Note: Descriptions are shown in the official language in which they were submitted.
1 32~q20
This invention relates generally to the
recirculation of video data through a video framestore to
create a variety of special effects. Thi~ invention further
relates to the combining of new Yideo data with
recirculating video data, on frame or alternate field
interpolation basis. This invention further relates to the
use of a recirculating frame store in a video combiner
system.
E~ACRGROUND OF THE INVENTION
In composing a television production, there is an
ever increasing need for variety of special effects. The
phrase, special effects, is used to broadly define the
selective altering and/or manipulating of video data to
create a visual effect to attract the attention of the
viewer. 5pecial effects are used in a variety of vidèo
production situations.
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There ~re ~ number o~ aev~ce~ th~t c~eate these
special e~ect~. Video ~itchers are one device that can
produce 6peci~1 effect~. ~he 6peciAl effect6 produced by
video switc~er are m~st comm~nly u~ed while ~w~tch$ng
~etween video sources. Common switcher 6pecial effects
include dissolves ~nd wipes. An example of a video switcher
that can produce a variety of di~801ve~ ~nd wipe6 is the AVC
video ~witcher of Ampex Corpo~ation.
Another device for producing special effects is
the digital special effects 6ystem, æuch as the AD0 digital
special effects æystem of Ampex Corp~ration. Digital
special effects systems can perform a number of special
effects such as video frame enlargement and reduction, frame
movement, frame rotation in 2 and 3 dimensions, and
perspective manipulation. Each of these effects can be
combined with other special effects to form even more
complex effects.
The output from a digital special effects system
commonly includes not only an output video signal, but also
a corresponding key signal. The key signal indicates the
level of the video signal, that is the ratio of the gain of
the video signal relative to its original gain in the
corresponding video signal. Xey signals can be created by a
variety of video devices.
There are two types of key signals. The first is
a bi-state key signal, which simply indicates whether the
corresponding part of the video signal is to be retained.
If the corresponding part of the video signal is to be
retained, the key signal has a value of one, and if it is
not to be retained, then the key signal has a value of zero.
A more generally useful type of key signal is a
linear key signal. Instead of having just two possible
values, the linear key can have any value from zero to one.
Thus, the value of a linear key can be used to partially
reduce the level of a video signal. When viewed on a video
monitor, a corresponding video image woula exhibit a level
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of tran~parency corre6ponding to the ~alue of the key
~isn~l. . .
- ~he llnear key i6 one method to ~llow two videG
~ign~ls to be ~dded, If two vldeo ~lgn~ls were ~imply
~dded, their combined dynamic range would be twice the
~mount that could be ~andled by the video 8y6tem. In order
to add two video 6ign~1s, their dyn~mic range must be reduce
6uch that when ~dded, their total dynamic r~nge i~ equal to
the maximum dynamic range or less. Process~ng the Yideo
~ignals with l~near keys i~ one method to effect this
dynamic range reduction.
A key signal is used to process a video signal. A
video signal is processed by a key ~ignal by multiplying the
key signal with the video signal. Parts of a video signal
which are processed with a corresponding part of a key
signal which has a value of zero, will result in keyed video
signal that has a signal level of zero. Conversely, when
processed with a key signal of one, the keyed video signal
will be left unchanged. When processed with some
intermediate value of a linear key, the signal level of the
video signal is reduced by that amount, effectively
resulting in the video signal appearing transparent, if
viewed on a video monit~r.
Two or more keyed video ~ignals can be combined
only they have been processed by key signals totaling one or
less. For example, if a first keyed video signal has been
processed by a key signal of 0.5 and a second keyed video
signal has been processed by a key of 0.4, the two keyed
video signals could be combined, because the total of the
key signals is 0.9, which is less than one. However, a
video signal processed by a key of O.5 cannot be combined
with a video signal processed by a key of 0.6, because the
total of the key signals would be 1.1, which is greater than
one. In practice, a decision is not usually made on whether
to combine video signals based on their associated keys, but
rather key signals are adjusted so as to allow the combining
of video signals.
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An unfortunate pro~lem ns~clated w~th the s~le of
~pecial effects mach~ne~ 15 th~t the ~ore often a partlcular
effect is u6ed, it~ novelty disappears and thu6 ~t6 ~bility
t~ ~ttr~ct attention d~m~nishe6. Thu~ there is ~ con~tnnt
need for new ef~ects. Additionally, the larger the library
of potential effects available to the operator, the les~
often the operator Will need to C811 upon a particular
effect. There 1~ a need, therefore, for a var~ety of
6pecial effect~.
Framestores have been used in the video industry
f or many years. A framestore is a mem~ry device that can
store one complete frame of vide~ data. ~ramestores are
commonly digital. Digital framestores allow manipulati~n of
stored video data. Digital framestores are commonly used in
digital special effects systems.
Framestores are typically configured to input a
frame of video from one part of a ~ystem and output the
frame to another part of the system. When a new frame of
video is inputted the framestore, the previous frame is
completely overwritten.
A frame of video is actually composed of two
interlaced fields of video. A frame of video contains a
certain number of horizontal lines of video information ~for
example, 525 lines in the NTSC system used in the United
States). Each field is composed of every other line which
are interlaced to form a fr~me of video data. A frame of
video is recorded by first recording one the fields an
successively recording the other field. A typical time
period between the recording of successive fields is o-
ne-sixtieth of a second (in NTSC system). If there is
significant movement in the images of the video signal,
there will be an annoying flicker when two fields are viewed
as a video still frame. This can be a problem when such
fields are combined in a framestore. One method to solve
this problem is to use only a process called alternate field
interpolation. Alternate field interpolation uses only one
field of video from each frame and interpolates the second
field from the first field. Because the second field is
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b~8ed entlrely on the f~r~t fleld, there 1B no ~ovement
between ~ield6 ~n ~ frame. The d$6adv~ntage of t~ ethod
i6 that one h~lf o~ the video in~ormat~on ~0 being thrown
away. ~hen there i6 l~ttle or no movement between field6,
the ent~re frame s~ould be used. Therefore, there ~8 a need
~or a method ~nd ~pparatus to prevent flicker when there ls
movement between two field~ of frame of video that makes use
of the entire original ~rame.
It would be adv~ntageous $f the output of a
frame~tore could be xecircul~ted back through the framestore
with the addition of new input frames. This would allow the
combining of many frames of video to from an output ~ignal.
A number of special effects can be created by this
recirculation, including blurs, smears, and trails, all
~ighly desirable special effects. Such recirculation
requires the ability to combine video signals. This ability
to combine video signals requires the ability to manipulate
video signals and associated key signals. Such a framestore
would require key signal processing, storage and
recirculating capability.
Another desirable special effect would be the
ability to decay or selectively remove recirculated frames.
Recirculated frames can be decayed in a variety of ways,
including decaying in a preset order or in a random pattern.
If decayed in some preset order, a method needs to be
provided to determine the order of decay. If removed
randomly, a method of generating the random decay needs to
be provi~ed.
