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Claims  |
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I claim:
1. A method for detecting a blank frame in a video signal, the method
comprising:
extracting the black level from the video signal to produce a black level
signal;
gating undesired portions from the video signal to produce a gated signal;
continuously extracting the luminance level from the gated signal to
produce an average luminance level signal representative of the average
luminance level of a frame; and
comparing the black level signal and the average luminance signal to
determine when the average luminance level signal is within a given
threshold of the black level signal.
2. A method according to claim 1, wherein extracting the black level
comprises; extracting the black level from each line of the video signal
to produce a series of black level pulses and smoothing the black level
pulses to produce the black level signal.
3. A method according to claim 2, wherein extracting the luminance level
comprises; extracting the luminance level from each line of the gated
signal to produce a series of luminance level pulses and smoothing the
luminance level pulses to produce the average luminance level signal.
4. A method according to claim 3, wherein extracting the black level
produces an uncompensated black level signal and further comprising;
extracting the peak luminance level from each line of the gated signal, to
produce a series of peak luminance level pulses and smoothing the peak
luminance level pulses to produce the peak luminance level signal and
compensating the uncompensated black level signal to produce the black
level signal.
5. A method according to claim 1, wherein the threshold is approximately 5%
of the black level signal.
6. A method according to claim 1 wherein extracting the black level
produces an uncompensated black level signal and further comprising;
extracting the peak luminance level of the gated signal to produce a peak
luminance level signal and compensating the uncompensated black level
signal with the peak luminance level signal to produce the black level
signal.
7. A method for detecting a blank frame in a video signal comprising:
extracting the black level from the video signal to produce an extracted
black level signal;
extracting the peak luminance level of the composite signal to produce an
extracted peak luminance level signal;
compensating the extracted black level signal with the extracted peak
luminance signal level to produce a compensated black level signal;
extracting the average luminance level for each frame of the video signal
to produce an extracted average luminance level signal; and
comparing the extended average luminance level signal to the compensated
black level signal to determine whether the extracted average luminance
level signal is within a threshold of the compensated black level signal.
8. A method for detecting a commercial advertisement on a video signal, the
method comprising; detecting a blank frame on the video signal, setting a
timer for a given period after the detection of a blank frame, and testing
for activity on the video signal during that period representative of a
commercial advertisement.
9. A method according to claim 8, the video signal being a video signal,
wherein detecting a blank frame comprises:
extracting the black level from the video signal to produce a black level
signal;
gating undesired portions from the video signal to produce a gated signal;
continuously extracting the luminance level from the gated signal to
produce an average luminance level signal representative of the average
luminance level of a frame; and
comparing the black level signal and the average luminance signal to
determine when the average luminance level signal is within a given
threshold of the black signal.
10. A method according to claim 9, wherein extracting the black level
comprises; extracting the black level from each line of the video signal
to produce a series of black level pulses and smoothing the black level
pulses to produce the black level signal.
11. A method according to claim 10, wherein extracting the luminance level
comprises; extracting the luminance level from each line of the gated
video signal to produce a series of luminance level pulses and smoothing
the luminance level pulses to produce the average luminance level signal.
12. A method according to claim 11, wherein extracting the black level
produces an uncompensated black level signal and further comprising;
extracting the peak luminance level from each line of the gated signal, to
produce a series of peak luminance level pulses and smoothing the peak
luminance level pulses to produce the peak luminance level signal and
compensating the uncompensated black level signal to produce the black
level signal.
13. A method according to claim 9, wherein the threshold is approximately
5% of the black level signal.
14. A method according to claim 9, wherein extracting the black level
produces an uncompensated black level and further comprising; extracting
the peak luminance level of the gated signal to produce a peak luminance
level signal and compensating the uncompensated black level signal with
the peak luminance level signal to produce the black level signal.
15. A method according to claim 14, wherein testing for activity comprises;
continuously integrating the luminance level from the video signal over a
number of frames to produce an integrated luminance level signal,
differentiating the integrated luminance level signal to determine its
rate of change.
