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Posted by PTravel on 09/26/36 11:42
"Everyguy" <everyguy@Nospam.com> wrote in message
news:GmWRf.1766$HW2.420@newsread3.news.pas.earthlink.net...
>I notice that if I limit DVD's of home video to 1 hour, the quality is
> considerably cleaner. The graininess that shows up in certain areas at
> times
> in the longer DVD - basically go away. Some people might not even notice
> the
> difference but I do.
>
> So why is it a commercial DVD can contain a complete movie plus whiz bang
> graphics and "extras" and still look very sharp, even on a computer
> monitor
> which I find generally has fuzzier resolution than a TV? Or even one of
> these "squeezed" DVD's on a CD with a full length movie can still look
> very
> good, with obviously far less data?
>
> Is it that the master they're working from is so much sharper it can take
> more degradation, or the process they use to compress the video, or...?
>
First of all, the source material on commercial DVDs is he highest-quality
(usually), which helps.
However, the big difference is in transcoding to mpeg2. Proper transcoding
takes multiple passes -- each frame must first be analyzed in sequence and,
only after the analysis has been performed, actually compressed. Consumer
software transcoders, such as are found in many low-end editing and DVD
authoring programs, are optimized for speed, rather than quality. DVD
camcorders and low-end computer capture cards that capture direct to mpeg do
single-pass encoding on-the-fly and produce poor quality transcodes.
There are consumer alternatives, however. I transcode using tmpgenc, a
standalone program. Tmpgenc is very "tweakable" and, at its highest-quality
settings can approach commercial DVD quality with good source material. The
downside is, it's very slow. A 2-hour video can take up to 24 hours to
transcode with tmpgenc on my 3 .1GHz P4 machine. However, the results are
worth the extra time, in my opinion.
>
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