While such a framestore could desirably be
operated as part of many video systems, such as a switcher
or digital special effects system, it could also be operated
as a stand alone unit. A particularly desirable use is in
conjunction with a video combiner or concentrator. A video
concentrator is a device which selectively combines various
video signals and their associated key signals to form one
or more output video signals. An example of such a video
concentrator, is the ADO Concentrator of Ampex Corporation.
Because of the variety of input signals available, the video
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concentrator 1~ an ldeal locnt~on for a ~pec~al effects
~r~me 8tore.
SUMMARY OF THE INVENTION
The present ~nvention fulfill~ a need for
prov~ding a variety of 6pec~1 effect6 by use of a
recirculating ~ame 6tore u6ing a variety of de~aying
method~. Additionally, the present invention provides for a
selective method of preventing flicker between su~cessive
fields of video. The present invention, further, provides
for the operation of a recir~ulatin~ framestore as part of a
video concentrator.
In accoxdance with the present invention, a video
framestore is provided with a recirculation path that allows
the output of the framestore to be combined with new input
video the combined video being returned to the framestore
for storage. The corresponding key signals for both the
recirculated video and input video are processed along with
the video and stored in a key framestore. This
co-processing of key signals along with the video signals
allows recirculation and combininq of video signals. A
number of control systems within the recirculating
framestore system enable the creation of a variety of
effects.
One control system used in connection with the
present invention is a key signal gain processor. Such gain
processors allow a uniform reduction in the gain of either
the recirculated key signal or the input key signal. These
key signals are used to further process the video signals
that are being added to or recirculated in the framestore.
The manipulation of these gain processors can define how
recirculated video is combined with the new input video.
Further, by setting the input gain to zero, no new video
signal will be combined into the framestore, 80 that the
video signals present in the framestore may be retained or
decayed, but not be written over by new input video ~ignals.
Setting the recirculation gain to zero causes no video
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slgnal to be reclrculate~, ~nd the fr~me6tore ~11 thus be
written over by lnput vldeo r
Using ~U8t the g~$n processor6, a still lmage or
freeze frame can be created or input vldeo signal6 can be
passed through un~ltered. Other effect6 can be cre~ted ~y
adjustment of the gain processors.
An ~mp~rt~nt aspect of a rec$rculating framestore
is the manner in whi~h recirculated video i6 dec~yed.
Different ~ethods of decaying video create different special
effects. One method ~s not to decay the recirculating video
signal at all. This creates the effect of the video images
always writing over old images, when viewed on a video
monitor. If there is movement in the video signal, a
non-decaying trail is created.
Video frames can also be decayed by the above
discussed gain processors. By setting the gain on the
recirculated key to a value less than one, but greater than
zero, recirculated images will fade on each recirculation
until they disappear. The closer the gain is to zero, the
faster the recirculated video will fade. Each image added
to the framestore will decay at the same rate, but will be
at different stages of decay, dependinq on when the image
was added to the framestore. At any one time, the
recirculated video might contain an image recently added as
well as images added much earlier, and if the recirculated
video was decayed by the gain processor, the images added to
the framestore earlier will be more transparent than those
added more recently, if viewed on a monitor.
Another control system to decay recirculating
video uses the key signal as a time. The recirculating key
signal is decayed by the gain processor in the selected
manner. However, the key signal is not allowed to process
the video signal, and the output key signal is maintained at
a value of one and does not reflect the diminishing value of
the key signal. When the key signal associated with a
particular image reaches a predetermined bottom threshold
value, the key signal is set to zero. The zero key value is
then used to process the video signal and is outputted as
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the ~ey ~ign~ he eff~ct of thl~ tlmed dec~y 1~ th~t
an im~ge 1~ moved and lt leave6 ~ trall of old ~mages~ eac~
old ~mage lnstant~neously dis~ppe~r w~thout ~ gr~u~l decay,
in the order ln which lt w~6 ~dded to the frame store. If
the images be~ng added are sm~ller than the bound~r~e6 of
the frame of video, the effect created appe~r6 ~omething
like the movement of a cent~pede, when viewed on a ~onitor.
As new images are addedto the front of the trail of ima~e~,
the oldest images are one by one disappearing off the bac~,
creating a desirable æpecial effect.
To create another effect, either of two preset
gain values are applied to the gain processor instead of a
uniform value being applied. ~his requires a recirculating
gain control generator which upon receiving a random signal,
selects either of the two possible gain values. The effect
thus created causes different parts of recirculated images
to randomly decay at two different rates. The effect
resembles the twinkling of stars at night.
The random signal generator used to create the
random control signal uses a random sequencer rather than a
random number generator. A good random number generator is
difficult to produce. The random sequencer, which produces
a random two state signal, is easier to implement and
produces a more truly random output. This two state output
is used in conjunction with a presetable counter. The
preset on the counter is used to determine a threshold
level. By adjusting the threshold level, the frequency of
the gain control signal can be controlled.
The present invention provides for a method of
solving the inter-field flicker problem by modification of
alternate field interpolation. In traditional alternate
field interpolation, only one of each pair of fields is
actually used. The present invention actually splits the
~ramestore and its video and key recirculation paths into
two channels, one for each field of video. These two
channels are completely recirculated during the period each
field is received, instead of being recirculated onceduring
the period a full ~rame is received.
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Thu6 when the fir~t flel~ 1~ be~ng prcces~ed, an
~nterpolated second field ~6 belng proce6~ed at the same
time. N~rmally one field 16 proces~ed at a time. Thi6
proce8~ing ~t the field rate m~int~ins t~e resolutlon of a
non-interpolated ~ignal, while el~minating inter-field frame
~licker.
An ideal l~cati~n for 8uch ~ recirc~lating
frame6tore i~ as part of ~ vldeo concentrator. By ~ts
nature, the recirculating fr~mestore must have ~cce~ to key
as well as video signals. In a video concentrator, all the
needed signals are available . Further, the effectiveness of
the special effects is enhance by a number of possible input
images, including multiple-image images that ~an be created
by the concentrator. The concentrator also allows the
output of the recirculating frame store to be combined with
other signals being outputted.
Various of the above-mentioned and further
features and advantaqes will be apparent from the specific
examples described hereinbelow of an exemplary apparatus and
method.
BRIEF DESCRIPTION OF TBE DRAWINGS
Figure 1 is a schematic representation of
components of a concentrator utilizing a recirculating
special effects framestore in accordance with this
invention.
Figure 2 is a schematic representation of a
recirculating special effects framestore in accordance with
the present invention.
Figure 3 is a schematic representation of a key
processor in accordance with the present invention.
Figure 4 is a representation of an output frame of
video of a recirculating special effects framestore view on
a video monitor.
Fiqure 5 is a schematic representation of a random
signal generator in accordance with this invention.
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Figure 6 is a schematic representation of the
control circuit for the luminance alternate field
interpolator.
Figures 7, 8 and 9 are waveforms of signals
appearing in the circuit of Figure 6.
