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Implement blargg ntsc filters

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- this implements blargg's nes ntsc filters using core options
- an optional height doubling is also added but disabled for performance reasons (might make that optional as a core option)
- since PS2 and PSP have their own blitter branches, these platforms do not have the ntsc filters since i dont have the means to test on those systems.
- compile with HAVE_NTSC=1 to have these options, HAVE_NTSC=0 disabled filter including core options
- HAVE_NTSC=1 is set as default, other than PS2 and PSP as stated above.
This commit is contained in:
negativeExponent
2020-01-26 10:22:42 +08:00
parent c379d1c56b
commit 266bc3b92f
12 changed files with 2091 additions and 42 deletions
Download Patch File Download Diff File Expand all files Collapse all files

5
Makefile.common
View File

@@ -17,6 +17,11 @@ else
SOURCES_C = $(CORE_DIR)/boards/*.c $(CORE_DIR)/input/*.c
endif
ifeq ($(HAVE_NTSC),1)
CFLAGS += -DHAVE_NTSC_FILTER -I$(CORE_DIR)/ntsc
SOURCES_C += $(CORE_DIR)/ntsc/nes_ntsc.c
endif
ifeq ($(HAVE_GRIFFIN),1)
SOURCES_C += $(CORE_DIR)/drivers/libretro/griffin.c
else

3
Makefile.libretro
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@@ -5,6 +5,7 @@ HAVE_GRIFFIN=1
STATIC_LINKING=0
ENDIANNESS_DEFINES=
SIGNED_CHAR=0
HAVE_NTSC=1
SPACE :=
SPACE := $(SPACE) $(SPACE)
@@ -180,6 +181,7 @@ else ifeq ($(platform), ps2)
EXTERNAL_ZLIB=1
RETROARCH_OBJECTS += ps2/SMS_Utils.o
HAVE_NTSC = 0
# PSP
else ifeq ($(platform), psp1)
@@ -192,6 +194,7 @@ else ifeq ($(platform), psp1)
PLATFORM_DEFINES += -falign-functions=32 -falign-loops -falign-labels -falign-jumps
STATIC_LINKING=1
EXTERNAL_ZLIB=1
HAVE_NTSC = 0
# Vita
else ifeq ($(platform), vita)

240
src/drivers/libretro/libretro.c
View File

@@ -144,6 +144,30 @@ extern CartInfo UNIFCart;
extern int show_crosshair;
extern int option_ramstate;
#ifdef HAVE_NTSC_FILTER
/* ntsc */
#include "nes_ntsc.h"
#define NTSC_NONE 0
#define NTSC_COMPOSITE 1
#define NTSC_SVIDEO 2
#define NTSC_RGB 3
#define NTSC_MONOCHROME 4
static unsigned use_ntsc = 0;
static unsigned burst_phase;
static nes_ntsc_t nes_ntsc;
static nes_ntsc_setup_t ntsc_setup;
static pal base_palette[64];
static uint8_t *ntsc_video_out = NULL; /* for ntsc blit buffer */
static void nes_ntsc_cleanup(void)
{
if (ntsc_video_out)
free(ntsc_video_out);
ntsc_video_out = NULL;
}
#endif /* HAVE_NTSC_FILTER */
/* emulator-specific callback functions */
void UpdatePPUView(int refreshchr) { }
@@ -836,16 +860,22 @@ void retro_get_system_info(struct retro_system_info *info)
void retro_get_system_av_info(struct retro_system_av_info *info)
{
unsigned width, height, maxwidth;
#ifdef PSP
unsigned width = NES_WIDTH - (use_overscan ? 16 : 0);
unsigned height = NES_HEIGHT - (use_overscan ? 16 : 0);
width = NES_WIDTH - (use_overscan ? 16 : 0);
height = NES_HEIGHT - (use_overscan ? 16 : 0);
#else
unsigned width = NES_WIDTH - (overscan_h ? 16 : 0);
unsigned height = NES_HEIGHT - (overscan_v ? 16 : 0);
width = NES_WIDTH - (overscan_h ? 16 : 0);
height = NES_HEIGHT - (overscan_v ? 16 : 0);
#endif
#ifdef HAVE_NTSC_FILTER
maxwidth = NES_NTSC_OUT_WIDTH(NES_WIDTH);
#else
maxwidth = NES_WIDTH;
#endif
info->geometry.base_width = width;
info->geometry.base_height = height;
info->geometry.max_width = NES_WIDTH;
info->geometry.max_width = maxwidth;
info->geometry.max_height = NES_HEIGHT;
info->geometry.aspect_ratio = (float)(use_par ? NES_8_7_PAR : NES_4_3);
info->timing.sample_rate = (float)sndsamplerate;
@@ -883,13 +913,17 @@ void retro_init(void)
static void retro_set_custom_palette(void)
{
uint8_t i,r,g,b;
unsigned i;
unsigned palette_changed;
pal color;
ipalette = 0;
use_raw_palette = false;
palette_changed = 0;
if (current_palette == PAL_DEFAULT || current_palette == PAL_CUSTOM
|| (GameInfo->type == GIT_VSUNI))
if ((current_palette == PAL_DEFAULT) ||
(current_palette == PAL_CUSTOM) ||
(GameInfo->type == GIT_VSUNI))
{
if (current_palette == PAL_CUSTOM)
{
@@ -902,35 +936,73 @@ static void retro_set_custom_palette(void)
* else it will load default NES palette.
* VS Unisystem should always use default palette.
*/
return;
}
if (current_palette == PAL_RAW) /* raw palette */
/* setup raw palette */
else if (current_palette == PAL_RAW)
{
use_raw_palette = true;
for (i = 0; i < 64; i++)
{
r = (((i >> 0) & 0xF) * 255) / 15;
g = (((i >> 4) & 0x3) * 255) / 3;
FCEUD_SetPalette( i, r, g, 0);
color.r = (((i >> 0) & 0xF) * 255) / 15;
color.g = (((i >> 4) & 0x3) * 255) / 3;
color.b = 0;
FCEUD_SetPalette( i, color.r, color.g, color.b);
}
return;
}
/* Setup this palette*/
for ( i = 0; i < 64; i++ )
else
{
unsigned palette_data = palettes[current_palette].data[i];
r = ( palette_data >> 16 ) & 0xff;
g = ( ( palette_data & 0xff00 ) >> 8 ) & 0xff;
b = ( palette_data & 0xff );
FCEUD_SetPalette( i, r, g, b);
FCEUD_SetPalette( i + 64, r, g, b);
FCEUD_SetPalette( i + 128, r, g, b);
FCEUD_SetPalette( i + 192, r, g, b);
unsigned *palette_data = palettes[current_palette].data;
for ( i = 0; i < 64; i++ )
{
unsigned data = palette_data[i];
color.r = ( data >> 16 ) & 0xff;
color.g = ( data >> 8 ) & 0xff;
color.b = ( data & 0xff );
FCEUD_SetPalette( i, color.r, color.g, color.b);
FCEUD_SetPalette( i + 64, color.r, color.g, color.b);
FCEUD_SetPalette( i + 128, color.r, color.g, color.b);
FCEUD_SetPalette( i + 192, color.r, color.g, color.b);
#ifdef HAVE_NTSC_FILTER
palette_changed = 1;
if (use_ntsc)
{
base_palette[i].r = color.r;
base_palette[i].g = color.g;
base_palette[i].b = color.b;
}
#endif
}
}
#ifdef HAVE_NTSC_FILTER
if (use_ntsc) {
switch (use_ntsc) {
case NTSC_COMPOSITE:
ntsc_setup = nes_ntsc_composite;
break;
case NTSC_SVIDEO:
ntsc_setup = nes_ntsc_svideo;
break;
case NTSC_RGB:
ntsc_setup = nes_ntsc_rgb;
break;
case NTSC_MONOCHROME:
ntsc_setup = nes_ntsc_monochrome;
break;
default:
break;
}
if (palette_changed)
ntsc_setup.base_palette = (unsigned char const*)base_palette;
else
ntsc_setup.base_palette = ipalette ? (unsigned char const*)palo : NULL;
nes_ntsc_init(&nes_ntsc, &ntsc_setup);
}
#endif
#if defined(RENDER_GSKIT_PS2)
if (ps2) {
ps2->updatedPalette = true;
@@ -990,6 +1062,9 @@ void retro_deinit (void)
#endif
libretro_supports_bitmasks = false;
DPSW_Cleanup();
#ifdef HAVE_NTSC_FILTER
nes_ntsc_cleanup();
#endif
}
void retro_reset(void)
@@ -1023,6 +1098,7 @@ static void check_variables(bool startup)
struct retro_variable var = {0};
struct retro_system_av_info av_info;
bool geometry_update = false;
bool palette_updated = false;
char key[256];
int i, enable_apu;
@@ -1038,6 +1114,27 @@ static void check_variables(bool startup)
option_ramstate = 0;
}
#ifdef HAVE_NTSC_FILTER
var.key = "fceumm_ntsc_filter";
if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var))
{
unsigned orig_value = use_ntsc;
if (strcmp(var.value, "disabled") == 0)
use_ntsc = NTSC_NONE;
else if (strcmp(var.value, "composite") == 0)
use_ntsc = NTSC_COMPOSITE;
else if (strcmp(var.value, "svideo") == 0)
use_ntsc = NTSC_SVIDEO;
else if (strcmp(var.value, "rgb") == 0)
use_ntsc = NTSC_RGB;
else if (strcmp(var.value, "monochrome") == 0)
use_ntsc = NTSC_MONOCHROME;
if (use_ntsc != orig_value)
palette_updated = true;
}
#endif
var.key = "fceumm_palette";
if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
@@ -1084,9 +1181,12 @@ static void check_variables(bool startup)
current_palette = 15;
if (current_palette != orig_value)
retro_set_custom_palette();
palette_updated = true;
}
if (palette_updated)
retro_set_custom_palette();
var.key = "fceumm_up_down_allowed";
if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
@@ -1715,28 +1815,74 @@ static void retro_run_blit(uint8_t *gfx)
video_cb(buf, width, height, pitch);
#else
incr += (overscan_h ? 16 : 0);
width -= (overscan_h ? 16 : 0);
height -= (overscan_v ? 16 : 0);
pitch -= (overscan_h ? 32 : 0);
gfx += (overscan_v ? ((overscan_h ? 8 : 0) + 256 * 8) : (overscan_h ? 8 : 0));
if (use_raw_palette)
#ifdef HAVE_NTSC_FILTER
if (use_ntsc)
{
extern uint8 PPU[4];
int deemp = (PPU[1] >> 5) << 2;
for (y = 0; y < height; y++, gfx += incr)
for ( x = 0; x < width; x++, gfx++)
fceu_video_out[y * width + x] = retro_palette[*gfx & 0x3F] | deemp;
int y;
unsigned out_width, out_height, out_pitch;
/*burst_phase ^= 1;
if (ntsc_setup.merge_fields) burst_phase = 0;*/
width = overscan_h ? 240 : 256;
height = overscan_v ? 224 : 240;
out_width = NES_NTSC_OUT_WIDTH(width);
out_height = height;
out_pitch = out_width * sizeof(uint16_t);
gfx += (overscan_v ? ((overscan_h ? 8 : 0) + 256 * 8) : (overscan_h ? 8 : 0));
nes_ntsc_blit(&nes_ntsc, (const unsigned char*)gfx, NES_WIDTH, burst_phase, width, height, ntsc_video_out, out_pitch);
#if 0 /* this doubles the height for proper scaling, disabled for performance reasons */
out_height <<= 1;
for (y = out_height / 2; --y >= 0;)
{
uint8_t const *in = ntsc_video_out + y * out_pitch;
uint8_t *out = ntsc_video_out + y * 2 * out_pitch;
int n;
for (n = out_width; n; --n)
{
unsigned prev = *(uint16_t*)in;
unsigned next = *(uint16_t*)(in + out_pitch);
/* mix 16-bit rgb without losing low bits */
unsigned mixed = prev + next + ((prev ^ next) & 0x0821);
/* darken by 12% */
*(uint16_t*)out = prev;
*(uint16_t*)(out + out_pitch) = (mixed >> 1) - (mixed >> 4 & 0x18E3);
in += 2;
out += 2;
}
}
#endif
video_cb(ntsc_video_out, out_width, out_height, out_pitch);
}
else
#endif /* HAVE_NTSC_FILTER */
{
for (y = 0; y < height; y++, gfx += incr)
for ( x = 0; x < width; x++, gfx++)
fceu_video_out[y * width + x] = retro_palette[*gfx];
incr += (overscan_h ? 16 : 0);
width -= (overscan_h ? 16 : 0);
height -= (overscan_v ? 16 : 0);
pitch -= (overscan_h ? 32 : 0);
gfx += (overscan_v ? ((overscan_h ? 8 : 0) + 256 * 8) : (overscan_h ? 8 : 0));
if (use_raw_palette)
{
extern uint8 PPU[4];
int deemp = (PPU[1] >> 5) << 2;
for (y = 0; y < height; y++, gfx += incr)
for (x = 0; x < width; x++, gfx++)
fceu_video_out[y * width + x] = retro_palette[*gfx & 0x3F] | deemp;
}
else
{
for (y = 0; y < height; y++, gfx += incr)
for (x = 0; x < width; x++, gfx++)
fceu_video_out[y * width + x] = retro_palette[*gfx];
}
video_cb(fceu_video_out, width, height, pitch);
}
video_cb(fceu_video_out, width, height, pitch);
#endif
}
@@ -2185,6 +2331,13 @@ bool retro_load_game(const struct retro_game_info *game)
if (environ_cb(RETRO_ENVIRONMENT_GET_SAVE_DIRECTORY, &sav_dir) && sav_dir)
FCEUI_SetSaveDirectory(sav_dir);
#ifdef HAVE_NTSC_FILTER
use_ntsc = 0;
memset(base_palette, 0, sizeof(base_palette));
memset(&nes_ntsc, 0, sizeof(nes_ntsc));
ntsc_video_out = (uint8_t*)malloc(NES_NTSC_OUT_WIDTH(NES_WIDTH) * (NES_HEIGHT * 2) * sizeof(uint16_t));
#endif
FCEUI_Initialize();
FCEUI_SetSoundVolume(sndvolume);
@@ -2260,7 +2413,7 @@ bool retro_load_game(const struct retro_game_info *game)
}
}
/* This doesn't map in 2004--2007 but those aren't really
* worthwhile to read from on a vblank anyway
* worthwhile to read from on a vblank anyway
*/
descs[i].flags = 0;
descs[i].ptr = PPU;
@@ -2340,6 +2493,9 @@ void retro_unload_game(void)
#if defined(RENDER_GSKIT_PS2)
ps2 = NULL;
#endif
#ifdef HAVE_NTSC_FILTER
nes_ntsc_cleanup();
#endif
}
unsigned retro_get_region(void)

