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29 uint8_t *filtered_top,
34 pixel *filtered_left_p = (
pixel *)filtered_left;
41 filtered_left_p[n - 1] = left_p[n - 1];
42 filtered_top_p[n - 1] = top_p[n - 1];
43 for (
i = n - 2;
i >= 0;
i--)
44 filtered_left_p[
i] = (left_p[
i + 1] + 2 * left_p[
i] + left_p[
i - 1] + 2) >> 2;
46 filtered_left_p[-1] = (left_p[0] + 2 * left_p[-1] + top_p[0] + 2) >> 2;
47 for (
i = n - 2;
i >= 0;
i--)
48 filtered_top_p[
i] = (top_p[
i + 1] + 2 * top_p[
i] + top_p[
i - 1] + 2) >> 2;
60 filtered_top_p[-1] = top_p[-1];
61 filtered_top_p[63] = top_p[63];
62 for (
i = 0;
i < 63;
i++)
63 filtered_top_p[
i] = ((64 - (
i + 1)) * top_p[-1] +
64 (
i + 1) * top_p[63] + 32) >> 6;
65 for (
i = 0;
i < 63;
i++)
66 left_p[
i] = ((64 - (
i + 1)) * left_p[-1] +
67 (
i + 1) * left_p[63] + 32) >> 6;
70 #define POS(x, y) src[(x) + stride * (y)]
75 int log2_size,
int c_idx)
78 ((x) >> sps->log2_min_pu_size)
80 (s->cur_frame->tab_mvf[(x) + (y) * min_pu_width])
81 #define MVF_PU(x, y) \
82 MVF(PU(x0 + ((x) * (1 << hshift))), PU(y0 + ((y) * (1 << vshift))))
83 #define IS_INTRA(x, y) \
84 (MVF_PU(x, y).pred_flag == PF_INTRA)
85 #define MIN_TB_ADDR_ZS(x, y) \
86 pps->min_tb_addr_zs[(y) * (sps->tb_mask+2) + (x)]
87 #define EXTEND(ptr, val, len) \
89 pixel4 pix = PIXEL_SPLAT_X4(val); \
90 for (i = 0; i < (len); i += 4) \
91 AV_WN4P(ptr + i, pix); \
94 #define EXTEND_RIGHT_CIP(ptr, start, length) \
95 for (i = start; i < (start) + (length); i += 4) \
96 if (!IS_INTRA(i, -1)) \
97 AV_WN4P(&ptr[i], a); \
99 a = PIXEL_SPLAT_X4(ptr[i+3])
100 #define EXTEND_LEFT_CIP(ptr, start, length) \
101 for (i = start; i > (start) - (length); i--) \
102 if (!IS_INTRA(i - 1, -1)) \
104 #define EXTEND_UP_CIP(ptr, start, length) \
105 for (i = (start); i > (start) - (length); i -= 4) \
106 if (!IS_INTRA(-1, i - 3)) \
107 AV_WN4P(&ptr[i - 3], a); \
109 a = PIXEL_SPLAT_X4(ptr[i - 3])
110 #define EXTEND_DOWN_CIP(ptr, start, length) \
111 for (i = start; i < (start) + (length); i += 4) \
112 if (!IS_INTRA(-1, i)) \
113 AV_WN4P(&ptr[i], a); \
115 a = PIXEL_SPLAT_X4(ptr[i + 3])
120 int hshift =
sps->hshift[c_idx];
121 int vshift =
sps->vshift[c_idx];
122 int size = (1 << log2_size);
123 int size_in_luma_h =
size << hshift;
124 int size_in_tbs_h = size_in_luma_h >>
sps->log2_min_tb_size;
125 int size_in_luma_v =
size << vshift;
126 int size_in_tbs_v = size_in_luma_v >>
sps->log2_min_tb_size;
127 int x = x0 >> hshift;
128 int y = y0 >> vshift;
129 int x_tb = (x0 >>
sps->log2_min_tb_size) &
sps->tb_mask;
130 int y_tb = (y0 >>
sps->log2_min_tb_size) &
sps->tb_mask;
131 int spin = c_idx && !size_in_tbs_v && ((2 * y0) & (1 <<
sps->log2_min_tb_size));
135 ptrdiff_t
stride =
s->cur_frame->f->linesize[c_idx] /
sizeof(
pixel);
