[aclug-L] Re: DVD Ripping

[James Lancaster <james@xxxxxxxxxxxxxxxxxx>]

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On Saturday 21 August 2004 11:39 pm, Jonathan Hall wrote:
> I've just begun experimenting with the process using the dvdrip program (a
> collection of perl scripts with a GUI front end).  I've ripped a sample
> portion of a DVD, and encoded it a couple times, both times with divx5, b=
ut
> at different video bit rates.  In both cases, when I play the clip, I get
> some distortion when the image moves.  Almost a bit of an after image, mo=
st
> noticable in areas of high contrast.  The distortion takes the form of
> horizontal lines.
>=20
> I was wondering if anyone might have a clue as to what is causing this.  =
Is
> it a defect/drawback of my video playback software, the encoding method, =
or
> the codec?  Or something else entirely?
>=20

I'll say I don't know for sure.=20

My thought is that that's interlacing artifacts. (A rather horrible problem=
 in
my opinion is the use of interlacing ANYWHERE in modern times, because=20
the video won't neccesarily look good on anything but an interlaced device,=
=20
and one of the things I don't like about some of the HDTV specs.)=20

Deinterlacing is a problem. There are several basic methods to combat it:=20
1) is simply to drop every other line and duplicate the others.
2) is to blur the two using various criteria=20
3) kernel deinterlacing, which I'm not to familiar with.=20
(probably many others that I'm not familar with)=20

(there's also telecine which is rather akward, and I don't know a good way =
to=20
explain as I myself need to look things up about it.)

> Also, somewhat related, but more generally... if anyone has experience
> ripping DVDs, what encoding software can you recommend?  And do you
> recommend any specific audio or video codecs?  What other things should I
> consider when ripping DVDs?
>=20

This is probably sounding like a broken record by now but:=20
mplayer/mencoder

Also, aside from a very few things that ffmpeg's libavcodec (lavc) doesn't =
do
better (things like very dark scenes with subtle gradients, If you are ripp=
ing to=20
divx, use lavc. (something transcode as well should be able to use, assumin=
g it's=20
compiled in/linked, as I recall you run debian, so you might have to do tha=
t on=20
your own. Also, you'll likely have to compile mplayer because debian seems =
to=20
dislike mplayer, and vice-versa. )=20

> And lastly... is anyone qualified and interested in giving a presentation=
 on
> this topic? :)  (If not, perhaps I will be in a month or two)
>=20

I probably could if people aren't getting sick to death of my presentations=
=2E=20

James

> Thanks!
>=20
> -- Jonathan
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