Added three sample video hooks. See the (rudimentary) documentation on what

they do and their capabilities.

Originally committed as revision 1265 to svn://svn.ffmpeg.org/ffmpeg/trunk

6 files changed, 841 insertions, 0 deletions

diff --git a/vhook/Makefile b/vhook/Makefile
new file mode 100644
index 0000000000..5f198058f0
--- /dev/null
+++ b/vhook/Makefile
@@ -0,0 +1,27 @@
+include ../config.mak
+
+CFLAGS=-fPIC $(OPTFLAGS) -g -Wall -I.. -I../libav -I../libavcodec -DHAVE_AV_CONFIG_H
+
+HOOKS=null.so fish.so
+
+ifeq ($(HAVE_IMLIB2),yes)
+    HOOKS += imlib2.so
+endif    
+
+all: $(HOOKS) hooks.html
+
+install:
+	install -s -m 755 $(HOOKS) $(INSTDIR)
+
+imlib2.so: imlib2.o
+	$(CC) -g -o $@ -shared $< -lImlib2
+	rm $<
+
+%.so: %.o
+	$(CC) -g -o $@ -shared $<
+
+%.html: %.texi
+	texi2html -monolithic -number $<
+
+clean:
+	rm -f *.o *.so *~
diff --git a/vhook/fish.c b/vhook/fish.c
new file mode 100644
index 0000000000..c25ba60719
--- /dev/null
+++ b/vhook/fish.c
@@ -0,0 +1,330 @@
+/*
+ * Fish Detector Hook
+ * Copyright (c) 2002 Philip Gladstone
+ *
+ * This file implements a fish detector. It is used to see when a 
+ * goldfish passes in front of the camera. It does this by counting
+ * the number of input pixels that fall within a particular HSV
+ * range.
+ *
+ * It takes a multitude of arguments:
+ *
+ * -h <num>-<num>    the range of H values that are fish
+ * -s <num>-<num>    the range of S values that are fish
+ * -v <num>-<num>    the range of V values that are fish
+ * -z                zap all non-fish values to black
+ * -l <num>          limit the number of saved files to <num>
+ * -i <num>          only check frames every <num> seconds
+ * -t <num>          the threshold for the amount of fish pixels (range 0-1)
+ * -d                turn debugging on
+ * -D <directory>    where to put the fish images
+ *
+ * This library 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 of the License, or (at your option) any later version.
+ *
+ * This library 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 library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+#include <stdlib.h>
+#include <fcntl.h>
+#include <getopt.h>
+#include <stdarg.h>
+#include <string.h>
+#include <sys/time.h>
+#include <stdio.h>
+#include <dirent.h>
+
+#include "framehook.h"
+#include "dsputil.h"
+
+#define SCALE_BITS 10
+ 
+#define C_Y  (76309 >> (16 - SCALE_BITS))
+#define C_RV (117504 >> (16 - SCALE_BITS))
+#define C_BU (138453 >> (16 - SCALE_BITS))
+#define C_GU (13954 >> (16 - SCALE_BITS))
+#define C_GV (34903 >> (16 - SCALE_BITS))                                       
+
+  
+typedef struct {
+    int h;  /* 0 .. 360 */
+    int s;  /* 0 .. 255 */
+    int v;  /* 0 .. 255 */
+} HSV;
+              
+typedef struct {
+    int zapping;
+    int threshold;
+    HSV dark, bright;
+    char *dir;
+    int file_limit;
+    int debug;
+    int min_interval;
+    INT64 next_pts;
+    int inset;
+    int min_width;
+} ContextInfo;
+
+static void dorange(const char *s, int *first, int *second, int maxval)
+{
+    sscanf(s, "%d-%d", first, second);
+    if (*first > maxval)
+        *first = maxval;
+    if (*second > maxval)
+        *second = maxval;
+}
+
+
+int Configure(void **ctxp, int argc, char *argv[])
+{
+    ContextInfo *ci;
+    int c;
+
+    *ctxp = av_mallocz(sizeof(ContextInfo));
+    ci = (ContextInfo *) *ctxp;
+
+    optind = 0;
+
+    ci->dir = "/tmp";
+    ci->threshold = 1000;
+    ci->file_limit = 100;
+    ci->min_interval = 1000000;
+    ci->inset = 10;     /* Percent */
+
+    while ((c = getopt(argc, argv, "w:i:dh:s:v:zl:t:D:")) > 0) {
+        switch (c) {
+            case 'h':
+                dorange(optarg, &ci->dark.h, &ci->bright.h, 360);
+                break;
+            case 's':
+                dorange(optarg, &ci->dark.s, &ci->bright.s, 255);
+                break;