138 int min_pu_width =
sps->min_pu_width;
141 lc->tu.intra_pred_mode;
151 pixel *top = top_array + 1;
152 pixel *filtered_left = filtered_left_array + 1;
153 pixel *filtered_top = filtered_top_array + 1;
154 int cand_bottom_left = lc->na.cand_bottom_left && cur_tb_addr >
MIN_TB_ADDR_ZS( x_tb - 1, (y_tb + size_in_tbs_v + spin) &
sps->tb_mask);
155 int cand_left = lc->na.cand_left;
156 int cand_up_left = lc->na.cand_up_left;
157 int cand_up = lc->na.cand_up;
158 int cand_up_right = lc->na.cand_up_right && !spin && cur_tb_addr >
MIN_TB_ADDR_ZS((x_tb + size_in_tbs_h) &
sps->tb_mask, y_tb - 1);
160 int bottom_left_size = (
FFMIN(y0 + 2 * size_in_luma_v,
sps->height) -
161 (y0 + size_in_luma_v)) >> vshift;
162 int top_right_size = (
FFMIN(x0 + 2 * size_in_luma_h,
sps->width) -
163 (x0 + size_in_luma_h)) >> hshift;
165 if (
pps->constrained_intra_pred_flag == 1) {
166 int size_in_luma_pu_v =
PU(size_in_luma_v);
167 int size_in_luma_pu_h =
PU(size_in_luma_h);
170 if (!size_in_luma_pu_h)
172 if (cand_bottom_left == 1 && on_pu_edge_x) {
173 int x_left_pu =
PU(x0 - 1);
174 int y_bottom_pu =
PU(y0 + size_in_luma_v);
175 int max =
FFMIN(size_in_luma_pu_v,
sps->min_pu_height - y_bottom_pu);
176 cand_bottom_left = 0;
177 for (
i = 0;
i <
max;
i += 2)
178 cand_bottom_left |= (
MVF(x_left_pu, y_bottom_pu +
i).pred_flag ==
PF_INTRA);
180 if (cand_left == 1 && on_pu_edge_x) {
181 int x_left_pu =
PU(x0 - 1);
182 int y_left_pu =
PU(y0);
183 int max =
FFMIN(size_in_luma_pu_v,
sps->min_pu_height - y_left_pu);
185 for (
i = 0;
i <
max;
i += 2)
186 cand_left |= (
MVF(x_left_pu, y_left_pu +
i).pred_flag ==
PF_INTRA);
188 if (cand_up_left == 1) {
189 int x_left_pu =
PU(x0 - 1);
190 int y_top_pu =
PU(y0 - 1);
191 cand_up_left =
MVF(x_left_pu, y_top_pu).pred_flag ==
PF_INTRA;
193 if (cand_up == 1 && on_pu_edge_y) {
194 int x_top_pu =
PU(x0);
195 int y_top_pu =
PU(y0 - 1);
196 int max =
FFMIN(size_in_luma_pu_h,
sps->min_pu_width - x_top_pu);
198 for (
i = 0;
i <
max;
i += 2)
199 cand_up |= (
MVF(x_top_pu +
i, y_top_pu).pred_flag ==
PF_INTRA);
201 if (cand_up_right == 1 && on_pu_edge_y) {
202 int y_top_pu =
PU(y0 - 1);
203 int x_right_pu =
PU(x0 + size_in_luma_h);
204 int max =
FFMIN(size_in_luma_pu_h,
sps->min_pu_width - x_right_pu);
206 for (
i = 0;
i <
max;
i += 2)
207 cand_up_right |= (
MVF(x_right_pu +
i, y_top_pu).pred_flag ==
PF_INTRA);
222 size - top_right_size);
227 if (cand_bottom_left) {
231 size - bottom_left_size);
234 if (
pps->constrained_intra_pred_flag == 1) {
235 if (cand_bottom_left || cand_left || cand_up_left || cand_up || cand_up_right) {
236 int size_max_x = x0 + ((2 *
size) << hshift) <
sps->width ?
237 2 *
size : (
sps->width - x0) >> hshift;
238 int size_max_y = y0 + ((2 *
size) << vshift) <
sps->height ?
