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/***************************************************************************** |
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* |
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* XviD VBR Library |
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* - Fixed quantizer controller implementation - |
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* |
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* Copyright (C) 2002 Edouard Gomez <ed.gomez@wanadoo.fr> |
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* |
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* This program is free software; you can redistribute it and/or modify |
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* it under the terms of the GNU General Public License as published by |
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* the Free Software Foundation; either version 2 of the License, or |
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* (at your option) any later version. |
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* |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU General Public License for more details. |
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* |
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* You should have received a copy of the GNU General Public License |
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* along with this program; if not, write to the Free Software |
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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* |
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* $Id$ |
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* |
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****************************************************************************/ |
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#include "../xvid.h" |
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#include "../image/image.h" |
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typedef struct |
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{ |
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int32_t quant_increment; |
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int32_t quant_base; |
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/* Number of quantizers in the *quant distribution */ |
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int nquant; |
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/* Quantizer distribution */ |
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int *quant; |
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} rc_fixed_t; |
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static int gcd(int a, int b) |
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{ |
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int r; |
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while(b) { |
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r = a % b; |
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a = b; |
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b = r; |
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} |
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return(a); |
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} |
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static int |
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distribute_quants(int **quants, int lquant, int n_lquant, int n_hquant) |
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{ |
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int i, n, _gcd; |
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int nlow, nhigh; |
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int low, high; |
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int q, r; |
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int a,b,min, max; |
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int *dist; |
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/* Low quant */ |
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low = lquant; |
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/* High quant is just low quant + 1 */ |
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high = low + 1; |
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/* How much low quants we have to distribute */ |
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nlow = n_lquant; |
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/* How much high quants we have to distribute */ |
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nhigh = n_hquant; |
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/* Simplify the pattern, respecting the current ratio nhigh/nlow */ |
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_gcd = gcd( nlow, nhigh); |
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nlow = nlow / _gcd; |
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nhigh = nhigh / _gcd; |
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/* Allocate the distributuion array */ |
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if((*quants = (int*)malloc((nhigh + nlow)*sizeof(int))) == NULL) |
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return (-1); |
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/* Validate distribution size */ |
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n = nlow + nhigh; |
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/* |
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* Our goal now is to find packet length so we distribute the quants |
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* the best we can. The solution i chose is quite simple. |
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* |
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* Let's 'max' be max(nlow, nhigh) |
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* Let's 'min' be min(nlow, nhigh) |
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* |
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* Then if we compute the euclidian division of 'max' by 'min', the |
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* quotient 'q' represents the length of 'max type quant' packets |
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* length. Let's call 'r' the remaining part of the euclidian division. |
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* |
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* We could stop there and have something like this: |
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* M == quant type of the quantity 'max' |
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* m == quant type of the quantity 'min' |
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* |
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* (MM.........Mm)*(MMMMMM...M) |
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* '----------' '--------' |
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* '----|------' |-> repeated 'r' times |
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* || |
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* ||--> repeated 'min' times |
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* |---> repeated 'q' times' |
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* |
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* |
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* Let's look if we have precision quants. |
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* |
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* We have 'min' packets of (q+1) length |
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* We have also a packet of length 'r' |
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* So : min*(q+1) + r == (min*q + r) + min == max + min == n |
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* |
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* Ok this is good :-) |
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* |
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* Now let's complicate things a bit :-))) |
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* |
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* We will distribute the last M quantizers all over the distribution |
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* array. To achieve that, we build packets of (q+2) quantizers containing |
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* qM + 1m as usual plus 1M from the last remaining M quantizer packet and |
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* usual packets of (q+1) with qM and 1m. |
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* |
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* So we will have this kind of distribution: |
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* |
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* (MM.........Mm)*(MMMM...Mm) |
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* '----------' '------' |
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* '----|------' '---|---' |
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* || ||--> repeated 'min-r' times |
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* || |---> repeated 'q' times |
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* ||--> repeated 'r' times |
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* |---> repeated 'q+1' times |
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* |
