[MPlayer-dev-eng] [PATCH] new debanding filter "gradfun"

Loren Merritt lorenm at u.washington.edu
Tue May 19 09:01:56 CEST 2009


This is a port/optimization of an Avisynth filter by the same name.
Original discussion: http://forum.doom9.org/showthread.php?t=108681

While the filter works as-is, ideally it should output 16bit yuv which 
would be dithered only in the final conversion of 8bit rgb. But MPlayer 
doesn't have any 16bit depth colorspaces, so I couldn't do that.

--Loren Merritt
-------------- next part --------------
commit fa7bb8e799adee4ca3db134283f6b0627b9412b6
Author: Loren Merritt <pengvado at akuvian.org>
Date:   Thu Jan 29 02:28:59 2009 +0000

    vf_gradfun

diff --git a/DOCS/man/en/mplayer.1 b/DOCS/man/en/mplayer.1
index 0f2152e..a70527d 100644
--- a/DOCS/man/en/mplayer.1
+++ b/DOCS/man/en/mplayer.1
@@ -7336,6 +7336,25 @@ Percentage of the pixels that have to be below the threshold (default: 98).
 Threshold below which a pixel value is considered black (default: 32).
 .RE
 .
+.TP
+.B gradfun[=strength[:radius]]
+Fix the banding artifacts that are sometimes introduced into nearly flat
+regions by truncation to 8bit colordepth. Interpolates the gradients that
+should go where the bands are, and dithers them.
+.sp 1
+This filter was designed for playback only. Do not use it prior to lossy
+compression, because compression tends to lose the dither and bring back
+the bands.
+.RSs
+.IPs <strength>
+Maximum amount by which the filter will change any one pixel.
+Also the threshold for detecting nearly flat regions (default: 1.2).
+.IPs <radius>
+Neighborhood to fit the gradient to. Larger radius makes for smoother
+gradients, but also prevents the filter from modifying pixels near
+detailed regions (default: 16).
+.RE
+.
 .
 .
 .SH "GENERAL ENCODING OPTIONS (MENCODER ONLY)"
diff --git a/Makefile b/Makefile
index 44a85f6..e0826d4 100644
--- a/Makefile
+++ b/Makefile
@@ -425,6 +425,7 @@ SRCS_COMMON = asxparser.c \
               libmpcodecs/vf_flip.c \
               libmpcodecs/vf_format.c \
               libmpcodecs/vf_framestep.c \
+              libmpcodecs/vf_gradfun.c \
               libmpcodecs/vf_halfpack.c \
               libmpcodecs/vf_harddup.c \
               libmpcodecs/vf_hqdn3d.c \
diff --git a/libmpcodecs/vf.c b/libmpcodecs/vf.c
index 46e41c3..08d0b13 100644
--- a/libmpcodecs/vf.c
+++ b/libmpcodecs/vf.c
@@ -48,6 +48,7 @@ extern const vf_info_t vf_info_yvu9;
 extern const vf_info_t vf_info_lavcdeint;
 extern const vf_info_t vf_info_eq;
 extern const vf_info_t vf_info_eq2;
+extern const vf_info_t vf_info_gradfun;
 extern const vf_info_t vf_info_halfpack;
 extern const vf_info_t vf_info_dint;
 extern const vf_info_t vf_info_1bpp;
@@ -138,6 +139,7 @@ static const vf_info_t* const filter_list[]={
     &vf_info_yvu9,
     &vf_info_eq,
     &vf_info_eq2,
+    &vf_info_gradfun,
     &vf_info_halfpack,
     &vf_info_dint,
     &vf_info_1bpp,
diff --git a/libmpcodecs/vf_gradfun.c b/libmpcodecs/vf_gradfun.c
new file mode 100644
index 0000000..379e72a
--- /dev/null
+++ b/libmpcodecs/vf_gradfun.c
@@ -0,0 +1,394 @@
+/*
+ * Copyright (C) 2009 Loren Merritt <lorenm at u.washignton.edu>
+ *
+ * This file is part of MPlayer.
+ *
+ * MPlayer is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * MPlayer 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with MPlayer; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * Debanding algorithm (from gradfun2db by prunedtree):
+ * Boxblur.
+ * Foreach pixel, if it's within threshold of the blurred value, make it closer.