16. A method according to claim 8, for detecting a blank frame in a video
signal comprising:
extracting the black level from the video signal to produce an extracted
black level signal;
extracting the peak luminance level of the composite signal to produce an
extracted peak luminance level signal;
compensating the extracted black level signal with the extracted peak
luminance signal level to produce a compensated black level signal;
extracting the average luminance level for each frame of the video signal
to produce an extracted average luminance level signal; and
comparing to determine whether the extracted average luminance level signal
is within a threshold of the compensated black level signal.
17. A method according to claim 9, wherein testing for activity comprises;
continuously integrating the average luminance level signal from the video
signal over a number of frames to produce an integrated luminance level
signal; differentiating the integrated luminance level signal to determine
its rate of change.
18. A method according to claim 17, wherein extracting the black level
comprises; extracting the black level from each line of the video signal
to produce a series of black level pulses and smoothing the black level
pulses to produce the black level signal; and wherein extracting the
luminance level comprises; extracting the luminance level from each line
of the gated video signal to produce a series of luminance level pulses
and smoothing the luminance level pulses to produce the average luminance
level signal.
19. A method according to claim 18, wherein extracting the black level
produces an uncompensated black level signal and further comprising;
extracting the peak luminance level from each line of the gated signal, to
produce a series of peak luminance level pulses and smoothing the peak
luminance level pulses to produce the peak luminance level signal and
compensating the uncompensated black level signal to produce the black
level signal.
20. A method according to claim 19, wherein the given period is
approximately 8 seconds.
21. A method according to claim 17, wherein extracting the black level
produces an uncompensated black level and further comprising; extracting
the peak luminance level of the gated signal to produce a peak luminance
level signal and compensating the uncompensated black level signal with
the peak luminance level signal to produce the black level signal.
22. A method according to claim 21, wherein the given period is
approximately 8 seconds.
23. A method according to claim 8, wherein the given period is
approximately 8 seconds.
24. A method according to claim 8, wherein testing for activity comprises;
continuously integrating the luminance level from the video signal over a
number of frames to produce an integrated luminance level signal;
differentiating the integrated luminance level signal to determine its
rate of change.
25. A method for producing a content control signal having set and clear
states representing a commercial and no commercial present in a video
signal respectively, the method comprising:
detecting a blank frame on the video signal;
after the detection of a blank frame setting an activity timer for a given
period and the content control signal;
testing for activity on the video signal during the period representative
of a commercial advertisement; and
clearing the content control signal when such activity is not detected
during the period.
26. A method according to claim 25, wherein detecting a blank frame
comprises:
extracting the black level from the video signal to produce a black level
signal;
gating undesired portions from the video signal to produce a gated signal;
continuously extracting the luminance level from the gated signal to
produce an average luminance level signal representative of the average
luminance level of a frame; and
comparing the black level signal and the average luminance level signal to
determine when the black level signal is within a given threshold of the
average luminance signal.
27. A method according to claim 26, wherein extracting the black level
comprises; extracting the black level from each line of the video signal
to produce a series of black level pulses and smoothing the black level
pulses to produce the black level signal.
28. A method according to claim 27, wherein extracting the luminance level
comprises; extracting the luminance level from each line of the gated
video signal to produce a series of luminance level pulses and smoothing
the luminance level pulses to produce the average luminance level signal.
29. A method according to claim 28, wherein extracting the black level
produces an uncompensated black level signal and further comprising;
extracting the peak luminance level from each line of the gated signal, to
produce a series of peak luminance level pulses and smoothing the peak
luminance level pulses to produce the peak luminance level signal and
compensating the uncompensated black level signal to produce the black
level signal.
30. A method according to claim 26, wherein the threshold is approximately
5% of the black level signal.
31. A method according to claim 26, wherein extracting the black level
produces an uncompensated black level and further comprising; extracting
the peak luminance level of the gated signal to produce a peak luminance
level signal and compensating the uncompensated black level signal with
the peak luminance level signal to produce the black level signal.
32. A method according to claim 31, wherein testing for activity comprises;
continuously integrating the luminance level from the video signal over a
number of frames to produce an integrated luminance level signal,
differentiating the integrated luminance level signal to determine its
rate of change.
