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Revision 1054 - (download) (annotate)
Mon Jun 9 13:55:56 2003 UTC (15 years, 11 months ago) by edgomez
File size: 30665 byte(s)
Added legal header
/******************************************************************************
 *
 *  XviD Bit Rate Controller Library
 *  - VBR 2 pass bitrate controller implementation -
 *
 *  Copyright (C)      2002 Foxer <email?>
 *                     2002 Dirk Knop <dknop@gwdg.de>
 *                2002-2003 Edouard Gomez <ed.gomez@free.fr>
 *                     2003 Pete Ross <pross@xvid.org>
 *
 *  This curve treatment algorithm is the one originally implemented by Foxer
 *  and tuned by Dirk Knop for the XviD vfw frontend.
 *
 *  This program 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.
 *
 *  This program 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: plugin_2pass2.c,v 1.1.2.20 2003-06-09 13:55:07 edgomez Exp $
 *
 *****************************************************************************/

#include <stdio.h>
#include <math.h>
#include <limits.h>

#include "../xvid.h"
#include "../image/image.h"

/*****************************************************************************
 * Some constants
 ****************************************************************************/

#define DEFAULT_KEYFRAME_BOOST 0
#define DEFAULT_PAYBACK_METHOD XVID_PAYBACK_PROP
#define DEFAULT_BITRATE_PAYBACK_DELAY 250
#define DEFAULT_CURVE_COMPRESSION_HIGH 0
#define DEFAULT_CURVE_COMPRESSION_LOW 0
#define DEFAULT_MAX_OVERFLOW_IMPROVEMENT 60
#define DEFAULT_MAX_OVERFLOW_DEGRADATION 60

/* Keyframe settings */
#define DEFAULT_KFTRESHOLD 10
#define DEFAULT_KFREDUCTION 20
#define DEFAULT_MIN_KEY_INTERVAL 1

/*****************************************************************************
 * Structures
 ****************************************************************************/

/* Statistics */
typedef struct {
    int type;               /* first pass type */
    int quant;              /* first pass quant */
	int blks[3];			/* k,m,y blks */
    int length;             /* first pass length */
    int scaled_length;      /* scaled length */
    int desired_length;     /* desired length; calcuated during encoding */

    int zone_mode;   /* XVID_ZONE_xxx */
    double weight;
} stat_t;

/* Context struct */
typedef struct
{
    xvid_plugin_2pass2_t param;

    /* constant statistical data */
	int num_frames;
	int num_keyframes;
	uint64_t target;	/* target filesize */

	int count[3];   /* count of each frame types */
	uint64_t tot_length[3];  /* total length of each frame types */
	double avg_length[3];   /* avg */
	int min_length[3];  /* min frame length of each frame types */
	uint64_t tot_scaled_length[3];  /* total scaled length of each frame type */
	int max_length;     /* max frame size */

	/* zone statistical data */
	double avg_weight;  /* average weight */
	int64_t tot_quant;   /* total length used by XVID_ZONE_QUANT zones */


	double curve_comp_scale;
	double movie_curve;

	/* dynamic */

	int * keyframe_locations;
	stat_t * stats;

	double quant_error[3][32];
	int quant_count[32];
	int last_quant[3];

	double curve_comp_error;
	int overflow;
	int KFoverflow;
	int KFoverflow_partial;
	int KF_idx;

	double fq_error;
} rc_2pass2_t;


/*****************************************************************************
 * Sub plugin functions prototypes
 ****************************************************************************/

static int rc_2pass2_create(xvid_plg_create_t * create, rc_2pass2_t ** handle);
static int rc_2pass2_before(rc_2pass2_t * rc, xvid_plg_data_t * data);
static int rc_2pass2_after(rc_2pass2_t * rc, xvid_plg_data_t * data);
static int rc_2pass2_destroy(rc_2pass2_t * rc, xvid_plg_destroy_t * destroy);

/*****************************************************************************
 * Plugin definition
 ****************************************************************************/

int
xvid_plugin_2pass2(void * handle, int opt, void * param1, void * param2)
{
    switch(opt) {
    case XVID_PLG_INFO :
        return 0;

    case XVID_PLG_CREATE :
        return rc_2pass2_create((xvid_plg_create_t*)param1, param2);

    case XVID_PLG_DESTROY :
        return rc_2pass2_destroy((rc_2pass2_t*)handle, (xvid_plg_destroy_t*)param1);

    case XVID_PLG_BEFORE :
        return rc_2pass2_before((rc_2pass2_t*)handle, (xvid_plg_data_t*)param1);

    case XVID_PLG_AFTER :
        return rc_2pass2_after((rc_2pass2_t*)handle, (xvid_plg_data_t*)param1);
    }

    return XVID_ERR_FAIL;
}

/*****************************************************************************
 * Sub plugin functions definitions
 ****************************************************************************/

