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SC200x Video Subsystem

SC200x Video Subsystem. Tony Sloan DTV Source Applications Broadband Entertainment Division July 2001. SC200x Video Training Agenda. Digital Video Colour Space - Colour Space Conversion - Sampling - 4:2:0 - 4:2:2 - 4:4:4 - Upsampling - Downsampling - ITU-R BT.656

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SC200x Video Subsystem

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  1. SC200x Video Subsystem Tony Sloan DTV Source Applications Broadband Entertainment Division July 2001

  2. SC200x Video Training Agenda • Digital Video • Colour Space - Colour Space Conversion - Sampling - 4:2:0 - 4:2:2 - 4:4:4 - Upsampling - Downsampling - ITU-R BT.656 • SC200x Video Mixer - Encoder - DACs • Still Plane & AV Decoder & Background Mixer - OSD & Cursor Mixer - Program Channel - Composite Channel - Multi-standard Encoder - DACs • Test Signals - Terminology • Line - Field - 525 / 625 - North American Test Signals - Terminology - Tests - Measurement

  3. SC200x Video Training • Digital Video

  4. RGB Gamma Correction • RGB is the starting point for Video and Graphics • But RGB Gamma Correction is required because:- • The CRT display is non-linear and computer generated graphics would lack light intensity at low amplitudes • Gamma Correction makes CRT intensity appear linear • Gamma corrected RGB (R’G’B’) = RGB where:- • Gamma () is 2.2 for NTSC • Gamma () is 2.8 for PAL and SECAM • Writing a 1 to bit 0 of the MCTRL register (0xbe50.0034) enables Gamma Correction for the OSD

  5. R’G’B’ Sampling 4:4:4 • R`G`B` Sampling • Sampled at 13.5MHz • 6.75MHz Low Pass Filtering • -40dB at 6.75MHz (1/2 Fs) • 8 bit ADC for Consumer • 10 bit ADC for Professional • R`G`B` is 4:4:4

  6. R’G’B’ to Y Pb Pr Matrix • R`G`B` to Y Pb Pr Matrix • Y = 0.299R` + 0.587G` + 0.114B` • B-Y = - 0.229R` - 0.587G` + (1 - 0.114)B` • R-Y = (1- 0.299)R` - 0.587G` - 0.114B` • This gives the following:- • Y = 0.299R` + 0.587G` + 0.114B` • B-Y = - 0.229R` - 0.587G` + 0.886B` • R-Y = 0.701R` - 0.587G` - 0.114B` • But the maximum signal excursion allowable is 1V peak to peak

  7. Y Pb Pr Normalising • R`G`B` to Y Pb Pr Matrix (continued.) • Y = 1Y • Pb = 0.564(B`-Y) • Pr = 0.713(R`-Y) • This gives the following:- • Y = 0.299R` + 0.587G` + 0.114B` • Pb = - 0.169R` - 0.331G` + 0.500B` • Pr = 0.500R` - 0.419G` - 0.081B` • Now the maximum signal excursion is 1V peak to peak

  8. Y Pb Pr Sampling 4:4:4 • Y Pb Pr Sampling #1 • Full resolution Chrominance • All sampled at 13.5MHz • 6.75MHz Low Pass Filtering • -40dB at 6.75MHz (1/2 Fs) • 8 bit ADC for Consumer • 10 bit ADC for Professional • Y Pb Pr is 4:4:4

  9. Y Pb Pr Sampling 4:2:2 • Y Pb Pr Sampling #2 • Y Sampled at 13.5MHz • 6.75MHz Y Low Pass Filtering • Pb Pr Sampled at 6.75MHz • 3.375MHz C Low Pass Filtering • -40dB at 6.75MHz (1/2 Fs) • 8 bit ADC for Consumer • 10 bit ADC for Professional • Y Pb Pr is 4:2:2

  10. ITU-R 601 Signal Amplitudes • 601 Levels • ITU-R.601 • Formerly CCIR.601 • 601Y has 220 levels and is offset by 16 decimal • 601Pb has 225 levels and is offset by 128 decimal • 601Pr has 225 levels and is offset by 128 decimal • Y is still referred to as Y • 601Pb is referred to as Cb • 601Pr is referred to as Cr

