Automatic gain control method and device
An automatic gain adjustment and gain adjustment technology, applied in the field of signal processing, can solve problems such as loss of brightness and chrominance information, abnormally large, and distortion of reference signals, etc., to avoid excessive gain, improve stability, and protect brightness and chroma information effect
Inactive Publication Date: 2013-01-23
新奇点智能科技集团有限公司
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[0004] The existing automatic gain control adjustment method can obtain better adjustment effect when the reference signal, that is, the horizontal sync head or the color pulse is not severely distorted; however, when CVBS is applied in a mobile environment, for example: when moving When the terminal transmits CVBS, as the location of the mobile terminal changes, the CVBS channel environment is also constantly changing, and the reference signal is likely to be distorted. When the reference signal is seriously deformed, the amplitude of the reference signal may become very small , at this time, using the existing method will often get an abnormally large gain value, resulting in the saturation of the CVBS used for decoding, and the loss of luminance and chrominance information
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[0042] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.
[0043] The horizontal sync header or color pulse of CVBS is referred to as the reference signal below.
[0044] figure 2 The composition diagram of the automatic gain adjustment device provided for the embodiment of the present invention, such as figure 2 As shown, it mainly includes: cache module 21, amplitude search module 22, maximum gain calculation module 23 and gain control module 24, and the length of cache module 21 is equal to the length of a row of CVBS, wherein:
[0045] Buffering module 21: receive and buffer the current line CVBS, and output the previous line CVBS of buffering to gain control module 34 successively, that is, one end of this module is currently receiving the mth line CVBS, then the other end of this module is sending to gain control module 34. The module 34 outputs the m-1th line of CVBS; here, the cac...
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The invention discloses an automatic gain control method and an automatic gain control device. The method comprises the following steps of: computing the ratio of amplitude of a reference signal to the amplitude of the whole composite video broadcast signal (CVBS) in the standard CVBS, wherein the reference signal is a sync-tip or a color burst; for any row of the CVBS, searching for the amplitude of the row of the CVBS, and computing the maximum gain of the row of the CVBS according to the ratio and the amplitude of the whole row of the CVBS; computing the gain of the row of the CVBS; and judging whether the gain of the row of the CVBS is lower than the maximum gain of the row of the CVBS, performing gain control on the row of the CVBS by adopting the gain if the gain of the row of the CVBS is lower than the maximum gain of the row of the CVBS, otherwise performing the gain control on the row of the CVBS by adopting the maximum gain. By the method and the device, when the reference signal is distorted, the problem of picture quality worsening caused by overhigh gain can be solved, the stability of the gain control is improved and luminance and chromaticity information is maximally protected.
Description
technical field [0001] The invention relates to signal processing technology, in particular to an automatic gain adjustment method and device. Background technique [0002] In analog TV signal reception, it is necessary to use automatic gain control technology to process the video signal whose amplitude is constantly changing, so that the amplitude of the decoded video signal is uniform. A common processing method is to use the amplitude of a line sync tip (sync-tip) or a color burst (color burst) in a composite video broadcast signal (CVBS, Composite Video Broadcast Signal) as a reference value for automatic gain adjustment. [0003] figure 1 The composition diagram of the standard CVBS is given, such as figure 1 As shown, CVBS includes from front to back: line synchronization header, color pulse and video content, where IRE is the unit of level, and for each part of CVBS, the difference between the highest level and the lowest level is the part’s Amplitude, such as: the...
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IPC IPC(8): H04N5/52
Inventor 张辉王西强钱炜杨利李志鑫
Owner 新奇点智能科技集团有限公司