Re: [AVTCORE] Question

[[e-mail] (Dale R. Worley)]

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