16
src/drivers/libretro/libretro_core_options.h
View File

@@ -77,6 +77,22 @@ struct retro_core_option_definition option_defs_common[] = {
},
"disabled",
},
#ifdef HAVE_NTSC_FILTER
{
"fceumm_ntsc_filter",
"NTSC Filter",
"Enable blargg NTSC filters.",
{
{ "disabled", NULL },
{ "composite", NULL },
{ "svideo", NULL },
{ "rgb", NULL },
{ "monochrome", NULL },
{ NULL, NULL },
},
"disabled"
},
#endif
{
"fceumm_palette",
"Color Palette",

139
src/ntsc/changes.txt Normal file
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@@ -0,0 +1,139 @@
nes_ntsc Change Log
-------------------
nes_ntsc 0.2.3
--------------
- Added ability to use a custom RGB palette in place of the NES color
circuitry (with the option of being before color emphasis). When using
this palette with otherwise default settings, RGB colors appear on
screen exactly as in custom palette.
- Moved configuration options to nes_ntsc_config.h, making it easier to
manage
- Made color emphasis support configurable in nes_ntsc_config.h (off by
default). Previously, there were separate functions; now there is only
one set of functions and whether they support color emphasis is
configurable. If color emphasis support is OFF, then nes_ntsc_init() and
related behave as before, and the nes_ntsc_init_emph() functionality is
not available. If color emphasis support is ON, then nes_ntsc_init() and
related behave as nes_ntsc_init_emph() and related did before, and
nes_ntsc_init() and related functionality is not available (so you would
need to update any code that uses palette_out and expects only 64 colors
to be written; see the end of demo.c for example).
- Removed hue_warping for now, due to its obscurity
- Greatly clarified and improved demo to read any uncompressed BMP image
and write filtered image when done
- Improved gamma to be properly applied to each RGB channel, and changed
default to compensate for difference between PC monitor and TV gamma
- Improved contrast to be properly applied to each RGB channel rather
than just luma
- Improved floating point calculations in library to be more stable and
not need double precision, which was causing problems with the sharpness
control on Windows when the DirectX libraries changed the FPU to single
precision mode
- Eliminated slight artifacts still visible when using the RGB preset
with field merging off
- Added extern "C" to header, allowing use in C++ without having to
rename the source file
- Made internal changes to factor out code common from all my NTSC
filter libraries, greatly simplifying things for me
nes_ntsc 0.2.0
--------------
- Significantly improved NTSC signal processing to give clearer image
and better sharpness control
- Added parameters for gamma, resolution, color bleed, artifacts, and
color fringing
- Added presets for composite video, S-video, RGB, and monochrome
- Added NES_NTSC_OUT_WIDTH() and NES_NTSC_IN_WIDTH() for calculating
input/output widths
- Improved default blitter to support emphasis and allow specification
of RGB output bit depth
- Improved demo with more controls and interpolation and darkening of
scanlines rather than duplicating them
- Improved documentation
- Interface changes: nes_ntsc_blit() now takes *input* size rather than
output size. NES_NTSC_BEGIN_ROW now takes two additional pixels.
- Deprecated: nes_ntsc_x_in/out_width, NES_NTSC_RGBnn_OUT, and
NES_NTSC_RAW_OUT
nes_ntsc 0.1.7
--------------
- Fixed color emphasis to affect xD colors instead of incorrectly
leaving them as always gray
- Added ability to generate a 64- or 512-color RGB palette for use when
full NTSC emulation isn't desired
- Documented more accurate burst_phase handling and included three test
ROMs for verifying proper implementation
- Moved color emphasis support to new nes_ntsc_emph_t structure,
eliminating the ugly global NES_NTSC_DISABLE_EMPHASIS configuration
macro
- Extended demo to use optional Sony decoder matrix and write standard
192-byte NES .PAL file using current settings
- Improved documentation slightly
- Lowered maximum saturation to avoid overflow of blue when blue color
emphasis is enabled
nes_ntsc 0.1.6
--------------
- Cleaned up hue, decoder matrix, and hue warping to do transformations
in the proper order and direction
nes_ntsc 0.1.5
--------------
- Added support for color emphasis/tint bits (can be turned off to
reduce memory usage)
- Added ability to specify optional decoder matrix
- Improved documentation
- Added constants for overscan borders
nes_ntsc 0.1.0
--------------
- First official version
- Completely rewrote algorithm to do all NTSC signal processing at
initialization time, putting results into a table for use during
blitting. This increased performance by over 300% and allowed many
improvements in quality and image options.
- Eliminated multiple output formats and options. Now you can define a
custom blitter for this.
- Added sharpness and "hue warping" controls
- Added option to merge even and odd artifacts to reduce flicker when
host monitor's refresh rate doesn't match emulator's frame rate.
- Added built-in horizontal rescaling. I never realized the old one was
way too wide.

504
src/ntsc/license.txt Normal file
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@@ -0,0 +1,504 @@
GNU LESSER GENERAL PUBLIC LICENSE
Version 2.1, February 1999
Copyright (C) 1991, 1999 Free Software Foundation, Inc.
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
Everyone is permitted to copy and distribute verbatim copies
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/* nes_ntsc 0.2.2. http://www.slack.net/~ant/ */
#include "nes_ntsc.h"
/* Copyright (C) 2006-2007 Shay Green. This module is free software; you
can redistribute it and/or modify it under the terms of the GNU Lesser
General Public License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version. This
module is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
details. You should have received a copy of the GNU Lesser General Public
License along with this module; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */
nes_ntsc_setup_t const nes_ntsc_monochrome = { 0,-1, 0, 0,.2, 0,.2,-.2,-.2,-1, 1, 0, 0, 0, 0 };
nes_ntsc_setup_t const nes_ntsc_composite = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0 };
nes_ntsc_setup_t const nes_ntsc_svideo = { 0, 0, 0, 0,.2, 0,.2, -1, -1, 0, 1, 0, 0, 0, 0 };
nes_ntsc_setup_t const nes_ntsc_rgb = { 0, 0, 0, 0,.2, 0,.7, -1, -1,-1, 1, 0, 0, 0, 0 };
#define alignment_count 3
#define burst_count 3
#define rescale_in 8
#define rescale_out 7
#define artifacts_mid 1.0f
#define fringing_mid 1.0f
#define std_decoder_hue -15
#define STD_HUE_CONDITION( setup ) !(setup->base_palette || setup->palette)
#include "nes_ntsc_impl.h"
/* 3 input pixels -> 8 composite samples */