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DETAILED DESCRIPTION
Flgure 1 i~ an ~ll~strAtlon o~ ~ typlcal vlde~
concentr~tor 10. An lnput bu6 12 recelve6 t~e v~rlou~ Lnput
s~gn~l6 ana route~ them to other part~ of the ~oncentr~tor
~ccording to control rignal 28, Input ~hannel~ 14, 16, 18,
~nd 20 ~nput both a video signal and ~ key Rignal. The
vide~ s~gnal ~ an ~nkeyed video signal, which i~ a video
s~gnal that ~s not been processed by it~ corresponding key
6ignal. The key signal accompanies the ~deo sign~l as an
indicator of the within the concentrator. The ource of
these input channels may be a number of video devices, such
as switchers or digital special effects system. While four
input signal pairs are shown, it is understood that any
number of input channels would be allowable.
There are preferably two background channels 22
and 24. These channels are vide~ signal only inputs that
usually provide a color background, although any video
signal can be used. Background channels 22 and 24 are used
to fill in the areas of the output frame that do not contain
keyed video signals. In areas where the linear key is
greater than 2ero but less than one, the background is added
to make the value total key signal equal to one. As with
the input channels, any number of background channels are
allowable.
The other input signal on input bus 12, is a framestore
channel input 26. Framestore channel input 26 contains both
a keyed video signal and an associated key 6ignal,
indicative of the key processing already performed on the
~ideo signal. ~ramestore channel input 26 is the output of
recirculating special effects framestore 30.
Input bus 12 routes the various signals to three
concentrator channels 32, 34 and 36. Control signal 28
determines which ~ignals are passed to which channel.
Control signal 28 is derived from operator inputs at a
c~ntrol panel.
The three concentrator channels 32, 34, 36 receive
input signals from input bus 12 according to control signals
28. Concentrator channel A, 32 and concentrator channel B,
34 preferably are identical channels. Both channels A, 32
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AV-335~ Cl
~nd B, 34, c~n accept any comb~natlon of lnput ch~nnel~
16, 10 ~n~ 20, or fr~mestore ch~nnel 2C, an~ comblne them
~cc~rd~ng t~ ~oncentr~tor control ~iqn~ls ~. Bac~ground
channel~ 22 and 24 can only be routed to concentr~tor
ch~nnel6 ~2 and 34. Becau6e the output o~ the fr~me~tore 30
~ust be outputted through one o~ the ot~er concentr~tor
~hannel~, there ~6 ~n opportunity to add n b~ckground ~ignal
at that Bt~ge. ~
The output of concentrator channel~ A and B, 32
and 34, are output ~i~nals 38 and 40. Output fiignals 38 and
40 both have a video signal and a key signal. Once again,
the key ~ignal i~ indicative of the previ~us key processing.
The output of concentrator framestore channel 36, i~ a
concentrator framestore channel output channel 46, which
contains both a vide~ and key signal inputted to
recirculatin~ special effects framestore 30.
In operation, signals are selected of input bus 12
and are fed to each of the concentrator channels, 32, 34 and
36. As an example, concentrator channel A, 32, receives tw~
input channels, 14 and 16, and a background channel 22. The
c~ncentrator control signals 44 dictate that input channel
14 should have priority over input channel 16. The video
signals of input channel 14 and 16 are processed and
combined accordingly, and then keyed into background channel
signal 22 to form a channel A output signal 38.
Continuinq the above example, input channels 18
and 20 are ed into concentrator framestore channel 36.
Input channels 18 and 20 are combined and outputted to the
recirculating framestore 30. In framestore 30, new images
are combined with old recirculated images according to
framestore control signal 47 and outputted to frame store
channel input 26 as a video and key ~ignals. Framestore
channel input 26 is fed to the input bus 12, and in turn fed
by the input bus 12 to concentrator channel B, 3~.
Background channel 22 i~ also fed to concentrator channel B,
34, where it is added as background to the framestore
channel input 26. The result is outputted as channel B
output signal8 40. These 8ignals can then be fed to any
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vl~eo ut~ atlon ~evlce, ~uch aB a ~onltor, ~l~eo t~pe
recor~er, or bro~cast ~y~tem.
In the a~ove ex~mple, the routing of ~lgnals W~8
arb~trar~ly cho~en to 111~6trat~ ~ typ~cal oper~tlon of the
concentrator. The operator ~a6 complete control over a
large number of potenti~l routin~6 of ~ignals.
Next, the operat~on of the rec~rculating
framestore 30 w~ll be d~scu6sed. Whi~e the frame~tore 30 i~
preferably located within a ~ideo concentrator, ~t ~8 clear
that it could operate with numerou6 video systems and as a
self contained system.
Referring now to Figure 2, recirculating
framestore 30 is shown. In ~igure 2 there are three types
of signals which are routed about the recirculating
framestore 30. They are video signals, which are shown as
double bus lines, key signals, and contr~l signals. If this
system is digital, which is the preferred embodiment, the
video and key signals of binary signals.
Both video and key signals are recirculated. The
video follows a relatively simply recirculation path and
will be discussed first. Input video signal 60 can
originate from a variety of video devices. If framestore 30
is part of the concentrator 10 of Figure 1, then input video
signal 60 will originate in concentrator framestore channel
36 as output signal 46.
Input video signal 60 is fed to video gain
processor 66 where it is processed with input gain signal
62. Input gain signals are numbers between zero and one,
and input gain signal 62 specifies the amount of gain
reduction to impose on input video signal 60. Input gain
signal 62 preferably is generated by a control system from
operator i~put. Video gain amplifier 66 can be implemen~ed
as a simple digital multiplier available in integrated
circuit packages.
The output of video gain proressor 66 is fed into
alternate field interpolator 64. Interpolator 64 operates
in two modes. The first mode is used where there is little
or no movement between fields of video. In this mode no
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interpolatlon take3 place. The second mode 18 used when
there is movement between the field~ of video. The operat~ng
mode ~s determined by lnterpolator ~ontrol signal 6B. This
signal preferably is generated by the control system from
operator input. When the operator notices a flicker in the
output signal displayed on a video monitor, the operator
sets this signal ~o the second mode.
If automatic generation of the interpolator
control signal 68 is desired, input video signal 60 can be
monitored by a motion detector in a well known manner. Sueh
a motion detector will set the interpolation control signal
68 to the second mode whenever motion greater than a
selected threshold amount is detected.
In~erpolator 64 has two channels, A and B.
Channel A receives video field one, and channel B receives
video field two. Channel A outputs an input channel A video
signal 70 to a channel A video combiner 72, where it is
combined with a recirculating channel A video signal 74.
Ch2nnel B outputs an input channel B vide~ signal 76 to a
channel B video combiner 78, where it is combined with a
recirculating channel B video signal 80.
If interpolator 64 is operating in the first mode,
corresponding to a condition of no movement on flicker, then
interpolator 64 acts as a routing device. According to a
field control signal 82, the input video signal from video
gain processor 66, is fed to either channel A or B for
output as either input channel A video signal 70 or input
channel B video signal 76. Field control signal 82 is
generated by the control system and indicates whether the
current field being received is the first or second field of
~he video frame.