+ * So now we have a smoothed and higher bitdepth version of all the shallow
+ * gradients, while leaving detailed areas untouched.
+ * Dither it back to 8bit.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <inttypes.h>
+#include <malloc.h>
+
+#include "config.h"
+#include "cpudetect.h"
+#include "img_format.h"
+#include "mp_image.h"
+#include "vf.h"
+#include "libvo/fastmemcpy.h"
+#include "libavutil/avutil.h"
+
+#if ARCH_X86
+#include "libavutil/x86_cpu.h"
+#endif
+
+struct vf_priv_s {
+    int thresh;
+    int radius;
+    uint16_t *buf;
+    void (*filter_line)(uint8_t *dst, uint8_t *src, uint16_t *dc, int width, int thresh, const uint16_t *dithers);
+    void (*blur_line)(uint16_t *dc, uint16_t *buf, uint16_t *buf1, uint8_t *src, int sstride, int width);
+};
+
+static const uint16_t __attribute__((aligned(16))) pw_7f[8] = {127,127,127,127,127,127,127,127};
+static const uint16_t __attribute__((aligned(16))) pw_ff[8] = {255,255,255,255,255,255,255,255};
+static const uint16_t __attribute__((aligned(16))) dither[8][8] = {
+    {  0, 96, 25,121,  7,103, 30,126 },
+    { 65, 33, 89, 56, 70, 38, 95, 63 },
+    { 16,112,  9,105, 22,119, 14,110 },
+    { 80, 49, 73, 40, 86, 55, 78, 46 },
+    {  5,100, 29,125,  2, 98, 26,122 },
+    { 69, 36, 92, 60, 66, 35, 90, 59 },
+    { 21,117, 13,108, 18,114, 10,106 },
+    { 84, 52, 76, 45, 82, 51, 75, 42 },
+};
+
+static void filter_line_c(uint8_t *dst, uint8_t *src, uint16_t *dc, int width, int thresh, const uint16_t *dithers) {
+    int x;
+    for(x=0; x<width; x++, dc+=x&1) {
+        int pix = src[x]<<7;
+        int delta = dc[0] - pix;
+        int m = abs(delta) * thresh >> 16;
+        m = FFMAX(0, 127-m);
+        m = m*m*delta >> 14;
+        pix += m + dithers[x&7];
+        dst[x] = av_clip_uint8(pix>>7);
+    }
+}
+
+static void blur_line_c(uint16_t *dc, uint16_t *buf, uint16_t *buf1, uint8_t *src, int sstride, int width) {
+    int x, v, old;
+    for(x=0; x<width; x++) {
+        v = buf1[x] + src[2*x] + src[2*x+1] + src[2*x+sstride] + src[2*x+1+sstride];
+        old = buf[x];
+        buf[x] = v;
+        dc[x] = v - old;
+    }
+}
+
+#if HAVE_SSSE3
+static void filter_line_mmx2(uint8_t *dst, uint8_t *src, uint16_t *dc, int width, int thresh, const uint16_t *dithers) {
+    intptr_t x;
+    if(width&3) {
+        x = width&~3;
+        filter_line_c(dst+x, src+x, dc+x/2, width-x, thresh, dithers);
+        width = x;
+    }
+    x = -width;
+    asm volatile(
+        "movd          %4, %%mm5 \n"
+        "pxor       %%mm7, %%mm7 \n"
+        "pshufw $0, %%mm5, %%mm5 \n"
+        "movq          %6, %%mm6 \n"
+        "movq          %5, %%mm4 \n"
+        "1: \n"
+        "movd     (%2,%0), %%mm0 \n"
+        "movd     (%3,%0), %%mm1 \n"
+        "punpcklbw  %%mm7, %%mm0 \n"
+        "punpcklwd  %%mm1, %%mm1 \n"
+        "psllw         $7, %%mm0 \n"
+        "pxor       %%mm2, %%mm2 \n"
+        "psubw      %%mm0, %%mm1 \n" // delta = dc - pix
+        "psubw      %%mm1, %%mm2 \n"
+        "pmaxsw     %%mm1, %%mm2 \n"
+        "pmulhuw    %%mm5, %%mm2 \n" // m = abs(delta) * thresh >> 16