239 2 *
size : (
sps->height - y0) >> vshift;
240 int j =
size + (cand_bottom_left? bottom_left_size: 0) -1;
241 if (!cand_up_right) {
242 size_max_x = x0 + ((
size) << hshift) <
sps->width ?
243 size : (
sps->width - x0) >> hshift;
245 if (!cand_bottom_left) {
246 size_max_y = y0 + ((
size) << vshift) <
sps->height ?
247 size : (
sps->height - y0) >> vshift;
249 if (cand_bottom_left || cand_left || cand_up_left) {
254 while (j < size_max_x && !
IS_INTRA(j, -1))
261 while (j < size_max_x && !
IS_INTRA(j, -1))
270 if (cand_bottom_left || cand_left) {
276 if (!cand_bottom_left)
278 if (x0 != 0 && y0 != 0) {
283 }
else if (x0 == 0) {
297 if (!cand_bottom_left) {
300 }
else if (cand_up_left) {
303 }
else if (cand_up) {
308 }
else if (cand_up_right) {
335 if (!
sps->intra_smoothing_disabled && (c_idx == 0 ||
sps->chroma_format_idc == 3)) {
337 int intra_hor_ver_dist_thresh[] = { 7, 1, 0 };
340 if (min_dist_vert_hor > intra_hor_ver_dist_thresh[log2_size - 3]) {
342 if (
sps->strong_intra_smoothing_enabled && c_idx == 0 &&
344 FFABS(top[-1] + top[63] - 2 * top[31]) < threshold &&
346 s->hpc.ref_filter_strong((uint8_t *)filtered_top,
348 (
const uint8_t *)top);
351 s->hpc.ref_filter_3tap[log2_size - 3](
352 (uint8_t *)filtered_left, (uint8_t *)filtered_top,
353 (
const uint8_t *)
left, (
const uint8_t *)top,
size);
354 left = filtered_left;
363 s->hpc.pred_planar[log2_size - 2]((uint8_t *)
src, (uint8_t *)top,
367 s->hpc.pred_dc((uint8_t *)
src, (uint8_t *)top,
371 s->hpc.pred_angular[log2_size - 2]((uint8_t *)
src, (uint8_t *)top,
378 #define INTRA_PRED(size) \
379 static void FUNC(intra_pred_ ## size)(HEVCLocalContext *lc, const HEVCPPS *pps, \
380 int x0, int y0, int c_idx) \
382 FUNC(intra_pred)(lc, pps, x0, y0, size, c_idx); \
393 const uint8_t *_left, ptrdiff_t
stride,
400 int size = 1 << trafo_size;
401 for (y = 0; y <
size; y++)
402 for (x = 0; x <
size; x++)
407 #define PRED_PLANAR(size)\
408 static void FUNC(pred_planar_ ## size)(uint8_t *src, const uint8_t *top, \
409 const uint8_t *left, ptrdiff_t stride) \
411 FUNC(pred_planar)(src, top, left, stride, size + 2); \
422 const uint8_t *_left,
423 ptrdiff_t
stride,
int log2_size,
int c_idx)
426 int size = (1 << log2_size);
435 dc >>= log2_size + 1;
440 for (j = 0; j <
size; j+=4)
443 if (c_idx == 0 &&
size < 32) {
444 POS(0, 0) = (
left[0] + 2 *
dc + top[0] + 2) >> 2;
445 for (x = 1; x <
size; x++)
446 POS(x, 0) = (top[x] + 3 *
dc + 2) >> 2;
447 for (y = 1; y <
size; y++)
454 const uint8_t *_left,
455 ptrdiff_t
stride,
int c_idx,
463 static const int intra_pred_angle[] = {
464 32, 26, 21, 17, 13, 9, 5, 2, 0, -2, -5, -9, -13, -17, -21, -26, -32,
