[vdr] Re: Minor problems in editing

[Klaus Schmidinger <Klaus.Schmidinger@cadsoft.de>]

Seppo Ingalsuo wrote:
> 
> Klaus Schmidinger wrote:
> > Malcolm Caldwell wrote:
> >
> >>On Mon, 2003-08-18 at 03:59, Kimmo Vuorinen wrote:
> >>>Have you applied vdr_iframe_patch from dxr3 plugin directory to your
> >>>vdr? I don't have any problems editing with dxr3 and fast forward /
> >>>reverse is also greatly improved by the patch.
> >>
> >>I had totally forgotten about this patch - no wonder 'fast forward used
> >>to work but now does not'!
> >>
> >>Does this patch cause problems for systems that do have full cards?
> >>
> >>Klaus: any chance of this patch going into vdr?
> >
> >
> > I'm not so sure whether this is generally a good idea.
> > IIRC the problem was that sometimes the tail of an I-frame
> > is in the same packet as the following P- or B-frame.
> > So when an I-frame is sent to the player device, there might
> > be some bytes missing at the end. Apparently the DVB cards
> > can handle this and play the I-frame just as well (maybe with
> > some artefacts), but the DXR3 seems to choke on this (please
> > somebody correct me if I'm wrong).
> >
> > With the mentioned patch, however, the data comprising a "still
> > picture" will in fact consist of a complete I-frame and some
> > P- or B-frame. I'm not sure what a player might make of that...
> 
> With this patch applied editing with dxr3 works without pain (and FF and
> rewind as well). Would a full-featured DVB then choke on additional and
> incomplete other frame types?

I tried the modification and found that during fast forward there were
heavy artefacts on my DVB-S, so I'm afraid this change can't go into
the official VDR source.

What we would need would be a way to have the rest of the I-frame
(which is now in an extra PES packet, together with the beginning of the
next P- or B-frame) somehow put into a packet of its own (even if this
makes it a very short packet) and thus allowing the index mechanism
to return the full data of exactly one I-frame and nothing else.

This would probably have to be done somewhere in VDR/remux.c.

Klaus


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