Re: [Hls-interest] Image-based subtitles and trickplay tracks

Hey Nicolas et al.

I'd certainly lend my (and Mux's) support for the second of these in
particular, a more elegant and interchangeable way to do trickplay would
really go a long way in helping in architectures composed around
just-in-time processing of media files.

Thanks.

On Wed, May 20, 2020 at 11:13 PM Weil, Nicolas <nicoweil@elemental.com>
wrote:

> Hello,
>
>
>
> We are often seeing two image-related topics causing interoperability
> problems as they are not currently covered by the HLS spec. Normalizing the
> implementations around an official specification for these two points would
> be great:
>
>
>
> *Image-based subtitles tracks*
> For workflow reasons and charset reasons, some content owners don't
> include text-based subtitles in the live channels sources that they provide
> to distributors, but rather image-based subtitles (like DVB-Sub). While
> it's possible to transform these subtitles as IMSC1 Image Profile as per
> DASH-IF IOP section 6.4.4, there is no equivalent IMSC1 Image Profile
> support in the HLS RFC, which means that companies will continue to rely on
> proprietary forks of the HLS RFC to support these use cases. Even if it
> wasn't supported by Apple players, it would be tremendously helpful for
> interoperability in the rest of the HLS ecosystem.
>
>
>
> *Image-based trickplay tracks*
> For player resources optimization reasons, the use of a video track as a
> trickplay artefact is not always possible, and a lot of player providers
> recommend the use of image thumbnails tracks instead of special low
> framerate video tracks. DASHIF IOP section 6.2.6 covers this use case but
> there is equivalent support in the HLS RFC. There is the Image Media
> playlists HLS extension proposal from Roku/Disney/WarnerMedia here
> https://github.com/image-media-playlist/spec but its relevance/adoption
> is currently limited by the fact that it's not part of the RFC. Same logic
> here: even if not supported by Apple players which don't need it as they
> can leverage I-frame tracks, it would be super useful for the rest of the
> HLS ecosystem to get this officially part of the RFC.
>
>
>
> Thanks for your consideration,
>
> Nicolas
>
>
>
> ----------------
>
> Nicolas Weil | *Senior Product Manager – Media Services*
>
> *AWS Elemental*
>
>
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-- 
Phil Cluff | Streaming Architect | +44 7983 406 937 | phil@mux.com