465 -26, -21, -17, -13, -9, -5, -2, 0, 2, 5, 9, 13, 17, 21, 26, 32
467 static const int inv_angle[] = {
468 -4096, -1638, -910, -630, -482, -390, -315, -256, -315, -390, -482,
469 -630, -910, -1638, -4096
472 int angle = intra_pred_angle[
mode - 2];
476 int last = (
size * angle) >> 5;
480 if (angle < 0 && last < -1) {
481 for (x = 0; x <=
size; x += 4)
483 for (x = last; x <= -1; x++)
484 ref_tmp[x] =
left[-1 + ((x * inv_angle[
mode - 11] + 128) >> 8)];
488 for (y = 0; y <
size; y++) {
489 int idx = ((y + 1) * angle) >> 5;
490 int fact = ((y + 1) * angle) & 31;
492 for (x = 0; x <
size; x += 4) {
493 POS(x , y) = ((32 -
fact) *
ref[x + idx + 1] +
494 fact *
ref[x + idx + 2] + 16) >> 5;
495 POS(x + 1, y) = ((32 -
fact) *
ref[x + 1 + idx + 1] +
496 fact *
ref[x + 1 + idx + 2] + 16) >> 5;
497 POS(x + 2, y) = ((32 -
fact) *
ref[x + 2 + idx + 1] +
498 fact *
ref[x + 2 + idx + 2] + 16) >> 5;
499 POS(x + 3, y) = ((32 -
fact) *
ref[x + 3 + idx + 1] +
500 fact *
ref[x + 3 + idx + 2] + 16) >> 5;
503 for (x = 0; x <
size; x += 4)
507 if (
mode == 26 && c_idx == 0 &&
size < 32) {
508 for (y = 0; y <
size; y++)
513 if (angle < 0 && last < -1) {
514 for (x = 0; x <=
size; x += 4)
516 for (x = last; x <= -1; x++)
517 ref_tmp[x] = top[-1 + ((x * inv_angle[
mode - 11] + 128) >> 8)];
521 for (x = 0; x <
size; x++) {
522 int idx = ((x + 1) * angle) >> 5;
523 int fact = ((x + 1) * angle) & 31;
525 for (y = 0; y <
size; y++) {
527 fact *
ref[y + idx + 2] + 16) >> 5;
530 for (y = 0; y <
size; y++)
531 POS(x, y) =
ref[y + idx + 1];
534 if (
mode == 10 && c_idx == 0 &&
size < 32) {
535 for (x = 0; x <
size; x += 4) {
573 #undef EXTEND_LEFT_CIP
574 #undef EXTEND_RIGHT_CIP
576 #undef EXTEND_DOWN_CIP
582 #undef MIN_TB_ADDR_ZS
static void FUNC() pred_angular_3(uint8_t *src, const uint8_t *top, const uint8_t *left, ptrdiff_t stride, int c_idx, int mode)
static void FUNC() ref_filter_3tap(uint8_t *filtered_left, uint8_t *filtered_top, const uint8_t *left, const uint8_t *top, int size)
#define PRED_PLANAR(size)
uint8_t ptrdiff_t const uint8_t * _src
#define EXTEND_LEFT_CIP(ptr, start, length)
static void FUNC() ref_filter_strong(uint8_t *filtered_top, uint8_t *left, const uint8_t *top)
#define MIN_TB_ADDR_ZS(x, y)
static av_always_inline void FUNC() intra_pred(HEVCLocalContext *lc, const HEVCPPS *pps, int x0, int y0, int log2_size, int c_idx)
#define EXTEND_DOWN_CIP(ptr, start, length)
static void FUNC() pred_angular_2(uint8_t *src, const uint8_t *top, const uint8_t *left, ptrdiff_t stride, int c_idx, int mode)
#define PIXEL_SPLAT_X4(x)
#define FFABS(a)
Absolute value, Note, INT_MIN / INT64_MIN result in undefined behavior as they are not representable ...