+        "psubw      %%mm6, %%mm2 \n"
+        "pminsw     %%mm7, %%mm2 \n" // m = -max(0, 127-m)
+        "pmullw     %%mm2, %%mm2 \n"
+        "paddw      %%mm4, %%mm0 \n" // pix += dither
+        "pmulhw     %%mm2, %%mm1 \n"
+        "psllw         $2, %%mm1 \n" // m = m*m*delta >> 14
+        "paddw      %%mm1, %%mm0 \n" // pix += m
+        "psraw         $7, %%mm0 \n"
+        "packuswb   %%mm0, %%mm0 \n"
+        "movd       %%mm0, (%1,%0) \n" // dst = clip(pix>>7)
+        "add           $4, %0 \n"
+        "jl 1b \n"
+        "emms \n"
+        :"+r"(x)
+        :"r"(dst+width), "r"(src+width), "r"(dc+width/2),
+         "rm"(thresh), "m"(*dithers), "m"(*pw_7f)
+        :"memory"
+    );
+}
+
+static void filter_line_ssse3(uint8_t *dst, uint8_t *src, uint16_t *dc, int width, int thresh, const uint16_t *dithers) {
+    intptr_t x;
+    if(width&7) {
+        // could be 10% faster if I somehow eliminated this
+        x = width&~7;
+        filter_line_c(dst+x, src+x, dc+x/2, width-x, thresh, dithers);
+        width = x;
+    }
+    x = -width;
+    asm volatile(
+        "movd           %4, %%xmm5 \n"
+        "pxor       %%xmm7, %%xmm7 \n"
+        "pshuflw $0,%%xmm5, %%xmm5 \n"
+        "movdqa         %6, %%xmm6 \n"
+        "punpcklqdq %%xmm5, %%xmm5 \n"
+        "movdqa         %5, %%xmm4 \n"
+        "1: \n"
+        "movq      (%2,%0), %%xmm0 \n"
+        "movq      (%3,%0), %%xmm1 \n"
+        "punpcklbw  %%xmm7, %%xmm0 \n"
+        "punpcklwd  %%xmm1, %%xmm1 \n"
+        "psllw          $7, %%xmm0 \n"
+        "psubw      %%xmm0, %%xmm1 \n" // delta = dc - pix
+        "pabsw      %%xmm1, %%xmm2 \n"
+        "pmulhuw    %%xmm5, %%xmm2 \n" // m = abs(delta) * thresh >> 16
+        "psubw      %%xmm6, %%xmm2 \n"
+        "pminsw     %%xmm7, %%xmm2 \n" // m = -max(0, 127-m)
+        "pmullw     %%xmm2, %%xmm2 \n"
+        "psllw          $1, %%xmm2 \n"
+        "paddw      %%xmm4, %%xmm0 \n" // pix += dither
+        "pmulhrsw   %%xmm2, %%xmm1 \n" // m = m*m*delta >> 14
+        "paddw      %%xmm1, %%xmm0 \n" // pix += m
+        "psraw          $7, %%xmm0 \n"
+        "packuswb   %%xmm0, %%xmm0 \n"
+        "movq       %%xmm0, (%1,%0) \n" // dst = clip(pix>>7)
+        "add            $8, %0 \n"
+        "jl 1b \n"
+        :"+r"(x)
+        :"r"(dst+width), "r"(src+width), "r"(dc+width/2),
+         "rm"(thresh), "m"(*dithers), "m"(*pw_7f)
+        :"memory"
+    );
+}
+
+#define BLURV(load)\
+    intptr_t x = -2*width;\
+    asm volatile(\
+        "movdqa %6, %%xmm7 \n"\
+        "1: \n"\
+        load"   (%4,%0), %%xmm0 \n"\
+        load"   (%5,%0), %%xmm1 \n"\
+        "movdqa  %%xmm0, %%xmm2 \n"\
+        "movdqa  %%xmm1, %%xmm3 \n"\
+        "psrlw       $8, %%xmm0 \n"\
+        "psrlw       $8, %%xmm1 \n"\
+        "pand    %%xmm7, %%xmm2 \n"\
+        "pand    %%xmm7, %%xmm3 \n"\
+        "paddw   %%xmm1, %%xmm0 \n"\
+        "paddw   %%xmm3, %%xmm2 \n"\
+        "paddw   %%xmm2, %%xmm0 \n"\
+        "paddw  (%2,%0), %%xmm0 \n"\
+        "movdqa (%1,%0), %%xmm1 \n"\
+        "movdqa  %%xmm0, (%1,%0) \n"\
+        "psubw   %%xmm1, %%xmm0 \n"\
