mirror of https://github.com/mpv-player/mpv
334 lines
7.5 KiB
C
334 lines
7.5 KiB
C
/*
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* decoder for Closed Captions
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*
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* This decoder relies on MPlayer's OSD to display subtitles.
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* Be warned that decoding is somewhat preliminary, though it basically works.
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*
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* Most notably, only the text information is decoded as of now, discarding
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* color, background and position info (see source below).
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*
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* by Matteo Giani
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*
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* uses source from the xine closed captions decoder
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "config.h"
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#include "sub_cc.h"
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#include "subreader.h"
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#include "libvo/video_out.h"
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#include "libvo/sub.h"
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#define CC_MAX_LINE_LENGTH 64
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static char chartbl[128];
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static subtitle buf1,buf2;
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static subtitle *fb,*bb;
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static unsigned int cursor_pos=0;
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static int initialized=0;
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#define CC_ROLLON 1
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#define CC_ROLLUP 2
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static int cc_mode=CC_ROLLON;
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static int cc_lines=4; ///< number of visible rows in CC roll-up mode, not used in CC roll-on mode
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static void display_buffer(subtitle * buf);
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static void build_char_table(void)
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{
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int i;
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/* first the normal ASCII codes */
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for (i = 0; i < 128; i++)
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chartbl[i] = (char) i;
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/* now the special codes */
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chartbl[0x2a] = 'á';
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chartbl[0x5c] = 'é';
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chartbl[0x5e] = 'í';
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chartbl[0x5f] = 'ó';
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chartbl[0x60] = 'ú';
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chartbl[0x7b] = 'ç';
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chartbl[0x7c] = '÷';
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chartbl[0x7d] = 'Ñ';
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chartbl[0x7e] = 'ñ';
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chartbl[0x7f] = '¤'; /* FIXME: this should be a solid block */
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}
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static void clear_buffer(subtitle *buf)
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{
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int i;
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buf->lines=0;
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for(i=0;i<SUB_MAX_TEXT;i++) if(buf->text[i]) {free(buf->text[i]);buf->text[i]=NULL;}
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}
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/**
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\brief scroll buffer one line up
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\param buf buffer to scroll
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*/
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static void scroll_buffer(subtitle* buf)
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{
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int i;
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while(buf->lines > cc_lines)
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{
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if(buf->text[0]) free(buf->text[0]);
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for(i = 0; i < (buf->lines - 1); i++) buf->text[i] = buf->text[i+1];
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buf->text[buf->lines-1] = NULL;
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buf->lines--;
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}
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}
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void subcc_init(void)
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{
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int i;
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//printf("subcc_init(): initing...\n");
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build_char_table();
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for(i=0;i<SUB_MAX_TEXT;i++) {buf1.text[i]=buf2.text[i]=NULL;}
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buf1.lines=buf2.lines=0;
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fb=&buf1;
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bb=&buf2;
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initialized=1;
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}
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static void append_char(char c)
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{
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if(!bb->lines) {bb->lines++; cursor_pos=0;}
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if(bb->text[bb->lines - 1]==NULL)
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{
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bb->text[bb->lines - 1]=malloc(CC_MAX_LINE_LENGTH);
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memset(bb->text[bb->lines - 1],0,CC_MAX_LINE_LENGTH);
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cursor_pos=0;
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}
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if(c=='\n')
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{
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if(cursor_pos>0 && bb->lines < SUB_MAX_TEXT)
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{
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bb->lines++;cursor_pos=0;
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if(cc_mode==CC_ROLLUP){ //Carriage return - scroll buffer one line up
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bb->text[bb->lines - 1]=calloc(1, CC_MAX_LINE_LENGTH);
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scroll_buffer(bb);
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}
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}
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}
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else
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{
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if(cursor_pos==CC_MAX_LINE_LENGTH-1)
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{
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fprintf(stderr,"CC: append_char() reached CC_MAX_LINE_LENGTH!\n");
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return;
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}
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bb->text[bb->lines - 1][cursor_pos++]=c;
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}
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//In CC roll-up mode data should be shown immediately
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if(cc_mode==CC_ROLLUP) display_buffer(bb);
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}
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static void swap_buffers(void)
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{
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subtitle *foo;
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foo=fb;
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fb=bb;
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bb=foo;
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}
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static void display_buffer(subtitle * buf)
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{
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vo_sub=buf;
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vo_osd_changed(OSDTYPE_SUBTITLE);
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}
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static void cc_decode_EIA608(unsigned short int data)
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{
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static unsigned short int lastcode=0x0000;
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unsigned char c1 = data & 0x7f;
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unsigned char c2 = (data >> 8) & 0x7f;
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if (c1 & 0x60) { /* normal character, 0x20 <= c1 <= 0x7f */
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append_char(chartbl[c1]);
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if(c2 & 0x60) /*c2 might not be a normal char even if c1 is*/
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append_char(chartbl[c2]);
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}
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else if (c1 & 0x10) // control code / special char
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{
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// int channel= (c1 & 0x08) >> 3;
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c1&=~0x08;
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if(data!=lastcode)
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{
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if(c2 & 0x40) { /*PAC, Preamble Address Code */
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append_char('\n'); /*FIXME properly interpret PACs*/