+            case 'v':
+                dorange(optarg, &ci->dark.v, &ci->bright.v, 255);
+                break;
+            case 'z':
+                ci->zapping = 1;
+                break;
+            case 'l':
+                ci->file_limit = atoi(optarg);
+                break;
+            case 'i':
+                ci->min_interval = 1000000 * atof(optarg);
+                break;
+            case 't':
+                ci->threshold = atof(optarg) * 1000;
+                break;
+            case 'w':
+                ci->min_width = atoi(optarg);
+                break;
+            case 'd':
+                ci->debug++;
+                break;
+            case 'D':
+                ci->dir = strdup(optarg);
+                break;
+            default:
+                fprintf(stderr, "Unrecognized argument '%s'\n", argv[optind]);
+                return -1;
+        }
+    }
+
+    fprintf(stderr, "Fish detector configured:\n");
+    fprintf(stderr, "    HSV range: %d,%d,%d - %d,%d,%d\n",
+                        ci->dark.h,
+                        ci->dark.s,
+                        ci->dark.v,
+                        ci->bright.h,
+                        ci->bright.s,
+                        ci->bright.v);
+
+    return 0;
+}
+
+static void get_hsv(HSV *hsv, int r, int g, int b)
+{
+    int i, v, x, f;
+         
+    x = (r < g) ? r : g;
+    if (b < x)
+        x = b;
+    v = (r > g) ? r : g;
+    if (b > v)
+        v = b;
+          
+    if (v == x) {
+        hsv->h = 0;
+        hsv->s = 0;
+        hsv->v = v;
+        return;
+    }
+       
+    if (r == v) {
+        f = g - b;
+        i = 0;
+    } else if (g == v) {
+        f = b - r;
+        i = 2 * 60;
+    } else {
+        f = r - g;
+        i = 4 * 60;
+    }
+        
+    hsv->h = i + (60 * f) / (v - x);
+    if (hsv->h < 0)
+        hsv->h += 360;
+
+    hsv->s = (255 * (v - x)) / v;
+    hsv->v = v;
+         
+    return;
+}                                                                               
+
+void Process(void *ctx, AVPicture *picture, enum PixelFormat pix_fmt, int width, int height, INT64 pts)
+{
+    ContextInfo *ci = (ContextInfo *) ctx;
+    UINT8 *cm = cropTbl + MAX_NEG_CROP;                                         
+    int rowsize = picture->linesize[0];
+
+    if (pts < ci->next_pts)
+        return;
+
+    if (width < ci->min_width)
+        return;
+
+    ci->next_pts = pts + 1000000;    
+
+    if (pix_fmt == PIX_FMT_YUV420P) {
+        UINT8 *y, *u, *v;
+        int width2 = width >> 1;
+        int inrange = 0;
+        int pixcnt;
+        int h;
+        int h_start, h_end;
+        int w_start, w_end;
+
+        h_end = 2 * ((ci->inset * height) / 200);
+        h_start = height - h_end;
+
+        w_end = (ci->inset * width2) / 100;
+        w_start = width2 - w_end;
+
+        pixcnt = ((h_start - h_end) >> 1) * (w_start - w_end);
+
+        y = picture->data[0];
+        u = picture->data[1];
+        v = picture->data[2];
+
+        for (h = h_start; h > h_end; h -= 2) {
+            int w;
+
+            for (w = w_start; w > w_end; w--) {
+                int r,g,b;
+                int Y, U, V;
+                HSV hsv;
+
+                U = u[0] - 128;
+                V = v[0] - 128;
+
+                Y = (y[0] - 16) * C_Y;
+
+                r = cm[(Y + C_RV * V + (1 << (SCALE_BITS - 1))) >> SCALE_BITS];
+                g = cm[(Y + - C_GU * U - C_GV * V + (1 << (SCALE_BITS - 1))) >> SCALE_BITS];
+                b = cm[(Y + C_BU * U + (1 << (SCALE_BITS - 1))) >> SCALE_BITS];
+
+                get_hsv(&hsv, r, g, b);
+
+                if (ci->debug > 1) 
+                    fprintf(stderr, "(%d,%d,%d) -> (%d,%d,%d)\n",
+                        r,g,b,hsv.h,hsv.s,hsv.v);
+
+
+                if (hsv.h >= ci->dark.h && hsv.h <= ci->bright.h &&