pixel_info_t const nes_ntsc_pixels [alignment_count] = {
{ PIXEL_OFFSET( -4, -9 ), { 1, 1, .6667f, 0 } },
{ PIXEL_OFFSET( -2, -7 ), { .3333f, 1, 1, .3333f } },
{ PIXEL_OFFSET( 0, -5 ), { 0, .6667f, 1, 1 } },
};
static void merge_kernel_fields( nes_ntsc_rgb_t* io )
{
int n;
for ( n = burst_size; n; --n )
{
nes_ntsc_rgb_t p0 = io [burst_size * 0] + rgb_bias;
nes_ntsc_rgb_t p1 = io [burst_size * 1] + rgb_bias;
nes_ntsc_rgb_t p2 = io [burst_size * 2] + rgb_bias;
/* merge colors without losing precision */
io [burst_size * 0] =
((p0 + p1 - ((p0 ^ p1) & nes_ntsc_rgb_builder)) >> 1) - rgb_bias;
io [burst_size * 1] =
((p1 + p2 - ((p1 ^ p2) & nes_ntsc_rgb_builder)) >> 1) - rgb_bias;
io [burst_size * 2] =
((p2 + p0 - ((p2 ^ p0) & nes_ntsc_rgb_builder)) >> 1) - rgb_bias;
++io;
}
}
static void correct_errors( nes_ntsc_rgb_t color, nes_ntsc_rgb_t* out )
{
int n;
for ( n = burst_count; n; --n )
{
unsigned i;
for ( i = 0; i < rgb_kernel_size / 2; i++ )
{
nes_ntsc_rgb_t error = color -
out [i ] - out [(i+12)%14+14] - out [(i+10)%14+28] -
out [i + 7] - out [i + 5 +14] - out [i + 3 +28];
DISTRIBUTE_ERROR( i+3+28, i+5+14, i+7 );
}
out += alignment_count * rgb_kernel_size;
}
}
void nes_ntsc_init( nes_ntsc_t* ntsc, nes_ntsc_setup_t const* setup )
{
int merge_fields;
int entry;
init_t impl;
float gamma_factor;
if ( !setup )
setup = &nes_ntsc_composite;
init( &impl, setup );
/* setup fast gamma */
{
float gamma = (float) setup->gamma * -0.5f;
if ( STD_HUE_CONDITION( setup ) )
gamma += 0.1333f;
gamma_factor = (float) pow( (float) fabs( gamma ), 0.73f );
if ( gamma < 0 )
gamma_factor = -gamma_factor;
}
merge_fields = setup->merge_fields;
if ( setup->artifacts <= -1 && setup->fringing <= -1 )
merge_fields = 1;
for ( entry = 0; entry < nes_ntsc_palette_size; entry++ )
{
/* Base 64-color generation */
static float const lo_levels [4] = { -0.12f, 0.00f, 0.31f, 0.72f };
static float const hi_levels [4] = { 0.40f, 0.68f, 1.00f, 1.00f };
int level = entry >> 4 & 0x03;
float lo = lo_levels [level];
float hi = hi_levels [level];
int color = entry & 0x0F;
if ( color == 0 )
lo = hi;
if ( color == 0x0D )
hi = lo;
if ( color > 0x0D )
hi = lo = 0.0f;
{
/* phases [i] = cos( i * PI / 6 ) */
static float const phases [0x10 + 3] = {
-1.0f, -0.866025f, -0.5f, 0.0f, 0.5f, 0.866025f,
1.0f, 0.866025f, 0.5f, 0.0f, -0.5f, -0.866025f,
-1.0f, -0.866025f, -0.5f, 0.0f, 0.5f, 0.866025f,
1.0f
};
#define TO_ANGLE_SIN( color ) phases [color]
#define TO_ANGLE_COS( color ) phases [(color) + 3]
/* Convert raw waveform to YIQ */
float sat = (hi - lo) * 0.5f;
float i = TO_ANGLE_SIN( color ) * sat;
float q = TO_ANGLE_COS( color ) * sat;
float y = (hi + lo) * 0.5f;
/* Optionally use base palette instead */
if ( setup->base_palette )
{
unsigned char const* in = &setup->base_palette [(entry & 0x3F) * 3];
static float const to_float = 1.0f / 0xFF;
float r = to_float * in [0];
float g = to_float * in [1];
float b = to_float * in [2];
q = RGB_TO_YIQ( r, g, b, y, i );
}
/* Apply color emphasis */
#ifdef NES_NTSC_EMPHASIS
{
int tint = entry >> 6 & 7;
if ( tint && color <= 0x0D )
{
static float const atten_mul = 0.79399f;
static float const atten_sub = 0.0782838f;
if ( tint == 7 )
{
y = y * (atten_mul * 1.13f) - (atten_sub * 1.13f);
}
else
{
static unsigned char const tints [8] = { 0, 6, 10, 8, 2, 4, 0, 0 };
int const tint_color = tints [tint];
float sat = hi * (0.5f - atten_mul * 0.5f) + atten_sub * 0.5f;
y -= sat * 0.5f;
if ( tint >= 3 && tint != 4 )
{
/* combined tint bits */
sat *= 0.6f;
y -= sat;
}
i += TO_ANGLE_SIN( tint_color ) * sat;
q += TO_ANGLE_COS( tint_color ) * sat;
}
}
}
#endif
/* Optionally use palette instead */
if ( setup->palette )
{
unsigned char const* in = &setup->palette [entry * 3];
static float const to_float = 1.0f / 0xFF;
float r = to_float * in [0];
float g = to_float * in [1];
float b = to_float * in [2];
q = RGB_TO_YIQ( r, g, b, y, i );
}
/* Apply brightness, contrast, and gamma */
y *= (float) setup->contrast * 0.5f + 1;
/* adjustment reduces error when using input palette */
y += (float) setup->brightness * 0.5f - 0.5f / 256;
{
float r, g, b = YIQ_TO_RGB( y, i, q, default_decoder, float, r, g );
/* fast approximation of n = pow( n, gamma ) */
r = (r * gamma_factor - gamma_factor) * r + r;
g = (g * gamma_factor - gamma_factor) * g + g;
b = (b * gamma_factor - gamma_factor) * b + b;
q = RGB_TO_YIQ( r, g, b, y, i );
}
i *= rgb_unit;
q *= rgb_unit;
y *= rgb_unit;
y += rgb_offset;
/* Generate kernel */
{
int r, g, b = YIQ_TO_RGB( y, i, q, impl.to_rgb, int, r, g );
/* blue tends to overflow, so clamp it */
nes_ntsc_rgb_t rgb = PACK_RGB( r, g, (b < 0x3E0 ? b: 0x3E0) );
if ( setup->palette_out )
RGB_PALETTE_OUT( rgb, &setup->palette_out [entry * 3] );
if ( ntsc )
{
nes_ntsc_rgb_t* kernel = ntsc->table [entry];
gen_kernel( &impl, y, i, q, kernel );
if ( merge_fields )
merge_kernel_fields( kernel );
correct_errors( rgb, kernel );
}
}
}
}
}
#ifndef NES_NTSC_NO_BLITTERS
void nes_ntsc_blit( nes_ntsc_t const* ntsc, NES_NTSC_IN_T const* input, long in_row_width,
int burst_phase, int in_width, int in_height, void* rgb_out, long out_pitch )
{
int chunk_count = (in_width - 1) / nes_ntsc_in_chunk;
for ( ; in_height; --in_height )
{
NES_NTSC_IN_T const* line_in = input;
NES_NTSC_BEGIN_ROW( ntsc, burst_phase,
nes_ntsc_black, nes_ntsc_black, NES_NTSC_ADJ_IN( *line_in ) );
nes_ntsc_out_t* restrict line_out = (nes_ntsc_out_t*) rgb_out;
int n;
++line_in;
for ( n = chunk_count; n; --n )
{
/* order of input and output pixels must not be altered */
NES_NTSC_COLOR_IN( 0, NES_NTSC_ADJ_IN( line_in [0] ) );
NES_NTSC_RGB_OUT( 0, line_out [0], NES_NTSC_OUT_DEPTH );
NES_NTSC_RGB_OUT( 1, line_out [1], NES_NTSC_OUT_DEPTH );
NES_NTSC_COLOR_IN( 1, NES_NTSC_ADJ_IN( line_in [1] ) );
NES_NTSC_RGB_OUT( 2, line_out [2], NES_NTSC_OUT_DEPTH );
NES_NTSC_RGB_OUT( 3, line_out [3], NES_NTSC_OUT_DEPTH );
NES_NTSC_COLOR_IN( 2, NES_NTSC_ADJ_IN( line_in [2] ) );
NES_NTSC_RGB_OUT( 4, line_out [4], NES_NTSC_OUT_DEPTH );
NES_NTSC_RGB_OUT( 5, line_out [5], NES_NTSC_OUT_DEPTH );
NES_NTSC_RGB_OUT( 6, line_out [6], NES_NTSC_OUT_DEPTH );
line_in += 3;
line_out += 7;
}
/* finish final pixels */
NES_NTSC_COLOR_IN( 0, nes_ntsc_black );
NES_NTSC_RGB_OUT( 0, line_out [0], NES_NTSC_OUT_DEPTH );
NES_NTSC_RGB_OUT( 1, line_out [1], NES_NTSC_OUT_DEPTH );
NES_NTSC_COLOR_IN( 1, nes_ntsc_black );
NES_NTSC_RGB_OUT( 2, line_out [2], NES_NTSC_OUT_DEPTH );
NES_NTSC_RGB_OUT( 3, line_out [3], NES_NTSC_OUT_DEPTH );
NES_NTSC_COLOR_IN( 2, nes_ntsc_black );
NES_NTSC_RGB_OUT( 4, line_out [4], NES_NTSC_OUT_DEPTH );
NES_NTSC_RGB_OUT( 5, line_out [5], NES_NTSC_OUT_DEPTH );
NES_NTSC_RGB_OUT( 6, line_out [6], NES_NTSC_OUT_DEPTH );
burst_phase = (burst_phase + 1) % nes_ntsc_burst_count;
input += in_row_width;
rgb_out = (char*) rgb_out + out_pitch;
}
}
#endif

