path: root/xine_post_autocrop.c

/*
 * Copyright (C) 2006 the xine project
 * 
 * This file is part of xine, a free video player.
 * 
 * xine 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.
 * 
 * xine 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 this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA
 *
 * $Id: xine_post_autocrop.c,v 1.2 2006-08-20 20:30:41 phintuka Exp $
 *
 * autocrop video filter by Petri Hintukainen 25/03/2006
 *
 * Automatically crop 4:3 letterbox frames to 16:9
 * 
 * based on expand.c
 *
 */

#ifdef HAVE_CONFIG_H 
#include "config.h"     /* ARCH_X86 */
#endif

#include <stdint.h>

#include <xine/xine_internal.h>
#include <xine/post.h>


/*#define TRACE_FRAME      */
/*#define USE_CROP         Crop frame at video_out instead of copying */
/*#define MARK_FRAME       Draw boundary markers on frames */
/*#define ENABLE_64BIT 1   Force using of 64-bit routines */

/*#define TRACE printf     */
#define TRACE(x...) do{}while(0)
#define INFO  printf

/*
  TODO: 
   - more reliable border detection, including channel logo detection
   - MMX routines
   - OSD re-positioning (?)
*/


/*
 * Constants
 */

#if defined(__WORDSIZE)
#  if __WORDSIZE == 64
#    warning Compiling for 64-bit system
#    define ENABLE_64BIT (sizeof(int) > 32)
#  endif
#endif

#define TRESHOLD       (0x1f)            /* "black" treshold value for Y-plane 
					    borders are not always black) */
#define TRESHOLD32     (0x1f1f1f1f)
#define TRESHOLD64     (UINT64_C(0x1f1f1f1f1f1f1f1f)) 
#define TRESHOLD_INV   (~(TRESHOLD))
#define TRESHOLD32_INV (~(TRESHOLD32))   
#define TRESHOLD64_INV (~(TRESHOLD64))
#define UVBLACK        (0x80)            /* "black" for U/V planes  */
#define UVBLACK32      (0x80808080)      /* (UVBLACK*0x01010101)    */
#define UVBLACK64      (UINT64_C(0x8080808080808080))


#define START_TIMER_INIT         (25) /* 1 second, unit: frames */
#define HEIGHT_LIMIT_LIFETIME (60*25) /* 1 minute, unit: frames */

/*
 * Plugin
 */

typedef struct autocrop_post_plugin_s
{
  post_plugin_t post_plugin;

  /* Current cropping status */
  int cropping_active; 

  /* Detected bars */
  int start_line;       
  int end_line;

  /* Previously detected bars
     - eliminate jumping if there is some noise at bar boundaries: 
       don't change cropped area unless it has been stable for
       some time */
  int prev_start_line;
  int prev_end_line;

  /* Delayed start for cropping */
  int start_timer;

  /* Last seen frame */
  int     prev_height;
  int     prev_width;
  int64_t prev_pts;

  /* eliminate jumping when when there are subtitles inside bottom bar:
     - when cropping is active and one frame has larger end_line 
       than previous, we enlarge frame.
     - after this, cropping is not resetted to previous value unless 
       bottom bar has been empty for certain time */
  int height_limit_active;  /* true if detected possible subtitles in bottom area */
  int height_limit;         /* do not crop bottom above this value (bottom of subtitles) */
  int height_limit_timer;   /* counter how many following frames must have black 
			       bottom bar until returning to full cropping
			       (used to reset height_limit when there are no subtitles) */
} autocrop_post_plugin_t;

/*
 *  debug tracing
 */

#ifndef TRACE_FRAME
#  define TRACEFRAME(x...)
#else
#  define TRACEFRAME(x...) printf(x)
#endif

#ifdef TRACE_FRAME
static int avg_line_Y_C(uint8_t *data, int length)
{
  int x, val = 0;
  for(x=32; x<length-32; x++)
    val += data[x];
  return val / (length-64);
}
#endif