+                    hsv.s >= ci->dark.s && hsv.s <= ci->bright.s &&
+                    hsv.v >= ci->dark.v && hsv.v <= ci->bright.v) {            
+                    inrange++;
+                } else if (ci->zapping) {
+                    y[0] = y[1] = y[rowsize] = y[rowsize + 1] = 0;
+                }
+
+                y+= 2;
+                u++;
+                v++;
+            }
+
+            y += picture->linesize[0] * 2 - width;
+            u += picture->linesize[1] - width2;
+            v += picture->linesize[2] - width2;
+        }
+
+        if (inrange * 1000 / pixcnt >= ci->threshold) {
+            /* Save to file */
+            int size;
+            char *buf;
+            AVPicture picture1;
+            static int frame_counter;
+            static int foundfile;
+
+            if (ci->debug) 
+                fprintf(stderr, "Fish: Inrange=%d of %d = %d threshold\n", inrange, pixcnt, 1000 * inrange / pixcnt);
+
+            if ((frame_counter++ % 20) == 0) {
+                /* Check how many files we have */
+                DIR *d;
+
+                foundfile = 0;
+
+                d = opendir(ci->dir);
+                if (d) {
+                    struct dirent *dent;
+
+                    while ((dent = readdir(d))) {
+                        if (strncmp("fishimg", dent->d_name, 7) == 0) {
+                            if (strcmp(".ppm", dent->d_name + strlen(dent->d_name) - 4) == 0) {
+                                foundfile++;
+                            }
+                        }
+                    }
+                    closedir(d);
+                }
+            }
+
+            if (foundfile < ci->file_limit) {
+                size = avpicture_get_size(PIX_FMT_RGB24, width, height);
+                buf = av_malloc(size);
+
+                avpicture_fill(&picture1, buf, PIX_FMT_RGB24, width, height);
+                if (img_convert(&picture1, PIX_FMT_RGB24, 
+                                picture, pix_fmt, width, height) >= 0) {
+                    /* Write out the PPM file */
+
+                    FILE *f;
+                    char fname[256];
+
+                    sprintf(fname, "%s/fishimg%ld_%lld.ppm", ci->dir, time(0), pts);
+                    f = fopen(fname, "w");
+                    if (f) {
+                        fprintf(f, "P6 %d %d 255\n", width, height);
+                        fwrite(buf, width * height * 3, 1, f);
+                        fclose(f);
+                    }
+                }
+
+                av_free(buf);
+                ci->next_pts = pts + ci->min_interval;    
+            }
+        }
+    }
+}
+
+/* To ensure correct typing */
+FrameHookConfigureFn ConfigureFn = Configure;
+FrameHookProcessFn ProcessFn = Process;
diff --git a/vhook/hooks.html b/vhook/hooks.html
new file mode 100644
index 0000000000..750d15cc92
--- /dev/null
+++ b/vhook/hooks.html
@@ -0,0 +1,95 @@
+<HTML>
+<HEAD>
+<!-- This HTML file has been created by texi2html 1.51
+     from hooks.texi on 20 November 2002 -->
+
+<TITLE>Video Hook Documentation</TITLE>
+</HEAD>
+<BODY>
+<H1>Video Hook Documentation</H1>
+<P>
+<P><HR><P>
+<H1>Table of Contents</H1>
+<UL>
+<LI><A NAME="TOC1" HREF="hooks.html#SEC1">1  Introduction</A>
+<UL>
+<LI><A NAME="TOC2" HREF="hooks.html#SEC2">1.1  null.c</A>
+<LI><A NAME="TOC3" HREF="hooks.html#SEC3">1.2  fish.c</A>
+<LI><A NAME="TOC4" HREF="hooks.html#SEC4">1.3  imlib2.c</A>
+</UL>
+</UL>
+<P><HR><P>
+
+<P>
+Video Hook Documentation
+<P>
+
+</P>
+
+
+
+<H1><A NAME="SEC1" HREF="hooks.html#TOC1">1  Introduction</A></H1>
+
+<P>
+The video hook functionality is designed (mostly) for live video. It allows
+the video to be modified or examined between the decoder and the encoder.
+
+</P>
+<P>
+Any number of hook modules can be placed inline, and they are run in the
+order that they were specified on the ffmpeg command line.
