Adds Haar like features detection to mplayer.
Needs OpenCV >= 0.9.7, applies cleanly to mplayer SVN trunk r29324 (2009-05-25).
        -- Sylvain Fourmanoit <syfou@users.sourceforge.net>

diff -ruN a/DOCS/man/en/mplayer.1 b/DOCS/man/en/mplayer.1
--- a/DOCS/man/en/mplayer.1	2009-05-23 13:29:47.975606248 -0400
+++ b/DOCS/man/en/mplayer.1	2009-05-26 02:25:20.156730427 -0400
@@ -7335,6 +7335,77 @@
 .IPs <threshold>
 Threshold below which a pixel value is considered black (default: 32).
 .RE
+.PD 1
+.
+.TP
+.B haardetect=/path/to/cascade_file.xml[:options]
+Detect Haar like features in frames, using the OpenCV library.  
+Can be used, for instance, to detect faces with real time or near real time
+performances from most sources on modern hardware. 
+Have a look at OpenCV documentation to know more.
+.RE
+.PD 1
+.sp 1
+.RS
+The required parameter is:
+.RE
+.PD 0
+.RSs
+.IPs /path/to/cascade_file.xml
+Full path to the cascade classifier file to use, as supported by OpenCV. 
+This library provides a number of ready-made cascade files
+for detecting a number of features, including frontal and profile 
+faces.
+.RE
+.PD 1
+.sp 1
+.RS
+The options are:
+.RE
+.PD 0
+.RSs
+.IPs quality=<value>
+Determine how many times the detection box will be scaled when 
+analyzing a frame by computing its initial size according to scale 
+(box = frame_height / (scale ^ quality)).
+Default will be 7 (reasonably fast, detect features 
+about a fourth of the image height at default scale). 
+Higher values will shrink the initial detection box, making it
+more likely to detect smaller features, but using
+more cycles (8x more cycles for 2x quality).
+At default scale, it does not make sense to make it greater than about 11, 
+unless you are looking for very small details in the frames.
+.IPs scale=<value>
+Set by how much to increase the box size between each search iteration. 
+Default is 1.2, meaning box will grow 20% at each step.
+Useful range is typically between 1.1 and 1.3.
+.IPs box=<value>
+Set the initial <value> x <value> detection box size: it is basically 
+the estimated minimal bounding box of the searched features. 
+Default box is set so that it will take 7 iterations to cover the image
+(see quality above). 
+If you set quality and box at the same time, box will have precedence.
+.IPs neighbors=<value>
+Set the minimal number of neighboring zones to consider for a match.  
+Default is 2, but you can safely set to 3 most of the time 
+for eliminating false positive at the expense of more cycles. 
+Upper bound for this value depends on the cascade classifier.
+.IPs delta=<value>
+Set minimal time interval (in seconds) separating two frames you want
+to perform detection on. 
+Default is zero, meaning that all frames are analyzed.  
+It's usually significantly faster to use -sstep if you got
+a seekable stream and there is no other reason to play it in full.
+.IPs logfile=<filename>
+Set filename to output detection results to.
+Default is haar.log.
+.RE
+.PD 1
+.sp 1
+.RS
+Options can be listed colon-separated in any order. 
+Using only their first letter (e.g. q=8 instead of quality=8) works.
+.RE
 .
 .
 .