33. A method according to claim 25, for detecting a blank frame in a video
signal comprising:
extracting the black level from the video signal to produce an extracted
black level signal;
extracting the peak luminance level of the video signal to produce an
extracted peak luminance level signal;
compensating the extracted black level signal with the extracted peak
luminance signal level to produce a compensated black level signal;
extracting the average luminance level for each frame of the video signal
to produce an extracted average luminance level signal; and
comparing to determine whether the extracted average luminance level signal
is within a threshold of the compensated black level signal.
34. A method according to claim 26, wherein testing for activity comprises;
continuously integrating the average luminance level signal from the video
signal over a number of frames to produce an integrated luminance level
signal; differentiating the integrated luminance level signal to determine
its rate of change.
35. A method according to claim 34, wherein extracting the black level
comprises; extracting the black level from each line of the video signal
to produce a series of black level pulses and smoothing the black level
pulses to produce the black level signal; and wherein extracting the
luminance level comprises; extracting the luminance level from each line
of the gated video signal to produce a series of luminance level pulses
and smoothing the luminance level pulses to produce the average luminance
level signal.
36. A method according to claim 35, wherein extracting the black level
produces an uncompensated black level signal and further comprising;
extracting the peak luminance level from each line of the gated signal, to
produce a series of peak luminance level pulses and smoothing the peak
luminance level pulses to produce the peak luminance level signal and
compensating the uncompensated black level signal to produce the black
level signal.
37. A method according to claim 36, wherein the given period is
approximately 8 seconds.
38. A method according to claim 34, wherein extracting the black level
produces an uncompensated black level and further comprising; extracting
the peak luminance level of the gated signal to produce a peak luminance
level signal and compensating the uncompensated black level signal with
the peak luminance level signal to produce the black level signal.
39. A method according to claim 38, wherein the given period is
approximately 8 seconds.
40. A method according to claim 25, wherein the given period is
approximately 8 seconds.
41. A method according to claim 25, wherein testing for activity comprises;
continuously integrating the luminance level from the video signal over a
number of frames to produce an integrated luminance level signal;
differentiating the integrated luminance level signal to determine its
rate of change.
42. A blank frame detector for operation on a video signal, the detector
comprising:
a primary black level extractor for extracting the black level of the video
signal;
line gating means gating undesired portions of the video signal;
a frame average luminance level extractor being connected to the line
gating means and for extracting the average luminance of a frame of the
video signal;
a blank frame comparator being connected to the black level extractor and
the frame average luminance level extractor for determining when the
extracted average luminance level of the field is within a given threshold
of the extracted black level of the frame.
43. A detector according to claim 42, further comprising; a sync pulse
extractor being connected to the primary black level extractor for
extracting the back porch of the video signal, and wherein the primary
black level extractor comprises a secondary black level extractor for
extracting the black level of the video signal during the back porch to
produce extracted black level pulses.
44. A detector according to claim 43, wherein the sync pulse extractor is
further connected to the line gating means and further extracts the
horizontal sync pulse of the video signal and the line gating means gates
the horizontal sync pulses of undesired lines to produce the gated signal.
45. A detector according to claim 44, wherein the primary black level
extractor further comprises a first smoother connected to the secondary
black level extractor for smoothing the extracted black level pulses.
46. A detector according to claim 45, wherein the frame average luminance
level extractor comprises; a secondary luminance level extractor for
extracting the luminance level of the gated signal.
47. A detector according to claim 46, wherein the frame average luminance
level extractor further comprises a second smoother connected to the
secondary luminance level extractor for smoothing the extracted luminance
level to produce the average luminance level.
48. A detector according to claim 47, wherein the primary black level
extractor extracts an uncompensated black level and the detector further
comprises; a secondary peak luminance level extractor for extracting the
peak luminance level of the gated signal to produce peak luminance level
pulses; a third smoother connected to the secondary peak luminance level
extractor for smoothing the peak luminance level pulses to produce a peak
luminance level signal, and a black level offset means connected to the
first smoother and the third smoother and the blank frame comparator for
compensating the uncompensated black level with the peak luminance level
signal to produce the black level.
