Synchronizing conversion apparatus and method as well as recording medium
First Claim
1. A synchronizing conversion apparatus for converting a synchronizing frequency of an image signal, comprising:
- an image memory;
write means for writing the image signal into said image memory in synchronism with a first synchronizing frequency signal inputted thereto;
read means for reading out the image signal from said image memory in synchronism with a second synchronizing frequency signal inputted to said read means and having a frequency different from that of the first synchronizing frequency signal;
detection means for detecting a phase difference between the first and second synchronizing frequency signals;
prediction means for predicting occurrence of outpacing between a read address and a write address for said image memory based on the phase difference detected by said detection means;
modification means for modifying a reading out timing of said read means in response to a result of the prediction of said prediction means; and
delay compensation means for executing delay compensation for the image signal read out by said read means in response to the result of the prediction of said prediction means.
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Abstract
The invention provides a synchronizing conversion apparatus wherein outpacing compensation can be executed with a circuit construction including a comparatively small number of components. A read control circuit produces a read control signal including a read address and a read timing based on an outpacing detection signal from a phase comparison circuit, which is generated taking a time required for processing of a memory access arbitration circuit into consideration, and a scene change detection signal from a scene change detection circuit. The read control signal is outputted to the memory access arbitration circuit. The memory access arbitration circuit arbitrates requests from a write control circuit and the read control circuit to control writing into and reading out from a frame memory.
14 Citations
9 Claims
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1. A synchronizing conversion apparatus for converting a synchronizing frequency of an image signal, comprising:
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an image memory;
write means for writing the image signal into said image memory in synchronism with a first synchronizing frequency signal inputted thereto;
read means for reading out the image signal from said image memory in synchronism with a second synchronizing frequency signal inputted to said read means and having a frequency different from that of the first synchronizing frequency signal;
detection means for detecting a phase difference between the first and second synchronizing frequency signals;
prediction means for predicting occurrence of outpacing between a read address and a write address for said image memory based on the phase difference detected by said detection means;
modification means for modifying a reading out timing of said read means in response to a result of the prediction of said prediction means; and
delay compensation means for executing delay compensation for the image signal read out by said read means in response to the result of the prediction of said prediction means. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A synchronizing conversion method for a synchronizing conversion apparatus for converting a synchronizing frequency of an image signal, comprising:
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a write step of writing the image signal into an image memory in synchronism with a first synchronizing frequency signal inputted to said synchronizing conversion apparatus;
a read step of reading out the image signal from said image memory in synchronism with a second synchronizing frequency signal inputted to said synchronizing conversion apparatus and having a frequency different from that of the first synchronizing frequency signal;
a detection step of detecting a phase difference between the first and second synchronizing frequency signals;
a prediction step of predicting occurrence of outpacing between a read address and a write address for said image memory based on the phase difference detected by the detection step;
a modification step of modifying a reading out timing of the read step in response to a result of the prediction of the prediction step; and
a delay compensation step of executing delay compensation for the image signal read out by the read step in response to the result of the prediction of the prediction step.
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9. A recording medium on which a computer-readable program for synchronizing conversion for converting a synchronizing frequency of an image signal is recorded, the program comprising:
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a write step of writing the image signal into an image memory in synchronism with a first synchronizing frequency signal inputted to said synchronizing conversion apparatus;
a read step of reading out the image signal from said image memory in synchronism with a second synchronizing frequency signal inputted to said synchronizing conversion apparatus and having a frequency different from that of the first synchronizing frequency signal;
a detection step of detecting a phase difference between the first and second synchronizing frequency signals;
a prediction step of predicting occurrence of outpacing between a read address and a write address for said image memory based on the phase difference detected by the detection step;
a modification step of modifying a reading out timing of the read step in response to a result of the prediction of the prediction step; and
a delay compensation step of executing delay compensation for the image signal read out by the read step in response to the result of the prediction of the prediction step.
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Specification