192
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/* NES NTSC video filter */
/* nes_ntsc 0.2.2 */
#ifndef NES_NTSC_H
#define NES_NTSC_H
#include "nes_ntsc_config.h"
#ifdef __cplusplus
extern "C" {
#endif
/* Image parameters, ranging from -1.0 to 1.0. Actual internal values shown
in parenthesis and should remain fairly stable in future versions. */
typedef struct nes_ntsc_setup_t
{
/* Basic parameters */
double hue; /* -1 = -180 degrees +1 = +180 degrees */
double saturation; /* -1 = grayscale (0.0) +1 = oversaturated colors (2.0) */
double contrast; /* -1 = dark (0.5) +1 = light (1.5) */
double brightness; /* -1 = dark (0.5) +1 = light (1.5) */
double sharpness; /* edge contrast enhancement/blurring */
/* Advanced parameters */
double gamma; /* -1 = dark (1.5) +1 = light (0.5) */
double resolution; /* image resolution */
double artifacts; /* artifacts caused by color changes */
double fringing; /* color artifacts caused by brightness changes */
double bleed; /* color bleed (color resolution reduction) */
int merge_fields; /* if 1, merges even and odd fields together to reduce flicker */
float const* decoder_matrix; /* optional RGB decoder matrix, 6 elements */
unsigned char* palette_out; /* optional RGB palette out, 3 bytes per color */
/* You can replace the standard NES color generation with an RGB palette. The
first replaces all color generation, while the second replaces only the core
64-color generation and does standard color emphasis calculations on it. */
unsigned char const* palette;/* optional 512-entry RGB palette in, 3 bytes per color */
unsigned char const* base_palette;/* optional 64-entry RGB palette in, 3 bytes per color */
} nes_ntsc_setup_t;
/* Video format presets */
extern nes_ntsc_setup_t const nes_ntsc_composite; /* color bleeding + artifacts */
extern nes_ntsc_setup_t const nes_ntsc_svideo; /* color bleeding only */
extern nes_ntsc_setup_t const nes_ntsc_rgb; /* crisp image */
extern nes_ntsc_setup_t const nes_ntsc_monochrome;/* desaturated + artifacts */
#ifdef NES_NTSC_EMPHASIS
enum { nes_ntsc_palette_size = 64 * 8 };
#else
enum { nes_ntsc_palette_size = 64 };
#endif
/* Initializes and adjusts parameters. Can be called multiple times on the same
nes_ntsc_t object. Can pass NULL for either parameter. */
typedef struct nes_ntsc_t nes_ntsc_t;
void nes_ntsc_init( nes_ntsc_t* ntsc, nes_ntsc_setup_t const* setup );
/* Filters one or more rows of pixels. Input pixels are 6/9-bit palette indicies.
In_row_width is the number of pixels to get to the next input row. Out_pitch
is the number of *bytes* to get to the next output row. Output pixel format
is set by NES_NTSC_OUT_DEPTH (defaults to 16-bit RGB). */
void nes_ntsc_blit( nes_ntsc_t const* ntsc, NES_NTSC_IN_T const* nes_in,
long in_row_width, int burst_phase, int in_width, int in_height,
void* rgb_out, long out_pitch );
/* Number of output pixels written by blitter for given input width. Width might
be rounded down slightly; use NES_NTSC_IN_WIDTH() on result to find rounded
value. Guaranteed not to round 256 down at all. */
#define NES_NTSC_OUT_WIDTH( in_width ) \
((((in_width) - 1) / nes_ntsc_in_chunk + 1) * nes_ntsc_out_chunk)
/* Number of input pixels that will fit within given output width. Might be
rounded down slightly; use NES_NTSC_OUT_WIDTH() on result to find rounded
value. */
#define NES_NTSC_IN_WIDTH( out_width ) \
(((out_width) / nes_ntsc_out_chunk - 1) * nes_ntsc_in_chunk + 1)
/* Interface for user-defined custom blitters */
enum { nes_ntsc_in_chunk = 3 }; /* number of input pixels read per chunk */
enum { nes_ntsc_out_chunk = 7 }; /* number of output pixels generated per chunk */
enum { nes_ntsc_black = 15 }; /* palette index for black */
enum { nes_ntsc_burst_count = 3 }; /* burst phase cycles through 0, 1, and 2 */
/* Begins outputting row and starts three pixels. First pixel will be cut off a bit.
Use nes_ntsc_black for unused pixels. Declares variables, so must be before first
statement in a block (unless you're using C++). */
#define NES_NTSC_BEGIN_ROW( ntsc, burst, pixel0, pixel1, pixel2 ) \
char const* const ktable = \
(char const*) (ntsc)->table [0] + burst * (nes_ntsc_burst_size * sizeof (nes_ntsc_rgb_t));\
NES_NTSC_BEGIN_ROW_6_( pixel0, pixel1, pixel2, NES_NTSC_ENTRY_, ktable )
/* Begins input pixel */
#define NES_NTSC_COLOR_IN( in_index, color_in ) \
NES_NTSC_COLOR_IN_( in_index, color_in, NES_NTSC_ENTRY_, ktable )
/* Generates output pixel. Bits can be 24, 16, 15, 32 (treated as 24), or 0:
24: RRRRRRRR GGGGGGGG BBBBBBBB (8-8-8 RGB)
16: RRRRRGGG GGGBBBBB (5-6-5 RGB)
15: RRRRRGG GGGBBBBB (5-5-5 RGB)
0: xxxRRRRR RRRxxGGG GGGGGxxB BBBBBBBx (native internal format; x = junk bits) */
#define NES_NTSC_RGB_OUT( index, rgb_out, bits ) \
NES_NTSC_RGB_OUT_14_( index, rgb_out, bits, 0 )
/* private */
enum { nes_ntsc_entry_size = 128 };
typedef unsigned long nes_ntsc_rgb_t;
struct nes_ntsc_t {
nes_ntsc_rgb_t table [nes_ntsc_palette_size] [nes_ntsc_entry_size];
};
enum { nes_ntsc_burst_size = nes_ntsc_entry_size / nes_ntsc_burst_count };
#define NES_NTSC_ENTRY_( ktable, n ) \
(nes_ntsc_rgb_t const*) (ktable + (n) * (nes_ntsc_entry_size * sizeof (nes_ntsc_rgb_t)))
/* deprecated */
/*#define NES_NTSC_RGB24_OUT( x, out ) NES_NTSC_RGB_OUT( x, out, 24 )
#define NES_NTSC_RGB16_OUT( x, out ) NES_NTSC_RGB_OUT( x, out, 16 )
#define NES_NTSC_RGB15_OUT( x, out ) NES_NTSC_RGB_OUT( x, out, 15 )
#define NES_NTSC_RAW_OUT( x, out ) NES_NTSC_RGB_OUT( x, out, 0 )
enum { nes_ntsc_min_in_width = 256 };
enum { nes_ntsc_min_out_width = NES_NTSC_OUT_WIDTH( nes_ntsc_min_in_width ) };
enum { nes_ntsc_640_in_width = 271 };
enum { nes_ntsc_640_out_width = NES_NTSC_OUT_WIDTH( nes_ntsc_640_in_width ) };
enum { nes_ntsc_640_overscan_left = 8 };
enum { nes_ntsc_640_overscan_right = nes_ntsc_640_in_width - 256 - nes_ntsc_640_overscan_left };
enum { nes_ntsc_full_in_width = 283 };
enum { nes_ntsc_full_out_width = NES_NTSC_OUT_WIDTH( nes_ntsc_full_in_width ) };
enum { nes_ntsc_full_overscan_left = 16 };
enum { nes_ntsc_full_overscan_right = nes_ntsc_full_in_width - 256 - nes_ntsc_full_overscan_left };*/
/* common 3->7 ntsc macros */
#define NES_NTSC_BEGIN_ROW_6_( pixel0, pixel1, pixel2, ENTRY, table ) \
unsigned const nes_ntsc_pixel0_ = (pixel0);\
nes_ntsc_rgb_t const* kernel0 = ENTRY( table, nes_ntsc_pixel0_ );\
unsigned const nes_ntsc_pixel1_ = (pixel1);\
nes_ntsc_rgb_t const* kernel1 = ENTRY( table, nes_ntsc_pixel1_ );\
unsigned const nes_ntsc_pixel2_ = (pixel2);\
nes_ntsc_rgb_t const* kernel2 = ENTRY( table, nes_ntsc_pixel2_ );\
nes_ntsc_rgb_t const* kernelx0;\
nes_ntsc_rgb_t const* kernelx1 = kernel0;\
nes_ntsc_rgb_t const* kernelx2 = kernel0
#define NES_NTSC_RGB_OUT_14_( x, rgb_out, bits, shift ) {\
nes_ntsc_rgb_t raw_ =\
kernel0 [x ] + kernel1 [(x+12)%7+14] + kernel2 [(x+10)%7+28] +\
kernelx0 [(x+7)%14] + kernelx1 [(x+ 5)%7+21] + kernelx2 [(x+ 3)%7+35];\
NES_NTSC_CLAMP_( raw_, shift );\
NES_NTSC_RGB_OUT_( rgb_out, bits, shift );\
}
/* common ntsc macros */
#define nes_ntsc_rgb_builder ((1L << 21) | (1 << 11) | (1 << 1))
#define nes_ntsc_clamp_mask (nes_ntsc_rgb_builder * 3 / 2)
#define nes_ntsc_clamp_add (nes_ntsc_rgb_builder * 0x101)
#define NES_NTSC_CLAMP_( io, shift ) {\
nes_ntsc_rgb_t sub = (io) >> (9-(shift)) & nes_ntsc_clamp_mask;\
nes_ntsc_rgb_t clamp = nes_ntsc_clamp_add - sub;\
io |= clamp;\
clamp -= sub;\
io &= clamp;\
}
#define NES_NTSC_COLOR_IN_( index, color, ENTRY, table ) {\
unsigned color_;\
kernelx##index = kernel##index;\
kernel##index = (color_ = (color), ENTRY( table, color_ ));\
}
/* x is always zero except in snes_ntsc library */
#define NES_NTSC_RGB_OUT_( rgb_out, bits, x ) {\
if ( bits == 16 )\
rgb_out = (raw_>>(13-x)& 0xF800)|(raw_>>(8-x)&0x07E0)|(raw_>>(4-x)&0x001F);\
if ( bits == 24 || bits == 32 )\
rgb_out = (raw_>>(5-x)&0xFF0000)|(raw_>>(3-x)&0xFF00)|(raw_>>(1-x)&0xFF);\
if ( bits == 15 )\
rgb_out = (raw_>>(14-x)& 0x7C00)|(raw_>>(9-x)&0x03E0)|(raw_>>(4-x)&0x001F);\
if ( bits == 0 )\
rgb_out = raw_ << x;\
}
#ifdef __cplusplus
}
#endif
#endif