/*
 * Black bar detection
 */

static int blank_line_Y_C(uint8_t *data, int length);
static int blank_line_UV_C(uint8_t *data, int length);
#if defined(ENABLE_64BIT)
static int blank_line_Y_C64(uint8_t *data, int length);
static int blank_line_UV_C64(uint8_t *data, int length);
#endif
#if defined(ARCH_X86)
static int blank_line_Y_mmx(uint8_t *data, int length);
static int blank_line_UV_mmx(uint8_t *data, int length);
#endif

static int blank_line_Y_INIT(uint8_t *data, int length);
static int blank_line_UV_INIT(uint8_t *data, int length);
static void autocrop_init_mm_accel(void);

int (*blank_line_Y)(uint8_t *data, int length) = blank_line_Y_INIT;
int (*blank_line_UV)(uint8_t *data, int length) = blank_line_UV_INIT;

static int blank_line_Y_C(uint8_t *data, int length)
{
  uint32_t *data32 = (uint32_t*)data;
  int x;
  
  length /= 4; /* 4 bytes / loop */
  length -= 8; /* skip right border (32 pixels) */
  x = 8;       /* skip left border (32 pixels) */

  for(; x<length; x++)
    if(data32[x] & TRESHOLD32_INV) {
      TRACEFRAME("Y fail @%d (=%x)  |  ", x, data32[x]);
      return 0;
    }

  return 1;
}

static int blank_line_UV_C(uint8_t *data, int length)
{
  uint32_t *data32 = (uint32_t*)data;
  int x;

  length /= 4; /* 4 bytes / loop */
  length -= 4; /* skip right border (32 pixels) */
  x = 4;       /* skip left border (32 pixels) */

  for(; x<length; x++)
    if(((data32[x]+0x03030303) & ~(0x07070707)) != UVBLACK32) {
      TRACEFRAME("UV fail @%d (=%x)  |  ", x, data32[x]);
      return 0;
    }

  return 1;
}

#if defined(ENABLE_64BIT)
static int blank_line_Y_C64(uint8_t *data, int length)
{
  uint64_t *data64 = (uint64_t*)data;
  int x;

  length /= 8; /* 8 bytes / loop */
  length -= 4; /* skip right border (32 pixels) */
  x = 4;       /* skip left border (32 pixels) */

  for(; x<length; x++)
    if(data64[x] & TRESHOLD64_INV) {
      TRACEFRAME("Y fail @%d (=%x)  |  ", x, data64[x]);
      return 0;
    }

  return 1;
}
#endif

#if defined(ENABLE_64BIT)
static int blank_line_UV_C64(uint8_t *data, int length)
{
  uint64_t *data64 = (uint64_t*)data;
  int x;

  length /= 8; /* 8 bytes / loop */
  length -= 2; /* skip right border (32 pixels) */
  x = 2;       /* skip left border (32 pixels) */

  for(; x<length; x++)
    if(((data64[x]+UINT64_C(0x0303030303030303)) & (~(UINT64_C(0x0707070707070707)))) != UVBLACK64) {
      TRACEFRAME("UV fail @%d (=%x)  |  ", x, data64[x]);
      return 0;
    }

  return 1;
}
#endif


#if defined(ARCH_X86)
/* ARCH_X86 is only defined in xine config.h which is not 
   accessible unless compiling inside xine source tree ... */
# if defined(__SSE__)
#  warning Compiling with SSE mnemonics support
# elif defined(__MMX__)
#  warning Compiling with MMX mnemonics support
# endif
static int blank_line_Y_mmx(uint8_t *data, int length)
{
  return blank_line_Y_C(data, length);
}

static int blank_line_UV_mmx(uint8_t *data, int length)
{
  return blank_line_UV_C(data, length);
}
#endif

static void autocrop_init_mm_accel(void)
{
  blank_line_Y  = blank_line_Y_C;
  blank_line_UV = blank_line_UV_C;
#if defined(ENABLE_64BIT)
  if(ENABLE_64BIT) {
    INFO("autocrop_init_mm_accel: using 64-bit integer operations\n");
    blank_line_Y  = blank_line_Y_C64;
    blank_line_UV = blank_line_UV_C64;
  }
#endif
#if defined(ARCH_X86)
# if 0
  if(xine_get_mm_accel() & SSE) {
    INFO("autocrop_init_mm_accel: using SSE\n");
    blank_line_Y  = blank_line_Y_SSE;
    blank_line_UV = blank_line_UV_SSE;
  }
# endif
#endif
#if defined(ARCH_X86) && !defined(ENABLE_64BIT)
# if 0
  else if(xine_get_mm_accel() & MMXEXT) {
    INFO("autocrop_init_mm_accel: using MMXEXT\n");
    blank_line_Y  = blank_line_Y_MMXEXT;
    blank_line_UV = blank_line_UV_MMXEXT;
  }
  else if(xine_get_mm_accel() & MMX) {
    /* mmx not faster than normal x64  (?) */
    INFO("autocrop_init_mm_accel: using MMX\n");
    blank_line_Y  = blank_line_Y_mmx;
    blank_line_UV = blank_line_UV_mmx;
  }
# endif
#endif
}