  11. 601 Sampling (8 bits) • 601 Sample Acquisition (8 bits) • Y Pb Pr Input • 4:2:2 Sampling • 601Y = (220/256)Y + 16 • Cb = (225/256)Pb + 128 • Cr = (225/256)Pr + 128

  12. 601 Signals Max. and Min. • 601 Levels • Y levels • 16 to 235 decimal • 0x10 to 0xeb • Cb levels • 16 to 240 decimal • 0x10 to 0xf0 • Cr levels • 16 to 240 decimal • 0x10 to 0xf0

  13. 601 4:2:2 Luma samples per line • 601 4:2:2 Samples • Luminance sampled at 13.5MHz • 864 samples per line for 625 line standard • 858 samples per line for 525 line standard • 720 Active samples per line for both standards • 144 Blanking samples per line for 625 line • 138 Blanking samples per line for 525 line

  14. 601 4:2:2 Chroma samples per line • Cb sampled at 6.75MHz • 432 Cb samples per line for 625 line standard • 429 Cb samples per line for 525 line standard • 360 Active Cb samples per line for both standards • 72 Blanking samples per line for 625 line standard • 69 Blanking samples per line for 525 line standard • Cr sampled at 6.75MHz • 432 Cr samples per line for 625 line standard • 429 Cr samples per line for 525 line standard • 360 Active samples per line for both standards • 72 Blanking samples per line for 625 line standard • 69 Blanking samples per line for 525 line standard

  15. Relationship between 4:4:4 and 4:2:2 • 601 Sample Relationship • Line • Line

  16. Upsampling from 4:2:2 to 4:4:4 • 601 4:2:2 to 4:4:4 Upsampling • Line • Line

  17. Downsampling from 4:4:4 to 4:2:2 • 601 4:4:4 to 4:2:2 Downsampling • Line • Line

  18. ITU-R BT.656 Specification basics • ITU-R BT.656 Specification • European derivative EBU Tech. 3247 • North American derivative SMPTE RP125 • 8 bits or 10 bits (8 bits only will be discussed) • 0x00 and 0xff are reserved for timing • 0x01 to 0xfe can be used for timing related data • 0x10 to 0xf0 is used for video data

  19. ITU-R BT.656 Multiplex • ITU-R BT.656 Multiplex Structure • Line • Samples @ 27MHz • Line

  20. 656 Timing Reference Signals (TRS) • ITU-R BT.656 Timing Reference Signals (TRS) • Comprises 4 data bytes and occurs twice in a video line • 1st - Indicates Start of Active Video - SAV • 2nd - Indicates End of Active Video - EAV • First 3 bytes of each TRS are common to both • FVH* denotes whether TRS is SAV or EAV

  21. 656 FVH* Byte • ITU-R BT.656 FVH* Byte • Bit 7 - Always logical ‘1’ • Bit 6 - Field - (0 for Field 1, 1 for Field 2) • Bit 5 - Vertical (0 for Active, 1 for V Blanking) • Bit 4 - Horizontal (0 for Active, 1 for H Blanking) • Bits [3:0] contains Hamming Protection

  22. 656 Start of Active Video • Start of Active Video - SAV • FVH = 0x80 • F = 0 Field 1 • V = 0 Active Field area • H = 0 Active Line area • P = 0 Hamming Protection

  23. 656 End of Active Video • End of Active Video - EAV • FVH = 0x9D • F = 0 Field 1 • V = 0 Active Field area • H = 1 Line Blanking • P = D Hamming Protection

  24. 656 to Analog Line Relationship • ITU-R BT.656 to Analog Line Relationship

  25. 656 to Analog Field Relationship • ITU-R BT.656 to Analog Field Relationship

  26. ITU-R BT.656 Parallel Interface • ITU-R BT.656 Physical Interface #1 • Parallel • 10 Differential pair ECL Data lines • 1 Differential pair ECL Clock line • 2 Grounds • 1 Unconnected • 25 way Female D-Type connectors on equipment • Voltage levels between - 0.9 volts and - 1.7 • Data Rate of 27MHz

