Preprocess Videos

preprocess_frame.c

@@ -0,0 +1,253 @@
+#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)))
+
+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;
+}
+
+
+void _process_frame_tickertext(AVFrame *frame, int width, int height, int index){
+	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];
+	sprintf(write_path,"lum_im%04d.jpg",index);
+	pixWrite(write_path,lum_im,IFF_JFIF_JPEG);
+
+
+	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;
+}