diff -ruN a/Makefile b/Makefile
--- a/Makefile	2009-05-23 13:29:47.975606248 -0400
+++ b/Makefile	2009-05-25 14:44:08.387237509 -0400
@@ -331,6 +331,7 @@
 SRCS_COMMON-$(XVID4)                 += libmpcodecs/vd_xvid4.c
 SRCS_COMMON-$(ZR)                    += libmpcodecs/vd_zrmjpeg.c \
                                         libmpcodecs/vf_zrmjpeg.c
+SRCS_COMMON-$(OPENCV)                += libmpcodecs/vf_haardetect.c 
 SRCS_COMMON = asxparser.c \
               codec-cfg.c \
               cpudetect.c \
diff -ruN a/configure b/configure
--- a/configure	2009-05-23 13:29:47.979605304 -0400
+++ b/configure	2009-05-25 14:44:08.391236248 -0400
@@ -261,6 +261,7 @@
   --disable-dvdread      disable libdvdread [autodetect]
   --disable-dvdread-internal  disable internal libdvdread [autodetect]
   --disable-libdvdcss-internal  disable internal libdvdcss [autodetect]
+  --disable-opencv       disable OpenCV lib [autodetect]
   --disable-cdparanoia   disable cdparanoia [autodetect]
   --disable-cddb         disable cddb [autodetect]
   --disable-bitmap-font  disable bitmap font support [enable]
@@ -630,6 +631,7 @@
 _dvdread=auto
 _dvdread_internal=auto
 _libdvdcss_internal=auto
+_opencv=auto
 _xanim=auto
 _real=auto
 _live=auto
@@ -1036,6 +1038,8 @@
   --disable-libdvdcss-internal)	_libdvdcss_internal=no	;;
   --enable-dvdnav)	_dvdnav=yes	;;
   --disable-dvdnav)	_dvdnav=no	;;
+  --enable-opencv)      _opencv=yes     ;;
+  --disable-opencv)     _opencv=no      ;;
   --enable-xanim)	_xanim=yes	;;
   --disable-xanim)	_xanim=no	;;
   --enable-real)	_real=yes	;;
@@ -5876,6 +5880,24 @@
 fi
 echores "$_libdvdcss_internal"
 
+echocheck "OpenCV"
+if test "$_opencv" = auto ; then
+    _opencv=no
+    cat > $TMPC <<EOF
+#include <opencv/cv.h>
+#include <opencv/highgui.h>
+
+int main(void) { cvLoadImage(NULL, 0); }
+EOF
+    cc_check '-lcv -lhighgui' && _opencv=yes
+fi
+if test "$_opencv" = yes ; then
+    def_opencv='#define CONFIG_OPENCV 1'
+    extra_ldflags="$extra_ldflags -lcv -lhighgui"
+else
+    def_opencv='#undef CONFIG_OPENCV'
+fi
+echores "$_opencv"
 
 echocheck "cdparanoia"
 if test "$_cdparanoia" = auto ; then
@@ -8207,6 +8229,7 @@
 DVDNAV_INTERNAL = $dvdnav_internal
 DVDREAD = $_dvdread
 DVDREAD_INTERNAL = $_dvdread_internal
+OPENCV = $_opencv
 DXR2 = $_dxr2
 DXR3 = $_dxr3
 ESD = $_esd
@@ -8556,6 +8579,7 @@
 $def_sortsub
 $def_stream_cache
 $def_pthread_cache
+$def_opencv
 
 
 /* CPU stuff */
diff -ruN a/libmpcodecs/vf.c b/libmpcodecs/vf.c
--- a/libmpcodecs/vf.c	2009-05-23 13:29:47.983605328 -0400
+++ b/libmpcodecs/vf.c	2009-05-25 14:44:08.391236248 -0400
@@ -97,6 +97,7 @@
 extern const vf_info_t vf_info_mcdeint;
 extern const vf_info_t vf_info_yadif;
 extern const vf_info_t vf_info_blackframe;
+extern const vf_info_t vf_info_haardetect;
 extern const vf_info_t vf_info_geq;
 extern const vf_info_t vf_info_ow;
 
@@ -190,6 +191,9 @@
 #endif
     &vf_info_yadif,
     &vf_info_blackframe,
+#ifdef CONFIG_OPENCV
+    &vf_info_haardetect,
