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comparison: media/libtheora/lib/quant.c
media/libtheora/lib/quant.c
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| -1:000000000000 | 0:76112a5357b4 |
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| 1 /******************************************************************** | |
| 2 * * | |
| 3 * THIS FILE IS PART OF THE OggTheora SOFTWARE CODEC SOURCE CODE. * | |
| 4 * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS * | |
| 5 * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE * | |
| 6 * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING. * | |
| 7 * * | |
| 8 * THE Theora SOURCE CODE IS COPYRIGHT (C) 2002-2009 * | |
| 9 * by the Xiph.Org Foundation and contributors http://www.xiph.org/ * | |
| 10 * * | |
| 11 ******************************************************************** | |
| 12 | |
| 13 function: | |
| 14 last mod: $Id: quant.c 17307 2010-06-27 06:02:15Z tterribe $ | |
| 15 | |
| 16 ********************************************************************/ | |
| 17 | |
| 18 #include <stdlib.h> | |
| 19 #include <string.h> | |
| 20 #include <ogg/ogg.h> | |
| 21 #include "quant.h" | |
| 22 #include "decint.h" | |
| 23 | |
| 24 /*The maximum output of the DCT with +/- 255 inputs is +/- 8157. | |
| 25 These minimum quantizers ensure the result after quantization (and after | |
| 26 prediction for DC) will be no more than +/- 510. | |
| 27 The tokenization system can handle values up to +/- 580, so there is no need | |
| 28 to do any coefficient clamping. | |
| 29 I would rather have allowed smaller quantizers and had to clamp, but these | |
| 30 minimums were required when constructing the original VP3 matrices and have | |
| 31 been formalized in the spec.*/ | |
| 32 static const unsigned OC_DC_QUANT_MIN[2]={4<<2,8<<2}; | |
| 33 static const unsigned OC_AC_QUANT_MIN[2]={2<<2,4<<2}; | |
| 34 | |
| 35 /*Initializes the dequantization tables from a set of quantizer info. | |
| 36 Currently the dequantizer (and elsewhere enquantizer) tables are expected to | |
| 37 be initialized as pointing to the storage reserved for them in the | |
| 38 oc_theora_state (resp. oc_enc_ctx) structure. | |
| 39 If some tables are duplicates of others, the pointers will be adjusted to | |
| 40 point to a single copy of the tables, but the storage for them will not be | |
| 41 freed. | |
| 42 If you're concerned about the memory footprint, the obvious thing to do is | |
| 43 to move the storage out of its fixed place in the structures and allocate | |
| 44 it on demand. | |
| 45 However, a much, much better option is to only store the quantization | |
| 46 matrices being used for the current frame, and to recalculate these as the | |
| 47 qi values change between frames (this is what VP3 did).*/ | |
| 48 void oc_dequant_tables_init(ogg_uint16_t *_dequant[64][3][2], | |
| 49 int _pp_dc_scale[64],const th_quant_info *_qinfo){ | |
| 50 /*Coding mode: intra or inter.*/ | |
| 51 int qti; | |
| 52 /*Y', C_b, C_r*/ | |
| 53 int pli; | |
| 54 for(qti=0;qti<2;qti++)for(pli=0;pli<3;pli++){ | |
| 55 /*Quality index.*/ | |
| 56 int qi; | |
| 57 /*Range iterator.*/ | |
| 58 int qri; | |
| 59 for(qi=0,qri=0;qri<=_qinfo->qi_ranges[qti][pli].nranges;qri++){ | |
| 60 th_quant_base base; | |
| 61 ogg_uint32_t q; | |
| 62 int qi_start; | |
| 63 int qi_end; | |
| 64 memcpy(base,_qinfo->qi_ranges[qti][pli].base_matrices[qri], | |
| 65 sizeof(base)); | |
| 66 qi_start=qi; | |
| 67 if(qri==_qinfo->qi_ranges[qti][pli].nranges)qi_end=qi+1; | |
| 68 else qi_end=qi+_qinfo->qi_ranges[qti][pli].sizes[qri]; | |
| 69 /*Iterate over quality indicies in this range.*/ | |
| 70 for(;;){ | |
| 71 ogg_uint32_t qfac; | |
| 72 int zzi; | |
| 73 int ci; | |
| 74 /*In the original VP3.2 code, the rounding offset and the size of the | |
| 75 dead zone around 0 were controlled by a "sharpness" parameter. | |
| 76 The size of our dead zone is now controlled by the per-coefficient | |
| 77 quality thresholds returned by our HVS module. | |
| 78 We round down from a more accurate value when the quality of the | |
| 79 reconstruction does not fall below our threshold and it saves bits. | |
| 80 Hence, all of that VP3.2 code is gone from here, and the remaining | |
| 81 floating point code has been implemented as equivalent integer code | |
| 82 with exact precision.*/ | |
| 83 qfac=(ogg_uint32_t)_qinfo->dc_scale[qi]*base[0]; | |
| 84 /*For postprocessing, not dequantization.*/ | |
| 85 if(_pp_dc_scale!=NULL)_pp_dc_scale[qi]=(int)(qfac/160); | |
| 86 /*Scale DC the coefficient from the proper table.*/ | |
| 87 q=(qfac/100)<<2; | |
| 88 q=OC_CLAMPI(OC_DC_QUANT_MIN[qti],q,OC_QUANT_MAX); | |
| 89 _dequant[qi][pli][qti][0]=(ogg_uint16_t)q; | |
| 90 /*Now scale AC coefficients from the proper table.*/ | |
| 91 for(zzi=1;zzi<64;zzi++){ | |
| 92 q=((ogg_uint32_t)_qinfo->ac_scale[qi]*base[OC_FZIG_ZAG[zzi]]/100)<<2; | |
| 93 q=OC_CLAMPI(OC_AC_QUANT_MIN[qti],q,OC_QUANT_MAX); | |
| 94 _dequant[qi][pli][qti][zzi]=(ogg_uint16_t)q; | |
| 95 } | |
| 96 /*If this is a duplicate of a previous matrix, use that instead. | |
| 97 This simple check helps us improve cache coherency later.*/ | |
| 98 { | |
| 99 int dupe; | |
| 100 int qtj; | |
| 101 int plj; | |
| 102 dupe=0; | |
| 103 for(qtj=0;qtj<=qti;qtj++){ | |
| 104 for(plj=0;plj<(qtj<qti?3:pli);plj++){ | |
| 105 if(!memcmp(_dequant[qi][pli][qti],_dequant[qi][plj][qtj], | |
| 106 sizeof(oc_quant_table))){ | |
| 107 dupe=1; | |
| 108 break; | |
| 109 } | |
| 110 } | |
| 111 if(dupe)break; | |
| 112 } | |
| 113 if(dupe)_dequant[qi][pli][qti]=_dequant[qi][plj][qtj]; | |
| 114 } | |
| 115 if(++qi>=qi_end)break; | |
| 116 /*Interpolate the next base matrix.*/ | |
| 117 for(ci=0;ci<64;ci++){ | |
| 118 base[ci]=(unsigned char)( | |
| 119 (2*((qi_end-qi)*_qinfo->qi_ranges[qti][pli].base_matrices[qri][ci]+ | |
| 120 (qi-qi_start)*_qinfo->qi_ranges[qti][pli].base_matrices[qri+1][ci]) | |
| 121 +_qinfo->qi_ranges[qti][pli].sizes[qri])/ | |
| 122 (2*_qinfo->qi_ranges[qti][pli].sizes[qri])); | |
| 123 } | |
| 124 } | |
| 125 } | |
| 126 } | |
| 127 } |
