/*************************************************************************** vbiparse.c Parse Philips codes and other data from VBI lines.**************************************************************************** Copyright Aaron Giles All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. * Neither the name 'MAME' nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY AARON GILES ''AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL AARON GILES BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.***************************************************************************/#include"osdcore.h"#include"vbiparse.h"#include<math.h>/*************************************************************************** DEBUGGING***************************************************************************/#define PRINTF_WHITE_FLAG 0/*************************************************************************** CONSTANTS***************************************************************************/#define MAX_SOURCE_WIDTH 1024#define MAX_CLOCK_DIFF 3/*************************************************************************** IMPLEMENTATION***************************************************************************//*------------------------------------------------- vbi_parse_manchester_code - parse a Manchester code from a line of video data-------------------------------------------------*/intvbi_parse_manchester_code(constUINT16*source,intsourcewidth,intsourceshift,intexpectedbits,UINT32*result){UINT8srcabs[MAX_SOURCE_WIDTH];UINT8min,max,mid,srcabsval;doubleclock,bestclock;intx,firstedge;intbesterr;/* fail if the width is too large */if(sourcewidth>MAX_SOURCE_WIDTH)return0;/* find highs and lows in the line */min=0xff;max=0x00;for(x=0;x<sourcewidth;x++){UINT8rawsrc=source[x]>>sourceshift;min=MIN(min,rawsrc);max=MAX(max,rawsrc);}/* bail if the line is all black or all white */if(max<0x80||min>0x80)return0;/* determine the midpoint and then set the thresholds to be halfway */mid=(min+max)/2;min=mid-(mid-min)/2;max=mid+(max-mid)/2;/* convert the source into absolute high/low */srcabsval=(source[0]>mid);for(x=0;x<sourcewidth;x++){UINT8rawsrc=source[x]>>sourceshift;if(rawsrc>=max)srcabsval=1;elseif(rawsrc<=min)srcabsval=0;srcabs[x]=srcabsval;}/* find the first transition; this is assumed to be the middle of the first bit */for(x=0;x<sourcewidth-1;x++)if(srcabs[x]!=srcabs[x+1])break;if(x==sourcewidth-1)return0;firstedge=x;/* now scan to find a clock that has a nearby transition on each beat */bestclock=0;besterr=1000;for(clock=(double)sourcewidth/(double)expectedbits;clock>=2.0;clock-=1.0/(double)expectedbits){interror=0;/* scan for all the expected bits */for(x=1;x<expectedbits;x++){intcurbit=firstedge+(double)x*clock;intoffby;/* look for a match that is off by an amount up to the maximum */for(offby=0;offby<=MAX_CLOCK_DIFF;offby++)if(srcabs[curbit+offby+0]!=srcabs[curbit+offby+1]||srcabs[curbit-offby+0]!=srcabs[curbit-offby+1])break;/* if we never found the edge, fail immediately */if(offby>MAX_CLOCK_DIFF)break;/* only continue if we're still in the running */error+=offby;if(error>=besterr)break;}/* if we got to the end, this is the best candidate so far */if(x==expectedbits){besterr=error;bestclock=clock;}}/* if nobody matched, fail */if(bestclock==0)return0;/* now extract the bits */for(x=0;x<expectedbits;x++){intleftstart=firstedge+ceil(((double)x-0.5)*bestclock);// int leftmid = firstedge + ((double)x - 0.25) * bestclock;intleftend=firstedge+floor(((double)x-0.0)*bestclock);intrightstart=firstedge+ceil(((double)x+0.0)*bestclock);// int rightmid = firstedge + ((double)x + 0.25) * bestclock;intrightend=firstedge+floor(((double)x+0.5)*bestclock);intleftavg,rightavg,leftabs,rightabs;intconfidence=0;inttx;/* compute left and right average values */leftavg=0;for(tx=leftstart;tx<=leftend;tx++)leftavg+=(UINT8)(source[tx]>>sourceshift)-mid;leftabs=(leftavg>=0);leftavg=(leftavg<0)?-leftavg:leftavg;rightavg=0;for(tx=rightstart;tx<=rightend;tx++)rightavg+=(UINT8)(source[tx]>>sourceshift)-mid;rightabs=(rightavg>=0);rightavg=(rightavg<0)?-rightavg:rightavg;/* all bits should be marked by transitions; fail if we don't get one */if(leftabs==rightabs)return0;/* store the bit and its confidence level */confidence=leftavg+rightavg;result[x]=(leftabs<rightabs)|(confidence<<1);}returnexpectedbits;}/*------------------------------------------------- vbi_parse_white_flag - compute the "white flag" from a line of video data-------------------------------------------------*/intvbi_parse_white_flag(constUINT16*source,intsourcewidth,intsourceshift){inthisto[256]={0};intminval=0xff;intmaxval=0x00;intsubtract;intpeakval;intresult;intx;/* compute a histogram of values */for(x=0;x<sourcewidth;x++){UINT8yval=source[x]>>sourceshift;histo[yval]++;}/* remove the lowest 1% of the values to account for noise and determine the minimum */subtract=sourcewidth/100;for(minval=0;minval<255;minval++)if((subtract-=histo[minval])<0)break;/* remove the highest 1% of the values to account for noise and determine the maximum */subtract=sourcewidth/100;for(maxval=255;maxval>0;maxval--)if((subtract-=histo[maxval])<0)break;/* this is useful for debugging issues with white flag detection */if(PRINTF_WHITE_FLAG){printf("Histo: min=%02X max=%02X\n",minval,maxval);for(x=0;x<256;x++)if(histo[x]!