+#endif
     &vf_info_ow,
     NULL
 };
diff -ruN a/libmpcodecs/vf_haardetect.c b/libmpcodecs/vf_haardetect.c
--- a/libmpcodecs/vf_haardetect.c	1969-12-31 19:00:00.000000000 -0500
+++ b/libmpcodecs/vf_haardetect.c	2009-05-26 01:44:27.848922969 -0400
@@ -0,0 +1,347 @@
+/*
+ * Detect Haar-Like Features from Frames
+ * (c) 2009 Sylvain Fourmanoit
+ *
+ * Based on OpenCV sample code: facedetect.c
+ * (c) 2000, Intel Corporation
+ *
+ * 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.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <opencv/cv.h>
+
+#include "config.h"
+#include "mp_msg.h"
+
+#include "img_format.h"
+#include "mp_image.h"
+#include "vf.h"
+
+struct vf_priv_s {
+  CvHaarClassifierCascade * cascade;
+  IplImage * image;
+  CvMemStorage * storage;
+  FILE * log;
+  unsigned int frame;
+  double threshold;
+  int    quality;
+  double scale_factor;
+  unsigned int box_size;
+  unsigned int min_neighbors;
+  double time_delta;
+};
+
+static int 
+cvErrorLog(int status, const char * func_name, const char * err_msg, 
+           const char * file_name, int line, struct vf_instance_s * vf) 
+{
+  mp_msg(MSGT_VFILTER, MSGL_WARN, "%s: OpenCV error - %s "
+         "(file: %s func: %s line: %u)", 
+         vf->info->name, err_msg, file_name, func_name, line);
+  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) 
+{
+  double ratio;
+
+  if (!vf->priv->box_size)
+    vf->priv->box_size = (int)(((double)height) / 
+                               exp(vf->priv->quality * 
+                                   log(vf->priv->scale_factor)));
+
+  if (!vf->priv->box_size) {
+    mp_msg(MSGT_VFILTER, MSGL_ERR,
+           "%s: computed box size is zero.\n", vf->info->name);
+    return 0;
+  }
+
+  if ((ratio = (((double)vf->priv->box_size) / height)) < .1)
+    mp_msg(MSGT_VFILTER, MSGL_WARN,
+           "%s: box size / height ratio is awfully small (%.1f%%)\n",
+           vf->info->name, ratio * 100);
+
+  if (!((vf->priv->image = cvCreateImage(cvSize(width, height), 8, 3)))) {
+    mp_msg(MSGT_VFILTER, MSGL_ERR,
+           "%s: could not create OpenCV image\n", vf->info->name);
+    return 0;
+  }
+
+  return vf_next_config(vf,width,height,d_width,d_height,flags,outfmt);
+}
+
+static int 
+query_format(struct vf_instance_s *vf, unsigned fmt) 
+{
+  switch (fmt) {
+    case IMGFMT_YV12:
+    case IMGFMT_I420:
+    case IMGFMT_IYUV:
+    case IMGFMT_YVU9:
+    case IMGFMT_Y800:
+    case IMGFMT_Y8:
+      /* preview would use vo_draw_alpha_yv12 */
+    case IMGFMT_IF09:
+    case IMGFMT_CLPL:
+    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);
+    default:
+      return 0;
+  }
+}
+
+static int 
+put_image(struct vf_instance_s* vf, mp_image_t *mpi, double pts)
+{
+  mp_image_t *dmpi;
+  int i, x, y;
+  char * yplane, * dest, * pos;
+  CvSeq * objects;
+  CvRect * r;
+
+  if (pts >= vf->priv->threshold) {
+    vf->priv->threshold = ((pts - vf->priv->threshold <= vf->priv->time_delta)?