49. A device according to claim 42, wherein the threshold is approximately
5%.
50. A device according to claim 42, wherein the primary black level
extractor extracts an uncompensated black level, and the blank frame
detector further comprises; a primary peak luminance level extractor being
connected to the line gating means for extracting the peak luminance level
of the gated signal, and a black level offset means being connected to the
primary black level extractor, the primary peak luminance level extractor
and the blank frame comparator for compensating the uncompensated black
level with the peak luminance level to produce the black level.
51. A blank frame detector for operation on a video signal, the detector
comprising:
a primary black level extractor for extracting the black level of the video
signal;
a primary peak luminance extractor for extracting the peak luminance level
of the video signal;
black level offset means connected to the primary black level extractor and
to the primary peak luminance level extractor for compensating the
extracted black level with a desired portion of the extracted peak
luminance level;
a frame average luminance level extractor for extracting the average
luminance level of the frame; and
a blank frame comparator connected to the black level offset means and the
frame average luminance level extractor for determining whether the
extracted average luminance level is within a threshold of the compensated
black level.
52. An identification unit for detecting a commercial advertisement on a
video signal, the unit comprising:
a blank frame detector for detecting blank frames on the video signal;
an activity timer being connected to the blank frame detector and being set
upon the detection of a blank frame in the signal; and
an activity detector being connected to the blank frame detector and the
activity timer for testing for activity representative of a commercial
advertisement in the signal during the time the activity timer is set.
53. A device according to claim 52, wherein the video signal is a video
signal and the blank frame detector comprises:
a primary black level extractor for extracting the black level of the video
signal;
line gating means gating undesired portions of the video signal;
a frame average luminance level extractor being connected to the line
gating means and for extracting the average luminance of a frame of the
video signal;
a blank frame comparator being connected to the black level extractor and
the frame average luminance level extractor for determining when the
extracted black level of the field is within a given threshold of the
extracted average luminance level of the frame.
54. A device according to claim 53, wherein the blank frame detector
further comprises; a sync pulse extractor being connected to the primary
black level extractor for extracting the back porch of the video signal,
and wherein the primary black level extractor comprises a secondary black
level extractor for extracting the black level of the video signal during
the back porch to produce extracted black level pulses.
55. A device according to claim 54, wherein the sync pulse extractor is
further connected to the line gating means and further extracts the
horizontal sync pulse of the video signal and the line gating means gates
the horizontal sync pulses of undesired lines and to produce the gated
signal.
56. A device according to claim 55, wherein the primary black level
extractor further comprises; a first smoother connected to the secondary
black level extractor for smoothing the extracted black level pulses.
57. A device according to claim 56, wherein the frame average luminance
level extractor comprises; a secondary luminance level extractor for
extracting the luminance level of the gated signal.
58. A device according to claim 57, wherein the frame average luminance
level extractor further comprises a second smoother connected to the
secondary luminance level extractor for smoothing the extracted luminance
level to produce the average luminance level.
59. A device according to 58, wherein the primary black level extractor
extracts an uncompensated black level and the detector further comprises;
a secondary peak luminance level extractor for extracting the peak
luminance level of the gated signal to produce peak luminance level
pulses; a third smoother connected to the secondary peak luminance level
extractor for smoothing the peak luminance level pulses to produce a peak
luminance level signal, and a black level offset means connected to the
first smoother and the third smoother and the blank frame comparator for
compensating the uncompensated black level with the peak luminance level
signal to produce the black level.
60. A device according to claim 53, wherein the threshold is approximately
5%.
61. A device according to claim 53, wherein the primary black level
extractor extracts an uncompensated black level, and the blank frame
detector further comprises; a primary peak luminance level extractor being
connected to the line gating means for extracting the peak luminance level
of the gated signal, and a black level offset means being connected to the
primary black level extractor, the primary peak luminance level extractor
and the blank frame comparator for compensating the uncompensated black
level with the peak luminance level to produce the black level.
