请问TVP5150AM1 BT656图像上下抖动是什么原因？

读出的寄存器的值如下：
tvp5150: Video input source selection #1 = 0x00
tvp5150: Analog channel controls = 0x15
tvp5150: Operation mode controls = 0x70
tvp5150: Miscellaneous controls = 0x3d
tvp5150: Autoswitch mask= 0xdc
tvp5150: Color killer threshold control = 0x10
tvp5150: Luminance processing controls #1 #2 and #3 = 60 00 00
tvp5150: Brightness control = 0x80
tvp5150: Color saturation control = 0x80
tvp5150: Hue control = 0x00
tvp5150: Contrast control = 0x80
tvp5150: Outputs and data rates select = 0x47
tvp5150: Configuration shared pins = 0x1a
tvp5150: Active video cropping start = 0x0000
tvp5150: Active video cropping stop = 0x0000
tvp5150: Genlock/RTC = 0x01
tvp5150: Horizontal sync start = 0x80
tvp5150: Vertical blanking start = 0x00
tvp5150: Vertical blanking stop = 0x00
tvp5150: Chrominance processing control #1 and #2 = 0c 54
tvp5150: Interrupt reset register B = 0x00
tvp5150: Interrupt enable register B = 0x00
tvp5150: Interrupt configuration register B = 0x00
tvp5150: Video standard = 0x04
tvp5150: Chroma gain factor: Cb=0x97 Cr=0x6b
tvp5150: Macrovision on counter = 0x0f
tvp5150: Macrovision off counter = 0x01
tvp5150: ITU-R BT.656.4 timing(TVP5150AM1 only)
tvp5150: Device ID = 5150
tvp5150: ROM version = (hex) 04.00
tvp5150: Vertical line count = 0x0271
tvp5150: Interrupt status register B = 0xdf
tvp5150: Interrupt active register B = 0x00
tvp5150: Status regs #1 to #5 = fe 08 25 45 83
tvp5150: Teletext filter enable = 0x00
tvp5150: Interrupt status register A = 0xc0
tvp5150: Interrupt enable register A = 0x40
tvp5150: Interrupt configuration = 0x06
tvp5150: VDP status register = 0x40
tvp5150: FIFO word count = 0x00
tvp5150: FIFO interrupt threshold = 0x80
tvp5150: FIFO reset = 0x00
tvp5150: Line number interrupt = 0x00
tvp5150: Pixel alignment register = 0x004e
tvp5150: FIFO output control = 0x01
tvp5150: Full field enable = 0x00
tvp5150: Line mode registers = 0x00
tvp5150: Full field mode register = 0x7f
tvp5150: 656 Revision Select Register = 0x00