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nes_ntsc 0.2.2: NES NTSC Video Filter
-------------------------------------
Author : Shay Green <gblargg@gmail.com>
Website : http://www.slack.net/~ant/
Forum : http://groups.google.com/group/blargg-sound-libs
License : GNU Lesser General Public License (LGPL)
Language: C or C++
Overview
--------
To perform NTSC filtering, first allocate memory for a nes_ntsc_t object
and call nes_ntsc_init(), then call nes_ntsc_blit() to perform
filtering. You can call nes_ntsc_init() at any time to change image
parameters.
nes_ntsc_blit() reads NES pixels and writes RGB pixels (16-bit by
default). The NES pixels are 6-bit raw palette values (0 to 0x3F). Edit
nes_ntsc_config.h to change this.
Color Emphasis Support
----------------------
Support for the three color emphasis bits in PPU register $2001 can be
enabled in nes_ntsc_config.h. By default, support is disabled and a
64-color palette is used. If enabled, a 512-color palette is used and
the three color emphasis bits from PPU $2001 are stored in bits 6-8 (bit
mask 0x1C0) of the input pixels to the blitter. Form the index as
follows:
index = (ppu_2001 << 1 & 0x1C0) | (palette_index & 0x3F).
RGB Palettes
------------
An RGB palette can be generated for use in a normal blitter. If color
emphasis is disabled, it's 64 colors (192 bytes); if enabled, it's 512
colors (1536 bytes). In your nes_ntsc_setup_t structure, point
palette_out to a buffer to hold the palette, then call nes_ntsc_init().
If you only need the palette and aren't going to be using the NTSC
filter, pass 0 for the first parameter.
A custom source RGB palette can also be used to replace the standard NES
color generation hardware. See the palette and base_palette members of
nes_ntsc_setup_t in nes_ntsc.h for more.
Image Parameters
----------------
Many image parameters can be adjusted and presets are provided for
composite video, S-video, RGB, and monochrome. Most are floating-point
values with a general range of -1.0 to 1.0, where 0 is normal. The
ranges are adjusted so that one parameter at an extreme (-1 or +1) and
the rest at zero shouldn't result in any internal overflow (garbage
pixels). Setting multiple parameters to their extreme can produce
garbage. Put another way, the state space defined by all parameters
within the range -1 to +1 is not fully usable, but some extreme corners
are very useful so I don't want to reduce the parameter ranges.
The sharpness and resolution parameters have similar effects. Resolution
affects how crisp pixels are. Sharpness merely enhances the edges by
increasing contrast, which makes things brighter at the edges. Artifacts
sets how much "junk" is around the edges where colors and brightness
change in the image, where -1 completely eliminates them. (Color) bleed
affects how much colors blend together and the artifact colors at the
edges of pixels surrounded by black. (Color) fringing affects how much
color fringing occurs around the edges of bright objects, especially
white text on a black background.
When using custom settings, initialize your nes_ntsc_setup_t using one
of the standard setups before customizing it. This will ensure that all
fields are properly initialized, including any added in future releases
of the library that your current code can't even know about.
nes_ntsc_setup_t setup;
setup = nes_ntsc_composite; /* do this first */
setup.sharpness = custom_sharpness;
nes_ntsc_init( ntsc, &setup );
Image Size
----------
For proper aspect ratio, the image generated by the library must be
doubled vertically.
Use the NES_NTSC_OUT_WIDTH() and NES_NTSC_IN_WIDTH() macros to convert
between input and output widths that the blitter uses. For example, if
you are blitting an image 256 pixels wide, use NES_NTSC_OUT_WIDTH( 256 )
to find out how many output pixels are written per row. Another example,
use NES_NTSC_IN_WIDTH( 640 ) to find how many input pixels will fit
within 640 output pixels. The blitter rounds the input width down in
some cases, so the requested width might not be possible. Use
NES_NTSC_IN_WIDTH( NES_NTSC_OUT_WIDTH( in_width ) ) to find what a given
in_width would be rounded down to.
Burst Phase
-----------
The burst_phase parameter to nes_ntsc_blit() should generally toggle
values between frames, i.e. 0 on first call to nes_ntsc_blit(), 1 on
second call, 0 on third call, 1 on fourth, etc. If merge_fields is
enabled (see below), you should always pass 0. Read further for more
detailed operation.
If you're using nes_ntsc_blit() to do partial screen updates,
burst_phase should be calculated as (burst_phase + row) % 3, where row
is the starting row (0 through 239). For example, if burst_phase is 1
for the current frame and you make two calls to nes_ntsc_blit() to blit
rows 0 to 100, then rows 101 to 239, for the first call you should pass
1 for burst_phase, and for the second call you should pass 0 for
burst_phase: (1 + 101) % 3 = 0. Do the same regardless of the
merge_fields setting.
For more accurate burst_phase operation, it should be adjusted at the
beginning of a frame based on the length of scanline 20: if 341 clocks
(normal), burst_phase = (burst_phase + 1) % 3, otherwise burst_phase =
(burst_phase + 2) % 3 (for shorter 340 clock scanline).
The included test ROMs verify proper burst_phase implementation. They
must pass in order; an earlier failing test means that later tests will
give meaningless results. The first two tests will pass with either
method of burst_phase handling described above; the third will only pass
with the more accurate handling. The tests flash sets of dots quickly
with the dot color being the only important aspect.
1.line_phase.nes - Tests for proper burst_phase on each scanline. All
dots on screen should be the same color.
2.frame_phase.nes - Tests for proper burst_phase toggling between
frames. Each row of dots should alternate between the same two colors
(if merge_fields is set to 1, they should all be the same color).
3.special_frame_phase.nes - Tests for proper burst_phase incrementing
between frames when $2001 rendering is enabled late in the frame. Each
rectangle of dots should be one color, and there should be three
different colors of rectangles (if merge_fields is set to 1, each
rectangle should be made of three colors of dots). There is a visual
glitch near the top of the screen for the first line of dots; this is
unrelated the test and should be ignored.
Flickering
----------
The displayed image toggles between two different pixel artifact
patterns at a steady rate, making it appear stable. For an emulator to
duplicate this effect, its frame rate must match the host monitor's
refresh rate, it must be synchronizing to the refresh (vsync), and it
must not be skipping any frames. If any of these don't hold, the image
will probably flicker much more than it would on a TV. It is important
that you play around with these factors to get a good feel for the
issue, and document it clearly for end-users, otherwise they will have
difficulty getting an authentic image.
The library includes a partial workaround for this issue, for the cases
where all the conditions can't be met. When merge_fields is set to 1,
nes_ntsc_blit() does the equivalent of blitting the image twice with the
two different phases and then mixes them together, but without any
performance impact. The result is similar to what you'd see if the
monitor's refresh rate were the same as the emulator's. It does reduce
the shimmer effect when scrolling, so it's not a complete solution to
the refresh rate issue.
The merge_fields option is also useful when taking a screenshot. If you
capture without merge_fields set to 1, you'll only get the even or odd
artifacts, which will make the image look more grainy than when the
emulator is running. Again, play around with this to get an idea of the
difference. It might be best to simply allow the user to choose when to
enable this option.
Note that when you have merge_fields set to 1, you should always pass 0
for the burst_phase parameter to nes_ntsc_blit() (unless doing partial
screen updates). If you don't, you'll still get some flicker.
Custom Blitter
--------------
You can write your own blitter, allowing customization of how input
pixels are obtained, the format of output pixels (15, 16, or 32-bit
RGB), optimizations for your platform, and additional effects like
efficient scanline doubling during blitting.
Macros are included in nes_ntsc.h for writing your blitter so that your
code can be carried over without changes to improved versions of the
library. The default blitter at the end of nes_ntsc.c shows how to use
the macros. Contact me for further assistance.
The NES_NTSC_BEGIN_ROW macro allows starting up to three pixels. The
first pixel is cut off; its use is in specifying a background color
other than black for the sliver on the left edge. The next two pixels
can be used to handle the extra one or two pixels not handled by the
main chunks of three pixels. For example if you want to blit 257 input
pixels on a row (for whatever odd reason), you would start the first two
with NES_NTSC_BEGIN_ROW( ... nes_ntsc_black, line_in [0], line_in [1] ),
then do the remaining 255 in chunks of three (255 is divisible by 3).
Limitations
-----------
The library's horizontal rescaling is too wide by about 3% in order to
allow a much more optimal implementation. This means that a 256 pixel
wide input image should appear as 581 output pixels, but with this
library appears as 602 output pixels. TV aspect ratios probably vary by
this much anyway. If you really need unscaled output, contact me and
I'll see about adding it.
Thanks
------
Thanks to NewRisingSun for his original code and explanations of NTSC,
which was a starting point for me learning about NTSC video and
decoding. Thanks to the Nesdev forum for feedback and encouragement.
Thanks to Martin Freij (Nestopia author) and Charles MacDonald (SMS Plus
author) for significant ongoing testing and feedback as the library has
improved. Thanks to byuu (bsnes author) and pagefault (ZSNES team) for
feedback about the SNES version.
--
Shay Green <gblargg@gmail.com>

