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Scrolling Ticker with Tesseract OCR
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Burhan Two committed Jun 30, 2018
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#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libavutil/imgutils.h>
#include <libswscale/swscale.h>

#include <stdio.h>

#include <leptonica/allheaders.h>
#include <tesseract/capi.h>

#define BLACK 20.0
#define YELLOW 70.0

#define min_f(a, b, c) (fminf(a, fminf(b, c)))
#define max_f(a, b, c) (fmaxf(a, fmaxf(b, c)))


int xflag = 0;
int last_index =0;
int skip_frames = 12;
void rgb2lab(float R, float G, float B,float *L, float *a, float *b){
//Conversion to the CIE-LAB color space to get the Luminance
float X, Y, Z, fX, fY, fZ;

X = 0.412453*R + 0.357580*G + 0.180423*B;
Y = 0.212671*R + 0.715160*G + 0.072169*B;
Z = 0.019334*R + 0.119193*G + 0.950227*B;

X /= (255 * 0.950456);
Y /= 255;
Z /= (255 * 1.088754);

if (Y > 0.008856)
{
fY = pow(Y, 1.0/3.0);
*L = 116.0*fY - 16.0;
}
else
{
fY = 7.787*Y + 16.0/116.0;
*L = 903.3*Y;
}

if (X > 0.008856)
fX = pow(X, 1.0/3.0);
else
fX = 7.787*X + 16.0/116.0;

if (Z > 0.008856)
fZ = pow(Z, 1.0/3.0);
else
fZ = 7.787*Z + 16.0/116.0;

*a = 500.0*(fX - fY);
*b = 200.0*(fY - fZ);

if (*L < BLACK) {
*a *= exp((*L - BLACK) / (BLACK / 4));
*b *= exp((*L - BLACK) / (BLACK / 4));
*L = BLACK;
}
if (*b > YELLOW)
*b = YELLOW;
}

int detect_stopper_color(int r, int g, int b){

//For Detecting Blue Color
if (r>=20 && r<=35){
if(g >=75 && g<=135){
if(b>=130 && b<=180){
return 1;
}
}
}
else return 0;
}

void die(const char *errstr) {
fputs(errstr, stderr);
exit(1);
}


void russian_ocr(PIX* img, int index){
TessBaseAPI *handle;
char *text;
FILE * fp;
char write_path[100];

handle = TessBaseAPICreate();

if(TessBaseAPIInit3(handle, NULL, "rus") != 0)
die("Russian Language Not Set for Tesseract\n");

TessBaseAPISetImage2(handle, img);

if(TessBaseAPIRecognize(handle, NULL) != 0)
die("Error in Tesseract recognition\n");

if((text = TessBaseAPIGetUTF8Text(handle)) == NULL)
die("Error getting text\n");

//Writing to a File
sprintf(write_path,"txt%04d.txt",index);
fp = fopen(write_path, "w");
fprintf(fp, "%s", text);
fclose(fp);

//Displaying it
fputs(text, stdout);

TessDeleteText(text);
TessBaseAPIEnd(handle);
TessBaseAPIDelete(handle);

}

void _process_frame_tickertext(AVFrame *frame, int width, int height, int index){
printf("index%d\n", index);
if (index >1600){
PIX *im;
PIX *edge_im;
PIX *lum_im;
PIX *feat_im;
char *subtitle_text=NULL;
im = pixCreate(width,height,32);
lum_im = pixCreate(width,height,32);
feat_im = pixCreate(width,height,32);
int i,j;



for(i=(92*height)/100;i<height;i++)
{
for(j=0;j<width;j++)
{
int p=j*3+i*frame->linesize[0];
int r=frame->data[0][p];
int g=frame->data[0][p+1];
int b=frame->data[0][p+2];
pixSetRGBPixel(im,j,i,r,g,b);
float L,A,B;
rgb2lab((float)r,(float)g,(float)b,&L,&A,&B);
if(L > 85)
pixSetRGBPixel(lum_im,j,i,255,255,255);
else
pixSetRGBPixel(lum_im,j,i,0,0,0);
}
}



//Handle the edge image
edge_im = pixCreate(width,height,8);
edge_im = pixConvertRGBToGray(im,0.0,0.0,0.0);
edge_im = pixSobelEdgeFilter(edge_im, L_VERTICAL_EDGES);
edge_im = pixDilateGray(edge_im, 21, 11);
edge_im = pixThresholdToBinary(edge_im,45);

for(i=92*(height/100);i<height;i++)
{
for(j=0;j<width;j++)
{
unsigned int p1,p2,p3;
pixGetPixel(edge_im,j,i,&p1);
pixGetPixel(lum_im,j,i,&p3);
if(p1==0&&p3>0)
pixSetRGBPixel(feat_im,j,i,255,255,255);
else
pixSetRGBPixel(feat_im,j,i,0,0,0);
}
}

char write_path[100];
int num_of_occr = 0;
int stop = 0;
for(i=(92*height)/100;i<height && !stop;i++){
for(j=0; j<width && !stop; j++){

int p=j*3+i*frame->linesize[0];
int r=frame->data[0][p];
int g=frame->data[0][p+1];
int b=frame->data[0][p+2];

//printf("r %d\n", r);
//printf("g %d\n", g);
// printf("b %d\n", b);

