Hi Shy,

I think the reason the server is sending back the "Not Implemented" error, 
is because there is no intermediate PAUSE request. Historically, a seek 
operation was implemented as a PAUSE-PLAY operation. The RTSP 1.0 spec is 
quite unclear about this and does not really specify what should be done, 
although it does not disallow this operation. However, it does mention that 
if a PLAY operation is in progress, a subsequent PLAY method can be ignored.

Here are two snippets from the original spec:

*****************************************************************************************
    The PLAY request positions the normal play time to the beginning of
    the range specified and delivers stream data until the end of the
    range is reached. PLAY requests may be pipelined (queued); a server
    MUST queue PLAY requests to be executed in order. That is, a PLAY
    request arriving while a previous PLAY request is still active is
    delayed until the first has been completed.
*****************************************************************************************
*****************************************************************************
    if a server has received requests to play ranges
    10 to 15 and then 13 to 20 (that is, overlapping ranges), the PAUSE
    request for NPT=14 would take effect while the server plays the first
    range, with the second PLAY request effectively being ignored,
    assuming the PAUSE request arrives before the server has started
    playing the second, overlapping range. Regardless of when the PAUSE
    request arrives, it sets the NPT to 14.
*****************************************************************************

The RTSP 2.0 spec (which is still work in progress), has clearer language 
about this and explicitly allows this kind of operation.

To summarize, if the Helix DNA Client is not pausing before playing ( from 
the seeked-to location), it is probably a bug and must be fixed.

Thanks,
Rishi.

At 03:36 PM 11/2/2005, Shy.Ward at nokia.com wrote:
>I am hoping someone can answer my question regarding a problem I'm
>having.
>
>Setup:
>
>Server: Helix Mobile Server Version 10.0.6.1882
>(linux-2.2-libc6-i586-server) (RealServer compatible)
>User-Agent: RealMedia Player (HelixDNAClient)/10.0.0.6006 (symbian)
>
>Sequence:
>While streaming a H263 file on a Symbian device I PAUSE the clip.
>I seek forward. Wait.
>I seek forward again. (without unpausing)
>The server returns a 501 not implemented.
>
>My question(s):
>Is this normal operation? Does the server require another pause before
>the second seek?
>This does not seem to happen on a QT server and also does not seem to be
>a problem with rm format.
>
>Thank you in advance for any information you may have. I have included a
>log file that was captured on the server.
>
>Regards,
>
>Shy Ward
>Nokia
>
>  <<shy_rtsp.log>>
>
>
>_______________________________________________
>Protocol-dev mailing list
>Protocol-dev at helixcommunity.org
>http://lists.helixcommunity.org/mailman/listinfo/protocol-dev


Rishi Mathew
Software Development Engineer
Helix Community
RealNetworks, Inc.
rmathew at real.com
http://www.helixcommunity.org
http://www.realnetworks.com/products/support/devsupport.html
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