Hi -
> From: Daniel Pittman <[EMAIL PROTECTED]>
>
> I have been using mpeg2enc from the current CVS tree together with
> transcode to encode DVD compliant MPEG-2 data from PAL DV input.
>
> No rescaling of the input material is done, and I only use the 'DNR'
> plugin for transcode which does fairly minimal noise reduction on the
> input material.
>
> The one big problem that I do have with the toolset is that I get
> ghosting in very dark scenes, to the point of making some stuff *very*
> uncomfortable to watch -- like seeing it through a heavy, dark fog or
> something.
Hmmm, the common problem mentioned has been "splotches of grey"
in low light scenes - hadn't heard 'ghosting' mentioned before.
> The mpeg2enc command line[1][2] is:
>
> ] mpeg2enc -v 0 -f 8 -b <bitrate> -F 3 -n p -a 2 -o <output> \
> -a 2 -q 2 -I 1 -r 24 -4 2 -2 1 -N 1.5 -Q 1.5
>
> The bitrate is usually around 5500 to 7000, and the ghosting doesn't
> seem to be greatly affected by that, sadly.
Hmmm, what about trying a little less agressive -N option? Perhaps
1.0 or 0.8 would help (but not increasing the high frequency
quantizers as much). The other thing that can cause artifacting
(at least it was mentioned as having that possibility) is the -Q
option. I'd try leaving that out and seeing what happens.
-q 2 is extremely low - a value of 5 or perhaps 4 is about as low
as I've ever gone. A "-q 4 -N 0.6" produces very good output and
preserves more of the detail than -N 1.5 can.
> So, is there anything that can be done to improve this? This is the one
Is the effect reduced if the DNR is not performed? Sometimes
the denoising filters have an effect that sounds like what you
mention seeing.
I'd try less aggressive hf "rolloff" (-N) and -q settings - could be
that the ghosting is being caused by by an interaction there.
Cheers,
Steven Schultz
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