+                           vf->priv->threshold:pts) + vf->priv->time_delta;
+
+    /* Just keep luma since we only care about grayscale  */
+    for (yplane = mpi->planes[0], dest = vf->priv->image->imageData, y = 0;
+         y < mpi->h; 
+         ++y, yplane += mpi->stride[0], dest += vf->priv->image->widthStep)
+      for (pos = dest, x=0; x < mpi->width; ++x) {
+        *(pos++) = yplane[x];
+        *(pos++) = yplane[x];
+        *(pos++) = yplane[x];
+      }
+
+    cvClearMemStorage(vf->priv->storage);
+    objects = cvHaarDetectObjects(vf->priv->image, 
+                                  vf->priv->cascade, 
+                                  vf->priv->storage,
+                                  vf->priv->scale_factor,
+                                  vf->priv->min_neighbors, 
+                                  CV_HAAR_DO_CANNY_PRUNING, 
+                                  cvSize(vf->priv->box_size, 
+                                         vf->priv->box_size));
+
+    for (i = 0; i < ((objects)?objects->total:0); ++i) {
+      r = (CvRect*)cvGetSeqElem(objects, i);
+      mp_msg(MSGT_VFILTER, MSGL_INFO, 
+             "%s: (%.3f s., frame %u) object %u at %ux%u+%u+%u\n", 
+             vf->info->name, pts, vf->priv->frame,  
+             i, r->width, r->height, r->x, r->y);
+      if (vf->priv->log)
+        fprintf(vf->priv->log, "%10.3f%10u%10u%10u%10u\n", 
+                pts, r->x, r->y, r->width, r->height);      
+    }
+  }
+  
+  dmpi = vf_get_image(vf->next, mpi->imgfmt, MP_IMGTYPE_EXPORT, 0,
+                      mpi->width, mpi->height);
+  
+  dmpi->planes[0] = mpi->planes[0];
+  dmpi->stride[0] = mpi->stride[0];
+  dmpi->planes[1] = mpi->planes[1];
+  dmpi->stride[1] = mpi->stride[1];
+  dmpi->planes[2] = mpi->planes[2];
+  dmpi->stride[2] = mpi->stride[2];
+
+  vf_clone_mpi_attributes(dmpi, mpi);
+
+  ++vf->priv->frame;
+  return vf_next_put_image(vf, dmpi, pts);
+}
+
+static int 
+control(struct vf_instance_s* vf, int request, void* data)
+{
+  return vf_next_control(vf,request,data);
+}
+
+static void 
+uninit(struct vf_instance_s *vf) {
+  if (vf->priv) {
+    if (vf->priv->cascade) cvRelease((void**)&vf->priv->cascade);
+    if (vf->priv->image) cvReleaseImage(&vf->priv->image);
+    if (vf->priv->storage) cvReleaseMemStorage(&vf->priv->storage);
+    if (vf->priv->log) fclose(vf->priv->log);
+    free(vf->priv);
+  }
+}
+
+static int 
+open(vf_instance_t *vf, char* args)
+{
+  int box_flag = 0;
+  char * ap, * q, * a;
+  char * profilename = NULL, * logfilename = "haar.log";
+  
+  if (!(vf->priv = calloc(1, sizeof(struct vf_priv_s))))
+    goto nomem;
+  
+  cvRedirectError((CvErrorCallback)cvErrorLog, (void*)vf, NULL);
+  
+  vf->config = config;
+  vf->put_image = put_image;
+  vf->control = control;
+  vf->uninit = uninit;
+  vf->query_format = query_format;
+
+  vf->priv->quality = 7;
+  vf->priv->scale_factor = 1.2;
+  vf->priv->min_neighbors = 2;
+  
+  if (args && !(args = strdup(args)))
+    goto nomem;
+  
+  if ((ap = args))
+    while(*ap) {
+      q = ap;
+      if ((ap = strchr(q, ':'))) *ap ++= 0; else ap = q + strlen(q);
+      if ((a = strchr(q, '='))) *a ++= 0; else a = q + strlen(q);
+      
+      if (q == args) {
+        profilename = q;
+        continue;
+      }
+
+      switch(*q) {
+        case 0:                                               break;
+        case 'q': vf->priv->quality = atoi(a);                break;
+        case 's': vf->priv->scale_factor = atof(a);           break;
+        case 'b': box_flag = 1; vf->priv->box_size = atoi(a); break;
