INTERNATIONAL ISO/IEC STANDARD 14496-30 Second edition 2018-11 AMENDMENT 1 2022-06 Information technology Coding of audio-visual objects - Part 30: Timed text and other visual overlays in Iso base media file format AMENDMENT 1: Timing improvements Technologies de I'information - Codage des objets audiovisuels - Partie 30: Texte temporisé et autres recouvrements visuels dans le format IsO de base pour les fichiers médias AMENDEMENT1: Ameliorations des temporisations Reference number IEC IS0/IEC 14496-30:2018/Amd. 1:2022(E) ISO @ IS0/IEC 2022 Copyright International Organization for Standardization IS0/IEC 14496-30:2018/Amd.1:2022(E) COPYRIGHT PROTECTED DOCUMENT IS0/IEC2022 All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission canbe requested from either Iso at the address below or ISO's member body in the country of the requester. ISO copyright office CP 40i : Ch. de Blandonnet 8 CH-1214 Vernier, Geneva Phone: +41 22 749 01 11 Email: [email protected] Website: www.iso.org Published in Switzerland haaztinaaza IS0/IEC2022-Allrightsreserved IS0/IEC 14496-30:2018/Amd. 1:2022(E) Information technology Coding of audio-visual objects : Part 30: Timed text and other visual overlays in Iso base media file format AMENDMENT 1: Timing improvements Clause 3 Replace the 3.1.2 entry with timed text stream stream of content, which when decoded results in textual content, possibly containing internal timing values, to be processed at a given presentation time and for a certain duration 4.2, second paragraph Replace the second sentence of the second paragraph, "The rendering of the sample happens at the composition time, taking into account edit lists if any, and for the whole sample duration, without timing behaviour", with: The rendering of the sample happens at the presentation time, i.e. taking into account edit lists if any, and for the sample duration, potentially trimmed by the edit list if any. As defined in ISOBMFE, the presentation is driven by the presentation time. The composition time is NOTE determined from the presentation time using the edit list (if present), and the sample active at that composition time is then processed. This specification assumes that at a given presentation time, the renderer is provided with the sample and the composition time, both of which correspond to the given presentation time. 5.3 Replace the entire subclause with: This subclause defines processing of timing information for TTML documents carried in a TTML track. The general timing processing defined in 4.2 applies, but specific aspects are refined in this subclause. Timing processing is defined only for TTML documents in which ttp:timeBase is 'media'. For other values, timing processing behaviour is undefined and such documents should not be carried in TTML tracks. When the rendering of a sample happens, the TTML document in the sample is provided to the TTML processor,togetherwiththetrackcompositiontimeTofthesampleandthesamplecomposition duration d. The TTML processor then uses the interval [T, T+d) together with the time coordinates [T;} produced by the "resolve timing" procedure, as defined in TTML, to determine which intermediate Copyight Internatioal Orgmz1$P61Ea2022n- All rights reserved