Video Interface: Difference between revisions
→0x0440 0000 - VI_CTRL
(Consistent names for test registers) |
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{{#invoke:Register table|definitions
| 31-17 | Undefined | Initialized to <code>0</code>
| 16 |
| 15-12 | PIXEL_ADVANCE[3:0] | Use <code>0b0011</code> for most effective behavior on N64. On the iQue Player a pixel advance of <code>0b0011</code> creates video glitches, applications typically use <code>0b0001</code> instead.
| 11 | KILL_WE | Diagnostics only, possibly kills VI DMA writes to line buffers making them safe to access via the test registers.
| 10 | Undefined | Initialized to <code>0</code>
| 9-8 | AA_MODE[1:0] | Anti-Alias Mode <br>11 {{=}} AA and resampling disabled, replicate pixels without interpolation <br>10 {{=}} AA disabled, resampling enabled, and operate as if everything is covered <br>01 {{=}} AA enabled, resampling enabled, and only fetches extra lines as needed <br>00 {{=}} AA enabled, resampling enabled, and will always fetch extra lines (required if <code>DEDITHER_ENABLE</code> is 1).
| 7 | TEST_MODE | Diagnostics only, enables usage of the line buffer test registers VI_TEST_ADDR/VI_STAGED_DATA. KILL_WE should also be set to avoid access races between the VI and CPU.
| 6 | SERRATE | Required if interlacing, permitted when progressive, often disabled <br>1 {{=}} Enabled <br>0 {{=}} Disabled
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'''Extra Details:'''
: '''
:: When enabled, the VI will run a de-dithering algorithm, trying to reverse the effects of dithering on each pixel to produce an higher resolution color information on the analog output. This is useful when the framebuffer is 16-bit and has been dithered while drawing. To do so, VI looks at the 8 neighbors around each pixel and perform an error correction; the algorithm used works best with images that have been dithered using the "Magic Square" dithering algorithm (that the RDP can be configured to do). The VI does de-dedithering only on pixels where coverage is full; on pixels with partial coverage, the standard AA algorithm is performed. '''NOTE''': this filter requires <code>AA_MODE</code> to be set to <code>00</code>, otherwise the image is corrupted by vertical streaks ([https://github.com/DragonMinded/libdragon/issues/159 as seen here]).
: '''DIVOT_ENABLE'''
:: When enabled, this feature fixes artifacts that the anti-aliasing algorithm leaves behind. The median color of three neighboring pixels, from any pixels on or next to silhouette edges, is selected to be displayed in place of the center pixel. Effectively removing any one pixel divots that can be seen in some fractal-based terrains. The anti-aliasing function encounters issues when multiple fragments occur on a single pixel. Since this filter is only used on edges, and not the surface of an object, texture details will not be affected. Be aware that bad quality effects can occur when the ''decal line'' rendering mode is used in conjunction with this filter, as the rendering mode generates edges that the filter can detect.
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