- If interpolator 64 is operating in the second
mode, alternate field interpolation is occurring. When
field oontrol signal 82 indicates that the first field is
being inputted, the input video signal is outputted directly
on channel A as input channel A video signal 70. From the
first field video ~ignal, a second field v~deo signal is
mterpolated and outputted by channel B as input channel
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AV-335~ C
vld~o lgn~l 76. ~he proce~s of altern~te f~el~
lnterpolat~on 16 ~ell knvwn to t~se !k~ d in the art.
When Yiel~ control sign~l 82 lndicate~ th~t the ~c~nd fiel~
1B being inputted, the lnput video ~ign~l $~ outputted .
~irectly on ch~nnel B a~ input ch~nnel ~ vldeo signal 76.
Fr~m the ~econd field v~deo ~ign21, ~ second field video
signal i6 interpolsted ~nd outputted by channel A a~ lnput
channel A video siqnal 70.
Input channel A video signal 70 18 combined w~th
recirculating channel A video fiiqnAl by channel A video
combiner 72. In the preferred embodLment, video combiner 72
i~ implemented as a digital adder, which is available as an
integrated circuit. Channel A video ~ombiner 72 outputs an
output channel A video signal 82. Output channel A vide~
~ignal 82 is fed to both output video ~witch 84 and cha~nel
A fieldstore 86.
Output video switch 84 is operated in tandem with
output key switch 88. Both switches are operated by output
field celect signal 90. Output field select signal 90 is
generated by interpolator 64 based upon field control signal
82. The switch positions are alternated corresponding every
field of video to form a standard video signal. The output
of video switch 84 is the output of framestore 30. If the
framestore 30 is located in the concentrator 10 of ~igure 19
the output video signal is part of the framestore input
channel 26.
Input channel B video signal 76 is combined with
recirculating channel B video signal by channel ~ video
combiner 78. Video co~biner 78 is the ~ame as channel A
video combiner 72. Channel B video combiner 78 outputs an
output channel B video signal 82. Output channel B video
~ignal 82 is fed to both output video switch 84 and channel
B fieldstore 84.
Output channel A video ~ignal 82 is also fed into
the channel A fieldstore~ ~ideo ~ignals are ~onstantly
being read in and out of fieldstore 86. Each pixel of video
data remains in the fieldstore for the time duration of one
field of video. ~ieldstore 86 outputs recirculating channel
^ ~ 1 328920 '~5' ~ AV-335B Cl
A vlde~ ~gnal 96, ~h~c~ 1~ fad to vl~oo ~ln pr~e-~or 98.
Vlfleo ga1n processor 98 i~ the ame a~ to lnput v1deo galn
pr~ces~or 66. Reclrculnt$ng channel A ~ldeo 1gnal 96 1~
proce~sed wlth a channel A key ~gnal 97. The deri~at~on of
thi8 key ~1gnal ~11 be dl~cus~ea bel~w. The output of
channel h ga$n proce660r ~ fed lnto ch~nnel A vldeo
comb~ner 72 and comb~ned ~ith video ~lgn~l 70 to produce
v~deo s~gnal 82 ~hieh i8 recircul~ted bac~ through the
field~tore 86.
~ he channel B video recirculation path i8
identical to channel A. Output channel B video signal 92 i6
also fed into the ~hannel B field store. ~ieldstore 94
outputs recirculating channel B video signal 100, which is
fed to ~ideo gain processor 102. Video gain processor 102
is the same as video gain processors 66 and 98.
Recirculating channel B video signal 100 is processed with a
channel B key signal 104. The derivation of this key signal
will be discussed below. The output of channel B gain
processor is fed into channel B ~ideo combiner 78 and
combined with video signal 76 to produce-video signal 92
which is recirculated back through the fieldstore 94. This
completes the input and recirculation paths for the video
signals in recirculating framest~re 30.
The path of the key ~iqnals will be discussed
next. Input ~ey signal 106 indicates the previous
processing of input video signal 60. ~ecause input video
signal 60 is directly processed with input gain signal 62,
input key signal 106 is also processed with that signal so
that it will remain reflective of the processing of input
video signal 60. Input key signal 106 is processed by input
key processor 108. Input key processor can be implemented
as a digital multiplier. The output of input key processor
108 i~ fed into interpolator 64.
Interpolator 64 dses process the input key ~ignal
106 in the same manner that the input video signal 60 is
processed. Key signal6 that correspond to the irst field
are routed to channel A and outputted as input channel A key
~ignal 110. Rey signals that correspond to the ~econd field
` 1 328920
-16- AV-3358 Cl
are routed to ~hannel B and outputted a~ input channel B key
~ignal 112. Input channel A and B key video ~gn~ls, 110
and 112, are fed to channel A and B key processors, 114 and
116, respectively.
Each of the channel A and ~ key processors, 114
snd 116, actually is a combination key processor, key loop,
and key store. Another input to key processor 114 and 116
is recirculation gain lla. The derivation of recirculation
gain 118 will be discussed below. To the key processor 114
and 116, recirculation gain 118 is used to process an
internal recirculating key signal.
~ eferring to Figure 3, the channel A key processor
114 is shown. It is understood that the channel B key
processor 116 is identical. Inside the key processor 114,
the input key signal 110 is subtracted from o~e by the
l-XIN processor 250 to form a remainder key signal 252. The.
remainder key signal 252 represents the amount of key signal
not used by the input video signal 70 of Figure 2. The
~ N processor 250 can be implemented, for example, as an
inverter and digital adder. The output of the 1-KIN -
processor 250 is fed to a minimum processor 254.
A recirculation key signal 25S represents the key
signal used by the video currently in the channel A field
store 86 of figure 2. The recirculation key signal 256 is
processed wi~h the recirculation gain signal 118 by key
signal processor 258. Key signal processor 258 is identical
to key signal processor 108. The resulting signal is the
processed recirculation key signal RRECIRc~ 260, which is
fed to minimum processor 254 with remainder key signal 252.
Minimum processor 254 determines ~he minimum of
the key signals input thereto and outputs the signal as
minimum key signal ~MIN~ ~62. Minimum processor 254 can be
implemented as a diqital comparator. The output of minimum
processor is fed to both key signal adder 266 and ratio
processor 264.
Ratio processor 264 determines the ratio of the
minimum key signal X~IN, 262, to the processed recirculation
key signal XREc~Rc, 260, to form the
1 3289~
-17- AY-3358 Cl
recirculat~ng ch~nnel A key ~ignal 128. Ratio proce~sor 264
can be ~mplemented a~ an ar~thmetic processor integrated
circuit, but is preferably implemented as a look-up table in
a ROM memory.
The output key signal 127 is ~lso fed to an
internal key store 268, from which ~t is outputted as the
re~irculation key signal 256. Key store is simply a memory
array of the same number of pixel locations as the channel
field stor~ 86.
The key processor 114 also outputs the sum of the
minimum key signal 262 and the input key signal XIN, 110, as
the recirculatins channel A output key signal 127.
Referring again to Figure 2, key processor 114 is
designed to allow input video 70 to use as much of the
available signal gain is it needs. It is said to have
priority over the recirculating video 96. All of the
remaining gain is available to the recirculating video 95.
