Image Processing Reference
In-Depth Information
Figure 2-3 Removing frames for temporal compression.
sion can be used at the point where video is imported into your workflow at the beginning
of the content chain as well as at the delivery end. If you are using video compression at
the input, you must be very careful not to introduce undesirable artifacts. For archival and
transcoding reasons, you should store only uncompressed source video if you can afford
sufficient storage capacity.
Some Real-World Scenarios
Let's examine some of the possible scenarios where video compression can provide assis-
tance. In some of these examples, video compression enables an entire commercial activ-
ity that simply would not be possible otherwise. We'll take a look at some areas of business
to see how compression helps them.
Mobile Journalism
News-gathering operations used to involve a team of people going out into the field to
operate bulky and very expensive equipment. As technology has progressed, cameras
have gotten smaller and easier to use. A film crew used to typically include a sound engi-
neer, cameraperson, and producer, as well as the journalist being filmed. These days, the
camera is very likely carried by the journalist and is set up to operate automatically.
Broadcast news coverage is being originated on videophones, mini-cams, and video-
enabled mobile-phone devices. The quality of these cameras is rapidly improving. To
maintain a comfortable size and weight for portable use, the storage capacity in terms of
hardware has very strict limits. Video compression increases the capacity and thus the
recording time available by condensing the data before recording takes place.
Current practice is to shoot on a small DV camera, edit the footage on a laptop, and
then send it back to base via a videophone or satellite transceiver. The quality will clearly
not be the same as that from a studio camera, but it is surprisingly good even though a
high compression ratio is used.
Trials are underway to determine whether useful results can be obtained with a PDA
device fitted with a video camera and integral mobile phone to send the material back to
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