Electronic Components Datasheet Search |
|
VP510 Datasheet(PDF) 4 Page - Zarlink Semiconductor Inc |
|
VP510 Datasheet(HTML) 4 Page - Zarlink Semiconductor Inc |
4 / 14 page VP 510 3 In the RGB to chrominance and luminance mode, when pre interpolation does not occur, only 8 unsigned integer bits are available from the look up table. Thus, within the 13 bit total, the top 2 bits plus the bottom 3 bits will be made into zero's. Intermediate precision within the matrix multiplier grows to 15 signed integer bits plus 6 fractional bits. The least signifi- cant 9 or 10 of the integer bits are selected at the output, and the fractional bits are rounded to 3 bits. Ten integer bits are used when the matrix is producing RGB from interpolated chrominance and luminance. This allows for undershoot and overshoot beyond the nominal 8 bit unsigned value. Only 9 integer bits are necessary when the matrix is producing chrominance, and the three fractional bits provide additional precision into the decimating filter. In fact, if the matrix is producing normalized chrominance, the coefficients will have been chosen to produce an output in the range ± 127. This range only requires 8 integer bits, and the ninth bit will be a repeated sign bit. Note that ±127 is actually representing ±0.5 in this context. When the NORM bit in the Control Register is reset, the chrominance outputs lie in the range ±1, or ±256 in our internal representation. The full 9 integer bits are then needed. LUMINANCE FILTER The luminance channel contains a 23 tap low pass filter with internally defined 10 bit signed coefficients. When the MODE bit in the Control Register is reset the filter will decimate the sampling rate by two. When the MODE bit is set the filter will interpolate the incoming data to produce outputs at twice the incoming sampling rate. The filter coefficients remain the same in both cases, but the gain is adjusted to preserve the energy content.. When the filter is producing decimated luminance it ac- cepts data from the matrix converter with 9 signed integer bits plus 3 fractional bits ( 9.3 ). Since luminance is always positive, however, the most significant bit will be zero. Words within the filter calculation are allowed to grow to 15 integer bits plus 6 fractional bits. This is then rounded to 15 bits plus 3 fractional bits, and finally the 10 least significant integer bits are chosen to give a 10.3 result. The 10 bit integer component allows for any undershoot or overshoot in the nominal 0 to 255 lumi- nance range. The three fractional bits are used to round the integer component to a 10 bit value. This is then clipped to a value between 0 and 255. Negative values become zero, and positive values greater then 255 will saturate at 255. Outputs will not saturate under normal operating conditions, and the circuit is only necessary to prevent overflow when the input swings between the maximum and minimum values. Figure 2 illustrates the bit significance at various points in the data path. When the filter is used to interpolate incoming luminance data, the 8 bit input is padded to the 9.3 format used previ- ously. The 13 bit output from the filter is applied to the matrix converter without further rounding. The response given by the filter is shown in Figure 3. Stop band attenuation is approximately 45 dB, and the maximum pass band ripple is 0.07 dB. These figures were obtained with 10 bit quantized coefficients and unquantized data. The effects of the various quantization steps within the filter, plus the reduction to 10 bits, is superimposed upon Figure 3. Also shown is the CCIR601 specification for a luminance or RGB 0.1 0.2 0.3 0.4 0.5 0 10 20 30 40 50 60 70 80 CCIR601 Specification Quantized Coefficients, FP Data Quantized Coefficients and Data 0.0 -0.05 -0.1 0.05 0.1 0.05 0.1 0.15 0.2 PASSBAND RIPPLE NORMALIZED FREQUENCY Figure 3. Response of the Luminance Filter Fig 2. Bit significance in the Y Filter ROUND MAC ARRAY SELECT 10 INTEGER BITS 08.000 9.3 From Pins From Matrix 1.9 Coefficents 15.6 15.3 10.3 To Matrix Converter in Interpolate Mode 10.0 CLIP TO 0 - 255 Unsigned 8.0 to Pins ROUND |
Similar Part No. - VP510 |
|
Similar Description - VP510 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |