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Posted by Radium on 10/09/06 00:25
http://www.freepatentsonline.com/4249212.html
Quotes:
1. "In the following description of the invention, input signals are
assumed to be 8-bit pulse-code-modulated (PCM) video signals which have
been produced by sampling and quantizing NTSC analogue composite video
signals in response to sampling pulses having a sampling frequency of
10.74 MHz."
2. "Referring to FIG. 1, the PCM video signal fed from an input
terminal IN is supplied directly and through a chroma-inverter 11 to a
first switch 12. In the NTSC color television signal, the subcarrier
phases between adjacent frames are different from each other by
180.degree.. In order to provide a frame-phase-compensated video signal
having the subcarrier in phase for every frame, a switching signal
generator 10, the chroma inverter 11 and the first switch 12 are
employed. The switching signal generator 10, which is supplied with the
vertical synchronizing signal SYNC separated from the NTSC analogue
composite video signal, generates a switching signal SW having a
repetition period equal to two frames (1/15 second) and having a pulse
width of one frame (1/30 second). The first switch 12 is driven by the
switching signal SW, thereby to provide the frame-phase-compensated
video signal a at its output. The frame-phase-compensated video signal
a is supplied through a second switch 13 to a picture memory 14 for
storage therein, which has a capacity of one frame of the 8-bit PCM
video signal, i.e., about 2.86 mega-bits, and then stored therein."
3. "The slicer circuit 16 provides a one-bit pulse c of logic "1" for
each sample of the PCM video signal when the absolute value."
4. "The chroma inverter 22 and the third switch 23 are identical to the
chroma inverter 11 and the first switch 12, respectively, and perform
the reverse phase-compensation to the latter to provide the NTSC PCM
video signal at a terminal 24."
http://www.talkaboutsatellitetv.com/group/rec.video.satellite.dbs/messages/176380.html
quote:
"There is uncompressed PCM for video. The data rate is 270 Mbit/sec for
standard definition, 525 line, 60 field interlaced. The computer folks
refer to this as 480i. For Hi def, the data rate bumps up to 1.5
Gbit/sec for 1920x1080 interlaced. This stuff is only seen in studios
and post production facilities."
Hmm. Well I would like to see some 2000 X 2000 X 2000 voxels
progressive [non-interlaced] 32-bit PCM video signals which have been
produced by sampling and quantizing SECAM analogue video signals in
response to sampling pulses having a sampling frequency of 1 Hz.
http://en.wikipedia.org/wiki/Voxel
VERY IMPORTANT NOTE: While NTSC and PAL use an amplitude-modulated
carrier for video, SECAM uses FM video.
I really like FM video. Don't know why ;-)
Bob Eld wrote in
http://groups.google.com/group/sci.electronics.basics/msg/1fe38e9f4f89aa01?hl=en&
:
> Simple answer: FM is wasteful of bandwidth with other things equal. The
> video signal needs about 3-1/2Mhz of bandwidh. It would be difficult to get
> this with FM unless the channel spacing was maybe 10 to 20MHz depending on
> modulation index.
What if the WMV [Windows Media Video] digital compression is used and
the color resolution is decrease sufficiently? Its possible to have a
supreme quality in terms of number of pixels and frame rate. All you
have to do is compress the WMV's color resolution and you can get a
bit-rate that is low enough not to hog bandwidth and at the same time,
the image resolution and frame rate will be that of a first-class video
signal.
Regards,
Radium
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