static int blank_line_Y_INIT(uint8_t *data, int length)
{
  autocrop_init_mm_accel();
  return (*blank_line_Y)(data, length);
}

static int blank_line_UV_INIT(uint8_t *data, int length)
{
  autocrop_init_mm_accel();
  return (*blank_line_UV)(data, length);
}

/*
 * Analyze frame
 *  - if frame needs cropping set crop_top & crop_bottom
 */

#ifdef MARK_FRAME
int dbg_top=0, dbg_bottom=0;
#endif

#define LOGOSKIP (frame->width/4)  /* skip logo (Y, top-right or top-left quarter) */

static void analyze_frame_yv12(vo_frame_t *frame, int *crop_top, int *crop_bottom)
{
#ifdef TRACE_FRAME
	post_video_port_t *port = (post_video_port_t *)frame->port;
	autocrop_post_plugin_t *this = (autocrop_post_plugin_t *)port->post;
#endif

  int y;
  int ypitch = frame->pitches[0];
  int upitch = frame->pitches[1];
  int vpitch = frame->pitches[2];
  uint8_t *ydata = frame->base[0];
  uint8_t *udata = frame->base[1];
  uint8_t *vdata = frame->base[2];
  int max_crop = (frame->height / 4) / 2; /* 4:3 --> 16:9 */

  /* from top -> down */
  ydata += 6 * ypitch;  /* skip 6 first lines */
  udata += 3 * upitch;
  vdata += 3 * vpitch;
  for(y = 4; y <= max_crop   *2 /* *2 = 20:9+subs -> 16:9 */ ; y += 2) {
    if(  ! ( blank_line_UV(udata,                (frame->width-LOGOSKIP)/2) ||
	     blank_line_UV(udata+LOGOSKIP/2,     (frame->width-LOGOSKIP)/2)    ) ||
	 ! ( blank_line_UV(vdata,                (frame->width-LOGOSKIP)/2) ||
	     blank_line_UV(vdata+LOGOSKIP/2,     (frame->width-LOGOSKIP)/2)    ) ||
	 ! ( blank_line_Y( ydata,                (frame->width-LOGOSKIP)  ) ||
	     blank_line_Y( ydata+LOGOSKIP,       (frame->width-LOGOSKIP)  )    ) ||
	 ! ( blank_line_Y( ydata+ypitch,         (frame->width-LOGOSKIP)  ) ||
	     blank_line_Y( ydata+ypitch+LOGOSKIP,(frame->width-LOGOSKIP)  )    )) {
      break;
    } else {
      ydata += 2 * ypitch;
      udata += upitch;
      vdata += vpitch;
    }
  }
  *crop_top = y;

  TRACEFRAME("Yavg %x | ", avg_line_Y_C(ydata,        frame->width));
  TRACEFRAME("Yavg %x | ", avg_line_Y_C(ydata+ypitch, frame->width));

  /* from bottom -> up */
  ydata = frame->base[0] + (frame->height   - 1)*ypitch;
  udata = frame->base[1] + (frame->height/2 - 1)*upitch;
  vdata = frame->base[2] + (frame->height/2 - 1)*vpitch;
  for(y = frame->height - 1; y >= frame->height-max_crop; y -=2 ) {
    if( ! blank_line_Y(ydata,        frame->width) ||
	! blank_line_Y(ydata-ypitch, frame->width) ||  
	! blank_line_UV(udata,       frame->width/2) ||
	! blank_line_UV(vdata,       frame->width/2)) {
      break;
    } else {
      ydata -= 2*ypitch;
      udata -= upitch;
      vdata -= vpitch;
    }
  }
  *crop_bottom = y;