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}
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else
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switch(c1)
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{
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case 0x10: break; // ext attribute
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case 0x11:
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if((c2 & 0x30)==0x30)
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{
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//printf("[debug]:Special char (ignored)\n");
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/*cc_decode_special_char()*/;
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}
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else if (c2 & 0x20)
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{
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//printf("[debug]: midrow_attr (ignored)\n");
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/*cc_decode_midrow_attr()*/;
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}
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break;
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case 0x14:
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switch(c2)
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{
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case 0x00: //CC roll-on mode
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cc_mode=CC_ROLLON;
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break;
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case 0x25: //CC roll-up, 2 rows
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case 0x26: //CC roll-up, 3 rows
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case 0x27: //CC roll-up, 4 rows
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cc_lines=c2-0x23;
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cc_mode=CC_ROLLUP;
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break;
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case 0x2C: display_buffer(NULL); //EDM
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clear_buffer(fb); break;
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case 0x2d: append_char('\n'); //carriage return
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break;
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case 0x2e: clear_buffer(bb); //ENM
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break;
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case 0x2f: swap_buffers(); //Swap buffers
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display_buffer(fb);
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clear_buffer(bb);
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break;
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}
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break;
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case 0x17:
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if( c2>=0x21 && c2<=0x23) //TAB
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{
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break;
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}
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}
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}
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}
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lastcode=data;
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}
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static void subcc_decode(unsigned char *inputbuffer, unsigned int inputlength)
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{
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/* The first number may denote a channel number. I don't have the
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* EIA-708 standard, so it is hard to say.
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* From what I could figure out so far, the general format seems to be:
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*
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* repeat
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*
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* 0xfe starts 2 byte sequence of unknown purpose. It might denote
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* field #2 in line 21 of the VBI. We'll ignore it for the
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* time being.
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*
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* 0xff starts 2 byte EIA-608 sequence, field #1 in line 21 of the VBI.
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* Followed by a 3-code triplet that starts either with 0xff or
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* 0xfe. In either case, the following triplet needs to be ignored
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* for line 21, field 1.
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*
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* 0x00 is padding, followed by 2 more 0x00.
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*
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* 0x01 always seems to appear at the beginning, always seems to
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* be followed by 0xf8, 8-bit number.
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* The lower 7 bits of this 8-bit number seem to denote the
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* number of code triplets that follow.
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* The most significant bit denotes whether the Line 21 field 1
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* captioning information is at odd or even triplet offsets from this
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* beginning triplet. 1 denotes odd offsets, 0 denotes even offsets.
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*
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* Most captions are encoded with odd offsets, so this is what we
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* will assume.
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*
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* until end of packet
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*/
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unsigned char *current = inputbuffer;
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unsigned int curbytes = 0;
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unsigned char data1, data2;
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unsigned char cc_code;
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int odd_offset = 1;
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while (curbytes < inputlength) {
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int skip = 2;
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cc_code = *(current);
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if (inputlength - curbytes < 2) {
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#ifdef LOG_DEBUG
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fprintf(stderr, "Not enough data for 2-byte CC encoding\n");
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#endif
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break;
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}
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data1 = *(current+1);
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data2 = *(current + 2);
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current++; curbytes++;
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switch (cc_code) {
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case 0xfe:
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/* expect 2 byte encoding (perhaps CC3, CC4?) */
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/* ignore for time being */
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skip = 2;
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break;
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case 0xff:
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/* expect EIA-608 CC1/CC2 encoding */
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// FIXME check parity!
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// Parity check omitted assuming we are reading from a DVD and therefore
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// we should encounter no "transmission errors".
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cc_decode_EIA608(data1 | (data2 << 8));
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skip = 5;
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break;
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case 0x00:
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/* This seems to be just padding */
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skip = 2;
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break;
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case 0x01:
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odd_offset = data2 & 0x80;
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if (odd_offset)
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skip = 2;
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else
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skip = 5;
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break;
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default:
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//#ifdef LOG_DEBUG
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fprintf(stderr, "Unknown CC encoding: %x\n", cc_code);
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//#endif
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skip = 2;
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break;
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}
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current += skip;
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curbytes += skip;
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}
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}
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void subcc_process_data(unsigned char *inputdata,unsigned int len)
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{
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if(!subcc_enabled) return;
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if(!initialized) subcc_init();
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subcc_decode(inputdata, len);
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}
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