Image Processing Reference
In-Depth Information
The QuickTime file format was used as a basis for the MPEG-4 file format and there-
fore they bear some similarity to one another. They are not identical enough that both for-
mats' files can be parsed by the same player applications or codecs but the design is
fundamentally the same. It is said that they come from “the same DNA.”
A variety of file structures are used but all the major formats have settled on the idea
of a structured chunk-based format composed of atomic objects. When video is streamed
the technicalities are very similar for broadcast TV and Web delivery.
File Size
File sizes will vary greatly according to what you have contained in them. Raw footage
that has been imported via a FireWire interface at broadcast quality will be the most bulky
that you have to deal with. It is tempting to compress it right away and discard the origi-
nal. This is probably a false economy unless that tactic is a necessary part of your work-
flow. It is better to provide sufficient disk space to work with uncompressed content for as
long as possible. Very large disks with capacities in excess of 500 GB or more are available.
Multiple disks can be assembled into a RAID array for reasonable sums of money and it
is not very hard to put a couple of Terabytes (TB) on a desktop. Table 16-1 enumerates
some file sizes for a 5-minute clip in various formats.
A more extensive table is provided in Appendix I. These file sizes might seem terri-
fying, but to put them into context, the spool files for wide-format plotters are orders of
magnitude bigger. Large poster-size plots can be enjoyed at a single glance while a video
file of the same size would run for a couple of hours even when stored in a high-quality
Table 16-1 File Sizes for a 5-Minute Video Clip
File size
3GPP 64 Kbps
2.867 MB
ISMA Profile 0 (MPEG-4)
4.6 MB
ISMA Profile 1 (MPEG-4)
14 MB
AVI with Cinepak codec
124.3 MB
150 MB
DV 25
1.00 GB
DV 50
1.9 GB
525i30 NTSC raw
2.575 GB
625i25 PAL raw
3.106 GB
4.5 GB
D-cinema, 24 fps 1920
1080 delivered on HDCAM
5.96 GB
D-cinema, 24 fps 1920
1080 raw
41.713 GB
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