#ifdef MARK_FRAME
  dbg_top = *crop_top; dbg_bottom = *crop_bottom;
#endif

  /* max. cropping is 1/8 at top and bottom (4:3 -> 16:9) 
   * exception: 16:9 ... 20:9 letterbox may be cropped more from top 
   *            if there are subtitles at bottom
   */
  if(*crop_top > (frame->height/8  *2))  /* *2 --> 20:9 -> 16:9 + subtitles */
    *crop_top = frame->height/8  *2 ;
  if(*crop_bottom < (frame->height*7/8))
    *crop_bottom = frame->height*7/8;

  if(*crop_top > (frame->height/8)) {
    /* if wider than 16:9, prefer cropping top */
    if(*crop_top + (frame->height - *crop_bottom) > frame->height/4) {
      int diff = *crop_top + (frame->height - *crop_bottom) - frame->height/4;
      diff &= ~1;
      TRACE("balance: %d,%d -> %d,%d\n",
	    *crop_top, *crop_bottom, 
	    *crop_top, *crop_bottom + diff);
      *crop_bottom += diff;
    }
  }

  /* stay inside frame and forget very small bars */
  if(*crop_top < 6)
    *crop_top = 0;
  if(*crop_bottom >= (frame->height-6))
    *crop_bottom = frame->height;
 
  if(*crop_top < frame->height/12 || *crop_bottom > frame->height*11/12) {
    /* Small bars -> crop only detected borders */
    if(*crop_top || *crop_bottom) {
      TRACE("Small bars -> <16:9 : start_line = %d end_line = %d (%s%d t%d)\n", 
	    *crop_top, *crop_bottom,
	    this->height_limit_active ? "height limit " : "",
	    this->height_limit,
	    this->height_limit_active ? this->height_limit_timer : 0);
    }
  } else {
    /* Large bars -> crop to 16:9 */
    TRACE("Large bars -> 16:9  : start_line = %d end_line = %d (%s%d t%d)\n", 
	  *crop_top, *crop_bottom, 
	  this->height_limit_active ? "height limit " : "",
	  this->height_limit,
	  this->height_limit_active ? this->height_limit_timer : 0);
    if(*crop_top < frame->height / 8)
      *crop_top = frame->height / 8;
    if(*crop_bottom < frame->height * 7 / 8)
      *crop_bottom = frame->height * 7 / 8;
  }

  /* adjust start and stop to even lines */
  (*crop_top)    = (*crop_top)        & (~1);
  (*crop_bottom) = (*crop_bottom + 1) & (~1);

  TRACEFRAME("Yavg %x | ", avg_line_Y_C(ydata,        frame->width));
  TRACEFRAME("Yavg %x\n",  avg_line_Y_C(ydata+ypitch, frame->width));
}

#ifdef MARK_FRAME
static void mark_frame_yv12(autocrop_post_plugin_t *this,
			    vo_frame_t *frame, int *crop_top, int *crop_bottom)
{
  int ypitch = frame->pitches[0];
  int upitch = frame->pitches[1];
  int vpitch = frame->pitches[2];
  uint8_t *ydata = frame->base[0];
  uint8_t *udata = frame->base[1];
  uint8_t *vdata = frame->base[2];

  /* draw markers to detected boundaries and expected boundaries */
  if(*crop_top > 4 && *crop_top < 200) {
    ydata = frame->base[0] + ((*crop_top)-2)*ypitch;
    udata = frame->base[1] + ((*crop_top)/2 -1)*upitch;
    memset(ydata, 0xff, frame->width/10);
    memset(ydata+ypitch, 0xff, frame->width/10);
    memset(udata, 0xff, frame->width/2/10);
    
