Detection and phase lock of pull-down video
Certain aspects of the invention may comprise a plurality of algorithms and architectures capable of performing 3:2 pull-down cadence detection and reverse 3:2 pull-down of a received video signal. In one embodiment, a method of identifying a pull-down field in a pull-down video stream comprises generating one or more temporally sequential variances, correlating the one or more temporally sequential variances to one or more temporal variance patterns associated with the pull-down video, wherein each of the one or more temporal variance patterns is associated with one or more unique field phases. In one embodiment, a system for identifying a pull-down field in a pull-down video stream comprises a memory, a first circuitry capable of computing a first equation, a second circuitry capable of computing a second equation, a third correlation circuitry, one or more counters, and a fourth circuitry capable of selecting a field phase.
1. A method of identifying a pull-down field in a 3:2 pull-down video stream, comprising:
generating one or more temporally sequential variances using said 3:2 pull-down video stream;
correlating said one or more temporally sequential variances to one or more temporal variance patterns associated with said 3:2 pull-down video stream, each of said one or more temporal variance patterns associated with one or more unique field phases;
generating one or more correlation coefficients associated with each of said one or more temporal variance patterns;
assessing whether said one or more correlation coefficients exceeds a first threshold value;
incrementing one or more counters associated with said one or more correlation coefficients if said one or more correlation coefficients exceeds said first threshold value;
assessing whether said one or more correlation coefficients is less than a second threshold value;
decrementing said one or more counters associated with said one or more correlation coefficients if said one or more correlation coefficients is less than said second threshold value;
determining if a counter of said one or more counters exceeds a third threshold;
selecting said one or more unique field phases as a repeat field phase if said counter exceeds said third threshold; and
identifying said pull-down field associated with said repeat field phase.
2. The method of claim 1 , wherein said first, said second, and said third threshold values are programmable.
3. The method of claim 1 , wherein said one or more temporal variance patterns comprises a sequence of values.
4. The method of claim 3 , wherein said sequence of values comprises four values having a magnitude of 1 and one value having a magnitude of zero.
5. The method of claim 1 , wherein said generating said one or more temporally sequential variances comprises:
determining absolute differences of corresponding pixels between one or more pairs of fields, said one or more pairs of fields temporally located two field periods apart within said 3:2 pull-down video stream;
generating one or more histograms using said absolute differences, said one or more histograms comprising a number of bins; and
first computing said one or more temporally sequential variances, each of said one or more sequential variances computed from a histogram of said one or more histograms, said histogram generated from a corresponding pair of fields of said one or more pairs of fields.
6. The method of claim 5 , wherein said bins are equally sized.
7. The method of claim 5 , wherein said one or more histograms comprises up to 64 bins.
8. The method of claim 7 , wherein each of said 64 bins has size equal to 4.
9. The method of claim 5 , wherein said one or more histograms comprises 5 bins.
10. The method of claim 5 , wherein said first computing is performed using the equation
sigma
=
bin
1
+
2
(
bin
2
+
bin
3
)
+
4
(
bin
4
+
bin
5
+
bin
6
+
bin
7
)
+
8
∑
n
=
8
63
bin
n
.
11. The method of claim 5 , wherein said first computing is performed using the equation
sigma=histogram 0 +2histogram 1 +4histogram 2 +8(histogram 3 +histogram 4 ).
12. The method of claim 5 , further comprising:
second computing one or more parameters for each of said one or more pairs of fields; and
resetting a counter of said one or more counters if said one or more parameters exceeds a fourth threshold.
13. The method of claim 12 , wherein said fourth threshold value comprises a programmable threshold value.
14. The method of claim 12 , wherein said resetting sets the count of said counter to zero.
15. The method of claim 12 , further comprising storing an indicator or flag within a memory, said indicator or flag indicating when said one or more parameters exceeds said fourth threshold, said one or more parameters calculated or computed using the equation:
repf_motion
=
(
bin
2
+
bin
3
)
+
2
(
bin
4
+
bin
5
+
bin
6
+
bin
7
)
+
4
∑
n
=
8
15
bin
n
+
8
∑
n
=
16
63
bin
n
.
16. The method of claim 12 , further comprising storing an indicator or flag within a memory, said indicator or flag indicating when said one or more parameters exceeds said fourth threshold, said one or more parameters calculated or computed using the equation:
repf _motion=histogram 1 +2histogram 2 +4histogram 3 +8histogram 4 .
17. The method of claim 12 , wherein said one or more parameters measures the unexpected field motion between said one or more pairs of fields.
18. The method of claim 17 , wherein said unexpected field motion is defined by the equation:
repf_motion
=
(
bin
2
+
bin
3
)
+
2
(
bin
4
+
bin
5
+
bin
6
+
bin
7
)
+
4
∑
n
=
8
15
bin
n
+
8
∑
n
=
16
63
bin
n
.
19. The method of claim 17 , wherein said unexpected field motion is defined
by the equation:
repf _motion=histogram 1 +2histogram 2 +4histogram 3 +8histogram 4 .
