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let be a little more scientific!

Economics.

1. digital video uncompressed (1:1):
exemple: D1, 4:2:2, components format (YUV), CCIR (in PAL 720x576);
problem: how to transfer D1 on your computer disk
answer: through a SDI board, but be ready for very large and fast discs
(about 1.26 Gb per minute, or 21 MB/sec. => RAID)
equipment cost: very high
production cost: high (shoot in 35", beta digital,...) - not for me


2. digital video compressed
a variety of format form Beta digital (2:1) to the cheap and popular DV
(5:1, 4:2:0 in Pal), all CCIR.
DV cost: low, exactly what i can afford...

Test.

We made some test here with a friend who owns DSP, from the video equipment
we have (DV) and some typical shootings (all in DV directly from camera or
tranferred from digital beta to DV): one static scene filmed on a tripod
with a walking man, one amateur jerky shot (hand held camera while
walking), one professional 16mm film transfered on digital beta and copied
on DV...
The amateur jerky shot has many difficult scenes with a lot of textures
(trees with leaves, walls of bricks, pavement,...) shot in fast travelling
and jerky movements.

We made a 4.7 gb DVD-R in DSP with all video encoded at 9.0 Mbs (high
quality)...All DV material was transferred through firewire on the Mac; no
editing or recompression, just the raw DV stream.

For the test, we showed the DVD and the original DV material to a group of
4 people (non specialists, average...). The test was made with the
original DV tape in a Sony DV VCR and the DVD in a Sony DVD player both
connected to the same monitor, and a switch to display one or the other. So
after some quick switches, the viewers could not know the source...

Results:
- amateur jerky shot: everybody clearly recognised a bad quality, near vhs,
with horrible grainy noise, which was the DVD;
- 16mm transferred film and static scene film on a tripod: near nobody
could distinguish between DV original and DVD.

Conclusions:
the only conclusion i can draw from this experiment is : the DSP encoder
from DV orginal material with fast moving scenes with lot of details and
textures... is not very good, even at high bitrate (9.0).


Questions:
As my experience of mpeg2 compression and other encoders is low, here are
first questions:

1. what would be the result with the DSP encoder working from uncompressed
video (D1) or 2:1, instead of DV at 5:1 (knowing that compressing a
compressed video enhances artifacts and noise...). Who has the experience
of using DSP in a production facility equipped with D1 and/or digital Beta?
(probably not many, as most of these facilities will buy a much more
expensive DVD authoring+encoder).

2. What are the results of other encoders on typical material such as our
amateur jerky movies with lot of textures???

Hope it helps.

Yves Bernard email@hidden
asbl iMAL vzw, Bruxelles/Brussel
http://www.imal.org
http://www.continent-imaw.net
fax: 32 2 215 44 40



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