    if(dbg_top < *crop_top) dbg_top = *crop_top;
    ydata = frame->base[0] + ((dbg_top - *crop_top))*ypitch;
    udata = frame->base[1] + ((dbg_top - *crop_top)/2)*upitch;
    memset(ydata, 0x80, frame->width/2);
    memset(ydata+ypitch, 0x80, frame->width/2);
    memset(udata, 0xff, frame->width/2/2);
  }
  if(*crop_bottom > 300) {
    if(*crop_bottom < frame->height - 2) {
      ydata = frame->base[0] + (*crop_bottom + 2)*ypitch;
      udata = frame->base[1] + ((*crop_bottom)/2)*upitch;
      memset(ydata, 0xff, frame->width);
      memset(ydata+ypitch, 0xff, frame->width);
      memset(udata, 0xff, frame->width/2);
    }
    if(dbg_bottom - *crop_top - 2 < frame->height) {
      ydata = frame->base[0] + (dbg_bottom - *crop_top - 2)*ypitch;
      udata = frame->base[1] + (dbg_bottom - *crop_top - 2)/2*upitch;
      memset(ydata, 0x80, frame->width/2);
      memset(ydata+ypitch, 0xff, frame->width/2);
      memset(udata, 0xff, frame->width/2/2);
    }
  }
  if(frame->height > 500) {
    // TODO: use frame height instead of assuming 576 ... -> 72
    vdata = frame->base[2] + ((72-*crop_top)/2)*vpitch;
vdata = frame->base[2] + (72/2)*vpitch;
    memset(vdata, 0xff, frame->width/2);
    vdata = frame->base[2] + ((frame->height-72+(576-*crop_bottom))/2)*vpitch;
vdata = frame->base[2] + ((frame->height-72)/2)*vpitch;
    memset(vdata, 0xff, frame->width/2);
  }
}
#endif

/* 
 * crop frame by copying 
 */
#ifndef USE_CROP
static int crop_copy(vo_frame_t *frame, xine_stream_t *stream)
{
  post_video_port_t *port = (post_video_port_t *)frame->port;
  autocrop_post_plugin_t *this = (autocrop_post_plugin_t *)port->post;
  vo_frame_t *new_frame;
    
  int y, result;
  int yp = frame->pitches[0], yp2;
  int up = frame->pitches[1], up2;
  int vp = frame->pitches[2], vp2;
  uint8_t *ydata = frame->base[0], *ydata2;
  uint8_t *udata = frame->base[1], *udata2;
  uint8_t *vdata = frame->base[2], *vdata2;

  int   new_height = frame->height;
  float new_ratio;

  /* top bar */
  ydata += this->start_line * yp;
  udata += (this->start_line/2) * up;
  vdata += (this->start_line/2) * vp;
  new_height -= this->start_line;

  /* bottom bar */
  new_height -= (frame->height - (this->end_line+2));

  new_ratio = 12.0/9.0 * ((float)frame->height / (float)new_height);
  new_frame = port->original_port->get_frame(port->original_port,
					     frame->width, new_height, 
					     new_ratio, frame->format, 
					     frame->flags | VO_BOTH_FIELDS);
  _x_post_frame_copy_down(frame, new_frame);

  yp2 = new_frame->pitches[0];
  up2 = new_frame->pitches[1];
  vp2 = new_frame->pitches[2];
  ydata2 = new_frame->base[0];
  udata2 = new_frame->base[1];
  vdata2 = new_frame->base[2];

  /*
    TODO:
    save channel logo mask (from top)
    - no changes in 3 sec -> next time crop it out ...
  */

  for(y=0; y < new_height/2; y++) {
    xine_fast_memcpy(ydata2, ydata, frame->width);
    ydata += yp;
    ydata2 += yp2;
    xine_fast_memcpy(ydata2, ydata, frame->width);
    ydata += yp;
    ydata2 += yp2;
    xine_fast_memcpy(udata2, udata, frame->width/2);
    udata += up;
    udata2 += up2;
    xine_fast_memcpy(vdata2, vdata, frame->width/2);
    vdata += vp;
    vdata2 += vp2;
  }

#if 0
  new_frame->height = new_height;
  new_frame->ratio = frame->ratio * ((float)frame->height) / ((float)new_frame->height);
#endif

#if 0
  static int k=0;
  if(++k > 50) {
    printf("%f (%f) %f (%f)    %f %f\n", new_frame->ratio, 16.0/9.0, frame->ratio, 4.0/3.0,
	   ((float)frame->width) / ((float)frame->height), 
	   ((float)new_frame->width) / ((float)new_frame->height));
    k=0;
  }
  static int t=0;
  if(++t > 50) {
    printf("new ratio: %1.3f (%1.3f/9.0) ; expected %1.3f (%1.3f/9.0)\n", 
	   new_frame->ratio, new_frame->ratio*9.0,
	   new_ratio, new_ratio*9.0);
    t=0;
  }
#endif

