[mythtv-users] Freevo, Tivo & MythTV

[Robin Gilks]

> That is true for all apps in my case, since my capture cards capture
> the over-the-air mpeg2 stream. There is no "direct-to-display" option
> here. In any case, it only takes a fraction of a second (about 1/30 of
> a second on average in the US ;) to decode a frame, so that shouldn't
> be an issue at all.

You are confusing analog TV signals with digital (mpeg2) ones. A frame in
the context of an mpeg stream is a frame that has a complete field - from
that frame (keyframe) until the next keyframe, only the differences are
transmitted. This means that if you start displaying just AFTER a
keyframe, you will get a ghostly outline moving about the screen gradually
painting the background as movement (assuming there is any) reveals it.
You will only get a complete picture on a keyframe - and that may be 2, 3
or 4 seconds down the line. MythTV generally inserts enough delay to have
captured a keyframe so that a complete image can be built. The screen is
(I think) held blank until that assumed complete image is in the buffer.

An optimisation would be to start displaying immediately a keyframe is
available - then complications arise when restarting from pause, code gets
duplicated for the 'special' case and you end up with bloat for no real
advantage.

Best of luck with your patch...

-- 
Robin Gilks