/* First a few local helping function prototypes */
static  int det_stats_length(rc_2pass2_t * rc, char * filename);
static  int load_stats(rc_2pass2_t *rc, char * filename);
static void zone_process(rc_2pass2_t *rc, const xvid_plg_create_t * create);
static void internal_scale(rc_2pass2_t *rc);
static void pre_process0(rc_2pass2_t * rc);
static void pre_process1(rc_2pass2_t * rc);

/*----------------------------------------------------------------------------
 *--------------------------------------------------------------------------*/

static int
rc_2pass2_create(xvid_plg_create_t * create, rc_2pass2_t **handle)
{
    xvid_plugin_2pass2_t * param = (xvid_plugin_2pass2_t *)create->param;
    rc_2pass2_t * rc;
    int i;

    rc = malloc(sizeof(rc_2pass2_t));
    if (rc == NULL) 
        return XVID_ERR_MEMORY;

    rc->param = *param;

	/*
	 * Initialize all defaults
	 */
#define _INIT(a, b) if((a) <= 0) (a) = (b)
    /* Let's set our defaults if needed */
	_INIT(rc->param.keyframe_boost, DEFAULT_KEYFRAME_BOOST);
	_INIT(rc->param.payback_method, DEFAULT_PAYBACK_METHOD);
	_INIT(rc->param.bitrate_payback_delay, DEFAULT_BITRATE_PAYBACK_DELAY);
    _INIT(rc->param.curve_compression_high, DEFAULT_CURVE_COMPRESSION_HIGH);
    _INIT(rc->param.curve_compression_low, DEFAULT_CURVE_COMPRESSION_LOW);
    _INIT(rc->param.max_overflow_improvement, DEFAULT_MAX_OVERFLOW_IMPROVEMENT);
    _INIT(rc->param.max_overflow_degradation,  DEFAULT_MAX_OVERFLOW_DEGRADATION);

    /* Keyframe settings */
	_INIT(rc->param.kftreshold, DEFAULT_KFTRESHOLD);
    _INIT(rc->param.kfreduction, DEFAULT_KFREDUCTION);
    _INIT(rc->param.min_key_interval, DEFAULT_MIN_KEY_INTERVAL);
#undef _INIT

	/* Initialize some stuff to zero */
	for(i=0; i<32; i++) rc->quant_count[i] = 0;

	for(i=0; i<3; i++) {
		int j;
		for (j=0; j<32; j++)
			rc->quant_error[i][j] = 0;
	}

	for (i=0; i<3; i++)
		rc->last_quant[i] = 0;

	rc->fq_error = 0;

	/* Count frames in the stats file */
	if (!det_stats_length(rc, param->filename)) {
		DPRINTF(XVID_DEBUG_RC,"ERROR: fopen %s failed\n", param->filename);
		free(rc);
		return XVID_ERR_FAIL;
	}

    /* Allocate the stats' memory */
	if ((rc->stats = malloc(rc->num_frames * sizeof(stat_t))) == NULL) {
        free(rc);
        return XVID_ERR_MEMORY;
    }

    /*
	 * Allocate keyframes location's memory
	 * PS: see comment in pre_process0 for the +1 location requirement
	 */
	rc->keyframe_locations = malloc((rc->num_keyframes + 1) * sizeof(int));
	if (rc->keyframe_locations == NULL) {
		free(rc->stats);
		free(rc);
		return XVID_ERR_MEMORY;
	}

	if (!load_stats(rc, param->filename)) {
		DPRINTF(XVID_DEBUG_RC,"ERROR: fopen %s failed\n", param->filename);
		free(rc->keyframe_locations);
		free(rc->stats);
		free(rc);
		return XVID_ERR_FAIL;
	}

	/* Compute the target filesize */
	if (rc->num_frames  < create->fbase/create->fincr) {
		/* Source sequence is less than 1s long, we do as if it was 1s long */
		rc->target = rc->param.bitrate / 8;
	} else {
		/* Target filesize = bitrate/8 * numframes / framerate */
		rc->target = 
			((uint64_t)rc->param.bitrate * (uint64_t)rc->num_frames * \
			 (uint64_t)create->fincr) / \
			((uint64_t)create->fbase * 8);
	}