20. The method of claim 5 , wherein the number of occurrences associated with said bins are implemented using one or more registers.
21. The method of claim 1 , wherein said one or more temporally sequential variances comprises a set of five variances.
22. The method of claim 1 , wherein said correlating is performed using Pearson's correlation.
23. The method of claim 1 , wherein said first threshold value varies over the range −1 to +1.
24. A system comprising:
a processor; and
a memory, said processor capable of executing a set of instructions, said set of instructions causes the system to perform the steps comprising:
generating one or more temporally sequential variances using said 3:2 pull-down video stream;
correlating said one or more temporally sequential variances to one or more temporal variance patterns associated with said 3:2 pull-down video stream, each of said one or more temporal variance patterns associated with one or more unique field phases;
generating one or more correlation coefficients associated with each of said one or more temporal variance patterns;
assessing whether said one or more correlation coefficients exceeds a first threshold value;
incrementing one or more counters associated with said one or more correlation coefficients if said one or more correlation coefficients exceeds said first threshold value;
assessing whether said one or more correlation coefficients is less than a second threshold value;
decrementing said one or more counters associated with said one or more correlation coefficients if said one or more correlation coefficients is less than said second threshold value;
determining if a counter of said one or more counters exceeds a third threshold;
selecting said one or more unique field phases as a repeat field phase if said counter exceeds said third threshold; and
identifying said pull-down field associated with said repeat field phase.
25. The system of claim 24 , wherein said first, said second, and said third threshold values are programmable.
26. The system of claim 24 , wherein said one or more temporal variance patterns comprises a sequence of values.
27. The system of claim 26 , wherein said sequence of values comprises four values having a magnitude of 1 and one value having a magnitude of zero.
28. The system of claim 24 , wherein said generating said one or more temporally sequential variances comprises:
determining absolute differences of corresponding pixels between one or more pairs of fields, said one or more pairs of fields temporally located two field periods apart within said 3:2 pull-down video stream;
generating one or more histograms using said absolute differences, said one or more histograms comprising a number of bins; and
first computing said one or more temporally sequential variances, each of said one or more sequential variances computed from a histogram of said one or more histograms, said histogram generated from a corresponding pair of fields of said one or more pairs of fields.
29. The system of claim 28 , wherein said bins are equally sized.
30. The system of claim 28 , wherein said one or more histograms comprises up to 64 bins.
31. The system of claim 30 , wherein each of said 64 bins has size equal to 4.
32. The system of claim 28 , wherein said one or more histograms comprises 5 bins.
33. The system of claim 28 , wherein said first computing is performed using the equation
sigma
=
bin
1
+
2
(
bin
2
+
bin
3
)
+
4
(
bin
4
+
bin
5
+
bin
6
+
bin
7
)
+
8
∑
n
=
8
63
bin
n
.
34. The system of claim 28 , wherein said first computing is performed using the equation
sigma=histogram 0 +2histogram 1 +4histogram 2 +8(histogram 3 +histogram 4 ).
35. The system of claim 28 , wherein said steps further comprises:
second computing one or more parameters for each of said one or more pairs of fields; and
resetting a counter of said one or more counters if said one or more parameters exceeds a fourth threshold.
36. The system of claim 35 , wherein said fourth threshold value comprises a programmable threshold value.
37. The system of claim 35 , wherein said resetting sets the value of said counter to zero.
38. The system of claim 35 , wherein said steps further comprises storing an indicator or flag within a memory, said indicator or flag indicating when said one or more parameters exceeds said fourth threshold, said one or more parameters calculated or computed using the equation:
repf_motion
=
(
bin
2
+
bin
3
)
+
2
(
bin
4
+
bin
5
+
bin
6
+
bin
7
)
+
4
∑
n
=
8
15
bin
n
+
8
∑
n
=
16
63
bin
n
.
39. The system of claim 35 , wherein said steps further comprises storing an indicator or flag within a memory, said indicator or flag indicating when said one or more parameters exceeds said fourth threshold, said one or more parameters calculated or computed using the equation:
repf _motion=histogram 1 +2histogram 2 +4histogram 3 +8histogram 4 .
40. The system of claim 35 , wherein said one or more parameters measures the unexpected field motion between said one or more pairs of fields.
41. The system of claim 40 , wherein said unexpected field motion is defined by the equation:
repf_motion
=
(
bin
2
+
bin
3
)
+
2
(
bin
4
+
bin
5
+
bin
6
+
bin
7
)
+
4
∑
n
=
8
15
bin
n
+
8
∑
n
=
16
63
bin
n
.
42. The system of claim 40 , wherein said unexpected field motion is defined by the equation:
repf _motion=histogram 1 +2histogram 2 +4histogram 3 +8histogram 4 .
43. The system of claim 28 , wherein the number of occurrences associated with said bins are implemented using one or more registers.
