On Saturday 07 October 2006 03:52, Nick Rout <[EMAIL PROTECTED]> wrote
about 'Re: [gentoo-user] {OT} dvdrip permissions error, alternative?':
> On Saturday 07 October 2006 06:50, Grant wrote:
> > > > I think I'll stick with:
> > > >
> > > > dd if=/dev/dvd of=image.dvd
> > >
> > > That won't work on CSS scrambled discs. You'll copy the scrambled
> > > data but not the key. Instead, use vobcopy followed by growisofs.
> >
> > What about this (it's what I've been doing):
> >
> > lsdvd && dd if=/dev/dvd of=image.dvd
> >
> > Is there any advantage to creating an ISO filesystem out of the image
> > if you aren't going to burn it?
>
> yes. ease of transfer, keping everyting togther. still playable with
> xine dvd://path/to.iso
>
> why are you naming it image.dvd instead of image.iso?
>
> > Also, is there any way to compress
> > the image without doing any kind of transcoding or that type of
> > reprocessing?
>
> the mpeg streams on the dvd ARE compressed. thats what the mpeg codec
> does. You can try the usual suspects - zip, bzip etc, but you won't get
> far.
>
> programs that reduce the size of DVD9 so that they will fit on a DVD5
> usually requantise the stream, I am not sure what that means, but it is
> much quicker than transcoding to another codec like xvid. xvid will, of
> course, give you a much smaller avi file.Increasing the quantization increases the number of pixels represented by a single data element in the stream. From what I understand, MPEG2 does very JPEG like compression, meaning that square groups of pixels with almost the same color will be stored as a single data element with the average color (and maybe some hinting). Increasing the quantization further merges some of these groups together, resulting in both quality and size reductions. > the analogy with flac is not really appropriate. flac is a lossless > compression, you start with an uncompressed wav file and end up with a > losslessly compressed audio file. A DVD is already lossy compressed to > mpeg2, so it is not logical to make an analogy with flac. Agreed. There are a number of lossless video codecs out there ( http://en.wikipedia.org/wiki/List_of_codecs#Lossless_data_compression_2 ), though certainly none are in wide use. I'd wager that since your are starting w/ an already compressed stream, converting to a lossless format would actually make the video larger. With DVD it isn't practical to transfer uncompressed video, perhaps we might see some uncompressed video available with HD-DVD or Blu-ray. -- "If there's one thing we've established over the years, it's that the vast majority of our users don't have the slightest clue what's best for them in terms of package stability." -- Gentoo Developer Ciaran McCreesh
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