+
+</P>
+<P>
+Three modules are provided and are described below. They are all intended to
+be used as a base for your own modules. 
+
+</P>
+<P>
+Modules are loaded using the -vhook option to ffmpeg. The value of this parameter
+is a space seperated list of arguments. The first is the module name, and the rest
+are passed as arguments to the Configure function of the module.
+
+</P>
+
+
+<H2><A NAME="SEC2" HREF="hooks.html#TOC2">1.1  null.c</A></H2>
+
+<P>
+This does nothing. Actually it converts the input image to RGB24 and then converts
+it back again. This is meant as a sample that you can use to test your setup.
+
+</P>
+
+
+<H2><A NAME="SEC3" HREF="hooks.html#TOC3">1.2  fish.c</A></H2>
+
+<P>
+This implements a 'fish detector'. Essentially it converts the image into HSV
+space and tests whether more than a certain percentage of the pixels fall into
+a specific HSV cuboid. If so, then the image is saved into a file for processing
+by other bits of code.
+
+</P>
+<P>
+Why use HSV? It turns out that HSV cuboids represent a more compact range of
+colors than would an RGB cuboid.
+
+</P>
+
+
+<H2><A NAME="SEC4" HREF="hooks.html#TOC4">1.3  imlib2.c</A></H2>
+
+<P>
+This allows a caption to be placed onto each frame. It supports inserting the
+time and date. By using the imlib functions, it would be easy to add your own
+graphical logo, add a frame/border, etc.
+
+</P>
+
+<P><HR><P>
+This document was generated on 20 November 2002 using the
+<A HREF="http://wwwcn.cern.ch/dci/texi2html/">texi2html</A>
+translator version 1.51.</P>
+</BODY>
+</HTML>
diff --git a/vhook/hooks.texi b/vhook/hooks.texi
new file mode 100644
index 0000000000..7eb2da8848
--- /dev/null
+++ b/vhook/hooks.texi
@@ -0,0 +1,49 @@
+\input texinfo @c -*- texinfo -*-
+
+@settitle Video Hook Documentation
+@titlepage
+@sp 7
+@center @titlefont{Video Hook Documentation}
+@sp 3
+@end titlepage
+
+
+@chapter Introduction
+
+
+The video hook functionality is designed (mostly) for live video. It allows
+the video to be modified or examined between the decoder and the encoder.
+
+Any number of hook modules can be placed inline, and they are run in the
+order that they were specified on the ffmpeg command line.
+
+Three modules are provided and are described below. They are all intended to
+be used as a base for your own modules. 
+
+Modules are loaded using the -vhook option to ffmpeg. The value of this parameter
+is a space seperated list of arguments. The first is the module name, and the rest
+are passed as arguments to the Configure function of the module.
+
+@section null.c
+
+This does nothing. Actually it converts the input image to RGB24 and then converts
+it back again. This is meant as a sample that you can use to test your setup.
+
+@section fish.c
+
+This implements a 'fish detector'. Essentially it converts the image into HSV
+space and tests whether more than a certain percentage of the pixels fall into
+a specific HSV cuboid. If so, then the image is saved into a file for processing
+by other bits of code.
+
+Why use HSV? It turns out that HSV cuboids represent a more compact range of
+colors than would an RGB cuboid.
+
+@section imlib2.c
+
+This allows a caption to be placed onto each frame. It supports inserting the
+time and date. By using the imlib functions, it would be easy to add your own
+graphical logo, add a frame/border, etc.
+
+
+@bye
diff --git a/vhook/imlib2.c b/vhook/imlib2.c
new file mode 100644
index 0000000000..3e11d9c1b2
--- /dev/null
+++ b/vhook/imlib2.c
@@ -0,0 +1,267 @@
+/*
+ * imlib2 based hook 
+ * Copyright (c) 2002 Philip Gladstone
+ * 
+ * This module implements a text overlay for a video image. Currently it
+ * supports a fixed overlay or reading the text from a file. The string
+ * is passed through strftime so that it is easy to imprint the date and
+ * time onto the image.
+ *
+ * Options:
+ *
+ * -c <color>           The color of the text
+ * -F <fontname>        The font face and size
+ * -t <text>            The text
+ * -f <filename>        The filename to read text from
+ * -x <num>             X coordinate to start text
+ * -y <num>             Y coordinate to start text
+ *
+ * This module is very much intended as an example of what could be done.
+ * For example, you could overlay an image (even semi-transparent) like
+ * TV stations do. You can manipulate the image using imlib2 functions
+ * in any way. 
