mirror of
https://github.com/joncampbell123/dosbox-x.git
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b0b406d8e5
- OUTPUT: Offload aspect ratio correction for Direct3D and OpenGL output modes from render code (these modes do it themselves) - xBRZ: Also offload it when xBRZ scaler is enabled (xBRZ does not like line duplication and can do correction itself) - OUTPUT: Store source aspect ratio translation parameters under 'sdl' structure, this may be used eventually for non-square pixel monitors aspect ratio correction - xBRZ: Make sure xBRZ scaler honors aspect ratio correction flag in 'surface' mode of operation and controls aspect ratio correction offload when enabling/disabling itself - xBRZ: Factor out scaling factor setup into its own function - xBRZ: Fix up duplicated code path breaking 'surface' output - MAIN: Split 'overlay' mode defaulting from primary 'if' set, making it simply choosing D3D/OGL/surface before primary 'if' goes - DOC: README.xbrz - DOC: clarify that SDL structure is initialized to zero in code comment, initialize defaults after memset()
61 lines
2.8 KiB
Plaintext
61 lines
2.8 KiB
Plaintext
xBRZ (https://sourceforge.net/projects/xbrz/) scaler is integrated into DOSBox-X.
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To enable, use
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scaler=xbrz
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or
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scaler=xbrz_bilinear
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option in [render] section.
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The difference between two options is in the post-scaling resize method.
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xBRZ scaler uses fixed scale factors, 2X to 6X, which are usually not exactly
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matching the display window. So nearest size xBRZ scaler output is then
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resized (upscaled/dowscaled) using either nearest neighbor ('xbrz') or
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bilinear ('xbrz_bilinear') algorithm to match the window size.
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It is highly recommended to use 'direct3d' or any of the 'opengl' output modes
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with xBRZ because bilinear post-scaler performance is terrible and nearest
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neighbor post-scaler does not provide good results.
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In 'direct3d' / 'opengl' output modes, there is no difference between
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'xbrz' and 'xbrz_bilinear' variants, because software post-scaler is not used
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and output is post-scaled by the output interface/hardware.
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Differences from reference implementation on xBRZ site / in Daum build:
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- DOSBox-X implementation supports 'surface', 'direct3d' and 'opengl' outputs
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(including opengl variants 'openglnb' and 'openglhq')
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- Windowed mode is fully working with xBRZ scaler enabled
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- You can combine xBRZ with 'direct3d' mode post-scalers to get i.e. TV effect
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- Enabling xBRZ scaler does not disable 'aspect' option, it is honored
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Things to notice:
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- The scaler is very CPU intensive so it will run with decent speed for
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games and demos only on high-end CPUs. Keep this in mind. You can try
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to correct performance for high output resolutions by using either
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'xbrz fixed scale factor' or 'xbrz max scale factor' options to limit
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xBRZ scale factor (lower factors improve performance), of course this
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reduces image quality for higher output resolutions proportionally.
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- Using 'direct3d' or 'opengl' mode actually improves performance a lot
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because it gets rid of the software post-scaler pass.
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- xBRZ scaler code uses parallel processing internally. There is also
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'xbrz slice' option that affects parallelism, its default (16) gives
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good results on 4-8 core CPUs.
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- When xBRZ scaler is enabled, internal DOSBox scaler options are disabled
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because any pre-scaling will break xBRZ algorithm. For the same very reason,
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'doublescan' option is always turned off internally when xBRZ is enabled.
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- When using xBRZ in 'surface' output mode and window/screen sizes less than
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2x of the original DOS resolution, 'xbrz' scaler can degrade quality instead
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of improving it, use 'direct3d'/'opengl' outputs or 'xbrz_bilinear' scaler
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variant to avoid this.
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Caveats / issues / things to do / incomplete:
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- In case video adapter interface uses non-standard color scheme / byte order,
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colors with xBRZ scaler enabled would most probably be garbled.
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[YET TO REPRODUCE ANYWHERE]
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