[mythtv] [PATCH] Use frame number as position map key

[Isaac Richards]

On Saturday 22 November 2003 05:32 pm, Doug Larrick wrote:
> One change I want to call out is that, when watching an in-progress
> recording, I have changed how the positionmap is managed.  If the
> current location has gone past the positionmap's end, we go and re-
> fetch the map from the database.  This change means that it's possible
> to fast-forward through a commercial that had not yet been recorded
> when you started watching.  The way I read it, the old code handled
> this case by writing new positionmap entries at every keyframe during
> normal play (OK, fine), and manufacturing even-cadence & even-bitrate
> map entries to cover skipped video during fast-forward (decidedly NOT
> ok for HDTV or DVB, or even a variable-bitrate local encoder).

Looking at this more, I don't this will work properly.

- The database is only updated every 15 seconds or so (so as to not be hitting 
the db every half second), so grabbing data from an in-progress recording 
will fail.  It should probably query the backend with something like the  
'nvr->FillPositionMap' stuff if it can, and then fall back to the database 
and then fall back to the old stream parsing code you removed =) (see next)

- The old code wasn't manufacturing data, it was parsing the stream (without 
decoding) to get the proper offsets for what it skipped over.

Isaac