62. A device according to claim 52, wherein the primary black level
extractor extracts an uncompensated black level, and the blank frame
detector further comprises; a primary peak luminance level extractor being
connected to the line gating means for extracting the peak luminance level
of the gated signal, and a black level offset means being connected to the
primary black level extractor, the primary peak luminance level extractor
and the blank frame comparator for compensating the uncompensated black
level with the peak luminance level to produce the black level.
63. A device according to claim 53, wherein the activity detector comprises
the average frame luminance level extractor, an integrator being connected
to the average frame luminance level extractor for integrating the average
frame luminance level over a number of frames, and a differentiator being
connected to the timer and the integrator determining the rate of change
of the integrated average force luminance level.
64. A device according to claim 63, wherein the blank frame detector
comprises; a blank frame detector for operation on a video signal, the
detector comprising:
a primary black level extractor for extracting the black level of the video
signal;
line gating means gating undesired portions of the video signal;
a frame average luminance level extractor being connected to the line
gating means and for extracting the average luminance of a frame of the
video signal;
a blank frame comparator being connected to the black level extractor and
the frame average luminance level extractor for determining when the
extracted black level of the field is within a given threshold of the
extracted average luminance level of the frame.
65. A device according to claim 64, wherein the blank frame detector
further comprises; a sync pulse extractor being connected to the primary
black level extractor for extracting the back porch of the video signal,
and wherein the primary black level extractor comprises a secondary black
level extractor for extracting the black level of the video signal during
the back porch to produce extracted black level pulses.
66. A device according to claim 65, wherein the sync pulse extractor is
further connected to the line gating means and further extracts the
horizontal sync pulse of the video signal and the line gating means gates
the horizontal sync pulses of undesired lines and to produce the gated
signal.
67. A device according to claim 66, wherein the primary black level
extractor further comprises a first smoother connected to the secondary
black level extractor for smoothing the extracted black level pulses.
68. A device according to claim 67, wherein the frame average luminance
level extractor comprises; a secondary luminance level extractor for
extracting the luminance level of the gated signal.
69. A device according to claim 68, wherein the frame average luminance
level extractor further comprises a second smoother connected to the
secondary luminance level extractor for smoothing the extracted luminance
level to produce the average luminance level.
70. A device according to claim 69, wherein the primary black level
extractor extracts an uncompensated black level and the detector further
comprises; a secondary peak luminance level extractor for extracting the
peak luminance level of the gated signal to produce peak luminance level
pulses; a third smoother connected to the secondary peak luminance level
extractor for smoothing the peak luminance level pulses to produce a peak
luminance level signal, and a black level offset means connected to the
first smoother and the third smoother and the blank frame comparator for
compensating the uncompensated black level with the peak luminance level
signal to produce the black level.
71. A device according to claim 52, wherein the threshold is approximately
5%.
72. A device according to claim 52, wherein the video signal is a video
signal and the activity detector comprises an integrator integrating the
luminance level of the composite video signal over a number of frames and
a differentiator connected to the integrator determining the rate of
change of the integrated signal.
73. A content control unit for controlling a storage device recording a
video signal to limit the recording of commercial material contained
thereon, the unit comprising:
an identification section comprising:
a blank frame detector for detecting blank frames in the video signal;
an activity timer being connected to the blank frame detector and being set
upon the detection of a blank frame in the video signal; and
an activity detector being connected to the blank frame detector and the
activity timer for testing for activity representative of a commercial
advertisement in the video signal during the time the activity timer is
set; and
a communication section being connected to the content control unit and
adapted to be coupled to the storage device for communicating instructions
based upon the detection of blank frames and the detection of such
activity by the identification section.
74. A content control system operating on a video signal containing
commercial material, the system comprising:
a storage device for recording the video signal;
a content control unit being connected to the storage device and
comprising:
an identification section comprising:
a blank frame detector for detecting blank frames in the video signal;
an activity timer being connected to the blank frame detector and being set
upon the detection of a blank frame in the video signal; and
an activity detector being connected to the blank frame detector and the
activity timer for testing for activity representative of a commercial
advertisement in the video signal during the time the activity timer is
set; and
a communication section being connected to the content control unit and
coupled to the storage device for communicating instructions based upon
the detection of blank frames and the detection of such activity by the
identification section. |
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Claims |
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Description |
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FIELD OF THE INVENTION
This invention relates generally to methods and apparatus for the
identification of video signals, and more particularly, to methods and
apparatus for detection and identification of portions of video signals
having specific material thereon. This invention also relates to methods
and apparatus for the elimination of portions of video signals having
specific material thereon and/or the accompanying audio signal.