+ *
+ * One caution is that this is an expensive process -- in particular the
+ * conversion of the image into RGB and back is time consuming. For some
+ * special cases -- e.g. painting black text -- it would be faster to paint
+ * the text into a bitmap and then combine it directly into the YUV
+ * image. However, this code is fast enough to handle 10 fps of 320x240 on a 
+ * 900MHz Duron in maybe 15% of the CPU.
+ *
+ * This library 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 of the License, or (at your option) any later version.
+ *
+ * This library 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 library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <getopt.h>
+#include <stdarg.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/time.h>
+#include <X11/Xlib.h>
+#include <Imlib2.h>                                                             
+
+#include "framehook.h"
+
+typedef struct {
+    int dummy;
+    Imlib_Font fn;
+    char *text;
+    char *file;
+    int r, g, b;
+    int x;
+    int y;
+    struct _CachedImage *cache;
+} ContextInfo;
+
+typedef struct _CachedImage {
+    struct _CachedImage *next;
+    Imlib_Image image;
+    int width;
+    int height;
+} CachedImage;
+
+
+int Configure(void **ctxp, int argc, char *argv[])
+{
+    int c;
+    ContextInfo *ci;
+    char *font = "LucidaSansDemiBold/16";
+    char *fp = getenv("FONTPATH");
+    char *color = 0;
+    FILE *f;
+
+    *ctxp = av_mallocz(sizeof(ContextInfo));
+    ci = (ContextInfo *) *ctxp;
+
+    optind = 0;
+
+    if (fp)
+        imlib_add_path_to_font_path(fp);
+
+    while ((c = getopt(argc, argv, "c:f:F:t:x:y:")) > 0) {
+        switch (c) {
+            case 'c':
+                color = optarg;
+                break;
+            case 'F':
+                font = optarg;
+                break;
+            case 't':
+                ci->text = strdup(optarg);
+                break;
+            case 'f':
+                ci->file = strdup(optarg);
+                break;
+            case 'x':
+                ci->x = atoi(optarg);
+                break;
+            case 'y':
+                ci->y = atoi(optarg);
+                break;
+            case '?':
+                fprintf(stderr, "Unrecognized argument '%s'\n", argv[optind]);
+                return -1;
+        }
+    }
+
+    ci->fn = imlib_load_font(font);
+    if (!ci->fn) {
+        fprintf(stderr, "Failed to load font '%s'\n", font);
+        return -1;
+    }
+    imlib_context_set_font(ci->fn);
+    imlib_context_set_direction(IMLIB_TEXT_TO_RIGHT);                           
+
+    if (color) {
+        char buff[256];
+        int done = 0;
+
+        f = fopen("/usr/lib/X11/rgb.txt", "r");
+        if (!f) {
+            fprintf(stderr, "Failed to find rgb.txt\n");
+            return -1;
+        }
+        while (fgets(buff, sizeof(buff), f)) {
+            int r, g, b;
+            char colname[80];
+
+            if (sscanf(buff, "%d %d %d %64s", &r, &g, &b, colname) == 4 &&
+                strcasecmp(colname, color) == 0) {
+                ci->r = r;
+                ci->g = g;
+                ci->b = b;
+                /* fprintf(stderr, "%s -> %d,%d,%d\n", colname, r, g, b); */
+                done = 1;
+                break;
+            }
+        }
+        fclose(f);
+        if (!done) {
+            fprintf(stderr, "Unable to find color '%s' in rgb.txt\n", color);
+            return -1;
+        }
+    }
+    imlib_context_set_color(ci->r, ci->g, ci->b, 255);
+    return 0;
+}
+
+static Imlib_Image get_cached_image(ContextInfo *ci, int width, int height)
+{
+    CachedImage *cache;
+
+    for (cache = ci->cache; cache; cache = cache->next) {
+        if (width == cache->width && height == cache->height)
+            return cache->image;
+    }
+
+    return NULL;
+}
+
+static void put_cached_image(ContextInfo *ci, Imlib_Image image, int width, int height)
+{
+    CachedImage *cache = av_mallocz(sizeof(*cache));
+
+    cache->image = image;
+    cache->width = width;
+    cache->height = height;
