Digital video amplitude limiting method for analog broadcasting TV signal
A technology for television signals and analog broadcasting, applied in the direction of color signal processing circuits, etc., can solve the problems of signal amplitude reduction, overall video picture quality degradation, and overall video picture quality degradation at the receiving end, etc., and achieve the effect of preventing the problem of excessive modulation.
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Embodiment 1
[0015] This embodiment is a method for digital video clipping of analog broadcast television signals. The system used in the method includes: an audio and video decoder, an audio data cache, an amplitude detector, a limiter, and an audio and video encoder. The system can be hardware or software. If it is hardware, it can be designed as a dedicated integrated circuit chip, or a chip like a programmable gate array can be used. If it is software, it can be set in the server for audio and video processing to use software to form audio and video decoders, audio data buffers, amplitude detectors, limiters, and audio and video encoders to realize the processing process. The video input and output of the system described in this embodiment are all digitized and documented.
[0016] Audio and video decoder: This module is located at the input interface, which decodes the documented video and audio files, provides video data in YCbCr 4:2:2 format for the subsequent amplitude detection ...
Embodiment 2
[0033] This embodiment is an improvement of the first embodiment, and is a refinement of the first embodiment on amplitude detection. The process of amplitude detection described in this embodiment is as follows figure 2 shown, including the following sub-steps:
[0034] Extract the Y, Cb, and Cr pixel data of a pixel in the file, and convert the pixel data into Y'UV data in the YUV domain, Y'=Y-16, U=[(Cb-128) / 0.564]×0.493, V=[(Cr-128) / 0.713]×0.877, see standard ITU-R BT.601-4 for details.
[0035] Calculate the absolute value |C| of the chrominance vector C and the analog level f corresponding to the brightness value 1 (Y'), the analog level value f corresponding to the chroma value 2 (|C|). in:
[0036] |C|=(U 2 +V 2 ) 1 / 2 ,
[0037] f 1 (Y')=Y'×3.1963,
[0038] f 2 (|C|) = |C|×6.26.
[0039] Calculate the modulated positive level peak value A + and negative level peak A - . where A + =f 1 (Y')+f 2 (|C|) / 2, A - = f 1 (Y')-f 2 (|C|) / 2. During modulation...
Embodiment 3
[0051] This embodiment is an improvement of the above embodiment, and is a refinement of the above embodiment regarding clipping. The limiting described in this embodiment includes the following sub-steps:
[0052] If it is judged that the upper limit exceeds the standard, assign the maximum possible upper limit level value to A after modulation of the pixel point + , namely A + =f 1 (y h ’) + f 2 (C)=H. Reverse the brightness level f according to the equation 1 (y h ’), then f 1 (y h ’)=H-f 2 (C) / 2, and then calculate the brightness value y in the YUV domain after clipping at this point h ’, modify the brightness value of the pixel in the YCbCr color gamut space to Y=y h ’+16.
[0053] If the lower limit exceeds the standard, set A - =f 1 (y l ’)-f 2 (C)=L, and then calculate the brightness level f after the lower limit limit according to the equation 1 (y l ’), then f 1 (y l ’)=H-f 2 (C) / 2, calculate the brightness value y of the YUV domain after the low...
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