BACKGROUND OF THE INVENTION
Systems for the identification of portions of a video signal having
specific material thereon, particularly commercial advertisements, are
known. The majority of these systems are for use in monitoring and
confirming the broadcasting of commercial advertisements and as such may
be termed logging systems.
These logging systems fall into two categories, those systems that detect
identifying signals present in a video signal and those that monitor and
analyze the material content of the video signal utilizing pattern
recognition and correlation techniques to identify the material.
Known logging systems detect identification signals encoded on the video
signal requiring the co-operation of the broadcasters to encode the
material with the identification signals prior to broadcast.
Other known logging systems monitor and analyze the content of the material
itself. An example of a system that utilizes the material content of a
broadcast signal to identify the material is described in U.S. Pat. No.
3,919,479 to Moon et al. The Moon et al. system employs a non-linear
analog transform to generate a low frequency envelope waveform. The
information in the low frequency envelope during a predetermined time
interval is digitized to generate a signature. The generated signatures
are compared with reference signatures to identify the material. The Moon
et al. system generates these signatures continuously and consequently
requires a large computer to process the generated data.
Various improvements in systems that monitor and analyze material content
have become known, and these are primarily concerned with reducing the
amount of data to be processed. Such a system is disclosed in U.S. Pat.
No. 4,230,990 to Lert, Jr. et al. The system disclosed in the Lert, Jr. et
al. patent reduces the amount of data that must be procesed, as compared
to the amount of data to be processed by the Moon et al. patent. Cues are
either externally generated or the material initiates the signature
generation and correlation process.
A further improvement in the art of such logging systems can be found in
U.S. Pat. No. 4,677,466 to Lert, Jr. et al. In this patent improvements
are made regarding stability influences on the correlation accuracy.
It will be seen however, that all of these logging systems, although
monitoring and analyzing program content, require fairly complex
processing apparatus and obtain correlation through the matching of
reference signatures to the extracted signatures.
To utilize or adapt systems of the logging type to other uses, specifically
to eliminate commercial advertisements with a minimum of disruption to the
desired program material is neither known in the art nor is it practical
in nature.
The other known systems for the identification of portions of a video
signal having specific material thereon more particularly concern the
elimination of commercial advertisements when recording desired program
material from a video signal.
Two systems are known in the art for the elimination of commercial
advertisements. The first of these is described in PCT application No. WO
81-00945 to Johnston and Koombes.
The Johnston and Koombes patent discloses a system that detects fade breaks
in the video and audio components of a television signal. Such detected
fade breaks are assumed to be the beginning of a single commercial in a
consecutive block of commercials. These detected fade breaks are used to
generate a signal which can trigger or retrigger a timing circuit. The
timing circuit generates a control signal of a length slightly greater
than the anticipated length of a standard commercial. This control signal
may then be applied to the pause control of a video tape recorder. The
intention of the method and apparatus disclosed in the Johnston and
Koombes patent is therefore the momentary halting of a video tape recorder
during the occurrence of a commercial interruption in a desired video
signal.
There are a number of shortcomings in said Johnston and Koombes patent. The
first is the inability of the apparatus disclosed to properly detect true
blank video frames or fields, almost always inserted between program to
commercial changes. Only a simple threshold processing method is
disclosed, which is unable to accurately process the wide range of levels,
content and quality of video signals encountered in a practical use and
embodiment. As a result false detection of fade breaks occurs and some
fade breaks are undetected.
The second shortcoming of the Johnston and Koombes patent is the inherent
inability to detect the resumption of the desired program after the
conclusion of any commercial breaks as the return to a program from a
commercial interruption is usually accompanied by a fade break. The fade
break will trigger the timing circuit and the recording video tape
recorder will be maintained in the pause mode for the length of the
control signal. Program material of a length slightly greater than a
standard commercial will go unrecorded. It is evident that there is a
significant loss of desired program material after the end of a commercial
break or series of breaks even when all signal conditions favour an
acceptable operational accuracy of the fade brake detecting threshold
apparatus.