	DPRINTF(XVID_DEBUG_RC, "Frame rate: %d/%d (%ffps)\n",
			create->fbase, create->fincr,
			(double)create->fbase/(double)create->fincr);
	DPRINTF(XVID_DEBUG_RC, "Number of frames: %d\n", rc->num_frames);
	DPRINTF(XVID_DEBUG_RC, "Target bitrate: %ld\n", rc->param.bitrate);
	DPRINTF(XVID_DEBUG_RC, "Target filesize: %lld\n", rc->target);

	/* Compensate the average frame overhead caused by the container */
	rc->target -= rc->num_frames*rc->param.container_frame_overhead;
	DPRINTF(XVID_DEBUG_RC, "Container Frame overhead: %d\n", rc->param.container_frame_overhead);
	DPRINTF(XVID_DEBUG_RC, "Target filesize (after container compensation): %lld\n", rc->target);

	/* 
	 * First data pre processing:
	 *  - finds the minimum frame length for each frame type during 1st pass.
	 *     rc->min_size[]
	 *  - determines the maximum frame length observed (no frame type distinction).
	 *     rc->max_size
	 *  - count how many times each frame type has been used.
	 *     rc->count[]
	 *  - total bytes used per frame type
	 *     rc->total[]
	 *  - store keyframe location
	 *     rc->keyframe_locations[]
	 */
	pre_process0(rc);

	/*
	 * When bitrate is not given it means it has been scaled by an external
	 * application
	 */
	if (rc->param.bitrate) {
		/* Apply zone settings */
		zone_process(rc, create);
		/* Perform curve scaling */
		internal_scale(rc);
	} else {
		/* External scaling -- zones are ignored */
		for (i=0;i<rc->num_frames;i++) {
			rc->stats[i].zone_mode = XVID_ZONE_WEIGHT;
			rc->stats[i].weight = 1.0;
		}
		rc->avg_weight = 1.0;
		rc->tot_quant = 0;
	}

	pre_process1(rc);

	*handle = rc;
	return(0);
}

/*----------------------------------------------------------------------------
 *--------------------------------------------------------------------------*/

static int
rc_2pass2_destroy(rc_2pass2_t * rc, xvid_plg_destroy_t * destroy)
{
    free(rc->keyframe_locations);
    free(rc->stats);
	free(rc);
	return(0);
}

/*----------------------------------------------------------------------------
 *--------------------------------------------------------------------------*/

static int
rc_2pass2_before(rc_2pass2_t * rc, xvid_plg_data_t * data)
{
	stat_t * s = &rc->stats[data->frame_num];
	int overflow;
	int desired;
	double dbytes;
	double curve_temp;
	double scaled_quant;
	int capped_to_max_framesize = 0;

	/*
	 * This function is quite long but easy to understand. In order to simplify
	 * the code path (a bit), we treat 3 cases that can return immediatly.
	 */

	/* First case: Another plugin has already set a quantizer */
    if (data->quant > 0)
		return(0);

	/* Second case: We are in a Quant zone */
	if (s->zone_mode == XVID_ZONE_QUANT) {
		rc->fq_error += s->weight;
		data->quant = (int)rc->fq_error;
		rc->fq_error -= data->quant;
		
		s->desired_length = s->length;

		return(0);
	}

	/* Third case: insufficent stats data */
	if (data->frame_num >= rc->num_frames)
		return 0;

	/* XXX: why by 8 */
	overflow = rc->overflow / 8;

	/*
	 * The rc->overflow field represents the overflow in current scene (between two
	 * IFrames) so we must not forget to reset it if we are entering a new scene
	 */
	if (s->type == XVID_TYPE_IVOP)
		overflow = 0;

	desired = s->scaled_length;

	dbytes = desired;
	if (s->type == XVID_TYPE_IVOP)
		dbytes += desired * rc->param.keyframe_boost / 100;
	dbytes /= rc->movie_curve;

	/*
	 * Apply user's choosen Payback method. Payback helps bitrate to follow the
	 * scaled curve "paying back" past errors in curve previsions.
	 */
	if (rc->param.payback_method == XVID_PAYBACK_BIAS) {
		desired = (int)(rc->curve_comp_error / rc->param.bitrate_payback_delay);
	} else {
		desired = (int)(rc->curve_comp_error * dbytes /
						rc->avg_length[s->type-1] / rc->param.bitrate_payback_delay);

		if (labs(desired) > fabs(rc->curve_comp_error))
			desired = (int)rc->curve_comp_error;
	}

	rc->curve_comp_error -= desired;