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* |
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* Let's check if it's still right: |
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* |
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* We'll have ((q+1)*r + q*(min-r))M quants == (q*r + r + q*min - q*r)M |
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* == (q*min + r)M |
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* == (max)M it's good |
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* And: (r + min - r)m quantizers == (min)m it's good too) |
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* |
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* NB: if the fixed quantizer is an integer then we have min == 0, so we |
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* must take care of it apart (else the euclidian division leads to |
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* an arithmetic signal - division by zero) |
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* |
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*/ |
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max = MAX(nlow, nhigh); |
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min = MIN(nlow, nhigh); |
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/* Euclidian division */ |
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if(min == 0) { |
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q = 0; |
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r = max; |
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} else { |
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q = max/min; |
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r = max%min; |
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} |
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/* How much packets of (q+1)M quantizers + 1m quantizer */ |
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a = r; |
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/* How much packets of (q)M quantizers + 1m quantizer */ |
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b = min - r; |
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/* |
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* Ok now we know everything we have to know to distribute those funny |
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* quantizers. What about just doing it ? |
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*/ |
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dist = *quants; |
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/* Distribute big packets */ |
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for(i=0; i<a; i++) { |
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int j; |
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/* Repeat q+1 times the M quantizer */ |
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for(j=0; j<(q+1); j++) *(dist++) = (max==nhigh)?high:low; |
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/* Put a m quantizer */ |
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*(dist++) = (min==nhigh)?high:low; |
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} |
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/* Distribute the little packets */ |
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for(i=0; i<b; i++) { |
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int j; |
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/* Repeat q times the M quantizer */ |
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for(j=0; j<q; j++) *(dist++) = (max==nhigh)?high:low; |
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/* Put a m quantizer */ |
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*(dist++) = (min==nhigh)?high:low; |
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} |
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return(n); |
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} |
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static int rc_fixed_create(xvid_plg_create_t * create, rc_fixed_t ** handle) |
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{ |
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xvid_plugin_fixed_t * param = (xvid_plugin_fixed_t *)create->param; |
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rc_fixed_t * rc; |
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int quant_low; |
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int nquant_low, nquant_high; |
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/* allocate context struct */ |
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if((rc = malloc(sizeof(rc_fixed_t))) == NULL) |
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return(XVID_ERR_MEMORY); |
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/* Copy data to private area */ |
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rc->quant_increment = param->quant_increment; |
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rc->quant_base = param->quant_base; |
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/* Cut down the precision up to 1/precision */ |
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quant_low = rc->quant_increment/rc->quant_base; |
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/* Force [1..31] range */ |
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if(quant_low < 1) { |
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quant_low = 1; |
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rc->quant_base = 1; |
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rc->quant_increment = quant_low; |
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} else if(quant_low > 30) { |
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quant_low = 31; |
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rc->quant_base = 1; |
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rc->quant_increment = quant_low; |
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} |
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/* How much low quants we have to distribute) */ |
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nquant_low = rc->quant_base*(quant_low+1) - rc->quant_increment; |
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nquant_high = rc->quant_base - nquant_low; |
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/* Distribute the quantizers */ |
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rc->nquant = distribute_quants(&rc->quant, |
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quant_low, |
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nquant_low, |
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nquant_high); |
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if(rc->quant == NULL) { |
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free(rc); |
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return(XVID_ERR_MEMORY); |
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} |
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*handle = rc; |
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return(0); |
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} |
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static int rc_fixed_destroy(rc_fixed_t * rc, xvid_plg_destroy_t * destroy) |
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{ |
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free(rc); |
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return(0); |
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} |
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static int rc_fixed_before(rc_fixed_t * rc, xvid_plg_data_t * data) |
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{ |
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data->quant = rc->quant[data->frame_num%rc->nquant]; |
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data->type = XVID_TYPE_AUTO; |
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return 0; |
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} |
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int xvid_plugin_fixed(void * handle, int opt, void * param1, void * param2) |
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{ |
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switch(opt) |
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{ |
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case XVID_PLG_INFO : |
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return 0; |
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case XVID_PLG_CREATE : |
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return rc_fixed_create((xvid_plg_create_t*)param1, param2); |
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case XVID_PLG_DESTROY : |
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return rc_fixed_destroy((rc_fixed_t*)handle, (xvid_plg_destroy_t*)param1); |
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case XVID_PLG_BEFORE : |
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return rc_fixed_before((rc_fixed_t*)handle, (xvid_plg_data_t*)param1); |
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case XVID_PLG_AFTER : |
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return 0; |
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} |
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return XVID_ERR_FAIL; |
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} |
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