Re: [AVTCORE] Question

[Julius Friedman <[e-mail]>]

Hello Dale, (et al)

I would like to address your response:

"In any case, why would we want to prevent seeking on a stored media
object?  I can see why if the media is an un-stored media stream, but in
that case, the software likely doesn't know the total length that the
media will have."

I will justify how "likely" this is as follows:

1) A Live 10 minute `media` which has been playing for 3 minutes, leaving
me 7 minutes in play but unable to seek.
   a) If the stream was stored or recorded this obviously wouldn't be an
issue

2) I have a server which requires authorization to seek but not to play.

3) I am a client and I have started playing and 'PAUSE' is not supported

4) I am a server re-streaming from a server where "Range" is not supported

"Perhaps referring to the mailing list discussion for this RFC would
reveal the answer."

Which mailing list is that? 'mmusic' they have also been addressed, several
times. I never get a response from them.

In any other case I hope all is well and that I haven't been marked as spam
or WORSE that there is something wrong with the list and my messages are
just not being received.

Anyway , thank you for your prompt response!

Sincerely,
Julius

On Sun, Dec 28, 2014 at 7:28 PM, Dale R. Worley <[e-mail]> wrote:

> Julius Friedman <[e-mail]> writes:
> > Rfc 2326 explicitly states that seeking can be disabled by not including
> > the end information in the range header.
> >
> > What if I want to have the end but I don't want to allow seeking?
> >
> > E.g. my clip is 10 minutes and I have already been playing for 3 and
> there
> > are 7 remaining; why can't I convey that and not allow seeking?
>
> I'm no expert in RTSP, but reading the RFC, it appears that the server
> indicates if seeking is allowed by the inclusion of the end-time:
>
>     D.2.1 Basic Playback
>
>      Client implementations may use the presence of length information
>      to determine if the clip is seekable, and visibly disable seeking
>      features for clips for which the length information is unavailable.
>
> Exactly why the server cannot indicate the total media length without
> implicitly stating the media is seekable, I don't know.  Perhaps it's
> because any such media is theoretically seekable, since it must already
> be instantiated as a stored data object.  Or perhaps it is because if
> seeking is not implemented, the user interface is expected to not
> display the "slider bar", and so there is no way to tell the user how
> much time remains in the media:
>
>      Client implementations may use the presence of length information
>      to determine if the clip is seekable, and visibly disable seeking
>      features for clips for which the length information is unavailable.
>      A common use of the presentation length is to implement a "slider
>      bar" which serves as both a progress indicator and a timeline
>      positioning tool.
>
> Perhaps referring to the mailing list discussion for this RFC would
> reveal the answer.
>
> In any case, why would we want to prevent seeking on a stored media
> object?  I can see why if the media is an un-stored media stream, but in
> that case, the software likely doesn't know the total length that the
> media will have.
>
> Dale
>