	/* XXX: warning */
	curve_temp = 0;

	if ((rc->param.curve_compression_high + rc->param.curve_compression_low) &&	s->type != XVID_TYPE_IVOP) {

		curve_temp = rc->curve_comp_scale;
		if (dbytes > rc->avg_length[s->type-1]) {
			curve_temp *= ((double)dbytes + (rc->avg_length[s->type-1] - dbytes) * rc->param.curve_compression_high / 100.0);
		} else {
			curve_temp *= ((double)dbytes + (rc->avg_length[s->type-1] - dbytes) * rc->param.curve_compression_low / 100.0);
		}

		desired += (int)curve_temp;
		rc->curve_comp_error += curve_temp - (int)curve_temp;
	} else {
		desired += (int)dbytes;
		rc->curve_comp_error += dbytes - (int)dbytes;
	}


	/*
	 * We can't do bigger frames than first pass, this would be stupid as first
	 * pass is quant=2 and that reaching quant=1 is not worth it. We would lose
	 * many bytes and we would not not gain much quality.
	 */
	if (desired > s->length) {
		rc->curve_comp_error += desired - s->length;
		desired = s->length;
	} else {
		if (desired < rc->min_length[s->type-1]) {
			if (s->type == XVID_TYPE_IVOP){
				rc->curve_comp_error -= rc->min_length[XVID_TYPE_IVOP-1] - desired;
			}
			desired = rc->min_length[s->type-1];
		}
	}

	s->desired_length = desired;

	/*
	 * if this keyframe is too close to the next, reduce it's byte allotment
	 * XXX: why do we do this after setting the desired length ?
	 */

	if (s->type == XVID_TYPE_IVOP) {
		int KFdistance = rc->keyframe_locations[rc->KF_idx] - rc->keyframe_locations[rc->KF_idx - 1];

		if (KFdistance < rc->param.kftreshold) {
			        
			KFdistance -= rc->param.min_key_interval;

			if (KFdistance >= 0) {
				int KF_min_size;

				KF_min_size = desired * (100 - rc->param.kfreduction) / 100;
				if (KF_min_size < 1)
					KF_min_size = 1;

				desired = KF_min_size + (desired - KF_min_size) * KFdistance /
					(rc->param.kftreshold - rc->param.min_key_interval);

				if (desired < 1)
					desired = 1;
			}
		}
	}

	/*
	 * The "sens commun" would force us to use rc->avg_length[s->type-1] but
	 * even VFW code uses the pframe average length. Note that this length is
	 * used with desired which represents bframes _and_ pframes length.
	 *
	 * XXX: why are we using the avg pframe length for all frame types ? 
	 */
	overflow = (int)((double)overflow * desired / rc->avg_length[XVID_TYPE_PVOP-1]);

	/* Reign in overflow with huge frames */
	if (labs(overflow) > labs(rc->overflow))
		overflow = rc->overflow;

	/* Make sure overflow doesn't run away */
	if (overflow > desired * rc->param.max_overflow_improvement / 100) {
		desired += (overflow <= desired) ? desired * rc->param.max_overflow_improvement / 100 :
			overflow * rc->param.max_overflow_improvement / 100;
	} else if (overflow < desired * rc->param.max_overflow_degradation / -100){
		desired += desired * rc->param.max_overflow_degradation / -100;
	} else {
		desired += overflow;
	}

	/* Make sure we are not higher than desired frame size */
	if (desired > rc->max_length) {
		capped_to_max_framesize = 1;
		desired = rc->max_length;
		DPRINTF(XVID_DEBUG_RC,"[%i] Capped to maximum frame size\n",
				data->frame_num);
	}

	/* Make sure to not scale below the minimum framesize */
	if (desired < rc->min_length[s->type-1]) {
		desired = rc->min_length[s->type-1];
		DPRINTF(XVID_DEBUG_RC,"[%i] Capped to minimum frame size\n",
				data->frame_num);
	}

	/*
	 * Don't laugh at this very 'simple' quant<->filesize relationship, it
	 * proves to be acurate enough for our algorithm
	 */
	scaled_quant = (double)s->quant*(double)s->length/(double)desired;

