Media Types in 3GPP Timed text draft (was: RE: [AVT] RTP andMedia Types)

[Jose Rey]

Dave, Magnus,

inline...
> -----Original Message-----
> From: avt-bounces at ietf.org [mailto:avt-bounces at ietf.org]On Behalf Of
> Dave Singer
> Sent: Tuesday, August 10, 2004 7:11 PM
> To: Magnus Westerlund; 'ietf-types at iana.org'
> Cc: IETF AVT WG
> Subject: Re: Media Types in 3GPP Timed text draft (was: RE: [AVT] RTP
> andMedia Types)
>
>
> At 5:55 PM +0200 8/9/04, Magnus Westerlund wrote:
> >Hi,
> >
> >As the RTP payload format is developed in IETF, rather than 3GPP I
> >think the MIME type used to identify that RTP payload format belongs
> >in the IETF tree. Especially as the vendor tree implies that the
> >3GPP has control over the registration and any updates, which I
> >don't think is appropriate for this payload format.
> >
> >The question is if 3GPP timed text should be registered in video,
> >text, or both. My reasoning behind actually registering in both
> >media types, would if one had clear indications that both are
> >appropriate for different usages of the RTP payload format.
>
> I think both is the worst choice;  it's asking for interop
> problems, isn't it?
>

As I said in my previous email, registering under 'text' top level type
would mean that the modifiers cannot be used.  Hence, we can differentiate
between applications that could make use of text w/o or w/ modifiers to help
in the decision:

also useful w/o modifiers (would be OK to use text/3gpp-tt)
====================
- captions (in most cases)
- instant messaging (?)
- timed text conversation (? )

only useful w/ modifiers (only makes sense with video/3gpp-tt)
========================
- commercial banners (decorated)
- news tickers (decorated)
- karaoke
- clickable text strings
- some captions (e.g. scrolling end actors' list)

Leaving aside that most captions could be useful w/o modifiers, the usage of
timed text for the 'text' type applications like instant messaging or text
conversation seems not very probable.  There are already simpler codecs and
payload formats to do this.   The whole set of features of timed text are
only available if the video/3gpp-tt is used... So maybe it is more
appropriate to register just under 'video'?

What about interop? Would it still be a problem if we register both?

Thanks,

Jose

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