//Detecting Blue Stoppers
//Skipping Thirty Frames and Detecting Blue Color
if (detect_stopper_color(r,g,b) == 1 && index % 30 == 0){
//printf("%s\n", "Stopper Detected");
xflag = 1;
//Hardcoded Bouding Box Locations
BOX* box = boxCreate(100, 525, 615, 25);
PIX* pixd= pixClipRectangle(feat_im, box, NULL);
last_index = index;
russian_ocr(pixd, index);
sprintf(write_path,"im%04d.jpg",index);
pixWrite(write_path,pixd,IFF_JFIF_JPEG);
boxDestroy(&box);
pixDestroy(&pixd);
stop = 1;
}
//Checking of text after blue stopper
else if(detect_stopper_color(r,g,b) == 0 && index %11 == 0 && xflag == 1){
BOX* box = boxCreate(100, 525, 615, 25);
PIX* pixd= pixClipRectangle(feat_im, box, NULL);
russian_ocr(pixd, index);
sprintf(write_path,"im%04d.jpg",index);
pixWrite(write_path,pixd,IFF_JFIF_JPEG);
boxDestroy(&box);
pixDestroy(&pixd);
xflag = 0;
stop = 1;
}
}

}

pixDestroy(&lum_im);
pixDestroy(&im);
pixDestroy(&edge_im);
pixDestroy(&feat_im);

}
}

int main(int argc, char * argv[]) {
AVFormatContext *pFormatCtx = NULL;
int i, frame_count, videoStreamIdx;
AVCodecContext *pCodecCtx = NULL;
AVCodec *pCodec = NULL;
AVFrame *pFrame = NULL;
AVFrame *pFrameRGB = NULL;
AVPacket packet;
int frameFinished;
int numBytes;
uint8_t *buffer = NULL;

AVDictionary *optionsDict = NULL;
struct SwsContext *sws_ctx = NULL;

if(argc < 2) {
printf("Please provide a video file\n");
return -1;
}

// Register all formats and codecs
av_register_all();

// Open video file
if(avformat_open_input(&pFormatCtx, argv[1], NULL, NULL)!=0)
return -1; // Couldn't open file

// Retrieve stream information
if(avformat_find_stream_info(pFormatCtx, NULL)<0)
return -1; // Couldn't find stream information

// Dump information about file onto standard error
av_dump_format(pFormatCtx, 0, argv[1], 0);

// Find the first video stream
videoStreamIdx = -1;
for(i=0; i<pFormatCtx->nb_streams; i++) {
if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO) {
videoStreamIdx = i;
break;
}
}

if(videoStreamIdx==-1)
return -1; // Didn't find a video stream

// Get a pointer to the codec context for the video stream
pCodecCtx=pFormatCtx->streams[videoStreamIdx]->codec;

// Find the decoder for the video stream
pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
if(pCodec==NULL) {
fprintf(stderr, "Unsupported codec!\n");
return -1; // Codec not found
}

// Open codec
if(avcodec_open2(pCodecCtx, pCodec, &optionsDict)<0)
return -1; // Could not open codec

// Allocate video frame
pFrame = av_frame_alloc();

// Allocate an AVFrame structure
pFrameRGB = av_frame_alloc();
if(pFrameRGB==NULL)
return -1;

// Determine required buffer size and allocate buffer
numBytes = avpicture_get_size(PIX_FMT_RGB24, pCodecCtx->width, pCodecCtx->height);
buffer = (uint8_t *)av_malloc(numBytes*sizeof(uint8_t));

sws_ctx = sws_getContext (
pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt,
pCodecCtx->width, pCodecCtx->height, PIX_FMT_RGB24,
SWS_BILINEAR, NULL, NULL, NULL
);

// Assign appropriate parts of buffer to image planes in pFrameRGB
// Note that pFrameRGB is an AVFrame, but AVFrame is a superset of AVPicture
avpicture_fill((AVPicture *)pFrameRGB, buffer, PIX_FMT_RGB24, pCodecCtx->width, pCodecCtx->height);

// Read frames and count the number of frames
frame_count = 0;
while(av_read_frame(pFormatCtx, &packet)>=0) {
//Is this a packet from a video stream?
if(packet.stream_index==videoStreamIdx) {
// Decode the video frame
avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);

//Did we get a video frame?
if(frameFinished) {
// Increment frame count
frame_count++;

// Convert the image from its native format to RGB
sws_scale(
sws_ctx, (uint8_t const * const *)pFrame->data, pFrame->linesize, 0,
pCodecCtx->height, pFrameRGB->data, pFrameRGB->linesize
);

_process_frame_tickertext(pFrameRGB,pCodecCtx->width,pCodecCtx->height,frame_count);
//_display_frame(pFrameRGB,pCodecCtx->width,pCodecCtx->height,frame_count);

//Now you have the frame and can do whatever you wish to


}
}

// Free the packet that was allocated by av_read_frame
av_free_packet(&packet);
}

// Free the RBG image
av_free(buffer);
av_free(pFrameRGB);

//Free the YUV frame
av_free(pFrame);

//Close the codec
avcodec_close(pCodecCtx);

//Close the video file
avformat_close_input(&pFormatCtx);

return 0;
}

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