Claims
- 1. A video signal converter comprising:
- a ROM table having frequencies, each of the frequencies being associated with already-existing formats of video signals;
- an operation panel;
- selecting means for selecting a first frequency Fi from the ROM table based on a format of a first video signal input through the operation panel, the first frequency Fi having the maximum value which satisfies a formula: Fi.ltoreq.(To.times.Fo)/Ti, where the Ti is a horizontal scanning period of the first video signal, the To is a horizontal scanning period of a second video signal, and the Fo is a second frequency;
- first clock generating means for generating a first clock of the first frequency Fi;
- second clock generating means for generating a second clock of the second frequency Fo;
- analog-to-digital converting means for converting the first analog video signal to first digital video data according to a sampling clock of the first frequency Fi;
- writing means for writing the first digital video data into a memory in synchronization with the first clock;
- reading means for reading the first digital video data from the memory in synchronization with the second clock to generate second digital video data; and
- digital-to-analog converting means for converting the second digital video data to a second analog video signal in synchronization with the second clock.
- 2. A video signal converter comprising:
- a ROM table having frequencies, each of the frequencies being associated with already-existing formats of video signals;
- an operation panel;
- selecting means for selecting a first frequency Fi from the ROM table based on a format of a first video signal input through the operation panel, the first frequency Fi having the maximum value which satisfies a formula: Fi.ltoreq.(To.times.Fo)/Ti, where the Ti is a horizontal scanning period of the first video signal, the To is a horizontal scanning period of a second video signal, and the Fo is a second frequency;
- first clock generating means for generating a first clock of the first frequency Fi;
- second clock generating means for generating a second clock of the second frequency Fo;
- analog-to-digital converting means for converting the first analog video signal to first digital video data according to a sampling clock of the first frequency Fi;
- writing means for writing the first digital video data into a memory in synchronization with the first clock;
- reading means for reading the first digital video data from the memory in synchronization with the second clock to generate second digital video data;
- an NTSC encoder for encoding the second digital video data to generate video data of the NTSC format; and
- digital-to-analog converting means for converting the NTSC video data to an NTSC analog video signal in synchronization with the second clock.
- 3. A video signal converter according to claim 2, wherein said first analog video signal is comprised of RGB signals.
- 4. A video signal converter according to claim 2, wherein said first analog video signal is a signal of HDTV format.
- 5. A video signal converter according to claim 2, wherein said second frequency Fo satisfies an equation: Fo=4.times.Fsc, where Fsc is a color subcarrier frequency of the NTSC format.
- 6. A video signal converter according to claim 3, wherein said second frequency Fo satisfies an equation: Fo=4.times.Fsc, where Fsc is a color subcarrier frequency of the NTSC format.
- 7. A video signal converter according to claim 4, wherein said second frequency Fo satisfies an equation: Fo=4.times.Fsc, where Fsc is a color subcarrier frequency of the NTSC format.
- 8. A video signal converter comprising:
- analog-to-digital converting means for converting a first analog video signal to first digital video data;
- a ROM table having width-to-height ratios of pixels, each of the ratios being associated with already-existing formats of video signals;
- an operation panel;
- line conversion ratio setting means for setting a line conversion ratio R which satisfies an equation: R=m/k, where the 1/m is a width-to-height ratio read from the ROM table based on a format of the first video signal input through the operation panel, the 1/k is a width-to-height ratio of a second video data;
- converting means for converting the first digital video data having a first number of scanning lines to the second digital video data having a second number of scanning lines, the second number being R-times the first number; and
- digital-to-analog converting means for converting the second digital video data to a second analog video signal.
- 9. A video signal converter comprising:
- analog-to-digital converting means for converting a first analog video signal to first digital video data;
- a ROM table having width-to-height ratios of pixels, each of the ratios being associated with already-existing formats of video signals;
- an operation panel;
- line conversion ratio setting means for setting a line conversion ratio R which satisfies an equation: R=m/k, where the 1/m is a width-to-height ratio read from the ROM table based on a format of the first video signal input through the operation panel, the 1/k is a width-to-height ratio of a second video data;
- converting means for converting the first digital video data having a first number of scanning lines to the second digital video data having a second number of scanning lines, the second number being R-times the first number;
- an NTSC encoder for encoding the second digital video data to generate video data of the NTSC format; and
- digital-to-analog converting means for converting the video data of the NTSC format to an analog video signal of the NTSC format.
- 10. A video signal converter according to claim 9, wherein said first analog video signal is comprised of RGB signals, each of the RGB signals having a width-to-height ratio 1/1 of each pixel, respectively.