	/*
	 * Quantizer has been scaled using floating point operations/results, we
	 * must cast it to integer
	 */
	data->quant = (int)scaled_quant;

	/* Let's clip the computed quantizer, if needed */
	if (data->quant < 1) {
		data->quant = 1;
	} else if (data->quant > 31) {
		data->quant = 31;
	} else if (s->type != XVID_TYPE_IVOP) {

		/*
		 * The frame quantizer has not been clipped, this appears to be a good
		 * computed quantizer, do not loose quantizer decimal part that we
		 * accumulate for later reuse when its sum represents a complete unit.
		 */
		rc->quant_error[s->type-1][data->quant] += scaled_quant - (double)data->quant;

		if (rc->quant_error[s->type-1][data->quant] >= 1.0) {
			rc->quant_error[s->type-1][data->quant] -= 1.0;
			data->quant++;
		} else if (rc->quant_error[s->type-1][data->quant] <= -1.0) {
			rc->quant_error[s->type-1][data->quant] += 1.0;
			data->quant--;
		}

	}

	/*
	 * Now we have a computed quant that is in the right quante range, with a
	 * possible +1 correction due to cumulated error. We can now safely clip
	 * the quantizer again with user's quant ranges. "Safely" means the Rate
	 * Control could learn more about this quantizer, this knowledge is useful
	 * for future frames even if it this quantizer won't be really used atm,
	 * that's why we don't perform this clipping earlier.
	 */
	if (data->quant < data->min_quant[s->type-1]) {
		data->quant = data->min_quant[s->type-1];
	} else if (data->quant > data->max_quant[s->type-1]) {
		data->quant = data->max_quant[s->type-1];
	}

	/*
	 * To avoid big quality jumps from frame to frame, we apply a "security"
	 * rule that makes |last_quant - new_quant| <= 2. This rule only applies
	 * to predicted frames (P and B)
	 */
	if (s->type != XVID_TYPE_IVOP && rc->last_quant[s->type-1] && capped_to_max_framesize == 0) {

		if (data->quant > rc->last_quant[s->type-1] + 2) {
			data->quant = rc->last_quant[s->type-1] + 2;
			DPRINTF(XVID_DEBUG_RC,
					"[%i] p/b-frame quantizer prevented from rising too steeply\n",
					data->frame_num);
		}
		if (data->quant < rc->last_quant[s->type-1] - 2) {
			data->quant = rc->last_quant[s->type-1] - 2;
			DPRINTF(XVID_DEBUG_RC,
					"[%i] p/b-frame quantizer prevented from falling too steeply\n",
					data->frame_num);
		}
	}

	/*
	 * We don't want to pollute the RC history results when our computed quant
	 * has been computed from a capped frame size
	 */
	if (capped_to_max_framesize == 0)
		rc->last_quant[s->type-1] = data->quant;

	/* Force frame type */
	data->type = s->type;

	return 0;
}

/*----------------------------------------------------------------------------
 *--------------------------------------------------------------------------*/

static int
rc_2pass2_after(rc_2pass2_t * rc, xvid_plg_data_t * data)
{
	const char frame_type[4] = { 'i', 'p', 'b', 's'};
	stat_t * s = &rc->stats[data->frame_num];

	/* Insufficent stats data */
    if (data->frame_num >= rc->num_frames)
        return 0;

    rc->quant_count[data->quant]++;

    if (data->type == XVID_TYPE_IVOP) {
        int kfdiff = (rc->keyframe_locations[rc->KF_idx] -	rc->keyframe_locations[rc->KF_idx - 1]);

        rc->overflow += rc->KFoverflow;
        rc->KFoverflow = s->desired_length - data->length;
		
        if (kfdiff > 1) {  /* non-consecutive keyframes */
            rc->KFoverflow_partial = rc->KFoverflow / (kfdiff - 1);
        }else{ /* consecutive keyframes */
			rc->overflow += rc->KFoverflow;
			rc->KFoverflow = 0;
			rc->KFoverflow_partial = 0;
        }
        rc->KF_idx++;
    } else {
        /* distribute part of the keyframe overflow */
        rc->overflow += s->desired_length - data->length + rc->KFoverflow_partial;
        rc->KFoverflow -= rc->KFoverflow_partial;
    }

