Graphics Programs Reference
In-Depth Information
Affordable High Definition
Just as DV set the world on fire when it burst on the scene in late 1995/early
1996, HDV has also captured the minds and revved up the imaginations of
independent filmmakers and video professionals when it exploded like a
supernova close to a decade later.
HDV has two faces. One is that of a shining goddess with incredible beauty
that stands tall as being something incredible to look at. Yet in post-production
stakes HDV also has the head of Medusa - look closely and you may not like
what you find.
My analogies may seem somewhat over-the-top but HDV has given to us an
acquisition medium which provides incredible quality at an amazing price. But
when it comes to editing the images unfortunately the picture has been
muddied by the difficulties which are inherent with the HDV format.
The compression used with HDV is known as long GoP MPEG-2 encoding. The
signal is recorded onto DV tape and requires the same amount of disc space as
DV. That's where the similarity ends. In technical terms DV is a frame-based
codec - every frame stands alone - while HDV (MPEG-2) use interframe
compression, this is where compression takes place according to the difference
between frames. This makes HDV a very computationally difficult format to
work with. As such everything works slower and the computer has to work a lot
harder to achieve results.
With the powerful Macs of today, when editing HDV, everything may appear to
be working as normal, particularly if it is cuts only in your HDV timeline. But
start adding the layers and effects and suddenly you may find that everything
becomes unwieldy.
This is because MPEG is muddy. It's all mashed together in a way where a single
frame is designated as the master frame for what is known as a Group of Pictures
(GOP). Each GOP occurs every 15 frames with Sony HDV or with the JVC
system, HDV2 or short GOP MPEG-2, the frames are 6 frames apart. So each
of the frames in the GOP, other than the master frame, is created by referring
to the master frame - analysing what moves and changes in all the other frames
that proceed it - and then building each of the frames in the GOP for Final Cut
