1 @TEMPLATE decoder_tmpl.c 2 Frame-by-frame MD5 Checksum 3 =========================== 4 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ INTRODUCTION 5 This example builds upon the simple decoder loop to show how checksums 6 of the decoded output can be generated. These are used for validating 7 decoder implementations against the reference implementation, for example. 8 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ INTRODUCTION 9 10 MD5 algorithm 11 ------------- 12 The Message-Digest 5 (MD5) is a well known hash function. We have provided 13 an implementation derived from the RSA Data Security, Inc. MD5 Message-Digest 14 Algorithm for your use. Our implmentation only changes the interface of this 15 reference code. You must include the `md5_utils.h` header for access to these 16 functions. 17 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ EXTRA_INCLUDES 18 #include "md5_utils.h" 19 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ EXTRA_INCLUDES 20 21 22 Processing The Decoded Data 23 --------------------------- 24 Each row of the image is passed to the MD5 accumulator. First the Y plane 25 is processed, then U, then V. It is important to honor the image's `stride` 26 values. 27 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PROCESS_DX 28 unsigned char md5_sum[16]; 29 MD5Context md5; 30 int i; 31 32 MD5Init(&md5); 33 34 for(plane=0; plane < 3; plane++) { 35 unsigned char *buf =img->planes[plane]; 36 37 for(y=0; y<img->d_h >> (plane?1:0); y++) { 38 MD5Update(&md5, buf, img->d_w >> (plane?1:0)); 39 buf += img->stride[plane]; 40 } 41 } 42 43 MD5Final(md5_sum, &md5); 44 for(i=0; i<16; i++) 45 fprintf(outfile, "%02x",md5_sum[i]); 46 fprintf(outfile, " img-%dx%d-%04d.i420\n", img->d_w, img->d_h, 47 frame_cnt); 48 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PROCESS_DX 49
