Bitmovin Compactibility of DVB subs presentation on DASH and HLS for specific standard in packaging (WebVTT, SMPTE-TTML, IMSC1)

Support
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Hi Bitmovin team,

We would like to understand or clarify from Bitmovin if there are any limitations on the player side regarding the presentation of DVB subs on DASH and HLS for specific standards in packaging (WebVTT, SMPTE-TTML, IMSC1).
Our video transcoding team (Harmonic) has raised a question regarding the compactness of the SMPTE-TTML AdaptationSet on the Bitmovin Players and the Bitmovin player supporting adaptations.
We kindly request your assistance in understanding which adaptations are supported by the Bitmovin Player. Specifically, we are interested in any suggestions from Bitmovin on making SMPTE-TTML visible on the Bitmovin Player.

Thanks,
Sanal

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Hi @sanal.nandakumar,

Thanks for asking. Subtitle format support and capabilities vary depending on the SDK (Web, Android, iOS, etc…), so I’d recommend that you have a look at this doc, and specifically at this table: Subtitles & Captions Support

Otherwise, it’d be great if you could clarify what SDK are you referring to and share a sample stream/subtitle URL that’s not displaying on the player as you’d expect.

Regards,
Alberto

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Hello @albertobitmovin
Thank you for the update. The query raised is more for checking whether bitmovin supports SMPTE-TTML. As per the documentation given SMPTE-TTML is not listed in the supported formats for Dash & HLS. We are asking this because SMPTE-TTML is basically based on TTML with some additional feature added. If you could help us confirm whether Bitmovin support this format it would be helpful. As of now both web and mobile SDKs are not displaying the subtitles coming with SMPTE-TTML format.

Below is the snippet of SMPTE-TT subtitle format

Discovery Channel (SMPTE-TT)

<AdaptationSet mimeType="application/mp4" startWithSAP="1" lang="spa" segmentAlignment="true">
  <Role schemeIdUri="urn:mpeg:dash:role:2011" value="subtitle" />
  <SegmentTemplate timescale="10000000" presentationTimeOffset="0" media="$RepresentationID$_Segment-$Time$.m4s" initialization="$RepresentationID$_init.m4i">
    <SegmentTimeline>
      <S t="84711327181216" d="40040000" r="14" />
    </SegmentTimeline>
  </SegmentTemplate>
  <Representation codecs="stpp" id="1697462510369item-08item" bandwidth="15000" />
</AdaptationSet>
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@albertobitmovin any update with clarifications seeked?

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Hi @sanal.nandakumar ,

Thanks for your feedback and apologies for the delayed reply here. SMPTE-TT with bitmaps should be supported on our Web SDK and on our iOS SDK (in this case, only when SystemUI is used, instead of Bitmovin’s UI), so if the issue persists I would suggest raising a support ticket so we could look into your specific case more in detail: Bitmovin Dashboard