If necessary, the recirculating video 96 is processed down
to the level of the remaining key space. If the
recirculating video 96 can use all the remaining gain, then
the output key signal 127 is one. However, if the recir-
culating video 96 has already been reduced, or will be
reduced by the recirculation gain signal 118 to a level less
than the remaining gain, then recirculating channel A key
signal 128 will be at that level and the output key signal
127 will represent the total of the input key signal 110 and
the minimum key signal 262 (Figure 3), which will be less
than one. Video signals that have been reduced in gain have
lost information because these signals exist in only limite-
d resolution. Thus when they are reduced, they lose
resolution and if increased in gain, they will not reproduce
their original values. Ihus video signal preferably are
only reduced in gain, and not generally increased.
The recirculating channel A and B key signals, 128
and 130 fed to channel A and B decay processors, 132 and
134, whose function will be explained below. If not
activated, decay proces~or 132 and 134 pass their input
~ignals unaffected. Thus recirculating channel A and ~ key
1 328920
A~-3358 Cl
~gnals are outputted as channel A and a ~ey signals 97 ~nd
104.
~ he channel A ~nd B output key slgnals are al~o
fea to channel A and B decay processor~ 132 and 134, ~nd are
also pass unaffected if decay processors 132 and 134 are not
activated as channel A and B key output s~gnals, 131 and
13~. The channel A and B key output ~ignals, 131 and 133,
are fed to ~ey switch 88. Xey switch 88 is operated in
tandem with video switch 84. The output of key switch 88 is
the output of framestore 30. If the framestore 30 is
located in the concentrator 10 of Figure one, the output key
signal is part of the framestore input channel 26.
The recirculation gain signal 118, used by both
key processors, is generated by recirculating gain processor
120. Recirculating gain processor 120 operates in two
modes. These mode are selected by gain control signal 1~6,
which is generated by the control system, preferably from
operator input. In the first mode, recirculating gain
processor 120 outputs recirculating gain 1, 1~2, and outputs
it as recirculation gain signal 118. This is considered the
normal operating mode.
In the second mode, recirculating gain processor
120 receives a random control signal 136. This two state
signal is generated by a random signal generator 150 of
Figure 5, to be discussed below. The random control signal
136 selects either recirculation gain 1, 122, or
recir~ulation gain 2, 124, as recirculation gain signal 118.
Decay processors 132 and 134, when activated,
output key signals having a value of one regardless of their
input signals, unless their input key signals are under a
low threshold level, when they output signals of zero. The
purpose of this processin~ will be discussed below.
This completes the discussion of the
interconnection of the elements of Figure 2. Next, the
operation of Figure 2 will be explained.
The operation of re~irculating framestore 30 i9
best understood w~thin a typical example. ~he goal of thi~
example i~ to create a special effect called a trail. A
2 8q 2 0 -19- ~ ~V-335~ C1
trall 1~ lllu-trat~ ln F~gure 4. ~lgure ~ 1- a
repre~entatlon of a vldeo ~lgnal vlewed on a vlaeo non~tor.
A ~e reduc~ frame 200 1~ ~ove~ fro~ a tartlng locat~on
210 to a flnal l~cation 200. AB lt ~oves along the path, ~t
leave~ old reduce~ frame6 such a~ 210, 212, 21~, 201 and
202.
In thi~ example the ~nput vldeo 60 IFlgure 2)
comprise~ a size reduced frame of v~deo ~n an ~therw~e
empty full fr~me 190. Such a v~deo signal can be created by
a digital 6pec~al effects 6ystem which ~s capable of
reducin~ a video 6ignal and positioning it within a full
frame of video. If reduced frame 210 were not partial
obscured by reduced frame 212, and reduced frame 210 were
t~e only reduced frame in full frame 190, then Figure 4
would be a representation of input video signal 60. It
should be assumed that frame 210 contains a video picture,
such as a field of flowers or a news anchorman reading the
news. Over a period of time, the frame of active video is
moved in relation to the full frame of video. Frame 210
follows the path shown by the other boxes in the full frame
on the video monitor. Unlike Figure 4, which actually
represents the desired trail effect to be created by the
recirculating framestore 30, input video 60 does not leave a
trail, but rather only one frame is visible at any one time.
The moving frame starts at the location of frame 210, and
follows the path shown and stops at the location of frame
200.
Input key signal 106 (Figure 2)is created with
input video fiignal 60 and has a value of one where it
corresponds to the reduce frame 200 and a value of zero
elsewhere. In this example, both the input gain signal 62
and recirculating gain ~ignal 118 are set at one. ~owever,
the effectc of changing these ~ignals will be discussed
below. For this example it i~ also assumed that fieldstores
86 and 94 ~tart empty.
Framestores are commonly 6aid to recirculate at
frame rate. Thi~ means that the contents of the framestore,
one $rame (two fields) of video, recirculates once in the
tLme it takes a new frame to be inputted. Because
1 32892~ -20_ AV-335~ Cl
frame~tose 30 18 ~ct~nlly compo~ed of two f~eld ~toros ~nd
recirculation p~ths, ~ramestore 30 can bc reclrcul~t~d at
field rate. This mean~ th~t the content~ of the fr~mestore
10 are completely recirculated in the time it ta~es to input
a new field. It is this doubled rate that allows
every-field interpolation ~y the interpolator 64. Operation
Of interpolator 64 on the luminance and chrominance
components of the input video signal 60 is described in two
sections of Ampex manual by David Trytko, one of the present
inventors, entitled "ADO Infinity - Target Framestore System
- System Theory and OperationK. A COpy of these sections
are attached hereto as The Appendix.
The input video signal 60 and input key signal 106
pass unaffected by processors 66 and 108, because the input
gain si~nal 62 in this example, is set to one. If
interpolator 64 is off, the first field of video and key are
sent to ch2nnel A. Nothing is sent to channel 8. Anything
recirculat n~ in channel B is allowed to recirculate without
additional material. The second field of video and key are
sent to channel B and nothing is sent to channel A.
If interpolator 64 is on, then as field one of
video and key is routed to channel A, an interpolated second
field of video and key is sent out on channel ~. When the
real second field is encountered, it is sent out on channel
B and an interpolated first field of video and key is sent
out on channel A. This alternating interpolation allows the
fieldstores to be updated with new material every field,
instead of every frame, producing improved picture quality
in the resulting video ima~e.
The common method of alternate field interpolation
in prior art devices would be to receive the first field and
video and pass them on channel A and send nothing on channel
B. Upon receiving the second field, the second field is
discarded and a new second field of video and key is
interpolated from the first field and sent out on channel ~.
Nothing ~s sent out on channel A. When the interpolator i8
off, the field stores are only updated with new material
every frame. Thi$ pre~erves the full resolution of the
origi~al fr~me of video. Under
1 ~28920 21- ~ AV-335B ~1
the co~mon Detho~ of ~nt~rpol~tlon, one of the flel~ ln a
frame 1B ai-c~raed ~n f~vor of an lnterpolate~ flel~ ~o a6
to el~n~te lnter-f~eld fl~cker. Interpol~tor 6~ u~es both
fields ln the fr~me to lnterpolate, an~ reduce or ellmlnate
flicker. By using both field~ ~nd updated on f~eld bAsls,
there i~ no los~ of re~olut~on ~s comp~red to the more
common ~et~od of altern~ted fi~ld interpolation.