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/* Configure library by modifying this file */
#ifndef NES_NTSC_CONFIG_H
#define NES_NTSC_CONFIG_H
/* Uncomment to enable emphasis support and use a 512 color palette instead
of the base 64 color palette. */
#define NES_NTSC_EMPHASIS 1
/* The following affect the built-in blitter only; a custom blitter can
handle things however it wants. */
/* Bits per pixel of output. Can be 15, 16, 32, or 24 (same as 32). */
#define NES_NTSC_OUT_DEPTH 16
/* Type of input pixel values. You'll probably use unsigned short
if you enable emphasis above. */
#define NES_NTSC_IN_T unsigned char
/* Each raw pixel input value is passed through this. You might want to mask
the pixel index if you use the high bits as flags, etc. */
#define NES_NTSC_ADJ_IN( in ) (in & 0x3F)
/* For each pixel, this is the basic operation:
output_color = color_palette [NES_NTSC_ADJ_IN( NES_NTSC_IN_T )] */
#endif

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/* nes_ntsc 0.2.2. http://www.slack.net/~ant/ */
/* Common implementation of NTSC filters */
#include <assert.h>
#include <math.h>
/* Copyright (C) 2006 Shay Green. This module is free software; you
can redistribute it and/or modify it under the terms of the GNU Lesser
General Public License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version. This
module is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
details. You should have received a copy of the GNU Lesser General Public
License along with this module; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */
#define DISABLE_CORRECTION 0
#undef PI
#define PI 3.14159265358979323846f
#ifndef LUMA_CUTOFF
#define LUMA_CUTOFF 0.20
#endif
#ifndef gamma_size
#define gamma_size 1
#endif
#ifndef rgb_bits
#define rgb_bits 8
#endif
#ifndef artifacts_max
#define artifacts_max (artifacts_mid * 1.5f)
#endif
#ifndef fringing_max
#define fringing_max (fringing_mid * 2)
#endif
#ifndef STD_HUE_CONDITION
#define STD_HUE_CONDITION( setup ) 1
#endif
#define ext_decoder_hue (std_decoder_hue + 15)
#define rgb_unit (1 << rgb_bits)
#define rgb_offset (rgb_unit * 2 + 0.5f)
enum { burst_size = nes_ntsc_entry_size / burst_count };
enum { kernel_half = 16 };
enum { kernel_size = kernel_half * 2 + 1 };
typedef struct init_t
{
float to_rgb [burst_count * 6];
float to_float [gamma_size];
float contrast;
float brightness;
float artifacts;
float fringing;
float kernel [rescale_out * kernel_size * 2];
} init_t;
#define ROTATE_IQ( i, q, sin_b, cos_b ) {\
float t;\
t = i * cos_b - q * sin_b;\
q = i * sin_b + q * cos_b;\
i = t;\
}
static void init_filters( init_t* impl, nes_ntsc_setup_t const* setup )
{
#if rescale_out > 1
float kernels [kernel_size * 2];
#else
float* const kernels = impl->kernel;
#endif
/* generate luma (y) filter using sinc kernel */
{
/* sinc with rolloff (dsf) */
float const rolloff = 1 + (float) setup->sharpness * (float) 0.032;
float const maxh = 32;
float const pow_a_n = (float) pow( rolloff, maxh );
float sum;
int i;
/* quadratic mapping to reduce negative (blurring) range */
float to_angle = (float) setup->resolution + 1;
to_angle = PI / maxh * (float) LUMA_CUTOFF * (to_angle * to_angle + 1);
kernels [kernel_size * 3 / 2] = maxh; /* default center value */
for ( i = 0; i < kernel_half * 2 + 1; i++ )
{
int x = i - kernel_half;
float angle = x * to_angle;
/* instability occurs at center point with rolloff very close to 1.0 */
if ( x || pow_a_n > (float) 1.056 || pow_a_n < (float) 0.981 )
{
float rolloff_cos_a = rolloff * (float) cos( angle );
float num = 1 - rolloff_cos_a -
pow_a_n * (float) cos( maxh * angle ) +
pow_a_n * rolloff * (float) cos( (maxh - 1) * angle );
float den = 1 - rolloff_cos_a - rolloff_cos_a + rolloff * rolloff;
float dsf = num / den;
kernels [kernel_size * 3 / 2 - kernel_half + i] = dsf - (float) 0.5;
}
}
/* apply blackman window and find sum */
sum = 0;
for ( i = 0; i < kernel_half * 2 + 1; i++ )
{
float x = PI * 2 / (kernel_half * 2) * i;
float blackman = 0.42f - 0.5f * (float) cos( x ) + 0.08f * (float) cos( x * 2 );
sum += (kernels [kernel_size * 3 / 2 - kernel_half + i] *= blackman);
}
/* normalize kernel */
sum = 1.0f / sum;
for ( i = 0; i < kernel_half * 2 + 1; i++ )
{
int x = kernel_size * 3 / 2 - kernel_half + i;
kernels [x] *= sum;
assert( kernels [x] == kernels [x] ); /* catch numerical instability */
}
}
/* generate chroma (iq) filter using gaussian kernel */
{
float const cutoff_factor = -0.03125f;
float cutoff = (float) setup->bleed;
int i;
if ( cutoff < 0 )
{
/* keep extreme value accessible only near upper end of scale (1.0) */
cutoff *= cutoff;
cutoff *= cutoff;
cutoff *= cutoff;
cutoff *= -30.0f / 0.65f;
}
cutoff = cutoff_factor - 0.65f * cutoff_factor * cutoff;
for ( i = -kernel_half; i <= kernel_half; i++ )
kernels [kernel_size / 2 + i] = (float) exp( i * i * cutoff );
/* normalize even and odd phases separately */
for ( i = 0; i < 2; i++ )
{
float sum = 0;
int x;
for ( x = i; x < kernel_size; x += 2 )
sum += kernels [x];
sum = 1.0f / sum;
for ( x = i; x < kernel_size; x += 2 )
{
kernels [x] *= sum;
assert( kernels [x] == kernels [x] ); /* catch numerical instability */
}
}
}
/*
printf( "luma:\n" );
for ( i = kernel_size; i < kernel_size * 2; i++ )
printf( "%f\n", kernels [i] );
printf( "chroma:\n" );
for ( i = 0; i < kernel_size; i++ )
printf( "%f\n", kernels [i] );
*/
/* generate linear rescale kernels */
#if rescale_out > 1
{
float weight = 1.0f;
float* out = impl->kernel;
int n = rescale_out;
do
{
float remain = 0;
int i;
weight -= 1.0f / rescale_in;
for ( i = 0; i < kernel_size * 2; i++ )
{
float cur = kernels [i];
float m = cur * weight;
*out++ = m + remain;
remain = cur - m;
}
}
while ( --n );
}
#endif
}
static float const default_decoder [6] =
{ 0.956f, 0.621f, -0.272f, -0.647f, -1.105f, 1.702f };
static void init( init_t* impl, nes_ntsc_setup_t const* setup )
{
impl->brightness = (float) setup->brightness * (0.5f * rgb_unit) + rgb_offset;
impl->contrast = (float) setup->contrast * (0.5f * rgb_unit) + rgb_unit;
#ifdef default_palette_contrast
if ( !setup->palette )
impl->contrast *= default_palette_contrast;
#endif
