mirror of
https://github.com/torvalds/linux.git
synced 2024-12-06 11:01:43 +00:00
d7493e518f
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
121 lines
4.0 KiB
Plaintext
121 lines
4.0 KiB
Plaintext
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;
|
|
}
|
|
|
|
--------------------------------------------------------------------------
|