base:pixel_aspect_ratio
no way to compare when less than two revisions
Differences
This shows you the differences between two versions of the page.
— | base:pixel_aspect_ratio [2015-04-17 04:33] (current) – created - external edit 127.0.0.1 | ||
---|---|---|---|
Line 1: | Line 1: | ||
+ | ====== Pixel Aspect Ratio ====== | ||
+ | |||
+ | The VIC-II' | ||
+ | |||
+ | For a 1:1 really square pixel, a pixel clock of 14.75000 MHz is needed. Without interlacing, | ||
+ | |||
+ | The above calculation only considers the difference in width between a C64 pixel and a 1:1 pixel. However, with a CRT-based display the height differs too if the raster line timing of the C64 doesn' | ||
+ | |||
+ | The PAL standard line frequency is 15.62500 kHz. The C64 is clocked at 0.98525 MHz and one line is 63 cycles which results in a line frequency of 0.98525 * 1000 / 63 = 15.63889 kHz. That makes 15.625 / 15.63889 = 0.99911. This means that the pixels are slightly shorter than a 1:1 pixel. | ||
+ | |||
+ | Together this results in a total PAR (X:Y) of 0.93568: | ||
+ | |||
+ | The following table contains the above calculations for all C64 variants: | ||
+ | |||
+ | | |1:1 pixel clock |1:1 line freq |CPU clock |cycles/ | ||
+ | |PAL | ||
+ | |PAL-N (Drean) | | ||
+ | |NTSC | | ||
+ | |NTSC (old) | | ||
base/pixel_aspect_ratio.txt · Last modified: 2015-04-17 04:33 by 127.0.0.1