impl->artifacts = (float) setup->artifacts;
if ( impl->artifacts > 0 )
impl->artifacts *= artifacts_max - artifacts_mid;
impl->artifacts = impl->artifacts * artifacts_mid + artifacts_mid;
impl->fringing = (float) setup->fringing;
if ( impl->fringing > 0 )
impl->fringing *= fringing_max - fringing_mid;
impl->fringing = impl->fringing * fringing_mid + fringing_mid;
init_filters( impl, setup );
/* generate gamma table */
if ( gamma_size > 1 )
{
float const to_float = 1.0f / (gamma_size - (gamma_size > 1));
float const gamma = 1.1333f - (float) setup->gamma * 0.5f;
/* match common PC's 2.2 gamma to TV's 2.65 gamma */
int i;
for ( i = 0; i < gamma_size; i++ )
impl->to_float [i] =
(float) pow( i * to_float, gamma ) * impl->contrast + impl->brightness;
}
/* setup decoder matricies */
{
float hue = (float) setup->hue * PI + PI / 180 * ext_decoder_hue;
float sat = (float) setup->saturation + 1;
float const* decoder = setup->decoder_matrix;
if ( !decoder )
{
decoder = default_decoder;
if ( STD_HUE_CONDITION( setup ) )
hue += PI / 180 * (std_decoder_hue - ext_decoder_hue);
}
{
float s = (float) sin( hue ) * sat;
float c = (float) cos( hue ) * sat;
float* out = impl->to_rgb;
int n;
n = burst_count;
do
{
float const* in = decoder;
int n = 3;
do
{
float i = *in++;
float q = *in++;
*out++ = i * c - q * s;
*out++ = i * s + q * c;
}
while ( --n );
if ( burst_count <= 1 )
break;
ROTATE_IQ( s, c, 0.866025f, -0.5f ); /* +120 degrees */
}
while ( --n );
}
}
}
/* kernel generation */
#define RGB_TO_YIQ( r, g, b, y, i ) (\
(y = (r) * 0.299f + (g) * 0.587f + (b) * 0.114f),\
(i = (r) * 0.596f - (g) * 0.275f - (b) * 0.321f),\
((r) * 0.212f - (g) * 0.523f + (b) * 0.311f)\
)
#define YIQ_TO_RGB( y, i, q, to_rgb, type, r, g ) (\
r = (type) (y + to_rgb [0] * i + to_rgb [1] * q),\
g = (type) (y + to_rgb [2] * i + to_rgb [3] * q),\
(type) (y + to_rgb [4] * i + to_rgb [5] * q)\
)
#define PACK_RGB( r, g, b ) ((r) << 21 | (g) << 11 | (b) << 1)
enum { rgb_kernel_size = burst_size / alignment_count };
enum { rgb_bias = rgb_unit * 2 * nes_ntsc_rgb_builder };
typedef struct pixel_info_t
{
int offset;
float negate;
float kernel [4];
} pixel_info_t;
#if rescale_in > 1
#define PIXEL_OFFSET_( ntsc, scaled ) \
(kernel_size / 2 + ntsc + (scaled != 0) + (rescale_out - scaled) % rescale_out + \
(kernel_size * 2 * scaled))
#define PIXEL_OFFSET( ntsc, scaled ) \
PIXEL_OFFSET_( ((ntsc) - (scaled) / rescale_out * rescale_in),\
(((scaled) + rescale_out * 10) % rescale_out) ),\
(1.0f - (((ntsc) + 100) & 2))
#else
#define PIXEL_OFFSET( ntsc, scaled ) \
(kernel_size / 2 + (ntsc) - (scaled)),\
(1.0f - (((ntsc) + 100) & 2))
#endif
extern pixel_info_t const nes_ntsc_pixels [alignment_count];
/* Generate pixel at all burst phases and column alignments */
static void gen_kernel( init_t* impl, float y, float i, float q, nes_ntsc_rgb_t* out )
{
/* generate for each scanline burst phase */
float const* to_rgb = impl->to_rgb;
int burst_remain = burst_count;
y -= rgb_offset;
do
{
/* Encode yiq into *two* composite signals (to allow control over artifacting).
Convolve these with kernels which: filter respective components, apply
sharpening, and rescale horizontally. Convert resulting yiq to rgb and pack
into integer. Based on algorithm by NewRisingSun. */
pixel_info_t const* pixel = nes_ntsc_pixels;
int alignment_remain = alignment_count;
do
{
/* negate is -1 when composite starts at odd multiple of 2 */
float const yy = y * impl->fringing * pixel->negate;
float const ic0 = (i + yy) * pixel->kernel [0];
float const qc1 = (q + yy) * pixel->kernel [1];
float const ic2 = (i - yy) * pixel->kernel [2];
float const qc3 = (q - yy) * pixel->kernel [3];
float const factor = impl->artifacts * pixel->negate;
float const ii = i * factor;
float const yc0 = (y + ii) * pixel->kernel [0];
float const yc2 = (y - ii) * pixel->kernel [2];
float const qq = q * factor;
float const yc1 = (y + qq) * pixel->kernel [1];
float const yc3 = (y - qq) * pixel->kernel [3];
float const* k = &impl->kernel [pixel->offset];
int n;
++pixel;
for ( n = rgb_kernel_size; n; --n )
{
float i = k[0]*ic0 + k[2]*ic2;
float q = k[1]*qc1 + k[3]*qc3;
float y = k[kernel_size+0]*yc0 + k[kernel_size+1]*yc1 +
k[kernel_size+2]*yc2 + k[kernel_size+3]*yc3 + rgb_offset;
if ( rescale_out <= 1 )
k--;
else if ( k < &impl->kernel [kernel_size * 2 * (rescale_out - 1)] )
k += kernel_size * 2 - 1;
else
k -= kernel_size * 2 * (rescale_out - 1) + 2;
{
int r, g, b = YIQ_TO_RGB( y, i, q, to_rgb, int, r, g );
*out++ = PACK_RGB( r, g, b ) - rgb_bias;
}
}
}
while ( alignment_count > 1 && --alignment_remain );
if ( burst_count <= 1 )
break;
to_rgb += 6;
ROTATE_IQ( i, q, -0.866025f, -0.5f ); /* -120 degrees */
}
while ( --burst_remain );
}
static void correct_errors( nes_ntsc_rgb_t color, nes_ntsc_rgb_t* out );
#if DISABLE_CORRECTION
#define CORRECT_ERROR( a ) { out [i] += rgb_bias; }
#define DISTRIBUTE_ERROR( a, b, c ) { out [i] += rgb_bias; }
#else
#define CORRECT_ERROR( a ) { out [a] += error; }
#define DISTRIBUTE_ERROR( a, b, c ) {\
nes_ntsc_rgb_t fourth = (error + 2 * nes_ntsc_rgb_builder) >> 2;\
fourth &= (rgb_bias >> 1) - nes_ntsc_rgb_builder;\
fourth -= rgb_bias >> 2;\
out [a] += fourth;\
out [b] += fourth;\
out [c] += fourth;\
out [i] += error - (fourth * 3);\
}
#endif
#define RGB_PALETTE_OUT( rgb, out_ )\
{\
unsigned char* out = (out_);\
nes_ntsc_rgb_t clamped = (rgb);\
NES_NTSC_CLAMP_( clamped, (8 - rgb_bits) );\
out [0] = (unsigned char) (clamped >> 21);\
out [1] = (unsigned char) (clamped >> 11);\
out [2] = (unsigned char) (clamped >> 1);\
}
/* blitter related */
#ifndef restrict
#if defined (__GNUC__)
#define restrict __restrict__
#elif defined (_MSC_VER) && _MSC_VER > 1300
#define restrict __restrict
#else
/* no support for restricted pointers */
#define restrict
#endif
#endif
#include <limits.h>
#if NES_NTSC_OUT_DEPTH <= 16
#if USHRT_MAX == 0xFFFF
typedef unsigned short nes_ntsc_out_t;
#else
#error "Need 16-bit int type"
#endif
#else
#if UINT_MAX == 0xFFFFFFFF
typedef unsigned int nes_ntsc_out_t;
#elif ULONG_MAX == 0xFFFFFFFF
typedef unsigned long nes_ntsc_out_t;
#else
#error "Need 32-bit int type"
#endif
#endif

