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/*****************************************************************
File RGBtoYUV411.cpp

Utility for converting a sequence of frames, stored in a single
file in raw RGB format, to a single output file in which they are
stored in YUV411 format.
This utility is a filter taking input on stdin and generating its
output on stdout.
Raw RGB format is simply a sequence of byte triples representing the
red, green and blue components of each pixel.
YUV411 is a planar format which stores the Y component of each frame,
as a sequence of bytes, followed by the U component followed by the V
component. That is the colour component are multiplexed framewise,
rather than pixel wise or in some other way. In YUV411 format the
U and V colour components are subsampled 4:1 horizontally.

Original Author: Tim Borer
****************************************************************/

#include <stdlib.h> //Contains EXIT_SUCCESS, EXIT_FAILURE
#include <iostream> //For cin, cout, cerr
using std::cout;
using std::cin;
using std::cerr;
using std::clog;
using std::endl;
using std::ios_base;

#include "setstdiomode.h"
using namespace dirac_vu;

int main(int argc, char * argv[] ) {

    if (argc != 4) {
        cout << "\"RGBtoYUV411\" command line format is:" << endl;
        cout << "    Argument 1: width (pixels) e.g. 720" << endl;
        cout << "    Argument 2: height (lines) e.g. 576" << endl;
        cout << "    Argument 3: number of frames e.g. 3" << endl;
        cout << "    Example: RGBtoYUV411 <foo >bar 720 576 3" << endl;
        cout << "        converts 3 frames, of 720x576 pixels, from file foo to file bar" << endl;
        return EXIT_SUCCESS; }

    //Get command line arguments
    int width = atoi(argv[1]);
    int height = atoi(argv[2]);
    int frames = atoi(argv[3]);

    //Set standard input and standard output to binary mode.
    //Only relevant for Windows (*nix is always binary)
    if ( setstdinmode(std::ios_base::binary) == -1 ) {
        cerr << "Error: could not set standard input to binary mode" << endl;
        return EXIT_FAILURE; }
    if ( setstdoutmode(std::ios_base::binary) == -1 ) {
        cerr << "Error: could not set standard output to binary mode" << endl;
        return EXIT_FAILURE; }

    //Allocate memory for input and output buffers.
    const int RGBBufferSize = 3*height*width;
    unsigned char *RGBBuffer = new unsigned char[RGBBufferSize];
    const int YBufferSize = height*width;
    const int UVBufferSize = height*width/4;
    unsigned char *YBuffer = new unsigned char[YBufferSize];
    unsigned char *UBuffer = new unsigned char[UVBufferSize];
    unsigned char *VBuffer = new unsigned char[UVBufferSize];

    //Define some working variables and arrays
    //Define buffers for filtering (width+2 to allow filtering edges)
    unsigned char *ULine = (new unsigned char[width+2])+1;
    unsigned char *VLine = (new unsigned char[width+2])+1;
    ULine[-1]=ULine[width]=128;
    VLine[-1]=VLine[width]=128;
    int *UHalfLine = (new int[(width/2)+2])+1;
    int *VHalfLine = (new int[(width/2)+2])+1;
    UHalfLine[-1]=UHalfLine[width/2]=128;
    VHalfLine[-1]=VHalfLine[width/2]=128;
    int R, G, B;
    int Y, U, V;

    //Create references for input and output stream buffers.
    //IO is via stream buffers for efficiency
    std::streambuf& inbuf = *(cin.rdbuf());
    std::streambuf& outbuf = *(cout.rdbuf());

    for (int frame=0; frame<frames; ++frame) {

        clog << "Processing frame " << (frame+1) << "\r";
            
        //Read frames of RGB
        if ( inbuf.sgetn(reinterpret_cast<char*>(RGBBuffer), RGBBufferSize) < RGBBufferSize ) {
            cerr << "Error: failed to read frame " << frame << endl;
            return EXIT_FAILURE; }

        for (int line=0; line<height; ++line) {

            int RGBIndex = 3*width*line;
            int YIndex = width*line;
            for (int pixel=0; pixel<width; ++pixel) {

                R = RGBBuffer[RGBIndex++];
                G = RGBBuffer[RGBIndex++];
                B = RGBBuffer[RGBIndex++];

                //Convert RGB to YUV
                Y = (( 66*R + 129*G +  25*B + 128)>>8)+ 16;
                U = ((-38*R -  74*G + 112*B + 128)>>8)+128;
                V = ((112*R -  94*G -  18*B + 128)>>8)+128;

                //Clip Y ready for output & copy UV ready for filtering
                YBuffer[YIndex++] = static_cast<unsigned char>( (Y<0) ? 0 : ((Y>255) ? 255 : Y) );
                ULine[pixel] = U;
                VLine[pixel] = V;
            }

            //Halfband filter and 2:1 subsample UV lines
            for (int pixel=0; pixel<width; pixel+=2) {
                UHalfLine[pixel/2] = ((ULine[pixel-1]+2*ULine[pixel]+ULine[pixel+1]+2)>>2);
                VHalfLine[pixel/2] = ((VLine[pixel-1]+2*VLine[pixel]+VLine[pixel+1]+2)>>2);
            }

            int UVIndex = width*line/4;
            for (int pixel=0; pixel<(width/2); pixel+=2) {

                //Halfband filter UV lines
                U = ((UHalfLine[pixel-1]+2*UHalfLine[pixel]+UHalfLine[pixel+1]+2)>>2);
                V = ((VHalfLine[pixel-1]+2*VHalfLine[pixel]+VHalfLine[pixel+1]+2)>>2);

                //Clip and copy UV to output buffer
                UBuffer[UVIndex] = static_cast<unsigned char>( (U<0) ? 0 : ((U>255) ? 255 : U) );
                VBuffer[UVIndex++] = static_cast<unsigned char>( (V<0) ? 0 : ((V>255) ? 255 : V) );
            }
        }

        //Write frames of Y then U then V components
        if ( outbuf.sputn(reinterpret_cast<char*>(YBuffer), YBufferSize) < YBufferSize ) {
            cerr << "Error: failed to write Y component of frame " << frame << endl;
            return EXIT_FAILURE; }
        if ( outbuf.sputn(reinterpret_cast<char*>(UBuffer), UVBufferSize) < UVBufferSize ) {
            cerr << "Error: failed to write U component of frame " << frame << endl;
            return EXIT_FAILURE; }
        if ( outbuf.sputn(reinterpret_cast<char*>(VBuffer), UVBufferSize) < UVBufferSize ) {
            cerr << "Error: failed to write V component of frame " << frame << endl;
            return EXIT_FAILURE; }
    }

    delete [] (&VHalfLine[-1]);
    delete [] (&UHalfLine[-1]);
    delete [] (&VLine[-1]);
    delete [] (&ULine[-1]);
    delete [] VBuffer;
    delete [] UBuffer;
    delete [] YBuffer;
    delete [] RGBBuffer;

    return EXIT_SUCCESS;
}