44. The system of claim 24 , wherein said one or more temporally sequential variances comprises a set of five variances.
45. The system of claim 24 , wherein said correlating is performed using Pearson's correlation.
46. The system of claim 24 , wherein said first threshold value varies over the range −1 to +1.
47. A system comprising:
one or more circuits operable for, at least:
generating one or more temporally sequential variances using said 3:2 pull-down video stream;
correlating said one or more temporally sequential variances to one or more temporal variance patterns associated with said 3:2 pull-down video stream, each of said one or more temporal variance patterns associated with one or more unique field phases;
generating one or more correlation coefficients associated with each of said one or more temporal variance patterns;
assessing whether said one or more correlation coefficients exceeds a first threshold value;
incrementing one or more counters associated with said one or more correlation coefficients if said one or more correlation coefficients exceeds said first threshold value;
assessing whether said one or more correlation coefficients is less than a second threshold value;
decrementing said one or more counters associated with said one or more correlation coefficients if said one or more correlation coefficients is less than said second threshold value;
determining if a counter of said one or more counters exceeds a third threshold;
selecting said one or more unique field phases as a repeat field phase if said counter exceeds said third threshold; and
identifying said pull-down field associated with said repeat field phase.
48. The system of claim 47 , wherein said first, said second, and said third threshold values are programmable.
49. The system of claim 47 , wherein said one or more temporal variance patterns comprises a sequence of values.
50. The system of claim 49 , wherein said sequence of values comprises four values having a magnitude of 1 and one value having a magnitude of zero.
51. The system of claim 47 , wherein said generating said one or more temporally sequential variances comprises:
determining absolute differences of corresponding pixels between one or more pairs of fields, said one or more pairs of fields temporally located two field periods apart within said 3:2 pull-down video stream;
generating one or more histograms using said absolute differences, said one or more histograms comprising a number of bins; and
first computing said one or more temporally sequential variances, each of said one or more sequential variances computed from a histogram of said one or more histograms, said histogram generated from a corresponding pair of fields of said one or more pairs of fields.
52. The system of claim 51 , wherein said bins are equally sized.
53. The system of claim 51 , wherein said one or more histograms comprises up to 64 bins.
54. The system of claim 53 , wherein each of said 64 bins has size equal to 4.
55. The system of claim 51 , wherein said one or more histograms comprises 5 bins.
56. The system of claim 51 , wherein said first computing is performed using the equation
sigma
=
bin
1
+
2
(
bin
2
+
bin
3
)
+
4
(
bin
4
+
bin
5
+
bin
6
+
bin
7
)
+
8
∑
n
=
8
63
bin
n
.
57. The system of claim 51 , wherein said first computing is performed using the equation
sigma=histogram 0 +2histogram 1 +4histogram 2 +8(histogram 3 +histogram 4 ).
58. The system of claim 51 , wherein said one or more circuits is further operable for, at least:
second computing one or more parameters for each of said one or more pairs of fields; and
resetting a counter of said one or more counters if said one or more parameters exceeds a fourth threshold.
59. The system of claim 58 , wherein said fourth threshold value comprises a programmable threshold value.
60. The system of claim 58 , wherein said resetting sets the value of said counter to zero.
61. The system of claim 58 , wherein said one or more circuits is further operable for, at least:
storing an indicator or flag within a memory, said indicator or flag indicating when said one or more parameters exceeds said fourth threshold, said one or more parameters calculated or computed using the equation:
repf_motion
=
(
bin
2
+
bin
3
)
+
2
(
bin
4
+
bin
5
+
bin
6
+
bin
7
)
+
4
∑
n
=
8
15
bin
n
+
8
∑
n
=
16
63
bin
n
.
62. The system of claim 58 , wherein said one or more circuits is further operable for, at least:
storing an indicator or flag within a memory, said indicator or flag indicating when said one or more parameters exceeds said fourth threshold, said one or more parameters calculated or computed using the equation:
repf _motion=histogram 1 +2histogram 2 +4histogram 3 +8histogram 4 .
63. The system of claim 58 , wherein said one or more parameters measures the unexpected field motion between said one or more pairs of fields.
64. The system of claim 63 , wherein said unexpected field motion is defined by the equation:
repf_motion
=
(
bin
2
+
bin
3
)
+
2
(
bin
4
+
bin
5
+
bin
6
+
bin
7
)
+
4
∑
n
=
8
15
bin
n
+
8
∑
n
=
16
63
bin
n
.
65. The system of claim 63 , wherein said unexpected field motion is defined by the equation:
repf _motion=histogram 1 +2histogram 2 +4histogram 3 +8histogram 4 .
66. The system of claim 51 , wherein the number of occurrences associated with said bins are implemented using one or more registers.
67. The system of claim 47 , wherein said one or more temporally sequential variances comprises a set of five variances.
68. The system of claim 47 , wherein said correlating is performed using Pearson's correlation.
69. The system of claim 47 , wherein said first threshold value varies over the range −1 to +1.