#ifdef MARK_FRAME
  mark_frame_yv12(this, new_frame, &this->start_line, &this->end_line);
#endif

  result = new_frame->draw(new_frame, stream);
  _x_post_frame_copy_up(frame, new_frame);
  new_frame->free(new_frame);
  
  return result;
}
#endif

/*
 * crop frame without copying 
 */
#ifdef USE_CROP
static int crop_nocopy(vo_frame_t *frame, xine_stream_t *stream)
{
  post_video_port_t *port = (post_video_port_t *)frame->port;
  autocrop_post_plugin_t *this = (autocrop_post_plugin_t *)port->post;
  int skip;

  if(this->cropping_active) {
    // TODO: use detected borders
    int new_height = (12.0*frame->height) / 16.0;
    frame->crop_top += (frame->height - new_height) / 2;
    frame->crop_bottom += (frame->height + 1 - new_height) / 2;
    // what ratio should be used now ... ?
    frame->ratio = 16.0/9.0;  
  }

  _x_post_frame_copy_down(frame, frame->next);
  skip = frame->next->draw(frame->next, stream);
  TRACE("crop: top %d, bottom %d\n", frame->crop_top, frame->crop_bottom);
  // cropping moves overlay too... even if it is already in right place :(
  _x_post_frame_copy_up(frame, frame->next);

  return skip;
}
#endif

/*
 *    Frame handling
 */

static int autocrop_draw(vo_frame_t *frame, xine_stream_t *stream)
{
  post_video_port_t *port = (post_video_port_t *)frame->port;
  autocrop_post_plugin_t *this = (autocrop_post_plugin_t *)port->post;
  int result;
  int detected_start, detected_end;

  /* use pts jumps to track stream changes (and seeks) */
  if(frame->pts > 0) {
    if(this->prev_pts>0) {
      int64_t dpts = frame->pts - this->prev_pts;
      if(dpts < INT64_C(-30*90000) || dpts > INT64_C(30*90000)) { /* 30 sec */
	if(this->height_limit_active) {
	  this->height_limit_timer = START_TIMER_INIT;
	  TRACE("short pts jump resetted height limit");
	}
      }
      if(dpts < INT64_C(-30*60*90000) || dpts > INT64_C(30*60*90000)) { /* 30 min */ 
	this->cropping_active = 0;
	TRACE("long pts jump resetted cropping");
      }
    }
    this->prev_pts = frame->pts;
  }

  /* reset ? */
  if(! this->cropping_active) {
    this->prev_start_line = 0;
    this->prev_end_line = frame->height;
    this->start_timer = START_TIMER_INIT;
    this->prev_pts = -1;
    if(this->height_limit_active) {
      TRACE("height limit reset (no cropping)");
    }
    this->height_limit_active = 0;
    this->height_limit = frame->height;
  }

  /* only 4:3 YV12 frames are cropped */
  if(frame->ratio != 4.0/3.0 || frame->format != XINE_IMGFMT_YV12) {
    this->cropping_active = 0;

  } else if(frame->bad_frame) {

  /* check for letterbox borders only from I-frames */
  } else if(frame->picture_coding_type == 1/*XINE_PICT_I_TYPE*/) {

    analyze_frame_yv12(frame, &this->start_line, &this->end_line);

    /* ignore very small bars */
    if(this->start_line > 10 || this->end_line < frame->height - 10) 
      this->cropping_active = 1;
    else 
      this->cropping_active = 0;
    
    this->prev_height = frame->height;
    this->prev_width = frame->width;
  } else {
    /* reset when format changes */
    if(frame->height != this->prev_height)
      this->cropping_active = 0;
    if(frame->width != this->prev_width)
      this->cropping_active = 0;
  }

  /* update timers */
  if(this->start_timer)
    this->start_timer--;

  if(this->height_limit_timer) {
    if (! --this->height_limit_timer) {
      this->height_limit_active = 0;
      this->height_limit = frame->height;
      TRACE("height limit timer expired");
    }
  } 

