mirror of https://github.com/mpv-player/mpv
86 lines
2.7 KiB
C
86 lines
2.7 KiB
C
/* ------------------------------------------------------------------------
|
|
* Creative YUV Video Decoder
|
|
*
|
|
* Dr. Tim Ferguson, 2001.
|
|
* For more details on the algorithm:
|
|
* http://www.csse.monash.edu.au/~timf/videocodec.html
|
|
*
|
|
* This is a very simple predictive coder. A video frame is coded in YUV411
|
|
* format. The first pixel of each scanline is coded using the upper four
|
|
* bits of its absolute value. Subsequent pixels for the scanline are coded
|
|
* using the difference between the last pixel and the current pixel (DPCM).
|
|
* The DPCM values are coded using a 16 entry table found at the start of the
|
|
* frame. Thus four bits per component are used and are as follows:
|
|
* UY VY YY UY VY YY UY VY...
|
|
* This code assumes the frame width will be a multiple of four pixels. This
|
|
* should probably be fixed.
|
|
* ------------------------------------------------------------------------ */
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <sys/types.h>
|
|
#include <unistd.h>
|
|
|
|
/* ------------------------------------------------------------------------
|
|
* This function decodes a buffer containing a CYUV encoded frame.
|
|
*
|
|
* buf - the input buffer to be decoded
|
|
* size - the size of the input buffer
|
|
* frame - the output frame buffer (UYVY format)
|
|
* width - the width of the output frame
|
|
* height - the height of the output frame
|
|
* bit_per_pixel - ignored for now: may be used later for conversions.
|
|
*/
|
|
void decode_cyuv(unsigned char *buf, int size, unsigned char *frame, int width, int height, int bit_per_pixel)
|
|
{
|
|
int i, xpos, ypos, cur_Y = 0, cur_U = 0, cur_V = 0;
|
|
char *delta_y_tbl, *delta_c_tbl, *ptr;
|
|
|
|
delta_y_tbl = buf + 16;
|
|
delta_c_tbl = buf + 32;
|
|
ptr = buf + (16 * 3);
|
|
|
|
for(ypos = 0; ypos < height; ypos++)
|
|
for(xpos = 0; xpos < width; xpos += 4)
|
|
{
|
|
if(xpos == 0) /* first pixels in scanline */
|
|
{
|
|
cur_U = *(ptr++);
|
|
cur_Y = (cur_U & 0x0f) << 4;
|
|
cur_U = cur_U & 0xf0;
|
|
*frame++ = cur_U;
|
|
*frame++ = cur_Y;
|
|
|
|
cur_V = *(ptr++);
|
|
cur_Y = (cur_Y + delta_y_tbl[cur_V & 0x0f]) & 0xff;
|
|
cur_V = cur_V & 0xf0;
|
|
*frame++ = cur_V;
|
|
*frame++ = cur_Y;
|
|
}
|
|
else /* subsequent pixels in scanline */
|
|
{
|
|
i = *(ptr++);
|
|
cur_U = (cur_U + delta_c_tbl[i >> 4]) & 0xff;
|
|
cur_Y = (cur_Y + delta_y_tbl[i & 0x0f]) & 0xff;
|
|
*frame++ = cur_U;
|
|
*frame++ = cur_Y;
|
|
|
|
i = *(ptr++);
|
|
cur_V = (cur_V + delta_c_tbl[i >> 4]) & 0xff;
|
|
cur_Y = (cur_Y + delta_y_tbl[i & 0x0f]) & 0xff;
|
|
*frame++ = cur_V;
|
|
*frame++ = cur_Y;
|
|
}
|
|
|
|
i = *(ptr++);
|
|
cur_Y = (cur_Y + delta_y_tbl[i & 0x0f]) & 0xff;
|
|
*frame++ = cur_U;
|
|
*frame++ = cur_Y;
|
|
|
|
cur_Y = (cur_Y + delta_y_tbl[i >> 4]) & 0xff;
|
|
*frame++ = cur_V;
|
|
*frame++ = cur_Y;
|
|
}
|
|
}
|
|
|