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Posted by Martin Heffels on 10/18/06 11:37
On Sun, 15 Jan 2006 20:58:29 GMT, "PTravel" <ptravel@travelersvideo.com>
wrote:
>"David McCall" <david.mccall@comcast.net> wrote in message
>news:DIxyf.6402$C%3.4086@trndny03...
>>
>> If you are going to edit it, then the question becomes more complicated.
>> HDV adds complexity to editing, from a programming standpoint.
>> Many people prefer to convert the HDV file to a less compressed format
>> for editing, and this makes for much bigger files.
>
>Is that true? I'm not working in HDV yet so I haven't tried it, but Adobe
>Premiere Pro, for example, has the ability to import HDV directly.
I think David is referring to the problem of cutting on the I-frames. In
DV25, each frame is compressed seperatly, and in HDV the frames are grouped
together in a serie, the first frame becomes a master-frame, and the second
frame is compressed based on the difference between the first frame and
itself. Then the third frame is based in the difference between the second
and itself.
All this leads to a higher compression-rate because you only have to save
the difference between two frames (hence it is always said that MPEG2 is
more efficient than DV25). However if you want to cut the, say fourth frame
in that sequence, you would have to have a look at all the previous frames
in order to recreate the foruth frame. On old computers, which are slower,
this led to a lag while editing. The newer ones are fast enough so you
don't notice this.
Another technique used is to convert the materials to an intermediate. Here
you use a form of very low compression, which is I-frame only again (each
frame compressed seperatly), and then you don't have that lag either.
Now, may people here tell you to go for the first solution, cut on a fast
computer. Purists (like me), would recommend the latter. The advantage of
the latter is that if you do multiple layer with multiple renders, you have
a lesser chance of render-artifacts. Also if you would do chroma-keying,
converting to an intermediate is better.
But in the end it is a matter of looking at your production-methods, which
type of MPEG2-editing suits you best.
cheers
-martin-
--
Never be afraid to try something new.
Remember that a lone amateur built the Ark.
A large group of professionals built the Titanic.
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