	DPRINTF(XVID_DEBUG_RC, "[%i] type:%c quant:%i stats1:%i scaled:%i actual:%i desired:%d overflow:%i\n",
			data->frame_num,
			frame_type[data->type-1],
			data->quant,
			s->length,
			s->scaled_length,
			data->length,
			s->desired_length,
			rc->overflow);

    return(0);
}

/*****************************************************************************
 * Helper functions definition
 ****************************************************************************/

#define BUF_SZ   1024
#define MAX_COLS 5

/* open stats file, and count num frames */
static int
det_stats_length(rc_2pass2_t * rc, char * filename)
{
    FILE * f;
    int n, ignore;
    char type;

    rc->num_frames = 0;
    rc->num_keyframes = 0;

    if ((f = fopen(filename, "rt")) == NULL)
        return 0;

    while((n = fscanf(f, "%c %d %d %d %d %d %d\n",
        &type, &ignore, &ignore, &ignore, &ignore, &ignore, &ignore)) != EOF) {
        if (type == 'i') {
            rc->num_frames++;
            rc->num_keyframes++;
        }else if (type == 'p' || type == 'b' || type == 's') {
            rc->num_frames++;
        }
    }

    fclose(f);

    return 1;
}

/* open stats file(s) and read into rc->stats array */

static int
load_stats(rc_2pass2_t *rc, char * filename)
{
    FILE * f;
    int i, not_scaled;
 

    if ((f = fopen(filename, "rt"))==NULL)
        return 0;
    
    i = 0;
	not_scaled = 0;
    while(i < rc->num_frames) {
        stat_t * s = &rc->stats[i];
        int n;
        char type;

		s->scaled_length = 0;
        n = fscanf(f, "%c %d %d %d %d %d %d\n", &type, &s->quant, &s->blks[0], &s->blks[1], &s->blks[2], &s->length, &s->scaled_length);
        if (n == EOF) break;
		if (n < 7) {
			not_scaled = 1;
		}

        if (type == 'i') {
            s->type = XVID_TYPE_IVOP;
        }else if (type == 'p' || type == 's') {
            s->type = XVID_TYPE_PVOP;
        }else if (type == 'b') {
            s->type = XVID_TYPE_BVOP;
        }else{  /* unknown type */
            DPRINTF(XVID_DEBUG_RC, "WARNING: unknown stats frame type, assuming pvop\n");
            s->type = XVID_TYPE_PVOP;
        }

        i++;
    }

    rc->num_frames = i;

	fclose(f);

    return 1;
}

#if 0
static void print_stats(rc_2pass2_t * rc)
{
    int i;
    DPRINTF(XVID_DEBUG_RC, "type quant length scaled_length\n");
	for (i = 0; i < rc->num_frames; i++) {
        stat_t * s = &rc->stats[i];
        DPRINTF(XVID_DEBUG_RC, "%d %d %d %d\n", s->type, s->quant, s->length, s->scaled_length);
    }
}
#endif

/* pre-process the statistics data 
    - for each type, count, tot_length, min_length, max_length
    - set keyframes_locations
*/

static void
pre_process0(rc_2pass2_t * rc)
{
    int i,j;

	/*
	 * *rc fields initialization
	 * NB: INT_MAX and INT_MIN are used in order to be immediately replaced
	 *     with real values of the 1pass
	 */
	 for (i=0; i<3; i++) {
		rc->count[i]=0;
		rc->tot_length[i] = 0;
		rc->min_length[i] = INT_MAX;
    }

	rc->max_length = INT_MIN;

	/*
	 * Loop through all frames and find/compute all the stuff this function
	 * is supposed to do
	 */
	for (i=j=0; i<rc->num_frames; i++) {
		stat_t * s = &rc->stats[i];

		rc->count[s->type-1]++;
		rc->tot_length[s->type-1] += s->length;

		if (s->length < rc->min_length[s->type-1]) {
			rc->min_length[s->type-1] = s->length;
		}

		if (s->length > rc->max_length) {
			rc->max_length = s->length;
		}

		if (s->type == XVID_TYPE_IVOP) {
			rc->keyframe_locations[j] = i;
			j++;
		}
	}

	/*
	 * Nota Bene:
	 * The "per sequence" overflow system considers a natural sequence to be
	 * formed by all frames between two iframes, so if we want to make sure
	 * the system does not go nuts during last sequence, we force the last
	 * frame to appear in the keyframe locations array.
	 */
    rc->keyframe_locations[j] = i;

