craigl at begeek
Jun 23, 2003, 6:27 PM
Post #2 of 7
(1207 views)
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Re: Asus Pundit and Interlaced Output, part III :)
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Will Dormann wrote:
> OK, It's good to see that I'm not the only one!
> Anyway, the SIS driver also has an option for reducing flicker. I
> have turned this off to see how it would affect my interlaced
> output. It didn't seem to help the video much, though I could
> definately see an increase of flicker in horizontal lines in X before
> mythfrontend starts up.
>
> A PVR250 system does indeed allow you to deinterlace the TV output.
> True, the capture is done via hardware, but once that's done you've
> got an interlaced MPEG2 file. Playback is done totally by software,
> just as it is with RTJPEG and MPEG-4. (well, maybe playback isn't
> done in the exact same method, but it is software playback). So if
> the Deinterlace playback option is enabled in MythTV, then it does
> deinterlace the video.
the stream may be interlaced deep inside libavcodec, but if you look at
the mythtv code, the only places deinterlacing is referred to is in the
recording side of things, as far as i can tell. and if you look at the
mpegrecorder.cpp, you will find the ChangeDeinterlacer() stubbed out.
it makes sense to deinterlace it while you're recording if you can, i
think. then it only needs to get done once. unfortunately though, this
excludes the hardware encoders.
> As I mentioned in a previous post, I did a capture via: cat
> /dev/video0 > /tmp/test.mpg
> and I would play it back with mplayer
> I figure, this way I would eliminate as many variables as possible.
> I've tried different resolutions, flicker options, overscan, and all
> that but have yet to find a solution that looks *good*. The most
> noticeable problem areas were panning scenes. (try pausing) Since
> the above test uses MythTV in no way, then I guess it's not at fault.
> :) But I think the topic is still relevant to this discussion list.
i don't think its mythtvs 'fault'. it is just a problem with dealing
with interlaced video. i have read other reports though, that when a
pvr250 file is deinterlaced (and in this particular case at least, also
converted to mpeg-4) it looked great. so, i gotta think there is some
merit to deinterlacing it on playback. i think i'm going to try, it
looks reasonably straightforward to incorporate the avcodec deinterlacer
at least.
i think this topic is definitely relevant to mythtv though, although it
isn't actual mythtv code we're dealing with here, its a couple users
talking about their mythtv experiences as a whole.
> I currently have deinterlacing enabled in MythTV and it has good
> results. The question is whether or not I am losing motion smoothness
> as a result of this, compared to "true" interlaced output.
well, again, i'm just not sure. from what i see, i would say you're not
deinterlacing, but i haven't stepped through all the code. i wish
someone who knew would provide a definitive answer though.
cheers
CraigL->Thx();
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