  /* no cropping to be done ? */
  if (frame->bad_frame || !this->cropping_active || this->start_timer>0) {
    _x_post_frame_copy_down(frame, frame->next);
    result = frame->next->draw(frame->next, stream);
    _x_post_frame_copy_up(frame, frame->next);
    return result;
  }

  /* "soft start" and border stabilization */
  detected_start = this->start_line;
  detected_end = this->end_line; 
  if(this->prev_start_line != this->start_line) {
    int diff = this->prev_start_line - this->start_line;
    if(diff < -4) diff = -4;
    else if(diff > 4) diff = 4;
    else diff = 0;
    this->start_line = this->prev_start_line - diff;
  }
  if(this->prev_end_line != this->end_line) {
    int diff = this->prev_end_line - this->end_line;
    if(diff < -4) diff = -4;
    else if(diff > 4) diff = 4;
    else diff = 0;
    this->end_line = this->prev_end_line - diff;
  }

  /* handle fixed subtitles inside bottom bar */
  if(abs(this->prev_start_line - this->start_line) > 5 ) {
    /* reset height limit if top bar changes */
    TRACE("height limit reset, top bar moved from %d -> %d\n", 
	  this->prev_start_line, this->start_line);
    this->height_limit_active = 0;
    this->height_limit = frame->height;
    this->height_limit_timer = 0;
  }
  if (this->end_line > this->prev_end_line) {
    if(!this->height_limit_active || 
       this->height_limit < this->end_line) {
      /* start or increase height limit */
      TRACE("height limit %d -> %d (%d secs)\n", 
	    this->height_limit, this->end_line, 
	    HEIGHT_LIMIT_LIFETIME/25);
      this->height_limit = this->end_line;
      this->height_limit_timer = HEIGHT_LIMIT_LIFETIME;
      this->height_limit_active = 1;
    }
    if(this->height_limit_active &&
       this->height_limit_timer < HEIGHT_LIMIT_LIFETIME/4) {
      /* keep heigh limit timer running */
      TRACE("height_limit_timer increment (still needed)\n");
      this->height_limit_timer = HEIGHT_LIMIT_LIFETIME/2;
    }
  }


  this->prev_start_line = this->start_line;
  this->prev_end_line = this->end_line;

  if(this->height_limit_active) {
    /* apply height limit */
    if(this->end_line < this->height_limit)
      this->end_line = this->height_limit;
  } else {
    this->height_limit = frame->height;
  }

  /*
   * do cropping 
   *  - using frame->crop_... does not seem to work with my xv and xine-lib-1.1.1. 
   *  - maybe cropping could be done by adjusting y/u/v data pointers 
   *    and height of frame ?
   *    -> no time-consuming copying 
   */
#ifdef USE_CROP
  result = crop_nocopy(frame, stream);
#else
  result = crop_copy(frame, stream);
#endif

  /* forget stabilized values */
  this->start_line = detected_start;
  this->end_line = detected_end; 

  return result;
}

static vo_frame_t *autocrop_get_frame(xine_video_port_t *port_gen, 
				       uint32_t width, uint32_t height, 
				       double ratio, int format, int flags)
{
  post_video_port_t *port = (post_video_port_t *)port_gen;
  post_plugin_t     *this = port->post;
  vo_frame_t        *frame;
  
  _x_post_rewire(this);
  
  if (ratio <= 0.0)
    if(height > 1)
      ratio = (double)width / (double)height;
  
  if (ratio == 4.0/3.0 && format == XINE_IMGFMT_YV12) {
    frame = port->original_port->get_frame(port->original_port,
					   width, height, 
					   12.0/9.0, format, flags);

    _x_post_inc_usage(port);
    frame = _x_post_intercept_video_frame(frame, port);
    
    frame->ratio = ratio;
    return frame;
  } 
  
  return port->original_port->get_frame(port->original_port,
					width, height, 
					ratio, format, flags);
}

static int autocrop_intercept_frame(post_video_port_t *port, vo_frame_t *frame)
{
  autocrop_post_plugin_t *this = (autocrop_post_plugin_t *)port->post;