+        case 'n': vf->priv->min_neighbors = atoi(a);          break;
+        case 'd': vf->priv->time_delta = atof(a);             break;
+        case 'l': logfilename = a;                            break;
+        case 'h':
+          mp_msg(MSGT_VFILTER, MSGL_INFO,
+                 "\n%s options:\n\n"
+                 "quality=value    "
+                 "- Set quality (default: %u)\n"
+                 "scale=value      "
+                 "- Set search scale factor (default: %.2f)\n"
+                 "box=value        "
+                 "- Set minimal feature size\n"
+                 "                 "
+                 "  (default is set so detection takes %u scaling steps)\n"
+                 "neighbors=value  "
+                 "- Set minimal number of neighbors (default: %u)\n"
+                 "delta=value      "
+                 "- Set delay in seconds between consecutive detections\n"
+                 "                 "
+                 "  (default is zero, meaning every frame is analyzed)\n"
+                 "logfile=filename "
+                 "- Set output log file (default: %s)\n\n",
+                 vf->info->name, 
+                 vf->priv->quality,
+                 vf->priv->scale_factor, 
+                 vf->priv->quality,
+                 vf->priv->min_neighbors,
+                 logfilename);
+          break;
+        default:
+          mp_msg(MSGT_VFILTER, MSGL_FATAL,
+                 "%s: Unknown argument %s.\n", vf->info->name, q);
+          goto fail;
+      }
+    }
+
+  if (!profilename || strlen(profilename) == 0) {
+    mp_msg(MSGT_VFILTER, MSGL_FATAL,
+           "%s: No Haar cascade classifier xml file specified\n", 
+           vf->info->name);
+    goto fail;
+  }
+
+  if (vf->priv->quality <= 1) {
+    mp_msg(MSGT_VFILTER, MSGL_FATAL,
+           "%s: Quality should be greater than 1\n", 
+           vf->info->name);
+    goto fail;
+  }
+
+  if (vf->priv->scale_factor <= 1) {
+    mp_msg(MSGT_VFILTER, MSGL_FATAL,
+           "%s: Scale factor should be greater than 1\n", 
+           vf->info->name);
+    goto fail;
+  }
+
+  if (box_flag) {
+    if (vf->priv->box_size <= 1) {
+      mp_msg(MSGT_VFILTER, MSGL_FATAL,
+             "%s: Box size should be greater than 1\n", 
+             vf->info->name);
+      goto fail;
+    }
+  } else vf->priv->box_size = 0;
+    
+  if (vf->priv->min_neighbors < 1) {
+    mp_msg(MSGT_VFILTER, MSGL_FATAL,
+           "%s: Minimal number of neighbors box size should be positive\n", 
+           vf->info->name);
+    goto fail;
+  }
+
+  if ((vf->priv->log = fopen(logfilename, "w")))
+    fprintf(vf->priv->log, 
+            "#      pts         x         y     width    height\n");
+  else
+    mp_msg(MSGT_VFILTER, MSGL_INFO, 
+           "%s: Could not open log file '%s' for writing\n",
+           vf->info->name, logfilename);
+  
+  if (!(vf->priv->cascade = (CvHaarClassifierCascade*)
+        cvLoad(profilename, 0, 0, 0))) {
+    mp_msg(MSGT_VFILTER, MSGL_FATAL,
+           "%s: Could not load Haar cascade classifier xml file '%s'\n", 
+           vf->info->name, profilename);
+    goto fail;
+  }
+
+  if (!(vf->priv->storage = cvCreateMemStorage(0)))
+    goto nomem;
+  
+  free(args);
+  return 1;
+nomem:
+  mp_msg(MSGT_VFILTER, MSGL_FATAL,
+         "%s: Not enough memory.\n", vf->info->name);
+fail:
+  uninit(vf);
+  free(args);
+  return 0;
+}
+
+const vf_info_t vf_info_haardetect = {
+  "detects Haar like features",
+  "haardetect",
+  "Sylvain Fourmanoit",
+  "Useful for detecting many kinds of features, including faces",
+  open,
+  NULL
+};