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1. About the Video and Vision Processing Suite
2. Getting Started with the Video and Vision Processing IPs
3. Video and Vision Processing IPs Functional Description
4. Video and Vision Processing IP Interfaces
5. Video and Vision Processing IP Registers
6. Video and Vision Processing IPs Software Programming Model
7. Protocol Converter IP
8. 1D LUT IP
9. 3D LUT IP
10. Adaptive Noise Reduction IP
11. Advanced Test Pattern Generator IP
12. AXI-Stream Broadcaster IP
13. Bits per Color Sample Adapter IP
14. Black Level Correction IP
15. Black Level Statistics IP
16. Chroma Key IP
17. Chroma Resampler IP
18. Clipper IP
19. Clocked Video Input IP
20. Clocked Video to Full-Raster Converter IP
21. Clocked Video Output IP
22. Color Plane Manager IP
23. Color Space Converter IP
24. Defective Pixel Correction IP
25. Deinterlacer IP
26. Demosaic IP
27. FIR Filter IP
28. Frame Cleaner IP
29. Full-Raster to Clocked Video Converter IP
30. Full-Raster to Streaming Converter IP
31. Genlock Controller IP
32. Generic Crosspoint IP
33. Genlock Signal Router IP
34. Guard Bands IP
35. Histogram Statistics IP
36. Interlacer IP
37. Mixer IP
38. Pixels in Parallel Converter IP
39. Scaler IP
40. Stream Cleaner IP
41. Switch IP
42. Text Box IP
43. Tone Mapping Operator IP
44. Test Pattern Generator IP
45. Unsharp Mask IP
46. Video and Vision Monitor Intel FPGA IP
47. Video Frame Buffer IP
48. Video Frame Reader Intel FPGA IP
49. Video Frame Writer Intel FPGA IP
50. Video Streaming FIFO IP
51. Video Timing Generator IP
52. Vignette Correction IP
53. Warp IP
54. White Balance Correction IP
55. White Balance Statistics IP
56. Design Security
57. Document Revision History for Video and Vision Processing Suite User Guide
31.4.1. Achieving Genlock Controller Free Running (for Initialization or from Lock to Reference Clock N)
31.4.2. Locking to Reference Clock N (from Genlock Controller IP free running)
31.4.3. Setting the VCXO hold over
31.4.4. Restarting the Genlock Controller IP
31.4.5. Locking to Reference Clock N New (from Locking to Reference Clock N Old)
31.4.6. Changing to Reference Clock or VCXO Base Frequencies (switch between p50 and p59.94 video formats and vice-versa)
31.4.7. Disturbing a Reference Clock (a cable pull)
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39.3.2. Coefficient Quantization
The scaler IP implements the filters when you select Polyphase algorithm using fixed-point logic, so you must supply the filter coefficients in a fixed-point format. You define the format for the coefficients with parameters that select whether they are signed or unsigned, the number of integer bits, and the number of fraction bits.
- Signed or unsigned: if you want to represent negative coefficients, turn on Use signed vertical coefficients. If all coefficients are positive values, reduce logic and turn off Use signed vertical coefficients.
- Integer bits: the number of integer bits defines the maximum value that can be represented.
- Fraction bits: the number of fraction bits defines the precision with which the IP can convert floating-point coefficients into the fixed-point format.
The overall bit width of each coefficient is the sum of the integer and fraction bits, plus one extra bit for signed coefficients. When using Lanczos coefficients, Intel recommends the following settings:
- Turn on Use signed vertical coefficients as the Lanczos function for any number of lobes greater than 1 requires negative values, so the coefficients must be signed.
- Use 1 integer bit as the maximum value required for any Lanczos coefficient is 1.0
- Use between 6 and 8 fraction bits.
Typically, the filter coefficients produce noninteger floating-point values. To convert each floating-point coefficient into its closest quantized representation in the selected fixed-point format:
- Multiply each coefficient by 2 frac , where frac is the number of fraction bits you select
- Apply float to integer conversion to each coefficient
However, small errors in the coefficient values introduced by the quantization process can accumulate so that the coefficients in each phase no longer sum to their intended value. Generally, the coefficients in any phase should sum to exactly 1.0. Any value greater than 1.0 increases the overall brightness of the resulting image. Any value less than 1.0 reduces the brightness. The coefficients can sum to more or less than 1.0 if you want a brighter or darker image. You should still ensure your coefficients sum to your original, intended value post quantization. To restore the coefficients to values that sum to the intended value:
Figure 104. Restore Coefficient Values
float quantization_error = 0.0;
for (int j = 0; j < taps; j++) {
quantization_error += original_float_coeff[j] - ((float)quant_coeff[j]);
if (quantization_error < -0.5) {
quant_coeff[j]--;
quantization_error += 1.0;
} else {
if (quantization_error > -0.5) {
quant_coeff[j]++;
quantization_error -= 1.0;
}
}
}