AJA KONA LHe Plus, Инструкция по установке и эксплуатации

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KONA LHe Plus Installation & Operation Guide — Understanding Typical
HDV
Data rate: 19 MB/second high definition720p, 25 MB/second high definition 1080i—supported
by internal syste m drive
Quality: Excellent
You can use KONA LHe Plus to convert HDV projects to unco m pressed—in real ti m e—for
m onitoring and/or output. KONA LHe Plus can capture unco m pressed fro m any input, directly
to HDV m edia. The KONA LHe Plus advanced scaling engine takes the native fra m e (long GOP
1440 HD) and outputs it via hardware—in real ti m e. Precision AJA circuitry re-sizes the video to
proper 1920 x 1080, providing quick playback of HDV for m onitoring and recording.
HDV captures HD i m ages via MPEG2 co m pression and allows for recording the signal to a
MiniDV tape. This MPEG2 co m pression is si m ilar to a DVD (although DVD is a progra m strea m vs.
HDV’s transport strea m and HDV uses a constant bit rate whereas DVDs use variable bit rates).
The issue for post production is that the HDV transport strea m is based around a long-GOP
structure (group of pictures) which produces i m ages based on infor m ation over a section of
ti m e, via I, P and B fra m es; Intrafra m es, predicted fra m es and bi-directional fra m es. For m ats that
do not use this sche m e treat fra m es as individual units, as in the progressive for m ats where a
fra m e truly is a fra m e, or as interlaced fra m es where two fields create the i m age. So m eti m es we
refer to these for m ats in contrast to MPEG for m ats, as I-fra m e for m ats where fra m es can be
easily defined as individual.
Since the fra m es of HDV have the long GOP structure to define the m , herein lies the proble m for
post-production; how can we work with the m aterial if we m ust know what lies before, after and
during? Luckily, the transport strea m MPEG2 can be trans m itted over IEEE1394 (aka FireWire).
This m eans that the co m pressed HD m aterial can be transferred into syste m s with the
appropriate hardware and software. While this see m s like a si m ple solution for post-
production, it m eans that the footage m ust be brought into the syste m as a rather heavily
co m pressed for m at and that the co m puter m ust continue to work with the m aterial as a MPEG2
transport strea m , which is incredibly processor intensive for the co m puter.
How does the AJA KONA LHe Plus card connect to HDV and digitize m aterial to unco m pressed
HD files for editing—or at the very least, to a lightly co m pressed I-Fra m e HD for m at? The answer
to this is provided in a feature co mm on to m any HDV devices: analog HD output via co m ponent
video. The co m ponent connectors on JVC ca m eras and decks, along with Sony ca m eras and
decks, allows for the output of the long GOP MPEG2 data as a standard HD video for m at such as
720P in the JVC products—or 1080i in the Sony products.
Since the KONA LHe Plus has the ability to digitize analog HD signals, the analog co m ponent
output of the HDV devices can si m ply be connected to the KONA inputs. Note that HD signal
cannot be transported over co m posite or S-Video (Y/C) cables, so the HDV device m ust have an
analog co m ponent HD output. The KONA LHe Plus also has the ability to ingest analog audio, so
the analog audio outputs of the HDV devices can be sent to the KONA card as well. (Also note
that these analog audio outputs on the HDV devices are usually unbalanced RCA connections
where the KONA card uses balanced XLR style connection so so
m e sort of audio level correction
device, such as a m ixer or a stand alone active interface a m plifier, should be used for accurately
attenuated audio.)
Finally, you will want to control your device. Where all of the video, audio and ti m ecode
infor m ation m oved over the FireWire cable, now you are dividing those tasks. Device control is
the m ost difficult to configure for HDV devices because so few HDV devices have i m ple m ented
any for m of device control other than IEEE1394. The one notable exception is the JVC BR-HD50
HDV deck which has a re m ote serial port for RS422 protocol and device control. Check the KONA
LHe Plus support area on the AJA website for a whitepaper on HDV, which gives details on using
KONA LHe Plus with various HDV equip
m ent.
Note: direct capture into HDV m edia on the LHe is not possible. Direct capture into the LHe
can only be done using unco m pressed, DVCPRO HD, or Pro Res. Regarding ProRes 422,
capturing HD resolution ProRes 422 fro m an HD source requires a Mac Pro with an Intel
Xeon processor.
USO
RESTRITO