So you want to record your retro rigs video, how can you do it?
Most modern video recorders no longer support older video standards, they stop at HD 1280 x 720 only and go upwards from that.
What do you do?? Taking videos with your cell phone leaves a lot to be desired...so make your own video digitizer!
First we need to know what video standard we are going to digitize. Is it interlaced? Most older standards were so now we have to patch them together to get the whole picture. What kind of sample rate do we need?? Where are we going to store it? We can use dual port rams to store our digitized results as we want to be able to hook this up to some device later on to either display or access it from a computer and stream it.
Looking over the video formats we can see that the vertical and horizontal sync pulses are either a hi pulse or a low pulse called + or -. So we have to count the incoming pulses time periods to determine if it's a + or -. Once we do that then we can count the number of horizontal pulses per a vertical time frame to get the number of Lines in a Frame of video. From that we can look up a database of video formats to determine what the video format is and adjust our sample clock to sample the incoming video at the right time.
The database will also tell us if the video is interlaced or not. We can then adjust our addressing bits for that to place the data bytes in memory so we can stream the output as one whole frame at a time. Interlaced means that we only show one half of a frame at a time, we show the even lines first followed by the odd lines next to get all the lines in a frame. If it's even line time the lowest address bit will be a zero and the odd lines will have the lowest address bit set to a one.
The address bits will be setup as follows:
{line counter}{dot counter}{Even or Odd}
The database will also contain all the video formats we need to figure out the relationships for all the signals coming in from the VGA port we will be digitizing from. Once we have a whole frame stored we can then send it along for output via HDMI to be streamed for wherever we need it next.
Format # H format V format Interlaced/Progressive V freq H total V total H freq Dot Clk Pixel Rep Adj Dot Clk Adj Dot Time Cell width Cell length Cell char Cell lines Horiz Write Window Shift Clock Time Window
160 100 1 60 240 115 6.90 1.66 1 1.66 603.86 16 16 10 6 80 0.10 9661.84
320 200 1 60 400 215 12.90 5.16 1 5.16 193.80 16 16 20 12 80 0.32 3100.78
640 480 1 50 720 495 24.75 17.82 1 17.82 56.12 16 16 40 30 80 1.11 897.87
0.31M3 VGA 640 480 1 59.94 800 525 31.47 25.17 1 25.17 39.72 16 16 40 30 160 1.57 635.56
1 640 480 1 59.94 800 525 31.47 25.17 1 25.17 39.72 16 16 40 30 160 1.57 635.56
1 640 480 1 60.00 800 525 31.50 25.20 1 25.20 39.68 16 16 40 30 160 1.58 634.92
17 720 576 1 50.00 864 625 31.25 27.00 1 27.00 37.04 16 16 45 36 144 1.69 592.59
18 720 576 1 50.00 864 625 31.25 27.00 1 27.00 37.04 16 16 45 36 144 1.69 592.59
2 720 480 1 59.94 858 525 31.47 27.00 1 27.00 37.04 16 16 45 30 138 1.69 592.59
3 720 480 1 59.94 858 525 31.47 27.00 1 27.00 37.04 16 16 45 30 138 1.69 592.59
2 720 480 1 60.00 858 525 31.50 27.03 1 27.03 37.00 16 16 45 30 138 1.69 592.00
3 720 480 1 60.00 858 525 31.50 27.03 1 27.03 37.00 16 16 45 30 138 1.69 592.00
0.31M3 VGA 640 480 1 72.81 800 525 38.22 30.58 1 30.58 32.70 16 16 40 30 160 1.91 523.22
0.31M3 VGA 640 480 1 75.00 800 525 39.38 31.50 1 31.50 31.75 16 16 40 30 160 1.97 507.94
640 350 1 85.08 832 445 37.86 31.50 1 31.50 31.75 16 16 40 21 192 1.97 507.94