The second system for the elimination of commercial advertisements is
described in PCT application No. WO 8300971 to Koombes.
The apparatus and method disclosed therein differs from that in the
Johnston and Koombes patent only in the replacement of the timer
originated control signal for operating the pause control of a video tape
recorder by a reciprocating editing control. The reciprocating editing
control memorizes where a fade break has been detected, if it has been
detected, on the tape recording of the video signal. The system controls
the video tape recorder over a suitable interface to exit the record mode,
reverse the tape to the memorized point of the fade break and to enter the
record mode again.
The reciprocating method used in the Koombes patent allows for a smaller
loss upon the return to the desired program than the timed pause method
disclosed in the Johnston and Koombes patent.
However, the shortcomings of the simple threshold detection process are
also common to the Koombes patent, as are the problems of interfacing a
practical embodiment thereof to the great number of diverse types of video
tape recorders in use.
Additionally the cumulative effects of the reciprocating process can lead
to the eventual failure of the drive motors of the video cassette
recorder. The reciprocating process can also be quite irritating to a
viewer who is simultaneously viewing the material in real-time.
Further, neither the timed pause system disclosed in the Johnston and
Koombes patent, nor the reciprocating recording system disclosed in the
Koombes patent, are suitable to real-time applications such as viewing the
video signal on a television at the time of broadcast and blanking audio
and/or video portions of the broadcast signal upon the identification of
commercial interruptions.
SUMMARY OF THE INVENTION
In a first aspect the present invention provides a method for detecting a
blank frame in a video signal, the method comprising: extracting the black
level from the video signal to produce a black level signal; gating
undesired portions from the video signal to produce a gated signal;
continuously extracting the luminance level from the gated signal to
produce an average luminance level signal representative of the average
luminance level of a frame; and comparing the black level signal and the
average luminance signal to determine when the average luminance level
signal is within a given threshold of the black level signal.
In a second aspect the present invention provides a method for detecting a
blank frame in a video signal comprising: extracting the black level from
the signal to produce an extracted black level signal; extracting the peak
luminance level of the signal to produce an extracted peak luminance level
signal; compensating the extracted black level signal with the extracted
peak luminance signal level to produce a compensated black level signal;
extracting the average luminance level for each frame of the video signal
to produce an extracted average luminance level signal; and comparing the
extracted average luminance level signal to the compensated black level
signal to determine whether the extracted average luminance level signal
is within a threshold of the compensated black level signal.
In a third aspect the present invention provides a method for detecting a
commercial advertisement on a video signal, the method comprising;
detecting a blank frame on the video signal, setting a timer for a given
period after the detection of a blank frame, and testing for activity on
the video signal during that period representative of a commercial
advertisement.
In a fourth aspect the present invention provides a method for producing a
content control signal having set and clear states representing a
commercial and no commercial present in a video signal respectively, the
method comprising: detecting a blank frame on the video signal; after the
detection of a blank frame setting an activity timer for a given period
and the content control signal; testing for activity on the video signal
during the period representative of a commercial advertisement; and
clearing the content control signal when such activity is not detected
during the period.
In a fifth aspect the present invention provides a blank frame detector for
operation on a video signal, the detector comprising: a primary black
level extractor for extracting the black level of the video signal; line
gating means gating undesired portions of the video signal; a frame
average luminance level extractor being connected to the line gating means
and for extracting the average luminance of a frame of the video signal; a
blank frame comparator being connected to the black level extractor and
the frame average luminance level extractor for determining when the
extracted average luminance level of the field is within a given threshold
of the extracted black level of the frame.