	DPRINTF(XVID_DEBUG_RC, "Min 1st pass IFrame length: %d\n", rc->min_length[0]);
	DPRINTF(XVID_DEBUG_RC, "Min 1st pass PFrame length: %d\n", rc->min_length[1]);
	DPRINTF(XVID_DEBUG_RC, "Min 1st pass BFrame length: %d\n", rc->min_length[2]);
}
    
/* calculate zone weight "center" */

static void
zone_process(rc_2pass2_t *rc, const xvid_plg_create_t * create)
{
    int i,j;
    int n = 0;

    rc->avg_weight = 0.0;
    rc->tot_quant = 0;


    if (create->num_zones == 0) {
        for (j = 0; j < rc->num_frames; j++) {
            rc->stats[j].zone_mode = XVID_ZONE_WEIGHT;
            rc->stats[j].weight = 1.0;
        }
        rc->avg_weight += rc->num_frames * 1.0;
        n += rc->num_frames;
    }


    for(i=0; i < create->num_zones; i++) {
        
        int next = (i+1<create->num_zones) ? create->zones[i+1].frame : rc->num_frames;

        if (i==0 && create->zones[i].frame > 0) {
            for (j = 0; j < create->zones[i].frame && j < rc->num_frames; j++) {
                rc->stats[j].zone_mode = XVID_ZONE_WEIGHT;
                rc->stats[j].weight = 1.0;
            }
            rc->avg_weight += create->zones[i].frame * 1.0;
            n += create->zones[i].frame;
        }

        if (create->zones[i].mode == XVID_ZONE_WEIGHT) {
            for (j = create->zones[i].frame; j < next && j < rc->num_frames; j++ ) {
                rc->stats[j].zone_mode = XVID_ZONE_WEIGHT;
                rc->stats[j].weight = (double)create->zones[i].increment / (double)create->zones[i].base;
            }
            next -= create->zones[i].frame;
            rc->avg_weight += (double)(next * create->zones[i].increment) / (double)create->zones[i].base;
            n += next;
        }else{  /* XVID_ZONE_QUANT */
            for (j = create->zones[i].frame; j < next && j < rc->num_frames; j++ ) {
                rc->stats[j].zone_mode = XVID_ZONE_QUANT;
                rc->stats[j].weight = (double)create->zones[i].increment / (double)create->zones[i].base;
                rc->tot_quant += rc->stats[j].length;
            }
        }
    }
    rc->avg_weight = n>0 ? rc->avg_weight/n : 1.0;

    DPRINTF(XVID_DEBUG_RC, "center_weight: %f (for %i frames);   fixed_bytes: %i\n", rc->avg_weight, n, rc->tot_quant);
}


/* scale the curve */

static void
internal_scale(rc_2pass2_t *rc)
{
	int64_t target  = rc->target - rc->tot_quant;
	int64_t pass1_length = rc->tot_length[0] + rc->tot_length[1] + rc->tot_length[2] - rc->tot_quant;
	double scaler;
	int i, num_MBs;

	/* Let's compute a linear scaler in order to perform curve scaling */
	scaler = (double)target / (double)pass1_length;

	if (target <= 0 || pass1_length <= 0 || target >= pass1_length) {
		DPRINTF(XVID_DEBUG_RC, "WARNING: Undersize detected\n");
        scaler = 1.0;
	}

    DPRINTF(XVID_DEBUG_RC,
			"Before correction: target=%i, tot_length=%i, scaler=%f\n",
			(int)target, (int)pass1_length, scaler);

	/*
	 * Compute min frame lengths (for each frame type) according to the number
	 * of MBs. We sum all blocks count from frame 0 (should be an IFrame, so
	 * blocks[0] should be enough) to know how many MBs there are.
	 *
	 * We compare these hardcoded values with observed values in first pass
	 * (determined in pre_process0).Then we keep the real minimum.
	 */
	num_MBs = rc->stats[0].blks[0] + rc->stats[0].blks[1] + rc->stats[0].blks[2];

	if(rc->min_length[0] > ((num_MBs*22) + 240) / 8)
		rc->min_length[0] = ((num_MBs*22) + 240) / 8;

	if(rc->min_length[1] > ((num_MBs) + 88)  / 8)
		rc->min_length[1] = ((num_MBs) + 88)  / 8;

	if(rc->min_length[2] > 8)
		rc->min_length[2] = 8;