=0)printf("%dx%02X\n",histo[x],x);}/* ignore if we have no dynamic range */if(maxval-minval<10){if(PRINTF_WHITE_FLAG)printf("White flag NOT detected; threshold too low\n");returnFALSE;}/* At this point, there are two approaches that have been tried: 1. Find the peak value and call it white if the peak is above the 90% line 2. Ignore the first and last 20% of the line and count how many pixels are above some threshold (75% line was used). Call it white if at least 80% of the pixels are above the threshold. Both approaches agree 99% of the time, but the first tends to be more correct when there is a discrepancy. *//* determine where the peak is */peakval=0;for(x=1;x<256;x++)if(histo[x]>histo[peakval])peakval=x;/* return TRUE if it is above the 90% mark */result=(peakval>minval+9*(maxval-minval)/10);if(PRINTF_WHITE_FLAG)printf("White flag %s: peak=%02X thresh=%02X\n",result?"detected":"NOT detected",peakval,minval+9*(maxval-minval)/10);returnresult;#ifdef UNUSED_CODE{intabove=0;intthresh;/* alternate approach: *//* ignore the first 1/5 and last 1/5 of the line for the remaining computations */source+=sourcewidth/5;sourcewidth-=2*(sourcewidth/5);/* count how many values were above the 75% mark of the range */thresh=minval+3*(maxval-minval)/4;for(x=0;x<sourcewidth;x++){UINT8yval=source[x]>>sourceshift;above+=(yval>=thresh);}/* if at least 80% of the pixels are above the threshold, we'll call it white */return((above*100)/sourcewidth>=80);}#endif}/*------------------------------------------------- vbi_parse_all - parse everything from a video frame-------------------------------------------------*/voidvbi_parse_all(constUINT16*source,intsourcerowpixels,intsourcewidth,intsourceshift,vbi_metadata*vbi){UINT32bits[2][24];UINT8bitnum;/* first reset it all */memset(vbi,0,sizeof(*vbi));/* get the white flag */vbi->white=vbi_parse_white_flag(source+11*sourcerowpixels,sourcewidth,sourceshift);/* parse line 16 */if(vbi_parse_manchester_code(source+16*sourcerowpixels,sourcewidth,sourceshift,24,bits[0])==24)for(bitnum=0;bitnum<24;bitnum++)vbi->line16=(vbi->line16<<1)|(bits[0][bitnum]&1);/* parse line 17 */if(vbi_parse_manchester_code(source+17*sourcerowpixels,sourcewidth,sourceshift,24,bits[0])==24)for(bitnum=0;bitnum<24;bitnum++)vbi->line17=(vbi->line17<<1)|(bits[0][bitnum]&1);/* parse line 18 */if(vbi_parse_manchester_code(source+18*sourcerowpixels,sourcewidth,sourceshift,24,bits[1])==24)for(bitnum=0;bitnum<24;bitnum++)vbi->line18=(vbi->line18<<1)|(bits[1][bitnum]&1);/* pick the best out of lines 17/18 *//* if we only got one or the other, that's all we have */if(vbi->line17==0)vbi->line1718=vbi->line18;elseif(vbi->line18==0)vbi->line1718=vbi->line17;/* if they agree, we're golden */elseif(vbi->line17==vbi->line18)vbi->line1718=vbi->line17;/* if they don't agree, we have to pick one */else{/* if both are frame numbers, and one is not valid BCD, pick the other */if((vbi->line17&VBI_MASK_CAV_PICTURE)==VBI_CODE_CAV_PICTURE&&(vbi->line18&VBI_MASK_CAV_PICTURE)==VBI_CODE_CAV_PICTURE){if((vbi->line17&0xf000)>0x9000||(vbi->line17&0xf00)>0x900||(vbi->line17&0xf0)>0x90||(vbi->line17&0xf)>0x9)vbi->line1718=vbi->line18;elseif((vbi->line18&0xf000)>0x9000||(vbi->line18&0xf00)>0x900||(vbi->line18&0xf0)>0x90||(vbi->line18&0xf)>0x9)vbi->line1718=vbi->line17;}/* if still nothing, then scan through the bits and pick the ones with the most confidence */if(vbi->line1718==0)for(bitnum=0;bitnum<24;bitnum++)vbi->line1718=(vbi->line1718<<1)|((bits[0][bitnum]>bits[1][bitnum])?(bits[0][bitnum]&1):(bits[1][bitnum]&1));}}/*------------------------------------------------- vbi_metadata_pack - pack the VBI data down into a smaller form for storage-------------------------------------------------*/voidvbi_metadata_pack(UINT8*dest,UINT32framenum,constvbi_metadata*vbi){dest[0]=framenum>>16;dest[1]=framenum>>8;dest[2]=framenum>>0;dest[3]=vbi->white;dest[4]=vbi->line16>>16;dest[5]=vbi->line16>>8;dest[6]=vbi->line16>>0;dest[7]=vbi->line17>>16;dest[8]=vbi->line17>>8;dest[9]=vbi->line17>>0;dest[10]=vbi->line18>>16;dest[11]=vbi->line18>>8;dest[12]=vbi->line18>>0;dest[13]=vbi->line1718>>16;dest[14]=vbi->line1718>>8;dest[15]=vbi->line1718>>0;}/*------------------------------------------------- vbi_metadata_unpack - unpack the VBI data from a smaller form into the full structure-------------------------------------------------*/voidvbi_metadata_unpack(vbi_metadata*vbi,UINT32*framenum,constUINT8*source){if(framenum!=NULL)*framenum=(source[0]<<16)|(source[1]<<8)|source[2];vbi->white=source[3];vbi->line16=(source[4]<<16)|(source[5]<<8)|source[6];vbi->line17=(source[7]<<16)|(source[8]<<8)|source[9];vbi->line18=(source[10]<<16)|(source[11]<<8)|source[12];vbi->line1718=(source[13]<<16)|(source[14]<<8)|source[15];}