📄 mp4_vld.c
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/**************************************************************************
* *
* This code has been developed by John Funnell. This software is an *
* implementation of a part of one or more MPEG-4 Video tools as *
* specified in ISO/IEC 14496-2 standard. Those intending to use this *
* software module in hardware or software products are advised that its *
* use may infringe existing patents or copyrights, and any such use *
* would be at such party's own risk. The original developer of this *
* software module and his/her company, and subsequent editors and their *
* companies (including Project Mayo), will have no liability for use of *
* this software or modifications or derivatives thereof. *
* *
* Project Mayo gives users of the Codec a license to this software *
* module or modifications thereof for use in hardware or software *
* products claiming conformance to the MPEG-4 Video Standard as *
* described in the Open DivX license. *
* *
* The complete Open DivX license can be found at *
* http://www.projectmayo.com/opendivx/license.php *
* *
**************************************************************************/
/**
* Copyright (C) 2001 - Project Mayo
*
* John Funnell
* Andrea Graziani
*
* DivX Advanced Research Center <darc@projectmayo.com>
*
**/
// mp4_vld.c //
#include <stdio.h>
#include "mp4_vars.h"
#include "getbits.h"
#include "mp4_vld.h"
/**
*
**/
/***/
event_t vld_intra_dct()
{
event_t event;
tab_type *tab = (tab_type *) NULL;
int lmax, rmax;
tab = vldTableB16(showbits(12));
if (!tab) { /* bad code */
event.run =
event.level =
event.last = -1;
return event;
}
if (tab->val != ESCAPE) {
event.run = (tab->val >> 6) & 63;
event.level = tab->val & 63;
event.last = (tab->val >> 12) & 1;
event.level = getbits(1) ? -event.level : event.level;
} else {
/* this value is escaped - see para 7.4.1.3 */
/* assuming short_video_header == 0 */
switch (showbits(2)) {
case 0x0 : /* Type 1 */
case 0x1 : /* Type 1 */
flushbits(1);
tab = vldTableB16(showbits(12)); /* use table B-16 */
if (!tab) { /* bad code */
event.run =
event.level =
event.last = -1;
return event;
}
event.run = (tab->val >> 6) & 63;
event.level = tab->val & 63;
event.last = (tab->val >> 12) & 1;
lmax = vldTableB19(event.last, event.run); /* use table B-19 */
event.level += lmax;
event.level = getbits(1) ? -event.level : event.level;
break;
case 0x2 : /* Type 2 */
flushbits(2);
tab = vldTableB16(showbits(12)); /* use table B-16 */
if (!tab) { /* bad code */
event.run =
event.level =
event.last = -1;
break;
}
event.run = (tab->val >> 6) & 63;
event.level = tab->val & 63;
event.last = (tab->val >> 12) & 1;
rmax = vldTableB21(event.last, event.level); /* use table B-21 */
event.run = event.run + rmax + 1;
event.level = getbits(1) ? -event.level : event.level;
break;
case 0x3 : /* Type 3 - fixed length codes */
flushbits(2);
event.last = getbits(1);
event.run = getbits(6); /* table B-18 */
getbits(1); /* marker bit */
event.level = getbits(12); /* table B-18 */
/* sign extend level... */
event.level = (event.level & 0x800) ? (event.level | (-1 ^ 0xfff)) : event.level;
getbits(1); /* marker bit */
break;
}
}
return event;
}
/***/
event_t vld_inter_dct()
{
event_t event;
tab_type *tab = (tab_type *) NULL;
int lmax, rmax;
tab = vldTableB17(showbits(12));
if (!tab) { /* bad code */
event.run =
event.level =
event.last = -1;
return event;
}
if (tab->val != ESCAPE) {
event.run = (tab->val >> 4) & 255;
event.level = tab->val & 15;
event.last = (tab->val >> 12) & 1;
event.level = getbits(1) ? -event.level : event.level;
} else {
/* this value is escaped - see para 7.4.1.3 */
/* assuming short_video_header == 0 */
int mode = showbits(2);
switch (mode) {
case 0x0 : /* Type 1 */
case 0x1 : /* Type 1 */
flushbits(1);
tab = vldTableB17(showbits(12)); /* use table B-17 */
if (!tab) { /* bad code */
event.run =
event.level =
event.last = -1;
return event;
}
event.run = (tab->val >> 4) & 255;
event.level = tab->val & 15;
event.last = (tab->val >> 12) & 1;
lmax = vldTableB20(event.last, event.run); /* use table B-20 */