The channel A input video signal 70, ~fter leaving
interp~l~tor 64, 16 combined with the channel A
recircul~ting vide~ ~4. Before beiny combined with the
channel A input video, recirculating video 74 must be
processed with the output cf the key processor 11~. For
this first frame of video, the fieldstore 86 was defined as
being empty. Thus the output of the framestore 30 is the
input vide~ signal. The input video signal 70 is stored in
fieldstore 86 and the input key signal 110 is stored in key
store 268 (Figure 3). The second field of video and key is
processed in the same manner.
For the sake of this example, it will be assumed
that the second frame of input video contains the size
reduced frame of video now moved from position 210 in Figure
4 to position 212. The input video signal 70 is passed
normally to video combiner 72,. The input key signal 110 is
also passed to key processor 114.
Referring to Figure 3, the input key ~ignal 110
defines the area of reduced frame 212 in Figure 4. The key
signal 110 is subtracted from one to form the remainder key
signal 252, which indicates what key signal 6pace is
available to the recirculating video. Xey store 268
contains the key signal from the first frame, which defines
the area of reduced frame 210 in Figure 4. Because the
recirculation gain 118 is defined as one for this example,
the minimum processor 254 determines the minimum between the
recirculating key signal and one minus the input key ~ignal.
There are three areas of interest in this determination.
First is the area outside both reduced frames 210
and 212 of Figure 4. In that area of the key ~ignal the
minimum value i~ zero from the recirculating key signal 260.
~ 3~ 8q ~ -22- AV-33S~ Cl
. ~he next area of the ~y l~nal ~ the ar~a of the ~econ~
r~Auce~ frame 212 (F~gure ~). Note ~hat thl~ rume
part~aily ob~ure~ tbe flr~t frame 210. ~h~ fr~me 1~ psrt
of the lnput key lgnal, by de~ign, ~t ~a~ pr~orlty ov~r any
~mage be~ng reclrculated. It ~hould be noted th~t ~ey
proce~80r 11~ could easlly be design ~uch th~t rec~rculated
key ~ignal would have priority over ~nput ~ey ~ignal~. In
the area defined by input key ~ign~l for the ~econd fr~me,
min~mum process~r 254 output~ ~ero from the one ~inu~ input
key 6ignal 110. The third ~rea 16 the ~rea of the first
reduced frame that i~ not obscured by the reduced frame 212
(Figure 4) ~n the ~econd input frame. Thi6 can be ~een as
the backward ~L~ shaped area labelled 210 in Figure 4. Both
input ~ignals to minimum processor 254 have this area of the
key signal at one. Thus the minimum key signal 262 only
defines this backward ~L~ ~haped arear
The minimum key signal 262 is added to the input
key signal to form the output key signal 131 and the
recirculation key signal to be stored in the key store 268.
This key signal indicates area of interest in the output key
signal is the combined srea of the first and second input
keys 6ignals defining the two overlapping reduced frames of
video, 210 and 212.
The ratio of the minimum key 262 and the
recirculating key 260 is the minimum key 262, which becomes
the channel A key fiignal 97. The ratio i5 used to determine
how to process the recirculating video signal to a desired
level while taking into account the previous processing of
that video 6ignal. The channel A key signal 97 is used to
process the recirculating video 96. Recirculating video 96
contains the reduced frame 210 (Figure 4) from the first
output frame. After being processed by the channel A key
fiignal 97, the recirculating video signal is no longer the
full reduced frame 210 (Figure 4) but rather an ~L~ shaped
area of video. When added to the input video signal 70, an
output video ~ignal 82 is formed which is a video ~ignal in
the 6hape of two overlapping reduced frames, 210 and 212.
Thi~ video 6ignal i6 al~o 6ent to the f~eldstore 86, to be
1 3 2 8 9 2 0 -2~ AV-~351l ~1
u~e~ e reolrcul~t~ ~deo ~lgn~l ~or the n~xt lnput
~rame.,
The above discu~ion h~ been ~e~tricted to channel A for
t~e ~ake of cl~rity ~ ~t i6 cle~r th~t lt ~pplles equ~lly to
chnnnel B and the 6econa f ield6 .
Referring to Figure ~, fr~me 210 ~6 referr~d to as
tr~l. A~ frames are ~dded, the ~ame process occur6 until
the end of the .~pot~ on with ~rame 20û afi the ~nal fr~me .
Each new fr~me would obscure a port$on o~ the previou6
frame, yielding a full fr~me 190 as 6hown in Figure ~. The
trail i~ a basic speci~l effect of the recirculating
framestore 30. Other special effects may be described as
variations on the trail effect. The following will dis~uss
the effects of changing the control 6ignals.
Changing the input gain signal 62 to a value less
than one causes the new frames to have a transparent look.
If the frame is not m~ved, then a number of input frames
must be to added on top of each other to form a frame of
full intensity. Because even an apparently still picture
contains a slight amount of mo~ement of the originating
camera, the image becomes a blurred wherever movement
occurs producing a desirable special effect. If the frame
is moving, then the Lmage smears, which is also considered a
desirable effect. If the input gain signal 94 were set to
zero, no new video would ~e added to the recirculation path.
If the recirculation gain 118 was set to one at the same
time a freeze effect would be created.
Changing the recirculation gain one, 122, causes a
decaying of old Lmages. Each old image would become more
transparent until it finally disappeared. The more times a
particular image is recirculated the more its key signal is
reduced. ~f the added images are ~oved while being added, a
very pleasing trail that resembles the tail of a comet, is
created.
~ here are two other systems within the
recirculating framestore 30 to create special effects. The
first is the decay processors and the second is the
recirculating gain pro~essor.
- ~ 3~89~ ~V-335B Cl
- ~he ~pec~al offect c~oat~ by t~e ~ac~y proce~r~ 132
and 134 u-es the r~clrculatinq ~y ~gn~l, 250 ~F~ure 4), ;~
~n ~ey proces~or~ and ~16, ~6 ~ collectlon of ~own
counter~. The re~rculatlng key ~ignal ~ ~ec~yed normally
by the rec~r~ulat~ng gain oignal 118, ~ut the recirculat~ng
~ey s~gnal~ ~re not ~llowed to decay the recirculating video
6ignal6, 96 and 100, or oUtpUt ~ey 6ignal~, 127 and 129.
$~e recirculat~ng~ vi~eo e~gnsl6 96 ~nd 100 are proce6~ed
with ~ gai~ of one ~nd t~e output ~ey signal is outpu~ted at
one. Th~s effect, re~erring to F~gure ~, allows t~e old
frame images to remain at full ~nten~ity each old frame
image instantaneously disappear~ in the order they were
added as their key values go below a lower threshold value.
The effect looks something like the movement of a centipede.
To accomplish this effect, decay processors 132
and 134, when activated, output a key signal of one,
regardless of their input, unless their input is below the
low threshold, when they output zero. The low threshold
value is necessary because the key signal will never
actually reach zero as it is always multiplied by an amount
which only reduces its value.