640 400 1 85.08 832 445 37.86 31.50 1 31.50 31.75 16 16 40 25 192 1.97 507.94
0.41M9 848 480 1 60.00 1088 517 31.02 33.75 1 33.75 29.63 16 16 53 30 240 2.11 474.08
720 400 1 85.04 936 446 37.93 35.50 1 35.50 28.17 16 16 45 25 216 2.22 450.70
0.31M3 VGA 640 480 1 85.06 800 525 44.66 35.73 1 35.73 27.99 16 16 40 30 160 2.23 447.86
0.48M3 SVGA 800 600 1 56.25 1024 625 35.16 36.00 1 36.00 27.78 16 16 50 37 224 2.25 444.44
0.48M3 SVGA 800 600 1 60.32 1056 628 37.88 40.00 1 40.00 25.00 16 16 50 37 256 2.50 400.00
0.79M3 XGA 1024 768 2 86.96 1264 817 35.52 44.90 1 44.90 22.27 32 32 32 24 240 2.81 356.35
0.48M3 SVGA 800 600 1 75.00 1056 625 46.88 49.50 1 49.50 20.20 16 16 50 37 256 3.09 323.23
0.48M3 SVGA 800 600 1 72.19 1040 666 48.08 50.00 1 50.00 20.00 16 16 50 37 240 3.13 320.00
29 1440 576 1 50.00 1728 625 31.25 54.00 1 54.00 18.52 32 32 45 18 288 3.38 296.30
30 1440 576 1 50.00 1728 625 31.25 54.00 1 54.00 18.52 32 32 45 18 288 3.38 296.30
0.48M3 SVGA 800 600 1 85.06 1048 631 53.67 56.25 1 56.25 17.78 16 16 50 37 248 3.52 284.45
0.79M3 XGA 1024 768 1 60.00 1344 806 48.36 65.00 1 65.00 15.38 32 32 32 24 320 4.06 246.15
0.98M9-R 1280 768 1 60.00 1440 790 47.40 68.25 1 68.25 14.65 32 32 40 24 160 4.27 234.43
1.02MA-R 1280 800 1 59.91 1440 823 49.31 71.00 1 71.00 14.08 32 32 40 25 160 4.44 225.35
0.48M3-R 800 600 1 119.97 960 636 76.30 73.25 1 73.25 13.65 16 16 50 37 160 4.58 218.43
32 1920 1080 1 23.98 2750 1125 26.97 74.18 1 74.18 13.48 32 32 60 33 830 4.64 215.70
34 1920 1080 1 29.97 2200 1125 33.72 74.18 1 74.18 13.48 32 32 60 33 280 4.64 215.70
4 1280 720 1 59.94 1650 750 44.96 74.18 1 74.18 13.48 32 32 40 22 370 4.64 215.70
5 1920 1080 2 59.94 2200 1125 33.72 74.18 1 74.18 13.48 32 32 60 33 280 4.64 215.70
4 1280 720 1 60.00 1650 750 45.00 74.25 1 74.25 13.47 32 32 40 22 370 4.64 215.49
19 1280 720 1 50.00 1980 750 37.50 74.25 1 74.25 13.47 32 32 40 22 700 4.64 215.49
5 1920 1080 2 60.00 2200 1125 33.75 74.25 1 74.25 13.47 32 32 60 33 280 4.64 215.49
20 1920 1080 2 50.00 2640 1125 28.13 74.25 1 74.25 13.47 32 32 60 33 720 4.64 215.49
32 1920 1080 1 24.00 2750 1125 27.00 74.25 1 74.25 13.47 32 32 60 33 830 4.64 215.49
33 1920 1080 1 25.00 2640 1125 28.13 74.25 1 74.25 13.47 32 32 60 33 720 4.64 215.49
34 1920 1080 1 30.00 2200 1125 33.75 74.25 1 74.25 13.47 32 32 60 33 280 4.64 215.49
0.79M3 XGA 1024 768 1 70.07 1328 806 56.48 75.00 1 75.00 13.33 32 32 32 24 304 4.69 213.33
0.79M3 XGA 1024 768 1 75.03 1312 800 60.02 78.75 1 78.75 12.70 32 32 32 24 288 4.92 203.17
0.98M9 1280 768 1 59.87 1664 798 47.78 79.50 1 79.50 12.58 32 32 40 24 384 4.97 201.26
1.02MA 1280 800 1 59.81 1680 831 49.70 83.50 1 83.50 11.98 32 32 40 25 400 5.22 191.62
1.04M9 1360 768 1 60.02 1792 795 47.71 85.50 1 85.50 11.70 32 32 42 24 432 5.34 187.14
1.29MA-R 1440 900 1 59.90 1600 926 55.47 88.75 1 88.75 11.27 32 32 45 28 160 5.55 180.28
0.79M3 XGA 1024 768 1 85.00 1376 808 68.68 94.50 1 94.50 10.58 32 32 32 24 352 5.91 169.31
1.47M3-R 1400 1050 1 59.95 1560 1080 64.74 101.00 1 101.00 9.90 32 32 43 32 160 6.31 158.42
0.98M9 1280 768 1 74.89 1696 805 60.29 102.25 1 102.25 9.78 32 32 40 24 416 6.39 156.48
1.29MA 1440 900 1 59.89 1904 934 55.93 106.50 1 106.50 9.39 32 32 45 28 464 6.66 150.24
1.02MA 1280 800 1 74.93 1696 838 62.79 106.50 1 106.50 9.39 32 32 40 25 416 6.66 150.24
1.00M3 1152 864 1 75.00 1600 900 67.50 108.00 1 108.00 9.26 32 32 36 27 448 6.75 148.15
1.23M3 1280 960 1 60.00 1800 1000 60.00 108.00 1 108.00 9.26 32 32 40 30 520 6.75 148.15
1.31M4 SXGA 1280 1024 1 60.02 1688 1066 63.98 108.00 1 108.00 9.26 32 32 40 32 408 6.75 148.15