putvlc.c
资源名称:mpeg2编解码.zip [点击查看]
上传用户:hkgotone
上传日期:2013-02-17
资源大小:293k
文件大小:6k
源码类别:
Windows Mobile
开发平台:
C/C++
- /* putvlc.c, generation of variable length codes */
- /* Copyright (C) 1996, MPEG Software Simulation Group. All Rights Reserved. */
- /*
- * Disclaimer of Warranty
- *
- * These software programs are available to the user without any license fee or
- * royalty on an "as is" basis. The MPEG Software Simulation Group disclaims
- * any and all warranties, whether express, implied, or statuary, including any
- * implied warranties or merchantability or of fitness for a particular
- * purpose. In no event shall the copyright-holder be liable for any
- * incidental, punitive, or consequential damages of any kind whatsoever
- * arising from the use of these programs.
- *
- * This disclaimer of warranty extends to the user of these programs and user's
- * customers, employees, agents, transferees, successors, and assigns.
- *
- * The MPEG Software Simulation Group does not represent or warrant that the
- * programs furnished hereunder are free of infringement of any third-party
- * patents.
- *
- * Commercial implementations of MPEG-1 and MPEG-2 video, including shareware,
- * are subject to royalty fees to patent holders. Many of these patents are
- * general enough such that they are unavoidable regardless of implementation
- * design.
- *
- */
- #include <stdio.h>
- #include "config.h"
- #include "global.h"
- #include "vlc.h"
- /* private prototypes */
- static void putDC _ANSI_ARGS_((sVLCtable *tab, int val));
- /* generate variable length code for luminance DC coefficient */
- void putDClum(val)
- int val;
- {
- putDC(DClumtab,val);
- }
- /* generate variable length code for chrominance DC coefficient */
- void putDCchrom(val)
- int val;
- {
- putDC(DCchromtab,val);
- }
- /* generate variable length code for DC coefficient (7.2.1) */
- static void putDC(tab,val)
- sVLCtable *tab;
- int val;
- {
- int absval, size;
- absval = (val<0) ? -val : val; /* abs(val) */
- if (absval>2047 || (mpeg1 && absval>255))
- {
- /* should never happen */
- sprintf(errortext,"DC value out of range (%d)n",val);
- error(errortext);
- }
- /* compute dct_dc_size */
- size = 0;
- while (absval)
- {
- absval >>= 1;
- size++;
- }
- /* generate VLC for dct_dc_size (Table B-12 or B-13) */
- putbits(tab[size].code,tab[size].len);
- /* append fixed length code (dc_dct_differential) */
- if (size!=0)
- {
- if (val>=0)
- absval = val;
- else
- absval = val + (1<<size) - 1; /* val + (2 ^ size) - 1 */
- putbits(absval,size);
- }
- }
- /* generate variable length code for first coefficient
- * of a non-intra block (7.2.2.2) */
- void putACfirst(run,val)
- int run,val;
- {
- if (run==0 && (val==1 || val==-1)) /* these are treated differently */
- putbits(2|(val<0),2); /* generate '1s' (s=sign), (Table B-14, line 2) */
- else
- putAC(run,val,0); /* no difference for all others */
- }
- /* generate variable length code for other DCT coefficients (7.2.2) */
- void putAC(run,signed_level,vlcformat)
- int run,signed_level,vlcformat;
- {
- int level, len;
- VLCtable *ptab;
- level = (signed_level<0) ? -signed_level : signed_level; /* abs(signed_level) */
- /* make sure run and level are valid */
- if (run<0 || run>63 || level==0 || level>2047 || (mpeg1 && level>255))
- {
- sprintf(errortext,"AC value out of range (run=%d, signed_level=%d)n",
- run,signed_level);
- error(errortext);
- }
- len = 0;
- if (run<2 && level<41)
- {
- /* vlcformat selects either of Table B-14 / B-15 */
- if (vlcformat)
- ptab = &dct_code_tab1a[run][level-1];
- else
- ptab = &dct_code_tab1[run][level-1];
- len = ptab->len;
- }
- else if (run<32 && level<6)
- {
- /* vlcformat selects either of Table B-14 / B-15 */
- if (vlcformat)
- ptab = &dct_code_tab2a[run-2][level-1];
- else
- ptab = &dct_code_tab2[run-2][level-1];
- len = ptab->len;
- }
- if (len!=0) /* a VLC code exists */
- {
- putbits(ptab->code,len);
- putbits(signed_level<0,1); /* sign */
- }
- else
- {
- /* no VLC for this (run, level) combination: use escape coding (7.2.2.3) */
- putbits(1l,6); /* Escape */
- putbits(run,6); /* 6 bit code for run */
- if (mpeg1)
- {
- /* ISO/IEC 11172-2 uses a 8 or 16 bit code */
- if (signed_level>127)
- putbits(0,8);
- if (signed_level<-127)
- putbits(128,8);
- putbits(signed_level,8);
- }
- else
- {
- /* ISO/IEC 13818-2 uses a 12 bit code, Table B-16 */
- putbits(signed_level,12);
- }
- }
- }
- /* generate variable length code for macroblock_address_increment (6.3.16) */
- void putaddrinc(addrinc)
- int addrinc;
- {
- while (addrinc>33)
- {
- putbits(0x08,11); /* macroblock_escape */
- addrinc-= 33;
- }
- putbits(addrinctab[addrinc-1].code,addrinctab[addrinc-1].len);
- }
- /* generate variable length code for macroblock_type (6.3.16.1) */
- void putmbtype(pict_type,mb_type)
- int pict_type,mb_type;
- {
- putbits(mbtypetab[pict_type-1][mb_type].code,
- mbtypetab[pict_type-1][mb_type].len);
- }
- /* generate variable length code for motion_code (6.3.16.3) */
- void putmotioncode(motion_code)
- int motion_code;
- {
- int abscode;
- abscode = (motion_code>=0) ? motion_code : -motion_code; /* abs(motion_code) */
- putbits(motionvectab[abscode].code,motionvectab[abscode].len);
- if (motion_code!=0)
- putbits(motion_code<0,1); /* sign, 0=positive, 1=negative */
- }
- /* generate variable length code for dmvector[t] (6.3.16.3), Table B-11 */
- void putdmv(dmv)
- int dmv;
- {
- if (dmv==0)
- putbits(0,1);
- else if (dmv>0)
- putbits(2,2);
- else
- putbits(3,2);
- }
- /* generate variable length code for coded_block_pattern (6.3.16.4)
- *
- * 4:2:2, 4:4:4 not implemented
- */
- void putcbp(cbp)
- int cbp;
- {
- putbits(cbptable[cbp].code,cbptable[cbp].len);
- }