[X4U] Re: Ambitious DVD Project.

[Craig A. Finseth]

	...
   > Most consumer DV cameras use "mini-DV", which is itself heavily
   > compressed.  Going directly to DVD will probably result in much _less_
   > compression.

   While I do agree that the MiniDV format is a compressed format, I 
   disagree that it is inferior to DVD.

   MiniDV is ~215MB/per minute --:> 120 minutes x 215 is 25.8 Gigabytes.

   A 120 minuted DVD is 4.3 Gigabytes.

   Please explain to me how MiniDV is compressed more than DVD.

Don't confuse bit rate with quality: you need to understand the
compression schemes used as well.

Each mini DV frame is based on MPEG-1 and is 640 x 480 x 8 bits and is
compressed with a fixed 5:1 ratio.  This makes it easy to process, but
is not a good scheme overall.  A frame of black video results in the
same number of bits as a highly detailed scene.

DVDs (the video ones you play on your TV) use MPEG-2.  MPEG-2 uses a
compression scheme similar to JPEG: luminance and chroma portions of
the image are separated and compressed separately.  MPEG-2 also allows
support I, B and P frames where the B and P frames only encode
differences from each other and from the I frames.  As a result, it
takes a lot more CPU to process but results in better compression
(i.e., higher quality at lower bit rates).  MPEG-4 can be even better.

Keep in mind also that the quality of the compressor comes into play.
There are lots of parameters to tweak and different ways of doing the
compression.  A low-quality MPEG-2 compressor can produce output that
is worse than mini DV.

My view is based on my experience in this case.  I had some old VHS
camcoder tapes (family videos).  They looked awful when played.  I
brought them to your basic strip-mall conversion place and had them
transferred to DVD.  Very much improved quality.

I then compared them to the tapes that I shot on my mini-DV camcorder.
I thought the VHS tapes on DVD were the best.  YMMV.

Craig