	/*
	 * Perform an initial scale pass.
	 * If a frame size is scaled underneath our hardcoded minimums, then we
	 * force the frame size to the minimum, and deduct the original & scaled
	 * frame length from the original and target total lengths
	 */
	for (i=0; i<rc->num_frames; i++) {
		stat_t * s = &rc->stats[i];
		int len;

        if (s->zone_mode == XVID_ZONE_QUANT) {
            s->scaled_length = s->length;
			continue;
		}

		/* Compute the scaled length */
		len = (int)((double)s->length * scaler * s->weight / rc->avg_weight);

		/* Compare with the computed minimum */
		if (len < rc->min_length[s->type-1]) {
			/* force frame size to our computed minimum */
			s->scaled_length = rc->min_length[s->type-1];
			target -= s->scaled_length;
			pass1_length -= s->length;
		} else {
			/* Do nothing for now, we'll scale this later */
			s->scaled_length = 0;
		}
	}

	/* Correct the scaler for all non forced frames */
	scaler = (double)target / (double)pass1_length;

	/* Detect undersizing */
    if (target <= 0 || pass1_length <= 0 || target >= pass1_length) {
		DPRINTF(XVID_DEBUG_RC, "WARNING: Undersize detected\n");
		scaler = 1.0;
	}

	DPRINTF(XVID_DEBUG_RC,
			"After correction: target=%i, tot_length=%i, scaler=%f\n",
			(int)target, (int)pass1_length, scaler);

	/* Do another pass with the new scaler */
	for (i=0; i<rc->num_frames; i++) {
		stat_t * s = &rc->stats[i];

		/* Ignore frame with forced frame sizes */
		if (s->scaled_length == 0)
			s->scaled_length = (int)((double)s->length * scaler * s->weight / rc->avg_weight);
	}
}

static void
pre_process1(rc_2pass2_t * rc)
{
    int i;
    double total1, total2;
    uint64_t ivop_boost_total;

    ivop_boost_total = 0;
    rc->curve_comp_error = 0;

    for (i=0; i<3; i++) {
        rc->tot_scaled_length[i] = 0;
    }

    for (i=0; i<rc->num_frames; i++) {
        stat_t * s = &rc->stats[i];

        rc->tot_scaled_length[s->type-1] += s->scaled_length;
       
        if (s->type == XVID_TYPE_IVOP) {
            ivop_boost_total += s->scaled_length * rc->param.keyframe_boost / 100;
        }
    }

    rc->movie_curve = ((double)(rc->tot_scaled_length[XVID_TYPE_PVOP-1] + rc->tot_scaled_length[XVID_TYPE_BVOP-1] + ivop_boost_total) /
			                (rc->tot_scaled_length[XVID_TYPE_PVOP-1] + rc->tot_scaled_length[XVID_TYPE_BVOP-1]));

    for(i=0; i<3; i++) {
        if (rc->count[i] == 0 || rc->movie_curve == 0) {
            rc->avg_length[i] = 1;
        }else{
            rc->avg_length[i] = rc->tot_scaled_length[i] / rc->count[i] / rc->movie_curve;
        }
    }

    /* --- */

    total1=total2=0;

    for (i=0; i<rc->num_frames; i++) {
        stat_t * s = &rc->stats[i];

        if (s->type != XVID_TYPE_IVOP) {
            double dbytes,dbytes2;

            dbytes = s->scaled_length / rc->movie_curve;
            dbytes2 = 0; /* XXX: warning */
            total1 += dbytes;

			if (dbytes > rc->avg_length[s->type-1]) {
				dbytes2=((double)dbytes + (rc->avg_length[s->type-1] - dbytes) * rc->param.curve_compression_high / 100.0);
			} else {
				dbytes2 = ((double)dbytes + (rc->avg_length[s->type-1] - dbytes) * rc->param.curve_compression_low / 100.0);
			}

			if (dbytes2 < rc->min_length[s->type-1])
				    dbytes2 = rc->min_length[s->type-1];

            total2 += dbytes2;
        }
    }

    rc->curve_comp_scale = total1 / total2;

	DPRINTF(XVID_DEBUG_RC, "middle frame size for asymmetric curve compression: pframe%d bframe:%d\n",
            (int)(rc->avg_length[XVID_TYPE_PVOP-1] * rc->curve_comp_scale),
			(int)(rc->avg_length[XVID_TYPE_BVOP-1] * rc->curve_comp_scale));

    rc->overflow = 0;
    rc->KFoverflow = 0;
    rc->KFoverflow_partial = 0;
    rc->KF_idx = 1;
}

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