  /* Crop only SDTV YV12 4:3 frames ... */
  int intercept = (frame->format == XINE_IMGFMT_YV12 && 
		   frame->ratio == 4.0/3.0 &&
		   frame->width  >= 480 && frame->width  <= 768 &&
		   frame->height >= 288 && frame->height <= 576);
  if(!intercept) {
    this->height_limit_active = 0;
  }

  return intercept;
}

#if 0
static int autocrop_intercept_ovl(post_video_port_t *port)
{
  post_expand_t         *this = (post_expand_t *)port->post;

  if (this->centre_cut_out_mode && this->cropping_active) return 0;
  /* we always intercept overlay manager */
  return 1;
}
#endif

#if 0
static int32_t autocrop_overlay_add_event(video_overlay_manager_t *this_gen, void *event_gen)
{
  post_expand_t         *this = (post_expand_t *)port->post;
  post_video_port_t     *port = _x_post_ovl_manager_to_port(this_gen);
  video_overlay_event_t *event = (video_overlay_event_t *)event_gen;

  if (event->event_type == OVERLAY_EVENT_SHOW) {
    switch (event->object.object_type) {
    case 0:
      /* regular subtitle */

      /* Subtitle overlays must be coming somewhere inside xine engine */
      event->object.overlay->y -= this->crop_top + this->crop_bottom;
      break;
    case 1:
      /* menu overlay */
      
      /* All overlays coming from VDR have this type */
    }
  }
  return port->original_manager->add_event(port->original_manager, event_gen);
}
#endif


/*
 *    Open/close
 */

static void autocrop_dispose(post_plugin_t *this_gen)
{
  if (_x_post_dispose(this_gen)) 
    free(this_gen);
}

static post_plugin_t *autocrop_open_plugin(post_class_t *class_gen, 
					    int inputs,
					    xine_audio_port_t **audio_target,
					    xine_video_port_t **video_target)
{
  if (video_target && video_target[ 0 ]) {
    autocrop_post_plugin_t *this = (autocrop_post_plugin_t*)xine_xmalloc(sizeof(autocrop_post_plugin_t));
    post_in_t           *input;
    post_out_t          *output;
    post_video_port_t   *port;
  
    if (this) {
      _x_post_init(&this->post_plugin, 0, 1);

      port = _x_post_intercept_video_port(&this->post_plugin, 
					  video_target[ 0 ], 
					  &input, &output);

      input->xine_in.name   = "video in";
      output->xine_out.name = "video out";
#if 0
      port->intercept_ovl          = autocrop_intercept_ovl;
      port->new_manager->add_event = autocrop_overlay_add_event;
#endif
      port->intercept_frame    = autocrop_intercept_frame;
      port->new_port.get_frame = autocrop_get_frame;
      port->new_frame->draw    = autocrop_draw;

      this->post_plugin.xine_post.video_input[ 0 ] = &port->new_port;
      this->post_plugin.dispose = autocrop_dispose;
  
      this->cropping_active = 0;
      this->start_line  = 0;
      this->end_line    = 0;

      this->prev_start_line = 0;
      this->prev_end_line = 576;

      autocrop_init_mm_accel();

      return &this->post_plugin;
    }
  }

  return NULL;
}


/*
 *    Plugin class
 */

static char *autocrop_get_identifier(post_class_t *class_gen)
{
  return "autocrop";
}

static char *autocrop_get_description(post_class_t *class_gen)
{
  return "Crop letterboxed 4:3 video to 16:9";
}

static void autocrop_class_dispose(post_class_t *class_gen)
{
  free(class_gen);
}

static void *autocrop_init_plugin(xine_t *xine, void *data)
{
  post_class_t *class = (post_class_t*)malloc(sizeof(post_class_t));
  
  if(class) {
    class->open_plugin     = autocrop_open_plugin;
    class->get_identifier  = autocrop_get_identifier;
    class->get_description = autocrop_get_description;
    class->dispose         = autocrop_class_dispose;
  }

  return class;
}


static post_info_t info = { XINE_POST_TYPE_VIDEO_FILTER };

const plugin_info_t xine_plugin_info[] __attribute__((visibility("default"))) =
{
  /* type, API, "name", version, special_info, init_function */  
  { PLUGIN_POST, 9, "autocrop", XINE_VERSION_CODE, &info, &autocrop_init_plugin },
  { PLUGIN_NONE, 0, "", 0, NULL, NULL }
};