- 11. A video signal converter according to claim 9, wherein said first analog video signal is a signal of HDTV format.
- 12. A video signal converter comprising:
- a ROM table having frequencies and width-to-height ratios of pixels, each of the frequencies and each of the ratios being associated with already-existing formats of video signals;
- an operation panel;
- selecting means for selecting a first frequency Fi from the ROM table based on a format of a first video signal input through the operation panel, the first frequency Fi having the maximum value which satisfies a formula: Fi.ltoreq.(To.times.Fo)/Ti, where the Ti is a horizontal scanning period of the first video signal, the To is a horizontal scanning period of a second video signal, and the Fo is a second frequency;
- first clock generating means for generating a first clock of the first frequency Fi; second clock generating means for generating a second clock of the second frequency Fo;
- analog-to-digital converting means for converting the first analog video signal to first digital video data according to a sampling clock of the first frequency Fi;
- line conversion ratio setting means for setting a line conversion ratio R which satisfies an equation: R=m/k, where the 1/m is width-to-height ratio read from the ROM table based on a format of the first video signal input through the operation panel, the 1/k is a width-to-height ratio of a second video data;
- converting means for converting the first digital video data having a first number of scanning lines to the second digital video data having a second number of scanning lines, the second number being R-times the first number;
- a frame memory
- writing means for writing the first digital video data into the frame memory in synchronization with the first clock;
- reading means for reading the first digital video data from the frame memory in synchronization with the second clock to generate the second digital video data; and
- digital-to-analog conversion means for converting the second digital video data to the second analog video signal in synchronization with the second clock.
- 13. A video signal converter comprising:
- a ROM table having frequencies and width-to-height ratios of pixels, each of the frequencies and each of the ratios being associated with already-existing formats of video signals;
- an operation panel;
- selecting means for selecting a first frequency Fi from the ROM table based on a format of a first video signal input through the operation panel, the first frequency Fi having the maximum value which satisfies a formula: Fi.ltoreq.(To.times.Fo)/Ti, where the Ti is a horizontal scanning period of the first video signal, the To is a horizontal scanning period of a second Video signal, and the Fo is a second frequency;
- first clock generating means for generating a first clock of the first frequency Fi;
- second clock generating means for generating a second clock of the second frequency Fo;
- analog-to-digital converting means for converting the first analog video signal to first digital video data according to a sampling clock of the first frequency Fi;
- line conversion ratio setting means for setting a line conversion ratio R which satisfies an equation: R=m/k, where the 1/m is width-to-height ratio read from the ROM table based on a format of the first video signal input through the operation panel, the 1/k is a width-to-height ratio of a second video data;
- converting means for converting the first digital video data having a first number of scanning lines to the second digital video data having a second number of scanning lines, the second number being R-times the first number;
- a frame memory
- writing means for writing the first digital video data into the frame memory in synchronization with the first clock;
- reading means for reading the first digital video data from the frame memory in synchronization with the second clock to generate the second digital video data; and
- an NTSC encoder for encoding the second digital video data to generate video data of the NTSC format; and
- digital-to-analog converting means for converting the video data of the NTSC format to an analog video signal of the NTSC format.
- 14. A video signal converter according to claim 13, wherein said first analog video signal is comprised of RGB signals, each of the RGB signals having a width-to-height ratio 1/1 of each pixel, respectively.
- 15. A video signal converter according to claim 13, wherein said first analog video signal is a signal of HDTV format.
- 16. A video signal converter according to claim 13, wherein said second frequency Fo satisfies an equation: Fo=4.times.Fsc, where Fsc is a color subcarrier frequency of the NTSC format.
- 17. A video signal converter according to claim 14, wherein said second frequency Fo satisfies an equation: Fo=4.times.Fsc, where Fsc is a color subcarrier frequency of the NTSC format.
- 18. A video signal converter according to claim 15, wherein said second frequency Fo satisfies an equation: Fo=4.times.Fsc, where Fsc is a color subcarrier frequency of the NTSC format.
Priority Claims (1)
Number |
Date |
Country |
Kind |
6-202763 |
Aug 1994 |
JPX |
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Parent Case Info
This application is a continuation of application Ser. No. 08/510,506 filed Aug. 2, 1995, now abandoned.
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4872054 |
Gray et al. |
Oct 1989 |
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5070395 |
Kitaura et al. |
Dec 1991 |
|
5363140 |
Isomoto et al. |
Nov 1994 |
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5410357 |
Rieger et al. |
Apr 1995 |
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Continuations (1)
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Number |
Date |
Country |
Parent |
510506 |
Aug 1995 |
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