+        "movdqa  %%xmm0, (%3,%0) \n"\
+        "add        $16, %0 \n"\
+        "jl 1b \n"\
+        :"+r"(x)\
+        :"r"(buf+width),\
+         "r"(buf1+width),\
+         "r"(dc+width),\
+         "r"(src+width*2),\
+         "r"(src+width*2+sstride),\
+         "m"(*pw_ff)\
+        :"memory"\
+    );
+
+#if HAVE_6REGS
+static void blur_line_sse2(uint16_t *dc, uint16_t *buf, uint16_t *buf1, uint8_t *src, int sstride, int width) {
+    if(((intptr_t)src|sstride)&15) {
+        BLURV("movdqu");
+    } else {
+        BLURV("movdqa");
+    }
+}
+#endif // HAVE_6REGS
+#endif // HAVE_SSSE3
+
+static void filter(struct vf_priv_s *ctx, uint8_t *dst, uint8_t *src, int width, int height, int dstride, int sstride, int r) {
+    int bstride = ((width+15)&~15)/2;
+    int y;
+    uint32_t dc_factor = (1<<21)/(r*r);
+    uint16_t *dc = ctx->buf+16;
+    uint16_t *buf = ctx->buf+bstride+32;
+    int thresh = ctx->thresh;
+
+    memset(dc, 0, (bstride+16)*sizeof(*buf));
+    for(y=0; y<r; y++)
+        ctx->blur_line(dc, buf+y*bstride, buf+(y-1)*bstride, src+2*y*sstride, sstride, width/2);
+    for(;;) {
+        if(y < height-r) {
+            int mod = ((y+r)/2)%r;
+            uint16_t *buf0 = buf+mod*bstride;
+            uint16_t *buf1 = buf+(mod?mod-1:r-1)*bstride;
+            int x, v;
+            ctx->blur_line(dc, buf0, buf1, src+(y+r)*sstride, sstride, width/2);
+            for(x=v=0; x<r; x++)
+                v += dc[x];
+            for(; x<width/2; x++) {
+                v += dc[x] - dc[x-r];
+                dc[x-r] = v * dc_factor >> 16;
+            }
+            for(; x<(width+r+1)/2; x++)
+                dc[x-r] = v * dc_factor >> 16;
+            for(x=-r/2; x<0; x++)
+                dc[x] = dc[0];
+        }
+        if(y == r) {
+            for(y=0; y<r; y++)
+                ctx->filter_line(dst+y*dstride, src+y*sstride, dc-r/2, width, thresh, dither[y&7]);
+        }
+        ctx->filter_line(dst+y*dstride, src+y*sstride, dc-r/2, width, thresh, dither[y&7]);
+        if(++y >= height) break;
+        ctx->filter_line(dst+y*dstride, src+y*sstride, dc-r/2, width, thresh, dither[y&7]);
+        if(++y >= height) break;
+    }
+}
+
+static void get_image(struct vf_instance_s* vf, mp_image_t *mpi)
+{
+    if(mpi->flags&MP_IMGFLAG_PRESERVE) return; // don't change
+    // ok, we can do pp in-place:
+    vf->dmpi = vf_get_image(vf->next, mpi->imgfmt,
+                            mpi->type, mpi->flags, mpi->width, mpi->height);
+    mpi->planes[0] = vf->dmpi->planes[0];
+    mpi->stride[0] = vf->dmpi->stride[0];
+    mpi->width = vf->dmpi->width;
+    if(mpi->flags&MP_IMGFLAG_PLANAR){
+        mpi->planes[1] = vf->dmpi->planes[1];
+        mpi->planes[2] = vf->dmpi->planes[2];
+        mpi->stride[1] = vf->dmpi->stride[1];
+        mpi->stride[2] = vf->dmpi->stride[2];
+    }
+    mpi->flags |= MP_IMGFLAG_DIRECT;
+}
+
+static int put_image(struct vf_instance_s* vf, mp_image_t *mpi, double pts) {
+    mp_image_t *dmpi = vf->dmpi;
+    int p;
+
+    if(!(mpi->flags&MP_IMGFLAG_DIRECT)) {
+        // no DR, so get a new image. hope we'll get DR buffer:
+        dmpi = vf_get_image(vf->next,mpi->imgfmt, MP_IMGTYPE_TEMP,
+                            MP_IMGFLAG_ACCEPT_STRIDE|MP_IMGFLAG_PREFER_ALIGNED_STRIDE,
+                            mpi->w, mpi->h);
+    }
+    vf_clone_mpi_attributes(dmpi, mpi);
+
+    for(p=0; p<mpi->num_planes; p++) {
+        int w = mpi->w;
+        int h = mpi->h;
+        int r = vf->priv->radius;
+        if(p) {
+            w >>= mpi->chroma_x_shift;
+            h >>= mpi->chroma_y_shift;
+            r = ((r>>mpi->chroma_x_shift) + (r>>mpi->chroma_y_shift)) / 2;
+            r = av_clip((r+1)&~1,4,32);
+        }
+        if(FFMIN(w,h) > 2*r)
+            filter(vf->priv, dmpi->planes[p], mpi->planes[p], w, h,
+                             dmpi->stride[p], mpi->stride[p], r);
+        else if(dmpi->planes[p] != mpi->planes[p])
+            memcpy_pic(dmpi->planes[p], mpi->planes[p], w, h,
+                       dmpi->stride[p], mpi->stride[p]);
+    }
+
+    return vf_next_put_image(vf, dmpi, pts);
+}
+
+static int query_format(struct vf_instance_s* vf, unsigned int fmt) {
+    switch(fmt){
+    case IMGFMT_YVU9:
+    case IMGFMT_IF09:
+    case IMGFMT_YV12:
+    case IMGFMT_I420:
+    case IMGFMT_IYUV:
+    case IMGFMT_CLPL:
+    case IMGFMT_Y800:
+    case IMGFMT_Y8:
+    case IMGFMT_NV12:
+    case IMGFMT_NV21:
+    case IMGFMT_444P:
+    case IMGFMT_422P:
+    case IMGFMT_411P:
+    case IMGFMT_HM12:
+        return vf_next_query_format(vf,fmt);
+    }
+    return 0;
+}
+
+static int config(struct vf_instance_s* vf,
+        int width, int height, int d_width, int d_height,
+        unsigned int flags, unsigned int outfmt) {
+    free(vf->priv->buf);
+    vf->priv->buf = memalign(16, ((width+15)&~15)*(vf->priv->radius+1)+64);
+    memset(vf->priv->buf, 0, width);
+    return vf_next_config(vf,width,height,d_width,d_height,flags,outfmt);
+}
+
+static void uninit(struct vf_instance_s* vf) {
+    if(!vf->priv) return;
+
+    free(vf->priv->buf);
+    free(vf->priv);
+    vf->priv=NULL;
+}
+
+static int open(vf_instance_t *vf, char* args) {
+    float thresh = 1.2;
+    int radius = 16;
+
+    vf->get_image=get_image;
+    vf->put_image=put_image;
+    vf->query_format=query_format;
+    vf->config=config;
+    vf->uninit=uninit;
+    vf->priv=malloc(sizeof(struct vf_priv_s));
+    memset(vf->priv, 0, sizeof(struct vf_priv_s));
+
+    if(args) sscanf(args, "%f:%d", &thresh, &radius);
+    vf->priv->thresh = (1<<15)/av_clipf(thresh,0.51,255);
+    vf->priv->radius = av_clip((radius+1)&~1,4,32);
+
+    vf->priv->blur_line = blur_line_c;
+    vf->priv->filter_line = filter_line_c;
+#if HAVE_SSSE3
+#if HAVE_6REGS
+    if(gCpuCaps.hasSSE2)
+        vf->priv->blur_line = blur_line_sse2;
+#endif
+    if(gCpuCaps.hasMMX2)
+        vf->priv->filter_line = filter_line_mmx2;
+    if(gCpuCaps.hasSSSE3)
+        vf->priv->filter_line = filter_line_ssse3;
+#endif
+
+    return 1;
+}
+
+const vf_info_t vf_info_gradfun = {
+    "gradient deband",
+    "gradfun",
+    "Loren Merritt",
+    "",
+    open,
+    NULL
+};


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