The other effect system is the recirculating gain
processor 120. Recirculating gain processor 120 is
activated by gain control signal 126. Unless activated,
recirculating gain processor 120 passes recirculating gain
one, 122, unchanged-. ~hen activated, it passes either
recirculating gain one, 122, or 2, 124, depending on the
state of random control signal 136. Both recirculating gain
one and 2 are generated by the control system from operator
input. For a maximum effect, these two values should be
relatively different in value, although they could be 6et to
any values. The effect created by this two-rate deoay is a
sort of twinkling of the trail, ~imilar to the twinkling of
star6 at night.
~ hile a random control signal can be created in a
variety of ways, the preferred method is shown in Figure 5.
The control random signal 136 is the carry ~ignal of up
counter 140. The frequency of the control random 6ignal 136
1 3 2 8 9 2 ~ -25~ 335B Cl
ls ~etor~ined by the preret lnput 1~2 of counter ~0. The
larger the pro~et, ~e ~re trequently the r~n~om control
algnal 136 will be l-sue~. -The pul~es used to lncr~ment the
counter ~re supplied to the clock input 1~ of th~ counter.
The frequency of the clock pulses hould be at the rate of
~igltal aampling of the system, that iB the rate the pixels
move through the system. The r~ndom factor i8 created by
random ~equencer, 146, whi~h randomly output either zero or
one into the enable the counter 1~0. ~he effect of thi6
Arrangement is that the counter 140 counts down fr~m the
preset 142 only when enabled by the random sequencer 146.
Counter 140 can be implemented as a simple digital up
counter. Random sequencer can be implemented as a white
noise generator with a threshold output.
In summary, the recirculating framestore can be
adjusted by a variety of control signals and system to
create a variety of special effects. When there is movement
between consecutive fields of video, the framestore can
operate in an interpolation mode the interpolator
interpolates every field as opposed to every frame, to
reduce or eliminate flicker. The recirculating framestore
can operate in many video devices and even as a stand alone
device, but is preferably 5ituated in a video concentrator,
which acts as a ideal input and output system for the
framestore.
While the embodiments disclosed herein are
preferred, it will be appreciated that they are merely
examples, and that various alternatives, m~difications,
variations or improvements thereon may be made by those
skilled in the art from this teaching, which are intended to
be encompassed by the following claims.
1 328920
~5 CONT~OL - LUM~NANC~ ALTERNAT~ ~ELD ~NSERPOLA~oR
~ he Lu~1n-ne ~t~rn-t~ ~leld Int-rpola~r p-r~orm- the
~ollovlnQ funct~on-
~
lS) Aver-g-~ the Curr~nt Line luminanc- ~nd Prev~ou~ Line
~min~nc- to cr--te n lnt~rpol-ted L~n- o~ lumin-nce p~eially
betveen the tYo.
~ ~I ) Formats thc Current Line ~d Interpolat~d tin~ ~ampl~ into
a 13.S ~hz Field I Lu~inance Output ~nd ~ 13.S Mhz ~ield 11 Lu~inance
OYtPUt tO t~e TF S SIGNAL Board .
Refer to ~lgure 7 and the schematic of Figure 6 during the
folloving xplanation. She Current L~ne luminance (Y) rample~ are
buffered in 9~ and are t~en lat~h~d in 2C ~nd 2D. The l~tch ~ignals
detailed on Flgur~ 7 r~pre-ent t~e ~mplcs latchæd intern~lly ~t t~e
output of the~e cl~ip- ~nd re not vieYable on an 06cilloscope. She
m~tu~lly xclusive ~ ~nd ~ ignall~ ~rom ~he ~emory Contrsl
Circuitry indicat~ Yhi~h ~iel~ i~ pre-ently being receiv-d. w~en
Field I 1- being rocei~ed, the Current Line ~ample~ beco~e ~he ~ield
I Lumirun~ tput (lt~I) ~y ~n~bl~ng the output of 2C Yith Fl .
Sl~l~rly, ~h-n F~el~ b-ing ~e~elv~d, the ~u~rent Line Ja~ples
be~ome the Fl-ld ~ Luminanee oueput (YFSI) by en~b~$ng ~e output of
2D vit~ ~I$.
-26-
1 328q20
~ n ord r to upd t- both ri-ad ~to~ - v-ry ~l-ld th Lumln~nc-
A~ ~n-t- r~ nt-rpo~-tor ~ynther~zes ~k~ n~ r~-ld by
~v-r~gln~ ~b- Curr ne Lln- ~n~ Pr-vlou~ L~n- Lumlnan~n 0~ eh. P~-~-nt
F~-ld In t~ y, n Sn~-rpol-~-d Lln- o~ ~m~nane ~p-cl~lly
k-tY--n eh- t~c ~r --nt lln - 1- er-~t-d ~n~ uJ-d to r-pr---nt th~
lnt-rl-c d l$n o~ t~ Ml--in~ F$-1d Th- cusr nt Lln (Y) and
Pr-~.r$ou- t ln (~Y) S 12nin~nc~ r- ~ r-g-d by 11~ ~OF, nd 9E
eo b-~ome on- lnput to n B-b~t t~ lnput l-etor llE nd lOE vho~e
other lnput ~- zero
~ n tb F~eld Mode l~'~me~Foar~ ~ 1), tbe lnt~rpolat~d amples ~re
~ t-d nd laee~ed $n lC nd lD Dur~n~ Field S, th -e ~mpl~s
become t~e F$eld II Lu~in~nc~ Output (YFlI) by n~bling the output of
lD Yith F~ During Field II, th-~e ~mple~ become the Fleld
Luminance Outpue (YFI) by nabling the output o~ lC Yith ~II In this
v~y, the ~ in~ F$-1d $~ lnterpolated from the Pr~-ent F$eld
P:oviding Lun~n-nc for both ~i-ld- durin~ every f$~1d eli~inates the
~nt-r-f$-1d motlon fllcker of V$d-o Fr-~e, but redu~e~ the
re-olut$on o~ th~ tor-d $~ge~
In t~ Fr~m- ~od- tFrame Mode ~ O), the ~el~ctor outputs ~ value
of z ro to r g~-t~r- lC ~nd lD Thl- llOv- the F$~1d Stor~ of the
M~- d ng Fl-ld to r c~rcul-t- d thout be$ng updat~d ~y Snpue Video
Sh- ~o ~ lu becomer th Fi-ld ~S ~u~$n n~e Output (YFSS) during
~$~ nd lt b co~e~ the F$~1~ S Lu~ln~nc- Output ~YF~) during
~l-ld S~. ~S# Fr~m~ Mod- pr~ tb ~r~ olution of the ~tored
$~g~r but 1- un~ble to r-m4v lnt~r-fl-ld mot~on ~l~ek~r
-27-
1 328920
and YFSS OutpuC- thu- r-Pr~ t th ~npl t Lu~ nc~
o~ tb~lr x<~ d ~ro~--or-.
