BT656 Encoder with Colour-Space Converter

BT_656_ENCODER is a digital video encoder with integrated colour-space converter. The encoder accepts 24-bit RGB pixels from sequential odd and even fields. These pixels are then mapped to the YCbCr colour-space and formatted correctly into a BT.656 output stream. The encoder begins operation after reset is de-asserted and on detection of input field '0'. Input pixels are sampled on the rising-edge of clk when the pixin_val and pixin_rdy signals are both asserted high. The pixin_vsync and the pixin_hsync flags are coincident with the first pixel of a field and line. The pixin_field flag indicates whether the field is odd or even.

The valid-ready flow-control interface shares a common format with all other Zipcores video IP and allows easy connectivity between IP cores. The valid-ready interface also allows simple connectivity with an input FIFO or external frame buffer.

The output of the encoder generates an industry standard ITU-R BT.656 format video stream together with a video_val signal that is asserted with the first valid byte of the output stream.

If the encoder is starved of pixels during the generation of an active line then the underflow flag will be asserted. In the event of an underflow condition, then design must be reset by asserting the reset signal low for at least one clock cycle. Operation will then resume as normal when the next input field is detected

• Synthesizable, technology independent VHDL IP Core
• Converts 24-bit RGB digital video to an industry standard 8-bit ITU-R BT.656 stream
• Integrated RGB888 to 4:2:2 YCbCr colour-space converter
• Both PAL and NTSC (576i and 480i) formats supported
• All signals synchronous with the pixel clock
• Small implementation size ideal for all types of FPGA
• Compatible with a wide range of  SD video encoder ICs

• BT.656 output video generation
• PAL & NTSC SDTV video format conversion
• Connectivity with a wide range of commercially available video  encoder ICs
• Simple and cost-effective method for generating digital video  outputs from your FPGA or ASIC