/**

* TheoraPlay; multithreaded Ogg Theora/Ogg Vorbis decoding.

*

* Please see the file LICENSE.txt in the source's root directory.

*

* This file written by Ryan C. Gordon.

*/

#if !THEORAPLAY_INTERNAL

#error Do not include this in your app. It is used internally by TheoraPlay.

#endif

static unsigned char *THEORAPLAY_CVT_FNNAME_420(const th_info *tinfo,

const th_ycbcr_buffer ycbcr)

{

const int w = tinfo->pic_width;

const int h = tinfo->pic_height;

unsigned char *pixels = (unsigned char *) malloc(w * h * 4);

if (pixels)

{

unsigned char *dst = pixels;

const int ystride = ycbcr[0].stride;

const int cbstride = ycbcr[1].stride;

const int crstride = ycbcr[2].stride;

const int yoff = (tinfo->pic_x & ~1) + ystride * (tinfo->pic_y & ~1);

const int cboff = (tinfo->pic_x / 2) + (cbstride) * (tinfo->pic_y / 2);

const unsigned char *py = ycbcr[0].data + yoff;

const unsigned char *pcb = ycbcr[1].data + cboff;

const unsigned char *pcr = ycbcr[2].data + cboff;

int posx, posy;

for (posy = 0; posy < h; posy++)

{

for (posx = 0; posx < w; posx++)

{

// http://www.theora.org/doc/Theora.pdf, 1.1 spec,

// chapter 4.2 (Y'CbCr -> Y'PbPr -> R'G'B')

// These constants apparently work for NTSC _and_ PAL/SECAM.

const float yoffset = 16.0f;

const float yexcursion = 219.0f;

const float cboffset = 128.0f;

const float cbexcursion = 224.0f;

const float croffset = 128.0f;

const float crexcursion = 224.0f;

const float kr = 0.299f;

const float kb = 0.114f;

const float y = (((float) py[posx]) - yoffset) / yexcursion;

const float pb = (((float) pcb[posx / 2]) - cboffset) / cbexcursion;

const float pr = (((float) pcr[posx / 2]) - croffset) / crexcursion;

const float r = (y + (2.0f * (1.0f - kr) * pr)) * 255.0f;

const float g = (y - ((2.0f * (((1.0f - kb) * kb) / ((1.0f - kb) - kr))) * pb) - ((2.0f * (((1.0f - kr) * kr) / ((1.0f - kb) - kr))) * pr)) * 255.0f;

const float b = (y + (2.0f * (1.0f - kb) * pb)) * 255.0f;

*(dst++) = (unsigned char) ((r < 0.0f) ? 0.0f : (r > 255.0f) ? 255.0f : r);

*(dst++) = (unsigned char) ((g < 0.0f) ? 0.0f : (g > 255.0f) ? 255.0f : g);

*(dst++) = (unsigned char) ((b < 0.0f) ? 0.0f : (b > 255.0f) ? 255.0f : b);

#if THEORAPLAY_CVT_RGB_ALPHA

*(dst++) = 0xFF;

#endif

} // for

// adjust to the start of the next line.

py += ystride;

pcb += cbstride * (posy % 2);

pcr += crstride * (posy % 2);

} // for

} // if

return pixels;

} // THEORAPLAY_CVT_FNNAME_420

// end of theoraplay_cvtrgb.h ...