+    cache->next = ci->cache;
+    ci->cache = cache;
+}
+
+void Process(void *ctx, AVPicture *picture, enum PixelFormat pix_fmt, int width, int height, INT64 pts)
+{
+    ContextInfo *ci = (ContextInfo *) ctx;
+    AVPicture picture1;
+    Imlib_Image image;
+    DATA32 *data;
+
+    image = get_cached_image(ci, width, height);
+
+    if (!image) {
+        image = imlib_create_image(width, height);
+        put_cached_image(ci, image, width, height);
+    }
+
+    imlib_context_set_image(image);
+    data = imlib_image_get_data();
+
+    if (pix_fmt != PIX_FMT_BGRA32) {
+        avpicture_fill(&picture1, (UINT8 *) data, PIX_FMT_BGRA32, width, height);
+        if (img_convert(&picture1, PIX_FMT_BGRA32, 
+                        picture, pix_fmt, width, height) < 0) {
+            goto done;
+        }
+    } else {
+        av_abort();
+    }
+
+    imlib_image_set_has_alpha(0);
+
+    {
+        int wid, hig, h_a, v_a;                                                   
+        char buff[1000];
+        char tbuff[1000];
+        char *tbp = ci->text;
+        time_t now = time(0);
+        char *p, *q;
+        int x, y;
+
+        if (ci->file) {
+            int fd = open(ci->file, O_RDONLY);
+
+            if (fd < 0) {
+                tbp = "[File not found]";
+            } else {
+                int l = read(fd, tbuff, sizeof(tbuff) - 1);
+
+                if (l >= 0) {
+                    tbuff[l] = 0;
+                    tbp = tbuff;
+                } else {
+                    tbp = "[I/O Error]";
+                }
+                close(fd);
+            }
+        }
+
+        strftime(buff, sizeof(buff), tbp, localtime(&now));
+
+        x = ci->x;
+        y = ci->y;
+
+        for (p = buff; p; p = q) {
+            q = strchr(p, '\n');
+            if (q)
+                *q++ = 0;
+
+            imlib_text_draw_with_return_metrics(x, y, p, &wid, &hig, &h_a, &v_a);
+            y += v_a;
+        }
+    }
+
+    if (pix_fmt != PIX_FMT_BGRA32) {
+        if (img_convert(picture, pix_fmt, 
+                        &picture1, PIX_FMT_BGRA32, width, height) < 0) {
+        }
+    }
+
+done:
+    ;
+}
+
+/* To ensure correct typing */
+FrameHookConfigureFn ConfigureFn = Configure;
+FrameHookProcessFn ProcessFn = Process;
diff --git a/vhook/null.c b/vhook/null.c
new file mode 100644
index 0000000000..1fcb04b1c6
--- /dev/null
+++ b/vhook/null.c
@@ -0,0 +1,73 @@
+/*
+ * Null Video Hook 
+ * Copyright (c) 2002 Philip Gladstone
+ *
+ * This library 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 of the License, or (at your option) any later version.
+ *
+ * This library 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 library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+#include <stdio.h>
+
+#include "framehook.h"
+
+typedef struct {
+    int dummy;
+} ContextInfo;
+
+
+int Configure(void **ctxp, int argc, char *argv[])
+{
+    fprintf(stderr, "Called with argc=%d\n", argc);
+
+    *ctxp = av_mallocz(sizeof(ContextInfo));
+    return 0;
+}
+
+void Process(void *ctx, AVPicture *picture, enum PixelFormat pix_fmt, int width, int height, INT64 pts)
+{
+    ContextInfo *ci = (ContextInfo *) ctx;
+    char *buf = 0;
+    AVPicture picture1;
+    AVPicture *pict = picture;
+
+    (void) ci;
+
+    if (pix_fmt != PIX_FMT_RGB24) {
+        int size;
+
+        size = avpicture_get_size(PIX_FMT_RGB24, width, height);
+        buf = av_malloc(size);
+
+        avpicture_fill(&picture1, buf, PIX_FMT_RGB24, width, height);
+        if (img_convert(&picture1, PIX_FMT_RGB24, 
+                        picture, pix_fmt, width, height) < 0) {
+            av_free(buf);
+            return;
+        }
+        pict = &picture1;
+    }
+
+    /* Insert filter code here */
+
+    if (pix_fmt != PIX_FMT_RGB24) {
+        if (img_convert(picture, pix_fmt, 
+                        &picture1, PIX_FMT_RGB24, width, height) < 0) {
+        }
+    }
+
+    av_free(buf);
+}
+
+/* To ensure correct typing */
+FrameHookConfigureFn ConfigureFn = Configure;
+FrameHookProcessFn ProcessFn = Process;