[MMUSIC] RTSP: New Range header construct

[Sean Sheedy <Sean.Sheedy at arrisi.com>]

I've (finally) added a new construct for Range that allows simple skip 
behavior (e.g., skipping 30 seconds over a commercial).  I proposed this 
late last year, and it was met with resounding silence, which I take as 
consent:

http://www.ietf.org/mail-archive/web/mmusic/current/msg06474.html

The actual text added to the draft:

-------------

4.5.  Normal Play Time

   The special constants "current+" and "current-" followed by a decimal
   fraction can be used to indicate a position relative to the currently
   playing location in the presentation.  The decimal fraction is always
   expressed as seconds to the left of the decimal point and fractions
   of a second to the right. "current+" indicates a position beyond the
   currently playing location, while "current-" indicates a position
   before the currently playing location.  If a "current+" position
   resolves to a position beyond the end of the media, it MUST be
   treated as equivalent to end of media.  If a "current-" position
   resolves to a position before the beginning of media (that is, it
   would result in a negative value), it MUST be treated as equivalent
   to NPT 0.0.
   [...]
      The "current+" and "current-" constants allow for skip semantics
      without additional round trips to the server to obtain the
      currently playing location.

4.6.  Absolute Time

   The special constants "current+" and "current-" may be used with
   absolute time in a manner similar to that of normal play time (NPT).
   As with NPT, the offset from the currently playing location is
   specified as decimal fraction in seconds.

13.5.1.  End-of-Stream

   The server MUST NOT use the "now", "current+" or "current-" constants
   in the Range header; it MUST use the actual numeric end position in
   the proper timescale.

13.6.  PAUSE

   Any play-request including symbolic values, such as the NPT
   timescale's "now", "current+" or "current-", MUST be resolved into
   the actual stream position of the pause point.

20.1.  Base Syntax

   npt-time         =  "now" / npt-sec / npt-hhmmss / npt-rel
   npt-sec          =  1*DIGIT [ "." *DIGIT ]
   npt-rel          =  ( "current+" / "current-" ) npt-sec

   utc-time         =  ( ( utc-date "T" utc-clock "Z" ) / npt-rel )

-------------

Cheers,
Sean

~--~--~--~--~--~--~--~--~--~--~--~--~--~--~--~--~--~--~--~--~--~--
Sean Sheedy
Staff System Software Engineer, Media and Communications Systems
Sean.Sheedy at arrisi.com | 503-531-6427 (Phone)
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