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-The cx23416 can produce (and the cx23415 can also read) raw YUV output. The
-format of a YUV frame is specific to this chip and is called HM12. 'HM' stands
-for 'Hauppauge Macroblock', which is a misnomer as 'Conexant Macroblock' would
-be more accurate.
-
-The format is YUV 4:2:0 which uses 1 Y byte per pixel and 1 U and V byte per
-four pixels.
-
-The data is encoded as two macroblock planes, the first containing the Y
-values, the second containing UV macroblocks.
-
-The Y plane is divided into blocks of 16x16 pixels from left to right
-and from top to bottom. Each block is transmitted in turn, line-by-line.
-
-So the first 16 bytes are the first line of the top-left block, the
-second 16 bytes are the second line of the top-left block, etc. After
-transmitting this block the first line of the block on the right to the
-first block is transmitted, etc.
-
-The UV plane is divided into blocks of 16x8 UV values going from left
-to right, top to bottom. Each block is transmitted in turn, line-by-line.
-
-So the first 16 bytes are the first line of the top-left block and
-contain 8 UV value pairs (16 bytes in total). The second 16 bytes are the
-second line of 8 UV pairs of the top-left block, etc. After transmitting
-this block the first line of the block on the right to the first block is
-transmitted, etc.
-
-The code below is given as an example on how to convert HM12 to separate
-Y, U and V planes. This code assumes frames of 720x576 (PAL) pixels.
-
-The width of a frame is always 720 pixels, regardless of the actual specified
-width.
-
-If the height is not a multiple of 32 lines, then the captured video is
-missing macroblocks at the end and is unusable. So the height must be a
-multiple of 32.
-
---------------------------------------------------------------------------
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-
-static unsigned char frame[576*720*3/2];
-static unsigned char framey[576*720];
-static unsigned char frameu[576*720 / 4];
-static unsigned char framev[576*720 / 4];
-
-static void de_macro_y(unsigned char* dst, unsigned char *src, int dstride, int w, int h)
-{
- unsigned int y, x, i;
-
- // descramble Y plane
- // dstride = 720 = w
- // The Y plane is divided into blocks of 16x16 pixels
- // Each block in transmitted in turn, line-by-line.
- for (y = 0; y < h; y += 16) {
- for (x = 0; x < w; x += 16) {
- for (i = 0; i < 16; i++) {
- memcpy(dst + x + (y + i) * dstride, src, 16);
- src += 16;
- }
- }
- }
-}
-
-static void de_macro_uv(unsigned char *dstu, unsigned char *dstv, unsigned char *src, int dstride, int w, int h)
-{
- unsigned int y, x, i;
-
- // descramble U/V plane
- // dstride = 720 / 2 = w
- // The U/V values are interlaced (UVUV...).
- // Again, the UV plane is divided into blocks of 16x16 UV values.
- // Each block in transmitted in turn, line-by-line.
- for (y = 0; y < h; y += 16) {
- for (x = 0; x < w; x += 8) {
- for (i = 0; i < 16; i++) {
- int idx = x + (y + i) * dstride;
-
- dstu[idx+0] = src[0]; dstv[idx+0] = src[1];
- dstu[idx+1] = src[2]; dstv[idx+1] = src[3];
- dstu[idx+2] = src[4]; dstv[idx+2] = src[5];
- dstu[idx+3] = src[6]; dstv[idx+3] = src[7];
- dstu[idx+4] = src[8]; dstv[idx+4] = src[9];
- dstu[idx+5] = src[10]; dstv[idx+5] = src[11];
- dstu[idx+6] = src[12]; dstv[idx+6] = src[13];
- dstu[idx+7] = src[14]; dstv[idx+7] = src[15];
- src += 16;
- }
- }
- }
-}
-
-/*************************************************************************/
-int main(int argc, char **argv)
-{
- FILE *fin;
- int i;
-
- if (argc == 1) fin = stdin;
- else fin = fopen(argv[1], "r");
-
- if (fin == NULL) {
- fprintf(stderr, "cannot open input\n");
- exit(-1);
- }
- while (fread(frame, sizeof(frame), 1, fin) == 1) {
- de_macro_y(framey, frame, 720, 720, 576);
- de_macro_uv(frameu, framev, frame + 720 * 576, 720 / 2, 720 / 2, 576 / 2);
- fwrite(framey, sizeof(framey), 1, stdout);
- fwrite(framev, sizeof(framev), 1, stdout);
- fwrite(frameu, sizeof(frameu), 1, stdout);
- }
- fclose(fin);
- return 0;
-}
-
---------------------------------------------------------------------------