the list of extensions added in IMSC1 in section 6.7, section 6.10, section 7.4, section 8.4 and in Appendix F. [http://www.w3.org/TR/ttml-imsc1/#features-and-extensions

Tests are listed in the table below.

Do not hesitate to direct questions and/or results to the IMSC1 Editor (Pierre-Anthony Lemieux <pal@sandflow.com>) and/or the TTWG mailing list [1] with [imsc] at the start of your email's subject.

Tests

Test Features Description Companies/Implementations
Company-1 GStreamer Prototype (BBC R&D) Green International Consulting (GIC)
<henry.gu at giconline.net>
castLabs GmbH SKYNAV
Implementation-1 Implementation-2 Implementation-3 castLabs Android Player SDK (v2) TTV, TTX, TTXV
Synchronization (Section 6.6)
frameSync1.ttml Text Profile When played against a 24 fps related video object (see [2] for example), each subtitle should appear on the frame specified in its text, with frame 0 corresponding to the related video object frame at t=0s within the instance document timeline. FAIL Not tested Not tested PASS PASS
ittp:aspectRatio (Section 6.7)
aspectRatio1.ttml Text Profile, ittp:aspectRatio Maintains 4:3 aspect ratio when rendering the caption PASS Not tested Not tested PASS PASS
aspectRatio2.ttml Text Profile, ittp:aspectRatio Maintains 16:9 aspect ratio when rendering the caption PASS Not tested Not tested PASS PASS
aspectRatio3.ttml Image Profile, ittp:aspectRatio Maintains 4:3 aspect ratio when rendering the caption PASS Not tested Not tested PASS PASS
aspectRatio4.ttml Image Profile, ittp:aspectRatio Maintains 16:9 aspect ratio when rendering the caption PASS Not tested Not tested PASS PASS
aspectRatio5.ttml Text Profile, ittp:aspectRatio Fills the related video object when rendering the caption PASS Not tested Not tested PASS PASS
aspectRatio6.ttml Image Profile, ittp:aspectRatio Fills the related video object when rendering the caption PASS Not tested Not tested PASS PASS
ittm:altText (Section 6.7.4)
altText1.ttml Image Profile, ittm:altText The contents of altText should not be displayed PASS Not tested Not tested PASS PASS
itts:forcedDisplay (Section 6.7.3)
forcedDisplay1.ttml Text Profile, itts:forcedDisplay The display of one of the two captions is controlled through the displayForcedOnlyMode application parameter Not tested Not tested Not tested PASS PASS
ebutts:linePadding (Section 7.4 - Extensions)
linePadding1.ttml Text Profile, ebutts:linePadding See Annex D at https://tech.ebu.ch/docs/tech/tech3380.pdf The rendered captions should match linePadding1_16x9.png assuming a 16:9 ratio root container or linePadding1_4x3.png for a 4:3 root container; the font does not need to be identical. FAIL PASS Not tested PASS PASS
ebutts:multiRowAlign (Section 7.4 - Extensions)
multiRowAlign1.ttml Text Profile, ebutts:multiRowAlign See Annex C at https://tech.ebu.ch/docs/tech/tech3380.pdf The rendered captions should match multiRowAlign1_16x9.png assuming a 16:9 ratio root container or multiRowAlign1_4x3.png for a 4:3 root container; the font does not need to be identical. FAIL PASS Not tested PASS PASS
ittp:progressivelyDecodable (Section 6.7.2)
progressivelyDecodable1.ttml Text Profile, ittp:progressivelyDecodable The presence of the ittp:progressivelyDecodable parameter should not affect rendering PASS Not tested Not tested PASS PASS
Reference Fonts (Section 7.3)
referenceFonts1.ttml Text Profile, Reference Fonts The rendered captions should match referenceFonts1-reference.png FAIL Not tested Not tested PASS PASS
Maximum rate subtitles (640px x 480px) created from Solekai022_854_29_640x75_MaxSdSubtitle_v7_subtitles (Section 8.4 - Extension @)
track5-frag0-sample1-subs0.ttml Image Profile [3] Not tested Not tested Not tested PASS PASS
track5-frag1-sample1-subs0.ttml Image Profile [4] Not tested Not tested Not tested PASS PASS
track5-frag2-sample1-subs0.ttml Image Profile [5] Not tested Not tested Not tested PASS PASS
track5-frag3-sample1-subs0.ttml Image Profile [6] Not tested Not tested Not tested PASS PASS
track5-frag4-sample1-subs0.ttml Image Profile [7] Not tested Not tested Not tested PASS PASS
track5-frag5-sample1-subs0.ttml Image Profile [8] Not tested Not tested Not tested PASS PASS
track6-frag0-sample1-subs0.ttml Text Profile [9], view results in video Not tested Not tested PASS PASS PASS
Maximum rate subtitles (1920px x 1080px) created from Solekai023_1920_23_1x1_MaxHdSubtitle_v7_subtitles (Section 8.4 - Extension @)
track5-frag0-sample1-subs0.ttml Image Profile [10] FAIL Not tested Not tested PASS PASS
track5-frag1-sample1-subs0.ttml Image Profile [11] FAIL Not tested Not tested PASS PASS
track5-frag2-sample1-subs0.ttml Image Profile [12] FAIL Not tested Not tested PASS PASS
track6-frag0-sample1-subs0.ttml Text Profile [13], view results in video FAIL Not tested PASS PASS PASS

NOTE: The complete test suite contributed by DECE, translated to IMSC1, is available at [14]. The corresponding test procedures are located at [15].