In a sixth aspect the present invention provides a blank frame detector for
operation on a video signal, the detector comprising: a primary black
level extractor for extracting the black level of the video signal; a
primary peak luminance extractor for extracting the peak luminance level
of the field in the frame; black level offset means connected to the
primary black level extractor and to the primary peak luminance level
extractor for compensating the extracted black level with a desired
portion of the extracted peak luminance level; a frame average luminance
level extractor for extracting the average luminance level of the frame;
and a blank frame comparator connected to the black level offset means and
the frame average luminance level extractor for determining whether the
extracted average luminance level is within a threshold of the compensated
black level.
In an seventh aspect the present invention provides an identification unit
for detecting a commercial advertisement on a video signal, the unit
comprising: a blank frame detector for detecting blank frames on the video
signal; an activity timer being connected to the blank frame detector and
being set upon the detection of a blank frame in the signal; and an
activity detector being connected to the blank frame detector and the
activity timer for testing for activity representative of a commercial
advertisement in the signal during the time the activity timer is set.
In a eighth aspect the present invention provides a content control unit
for controlling a storage device recording a video signal to limit the
recording of commercial material contained thereon, the unit comprising:
an identification section comprising: a blank frame detector for detecting
blank frames in the video signal; an activity timer being connected to the
blank frame detector and being set upon the detection of a blank frame in
the video signal; and an activity detector being connected to the blank
frame detector and the activity timer for testing for activity
representative of a commercial advertisement in the video signal during
the time the activity timer is set; and a communication section being
connected to the content control unit and adapted to be coupled to the
storage device for communicating instructions based upon the detection of
blank frames and the detection of such activity by the identification
section.
In a ninth aspect the present invention provides a content control system
operating on a video signal containing commercial material, the system
comprising: a storage device for recording the video signal; a content
control unit being connected to the storage device and comprising: an
identification section comprising: a blank frame detector for detecting
blank frames in the video signal; an activity timer being connected to the
blank frame detector and being set upon the detection of a blank frame in
the video signal; and an activity detector being connected to the blank
frame detector and the activity timer for testing for activity
representative of a commercial advertisement in the video signal during
the time the activity timer is set; and a communication section being
connected to the content control unit and coupled to the storage device
for communicating instructions based upon the detection of blank frames
and the detection of such activity by the identification section.
It is an object of the present invention to provide methods and apparatus
for identifying and for eliminating specific material, namely commercial
advertisements, from video signals that in their various embodiments
overcome many of the disadvantages of systems presently known in the art.
It is another object of the present invention in at least one of its
embodiments to provide for identification of commercial advertisements and
their subsequent elimination with decreased undesirable disruption to the
broadcasting program material.
It is another object of the present invention in at least one of its
embodiments to provide for such identification for real-time applications.
It is still another object of the present invention in at least one of its
embodiments to provide means to interface at least one embodiment of the
present invention to most video tape recorders and television receivers.
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the present invention, and to show more
clearly how it may be carried into effect, reference will now be made, by
way of example to the accompanying drawings, which show preferred
embodiments of the present invention, and in which:
FIG. 1 is a block diagram of a content control system according to the
preferred embodiment of the present invention;
FIG. 2a is a diagram of one field of a composite video signal;
FIG. 2b is a diagram of the other field of a composite video signal;
FIG. 2c is a diagram of the detail of FIG. 2b between lines 3--3;
FIG. 2d is a diagram of detail of FIG. 2b between lines 4--4;
FIG. 2e is a diagram of detail of FIG. 2c between lines 5--5;
FIG. 3 is a block diagram of an identification section employed in the
content control system of FIG. 1; and
FIG. 4 is a block diagram of a communication section of the content control
system of FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE PRESENT INVENTION
Reference will now be made to FIG. 1. A content control system has a
content control unit 3, a storage device 5 and a viewing apparatus 7. The
storage device 5 utilized in the preferred embodiment is a video cassette
recorder (VCR) 5 and will be described as such. Similarly, the viewing
apparatus 7 in the preferred embodiment is a television (TV) 7. It is to
be understood that other embodiments employing alternate storage devices 5
such as reel-to-reel video tape recorders or suitably interfaced audio
recorders and alternate viewing apparatuses such as monitors would fall
within the spirit and scope of the invention.
Each of the control unit 3, VCR 5 and TV 7 has an input 9, 11, 13
respectively for a video signal. I | | |