  27. ITU-R BT.656 Serial Interface • ITU-R BT.656 Physical interface #2 • Serial • 1 High Speed 75 ohm interface • 75 ohm BNC connections • Voltage Levels between 740mV and 860mV • Data Rate of 270MHz

  28. SC200x Video Training • Mixer / Encoder / DACs

  29. Mixer Background Colour • Programmable Mixer Background • Video Format • Address 0xbe50.0050 • Background is a Flat field • Data can be considered as 4:2:2 or 4:4:4

  30. AV Decoder Background Colour • Programmable AV Decoder Background • Video Format • Addresses are 0xbe42.0428 (Y) .042c(Cb) .0430(Cr) • Background is a Flat field • Selected when bits [7:6] of 0xbe42.0424 = 0x2 • Data can be considered as 4:2:2 or 4:4:4

  31. Conversion from 4:2:0 to 4:2:2 • AV Decoder Video Format

  32. Still Plane Colour • Still Plane Video format • Video Format is 4:2:2 • Stored in SDRAM at sequential locations • SDRAM Start Address is stored in 0xbe63.0010

  33. Program Mixer • Background/AV Decoder/Still Plane Mixer

  34. Program Mixer Control • Background/AV Decoder/Still Mixer Control • Address 0xbe50.0034 • Bits [9:8] • 00 - Background only • 01 - Video only • 10 - Video and Still • 11 - Black • Bits [3:2] • 00 - Video over Still • 01 - Still over Video • 10 - Still only, Video off • 11 - Video only, Still off

  35. OSD 32bpp Direct Colour Mode • OSD Direct Colour Mode Format 32 bits per pixel • RGB or YCbCr • OSD Data is stored in SDRAM • Video Format (with Alpha Blend) is 4:4:4:4

  36. OSD 16bpp Direct Colour Mode RGB • OSD Direct Colour Mode Format 16 bits per pixel #1 • Alpha RGB - 4:4:4:4 bits - 1:5:5:5 bits - 0:5:6:6 bits

  37. OSD 16bpp Direct Colour Mode YCbCr • OSD Direct Colour Mode Format 16 bits per pixel #2 • Alpha YCbCr - 4:5:3:4 bits - 1:6:4:5 bits - 0:6:5:5

  38. OSD Plane 32 bit YCbCr YCbCr 16 (one region) Gustave Eiffel won the tower competition for the Universal Exposition in 1889 and left behind a lasting legacy. RGB16 SQPIX 32 bit - RGB 720x576 Multiple OSD Planes • OSD Plane • Only 1 OSD per line • Mix of Colour Spaces • Square Pixel support

  39. Cursor Colour • Cursor Video Format • YCbCr only • Data is stored in registers within the chip • Addresses 0xbe62.0600 to 0xbe62.063c • Video Format (with Alpha Blend) is 4:4:4:4

  40. 32 pixels wide 32 pixels high Cursor Features • Cursor • 32 x 32 Pixels • 16 Colour CLUT • 129 Alpha Blends

  41. OSD and Cursor Mixer • OSD and Cursor Mixer

  42. Composite Mixer • Composite Mixer

  43. Upsampling Using Replication • Actual Upsampling in the SC200x

  44. Downsampling Using Decimation • Actual Downsampling used in the SC200x

  45. Program Channel Path • Program Channel

  46. Composite Channel Path • Composite Channel

  47. Encoder YUV Scaling • Multi-standard Encoder #1 • YUV Derivation • 9 tap Low Pass Filter to limit Chroma Bandwidth • YCbCr to YUV Scaling

  48. Encoder Subcarrier Modulation • Multi-standard Encoder #2 • Subcarrier Modulation • Burst phase is adjustable

  49. Phase Modulation for NTSC-M • Subcarrier Modulation for NTSC-M • For all lines • Yellow 167 degrees • Cyan 283 degrees • Green 241 degrees • Magenta 61 degrees • Red 103 degrees • Blue 347 degrees • Burst 180 degrees

  50. Luma/Chroma Relationship • Luminance and Chrominance Relationship • 75% Color Bars NTSC shown • 75% Amplitude - 100% Saturation

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