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nes_ntsc 0.2.2: NES NTSC Video Filter
-------------------------------------
This library filters a NES image to match what a TV would show, allowing
an authentic image in an emulator. It uses a highly optimized algorithm
to perform the same signal processing as an NTSC decoder in a TV, giving
very similar pixel artifacts and color bleeding. The usual picture
controls can be adjusted: hue, saturation, contrast, brightness, and
sharpness. Additionally, the amount of NTSC chroma and luma artifacts
can be reduced, allowing an image that corresponds to composite video
(artifacts), S-video (color bleeding only), RGB (clean pixels), or
anywhere inbetween.
The output is scaled to the proper horizontal width, leaving it up the
emulator to simply double the height. An optional even/odd field merging
feature is provided to reduce flicker when the host display's refresh
rate isn't 60 Hz. Specialized blitters can be easily written using a
special interface, allowing customization of input and output pixel
formats, optimization for the host platform, and efficient scanline
doubling.
Blitting a 256x240 source image to a 602x240 pixel 16-bit RGB memory
buffer at 60 frames per second uses 8% CPU on a 2.0 GHz Athlon 3500+ and
40% CPU on a 10-year-old 400 MHz G3 PowerMac.
Author : Shay Green <gblargg@gmail.com>
Website : http://www.slack.net/~ant/
Forum : http://groups.google.com/group/blargg-sound-libs
License : GNU Lesser General Public License (LGPL)
Language: C or C++
Getting Started
---------------
Build a program from demo.c, nes_ntsc.c, and the SDL multimedia library
(see http://libsdl.org/). Run it with "test.bmp" in the same directory
and it should show the filtered image. See demo.c for more.
See nes_ntsc.txt for documentation and nes_ntsc.h for reference. Post to
the discussion forum for assistance.
Files
-----
readme.txt Essential information
nes_ntsc.txt Library documentation
changes.txt Changes made since previous releases
license.txt GNU Lesser General Public License
benchmark.c Measures frame rate and processor usage of library
demo.c Displays and saves NTSC filtered image
demo_impl.h Internal routines used by demo
test.bmp Test image for demo
tests/ Test ROMs to verify burst phase operation
nes_ntsc_config.h Library configuration (modify as needed)
nes_ntsc.h Library header and source
nes_ntsc.c
nes_ntsc_impl.h
--
Shay Green <gblargg@gmail.com>