--28--
1 328920
~S CONS~OL--ChRO~A~XEY ALTERNA~E ~S~LD ~UTERPOLA~o~
~ h~ Chsom~X~y ~l~-rn-t- rl-~d Snt-rpol~Dr F-r~orm~ th~
~olloY$ng ~unc~cn--
(I) Av r-g-- th~ rr~nt i.~ne Chroma/RQy an~ Pr-v~ou- Llne
C~rom-/Xey to cr--te n Interpolae-d Lln~ o~ roma~Kcy p-cially
~e~Yeen the tvo.
(II) For~t- t~e Current Lin~ nd Int-rpolat-d L~n- 6.~5 Mhz
Chrom~ pl~- into ~ult~pl-xed 13.5 M~z Chroma Output by
alternating Field ~ Chroma amples (CI) uith ~ield I~ Chroma ~amples
(C~I).
~ II) Form~t- t~e Current Line ~nd Interpolated Line 6.75Mh2 Xey
~amples lnto ~ultipl~xed 13.SH~z Key Output by ltern-ting ~ield I
~ey amples (~ t~ Fi~ld S~ ~ey ~amples ~XIl).
Re~er eO F~gNr~ 8 and the schematic of Figure 6 during the
folloYing xpl-n3tlon- T~- Current Line C~roma/K-y (XC) ~mpl~ ~re
~uf~red ln ~E ~nd ~ come the lnput- to 2E nd 2~. The Curr-nt Line
C~rom~ ~a~pl~ ~re late~ed ~n 2E Yith ~g~ nd t~ Curr-nt Line Xey
~mpl~ tc~Jd ln 2~ Y~th .5X. ~ tc~ ign~ t~iled on
~gure 7~pr~r~nt e~ npl~ tc~ d lnt~rna~y at t~ output o~
tb~-~ ch~p~ ~nd ~r- no~ Y ~l- on n 08cil~o~0p-.
-29-
1 328~20
~n o~ to llpae- ~oth ~ to~o- ~ry tl-l~, th C~ro~ y
J~lt-~at~ nt~ tor ~nt~ th ~ no rl-ld ~y
v r~ g t~ nt Lln ~nd P~r~ ~n Ch~_~ Y 0~ th
nt rl-ld Sn tbl- ~y, n 2nt-rpol~t~ ~n- o~ Cl~aOl~Qy
~cl-lly ~t~n th t~o p~ nt ~ t~ uJ-d eO
r~pr-~-nt tb~ ~nt-rl-~ lln- o~ lng ?l-ld. ~ nt Llne
(XC1 and p~ ou~ Lln t~XC) C~rom~-y ~ r- svs~og~d by ~,
~F, 9E, ~nd 6G .
~h- tro~ nt ~ormat or tb c~rom~ r-q~ir~ ign
xt-n~ion o~ t~ st $~ni~eant blt o~ -ch Ampl~ k ~or~
addit~on ean ~e p~r~or~ d- ~he X~y ~pl--, hov v-r, ~r- ln un-igned
~n~ry ~ormat an~ efinnot b~ ~gn ~xt-n~-~. Th- t~o -ct~on~ o~ 6G
ratis~y the~e r~qu~r~ment~ ~y ign ~xtending the MS9 o~ t~e C~roma
a~ple~ ~.SX - 1) and introducing ~n M5~ o~ zero ~or th~ X-y ~mples
.5x - O).
Th~ ~nt-~po~-t-d Chroma/K-y ~mple~ r~ on- input to ~n ~-bit
tno input ~ ctor 7C and 7~ ~o-e ot~ar ln~ut ~ Z~ro. Dur~n~ F~eld
Hode tFram ~b~- - 13, lE ~ill late~ an Int-rpolat~d Chro~a ~a~ple
~$th .5X and lF Y~ tch a~ ~nt-rpolat~d Key ~mple ~ith .SX.
Durlng r~.~ No~- (F~ Msde - O), lE ~nd 1~ ~ill both latc~ ~ro
V~lu~
Tb ~orm~t o~ tb- 13.S~h2 Chro~ Output to th- ~S SI~NA~ ~oard
oontaln- t~ld ~ C~rom~ ~pl~- Yhi~ 5X 1- lsv, ~nd F$-1~ SS Chroma
s~mpl-~ vh~ X 1- b~g~. Du~n~ r~ S, 3A-6 ~ .SX and 3A-~ 8 ~SX~
-30-
~ 328920
r, 2~ abl--d an~ out~t~ rr-nt C~roaa
S~. ~Ihl3.~ 19)~, Slt 1~ onab~ ~d o~tput~ 2nt-~po~t~d
CSI ln Fl-la ~ or ~ ~o v~ or CII ~n F~
~d-. ~ln~ rl-~d ~s"a-6 ~ nd 3A-8 .5X, r~r~ln~ t~
ord-r. ~,- .5X ~- lov, lE l~ bl-d end out~ut- ~n ~nt-rpol~t~d
~hro~ s~ or C2 lrl rl~ Dd- or n ~-ro v~lu- for C~S ln ~r~m~
~d~. l~I- .SX 1- )~gh, 2E ~ n~bI-d and oue~ut- Curr~nt CSIroma
r~mpl~ ~or C~.
Th ~on~t o~ th~ 13.5M~ 1~-y Output to th~ T~S SICNAI, Board
~ t-ln~ F~ S ~Qy ~mpl~ .5X ~ hl~, and Fl~ld S~ X-y
U:lp~ fhll- .5X 18 lo~- Durlr~g Fl~ld I, 3A-6 ~ .Sx ~r~d 3A-~ ~ .SX.
X l- hlg)lo 2F lr nabl~ n~ outputs ~ curr~ne R y ~mplQ ~or
XI. ~hll- . 5x ~ , lF 1~ n-bl-~ ~nd output3 ~n Snt~rpolated xey
a~npl~ ~or XII ln Fl~ld t~de or zero v~lue for RII ln Fram~ Mode.
During Fi~ld IS, 3A-6 ~ .~ and 3A-8 ~ .SX, r-ver-~n~ the order.
~il~ .SX ~ h~gh, lF ~- ~bl-~ and output~ ~n Sntr~polated Xey
r~mple ~or XI ln Fl-l~ ~d- or ~-ro v~lu~ for ~ ~n Frame ~ode.
~ilc .5X ~ loY, 2F 1- n~blff~ ~nd output- a eurr~nt Key ~ple ~or
Rli.
P~r~d~ nput Cbro~`X y o~ or ~oth f$~1d~ ~ur$ng evory
fltl~l ln ~l--ld ~ ~n t~- t~ lnt-r~ ld ~ot~on n~cker o~
Vl~!l o Fr~e, but r ~u~s thQ n~olutlor~ of the ~tor d :~ga-.
~n t~# F~ , th ~l~ceor out~ut8 z-ro ~lu - ~or th~
M~--lng r~ Chr~/K y ~mpl~ A~ F~ Storn of t31e
--31--
1 328q20
-dn5~ Pl-~ to r c~rc~ t- ~t~out ~lnlJ u~t~ ~3y Snput Vld-o.
~ Fra~ ~ t~ rr-~ r -olutlon o~ th- tor~ l~g -
INt 1- un~ to r ~ lnt-r~ otlon ~llck r-
--32--
