System and method for compressing video data for video conferencing at a reduced frame rate
First Claim
1. A method for compressing video data from a video source located at a first node and for first transmission to a second node in order to enable second transmission from additional video sources to the second node, the second transmission being separate from the first transmission, the method comprising:
- at the first node, sequentially storing a first number of fields N at a selected rate and dropping a second number of fields P to achieve a compression ratio of (P+N);
N in order to enable transmission from the additional video sources to the second node; and
converting the video signals from analog to digital prior to storing in a digital memory and converting the video data from digital to analog upon transferring the data for transmission of the first number of fields to the second node without transmitting the second number of fields to the second node.
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Accused Products
Abstract
The compression of composite video data is provided in order to reduce bandwidth and thereby increase the amount of bandwidth available for transmission. Composite video signals that include a plurality of fields are received at a selected clock frequency. A first selected number of fields is stored and a second selected number of fields is dropped. In a Frequency Division Multiplexing mode, the data is read out at a fraction of the selected clock frequency corresponding to the stored portion. In a Time Division Multiplexing mode, the data is read out at the selected clock frequency during selected intervals having a duration corresponding to the time it took to receive the stored fields. No data is read out during an interval having a duration equal to the time it took to scan the dropped fields, such time being allocated to the compressed information from other users of the same shared transmission medium.
21 Citations
19 Claims
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1. A method for compressing video data from a video source located at a first node and for first transmission to a second node in order to enable second transmission from additional video sources to the second node, the second transmission being separate from the first transmission, the method comprising:
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at the first node, sequentially storing a first number of fields N at a selected rate and dropping a second number of fields P to achieve a compression ratio of (P+N);
N in order to enable transmission from the additional video sources to the second node; andconverting the video signals from analog to digital prior to storing in a digital memory and converting the video data from digital to analog upon transferring the data for transmission of the first number of fields to the second node without transmitting the second number of fields to the second node. - View Dependent Claims (2, 3, 5, 6, 7, 8)
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4. A method for compressing video data from a video source located at a first node and for first transmission to a second node in order to enable second transmission from additional video sources to the second node, the second transmission being separate from the first transmission, the method comprising:
at the first node, sequentially storing a first number of fields N at a selected rate and dropping a second number of fields P to achieve a compression ratio of (P+N);
N in order to enable transmission from the additional video sources to the second node, wherein the storing step includes storing the data in an analog charge coupled device and transferring data for transmission of the first number of fields by shifting stored charges within the analog charge coupled device for transmission of the first number of fields to the second node without transmitting the second number of fields to the second node.- View Dependent Claims (17, 18)
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9. A method for compressing video data from a video source in order to enable transmission from additional video sources, the method comprising:
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sequentially storing a first number of fields N at a selected rate as compressed video data and dropping a second number of fields P to achieve a compression ratio of (P+N);
N in order to enable transmission from the additional video sources;transmitting the compressed video data to a receiving device; inserting a V-SYNC in place of 1/2 line of each field in order to eliminate color phase discontinuity; and playing back the stored fields.
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10. A method for compressing video data from a video source in order to enable transmission from additional video sources, the method comprising:
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sequentially storing a first number of fields N at a selected rate to form compressed video data and dropping a second number of fields P to achieve a compression ratio of (P+N);
N in order to enable transmission from the additional video sources; anddecompressing the compressed video data, the decompressing comprising; receiving the N fields; storing the N fields; and playing the N fields back at N+P times the selected rate. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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19. A method for compressing video data transmitted by a first transmission from a video source in order to enable second transmission from additional video sources, the second transmission being separate from the first transmission, the method comprising:
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sequentially storing a first number of fields N at a selected rate and dropping a second number of fields P to achieve a compression ratio of (P+N);
N in order to enable transmission from the additional video sources; andtransferring the stored fields of storage at a reduced rate, wherein the reduced rate is equal to the selected rate multiplied by N/(P+N), in order to decrease an original frequency bandwidth used for transmission by a factor of substantially (P+N)/N.
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Specification