event.level += lmax;
event.level = getbits(1) ? -event.level : event.level;
break;
case 0x2 : /* Type 2 */
flushbits(2);
tab = vldTableB17(showbits(12)); /* use table B-16 */
if (!tab) { /* bad code */
event.run =
event.level =
event.last = -1;
break;
}
event.run = (tab->val >> 4) & 255;
event.level = tab->val & 15;
event.last = (tab->val >> 12) & 1;
rmax = vldTableB22(event.last, event.level); /* use table B-22 */
event.run = event.run + rmax + 1;
event.level = getbits(1) ? -event.level : event.level;
break;
case 0x3 : /* Type 3 - fixed length codes */
flushbits(2);
event.last = getbits(1);
event.run = getbits(6); /* table B-18 */
getbits(1); /* marker bit */
event.level = getbits(12); /* table B-18 */
/* sign extend level... */
event.level = (event.level & 0x800) ? (event.level | (-1 ^ 0xfff)) : event.level;
getbits(1); /* marker bit */
break;
}
}
return event;
}
/***/
event_t vld_event(int intraFlag)
{
if (intraFlag) {
return vld_intra_dct();
} else {
return vld_inter_dct();
}
}
/***/
/* Table B-19 -- ESCL(a), LMAX values of intra macroblocks */
int vldTableB19(int last, int run) {
if (!last){ /* LAST == 0 */
if (run == 0) {
return 27;
} else if (run == 1) {
return 10;
} else if (run == 2) {
return 5;
} else if (run == 3) {
return 4;
} else if (run <= 7) {
return 3;
} else if (run <= 9) {
return 2;
} else if (run <= 14) {
return 1;
} else { /* illegal? */
return 0;
}
} else { /* LAST == 1 */
if (run == 0) {
return 8;
} else if (run == 1) {
return 3;
} else if (run <= 6) {
return 2;
} else if (run <= 20) {
return 1;
} else { /* illegal? */
return 0;
}
}
}
/***/
/* Table B-20 -- ESCL(b), LMAX values of inter macroblocks */
int vldTableB20(int last, int run) {
if (!last){ /* LAST == 0 */
if (run == 0) {
return 12;
} else if (run == 1) {
return 6;
} else if (run == 2) {
return 4;
} else if (run <= 6) {
return 3;
} else if (run <= 10) {
return 2;
} else if (run <= 26) {
return 1;
} else { /* illegal? */
return 0;
}
} else { /* LAST == 1 */
if (run == 0) {
return 3;
} else if (run == 1) {
return 2;
} else if (run <= 40) {
return 1;
} else { /* illegal? */
return 0;
}
}
}
/***/
/* Table B-21 -- ESCR(a), RMAX values of intra macroblocks */
int vldTableB21(int last, int level) {
if (!last){ /* LAST == 0 */
if (level == 1) {
return 14;
} else if (level == 2) {
return 9;
} else if (level == 3) {
return 7;
} else if (level == 4) {
return 3;
} else if (level == 5) {
return 2;
} else if (level <= 10) {
return 1;
} else if (level <= 27) {
return 0;
} else { /* illegal? */
return 0;
}
} else { /* LAST == 1 */
if (level == 1) {
return 20;
} else if (level == 2) {
return 6;
} else if (level == 3) {
return 1;
} else if (level <= 8) {
return 0;
} else { /* illegal? */
return 0;
}
}
}
/***/
/* Table B-22 -- ESCR(b), RMAX values of inter macroblocks */
int vldTableB22(int last, int level) {
if (!last){ /* LAST == 0 */
if (level == 1) {
return 26;
} else if (level == 2) {
return 10;
} else if (level == 3) {
return 6;
} else if (level == 4) {
return 2;
} else if (level <= 6) {
return 1;
} else if (level <= 12) {
return 0;
} else { /* illegal? */
return 0;
}
} else { /* LAST == 1 */
if (level == 1) {
return 40;
} else if (level == 2) {
return 1;
} else if (level == 3) {
return 0;
} else { /* illegal? */
return 0;
}
}
}
/***/
tab_type *vldTableB16(int code) {
tab_type *tab;
if (code >= 512) {
tab = &(mp4_tables->tableB16_1[(code >> 5) - 16]);
} else if (code >= 128) {
tab = &(mp4_tables->tableB16_2[(code >> 2) - 32]);
} else if (code >= 8) {
tab = &(mp4_tables->tableB16_3[(code >> 0) - 8]);
} else {
/* invalid Huffman code */
return (tab_type *) NULL;
}
flushbits(tab->len);
return tab;
}
/***/
tab_type *vldTableB17(int code) {
tab_type *tab;
if (code >= 512) {
tab = &(mp4_tables->tableB17_1[(code >> 5) - 16]);
} else if (code >= 128) {
tab = &(mp4_tables->tableB17_2[(code >> 2) - 32]);
} else if (code >= 8) {
tab = &(mp4_tables->tableB17_3[(code >> 0) - 8]);
} else {
/* invalid Huffman code */
return (tab_type *) NULL;
}
flushbits(tab->len);
return tab;
}
/***/
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