| 摘要 |
For conversion of component (VGA) video to television, a hardware efficient process implements line rate vertical scaling within a single integrated circuit without the support of external memory. Scaling and filtering are combined into a single process which is a polyphase filter. The polyphase filter is a low pass filter with a fixed cut off frequency and a programmable delay. By changing the coefficients of the kernel of the polyphase filter, the scaled video signal is time shifted by fractions of the pixel clock. In one example, for every nine incoming horizontal video scan lines, eight lines are outputted thus accomplishing the vertical scaling. The vertical scaling may include a field buffer memory for accommodating a range of incoming video refresh rates, or in concert with special timing of incoming video, may omit the field buffer memory and instead use a one or two line FIFO memory.
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