mirror of
https://github.com/mpv-player/mpv
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0d8c217a2f
git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@3970 b3059339-0415-0410-9bf9-f77b7e298cf2
86 lines
2.7 KiB
C
86 lines
2.7 KiB
C
/* ------------------------------------------------------------------------
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* Creative YUV Video Decoder
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*
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* Dr. Tim Ferguson, 2001.
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* For more details on the algorithm:
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* http://www.csse.monash.edu.au/~timf/videocodec.html
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*
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* This is a very simple predictive coder. A video frame is coded in YUV411
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* format. The first pixel of each scanline is coded using the upper four
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* bits of its absolute value. Subsequent pixels for the scanline are coded
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* using the difference between the last pixel and the current pixel (DPCM).
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* The DPCM values are coded using a 16 entry table found at the start of the
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* frame. Thus four bits per component are used and are as follows:
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* UY VY YY UY VY YY UY VY...
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* This code assumes the frame width will be a multiple of four pixels. This
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* should probably be fixed.
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* ------------------------------------------------------------------------ */
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/types.h>
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#include <unistd.h>
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/* ------------------------------------------------------------------------
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* This function decodes a buffer containing a CYUV encoded frame.
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*
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* buf - the input buffer to be decoded
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* size - the size of the input buffer
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* frame - the output frame buffer (UYVY format)
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* width - the width of the output frame
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* height - the height of the output frame
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* bit_per_pixel - ignored for now: may be used later for conversions.
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*/
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void decode_cyuv(unsigned char *buf, int size, unsigned char *frame, int width, int height, int bit_per_pixel)
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{
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int i, xpos, ypos, cur_Y = 0, cur_U = 0, cur_V = 0;
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char *delta_y_tbl, *delta_c_tbl, *ptr;
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delta_y_tbl = buf + 16;
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delta_c_tbl = buf + 32;
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ptr = buf + (16 * 3);
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for(ypos = 0; ypos < height; ypos++)
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for(xpos = 0; xpos < width; xpos += 4)
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{
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if(xpos == 0) /* first pixels in scanline */
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{
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cur_U = *(ptr++);
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cur_Y = (cur_U & 0x0f) << 4;
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cur_U = cur_U & 0xf0;
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*frame++ = cur_U;
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*frame++ = cur_Y;
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cur_V = *(ptr++);
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cur_Y = (cur_Y + delta_y_tbl[cur_V & 0x0f]) & 0xff;
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cur_V = cur_V & 0xf0;
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*frame++ = cur_V;
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*frame++ = cur_Y;
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}
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else /* subsequent pixels in scanline */
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{
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i = *(ptr++);
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cur_U = (cur_U + delta_c_tbl[i >> 4]) & 0xff;
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cur_Y = (cur_Y + delta_y_tbl[i & 0x0f]) & 0xff;
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*frame++ = cur_U;
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*frame++ = cur_Y;
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i = *(ptr++);
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cur_V = (cur_V + delta_c_tbl[i >> 4]) & 0xff;
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cur_Y = (cur_Y + delta_y_tbl[i & 0x0f]) & 0xff;
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*frame++ = cur_V;
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*frame++ = cur_Y;
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}
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i = *(ptr++);
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cur_Y = (cur_Y + delta_y_tbl[i & 0x0f]) & 0xff;
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*frame++ = cur_U;
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*frame++ = cur_Y;
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cur_Y = (cur_Y + delta_y_tbl[i >> 4]) & 0xff;
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*frame++ = cur_V;
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*frame++ = cur_Y;
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}
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}
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