static av_always_inline void FUNC() pred_angular(uint8_t *_src, const uint8_t *_top, const uint8_t *_left, ptrdiff_t stride, int c_idx, int mode, int size)
#define EXTEND_UP_CIP(ptr, start, length)
#define EXTEND_RIGHT_CIP(ptr, start, length)
Tag MUST be and< 10hcoeff half pel interpolation filter coefficients, hcoeff[0] are the 2 middle coefficients[1] are the next outer ones and so on, resulting in a filter like:...eff[2], hcoeff[1], hcoeff[0], hcoeff[0], hcoeff[1], hcoeff[2] ... the sign of the coefficients is not explicitly stored but alternates after each coeff and coeff[0] is positive, so ...,+,-,+,-,+,+,-,+,-,+,... hcoeff[0] is not explicitly stored but found by subtracting the sum of all stored coefficients with signs from 32 hcoeff[0]=32 - hcoeff[1] - hcoeff[2] - ... a good choice for hcoeff and htaps is htaps=6 hcoeff={40,-10, 2} an alternative which requires more computations at both encoder and decoder side and may or may not be better is htaps=8 hcoeff={42,-14, 6,-2}ref_frames minimum of the number of available reference frames and max_ref_frames for example the first frame after a key frame always has ref_frames=1spatial_decomposition_type wavelet type 0 is a 9/7 symmetric compact integer wavelet 1 is a 5/3 symmetric compact integer wavelet others are reserved stored as delta from last, last is reset to 0 if always_reset||keyframeqlog quality(logarithmic quantizer scale) stored as delta from last, last is reset to 0 if always_reset||keyframemv_scale stored as delta from last, last is reset to 0 if always_reset||keyframe FIXME check that everything works fine if this changes between framesqbias dequantization bias stored as delta from last, last is reset to 0 if always_reset||keyframeblock_max_depth maximum depth of the block tree stored as delta from last, last is reset to 0 if always_reset||keyframequant_table quantization tableHighlevel bitstream structure:==============================--------------------------------------------|Header|--------------------------------------------|------------------------------------|||Block0||||split?||||yes no||||......... intra?||||:Block01 :yes no||||:Block02 :....... ..........||||:Block03 ::y DC ::ref index:||||:Block04 ::cb DC ::motion x :||||......... :cr DC ::motion y :||||....... ..........|||------------------------------------||------------------------------------|||Block1|||...|--------------------------------------------|------------ ------------ ------------|||Y subbands||Cb subbands||Cr subbands||||--- ---||--- ---||--- ---|||||LL0||HL0||||LL0||HL0||||LL0||HL0|||||--- ---||--- ---||--- ---||||--- ---||--- ---||--- ---|||||LH0||HH0||||LH0||HH0||||LH0||HH0|||||--- ---||--- ---||--- ---||||--- ---||--- ---||--- ---|||||HL1||LH1||||HL1||LH1||||HL1||LH1|||||--- ---||--- ---||--- ---||||--- ---||--- ---||--- ---|||||HH1||HL2||||HH1||HL2||||HH1||HL2|||||...||...||...|||------------ ------------ ------------|--------------------------------------------Decoding process:=================------------|||Subbands|------------||||------------|Intra DC||||LL0 subband prediction ------------|\ Dequantization ------------------- \||Reference frames|\ IDWT|------- -------|Motion \|||Frame 0||Frame 1||Compensation . OBMC v -------|------- -------|--------------. \------> Frame n output Frame Frame<----------------------------------/|...|------------------- Range Coder:============Binary Range Coder:------------------- The implemented range coder is an adapted version based upon "Range encoding: an algorithm for removing redundancy from a digitised message." by G. N. N. Martin. The symbols encoded by the Snow range coder are bits(0|1). The associated probabilities are not fix but change depending on the symbol mix seen so far. bit seen|new state ---------+----------------------------------------------- 0|256 - state_transition_table[256 - old_state];1|state_transition_table[old_state];state_transition_table={ 0, 0, 0, 0, 0, 0, 0, 0, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 190, 191, 192, 194, 194, 195, 196, 197, 198, 199, 200, 201, 202, 202, 204, 205, 206, 207, 208, 209, 209, 210, 211, 212, 213, 215, 215, 216, 217, 218, 219, 220, 220, 222, 223, 224, 225, 226, 227, 227, 229, 229, 230, 231, 232, 234, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 248, 0, 0, 0, 0, 0, 0, 0};FIXME Range Coding of integers:------------------------- FIXME Neighboring Blocks:===================left and top are set to the respective blocks unless they are outside of the image in which case they are set to the Null block top-left is set to the top left block unless it is outside of the image in which case it is set to the left block if this block has no larger parent block or it is at the left side of its parent block and the top right block is not outside of the image then the top right block is used for top-right else the top-left block is used Null block y, cb, cr are 128 level, ref, mx and my are 0 Motion Vector Prediction:=========================1. the motion vectors of all the neighboring blocks are scaled to compensate for the difference of reference frames scaled_mv=(mv *(256 *(current_reference+1)/(mv.reference+1))+128)> the median of the scaled top and top right vectors is used as motion vector prediction the used motion vector is the sum of the predictor and(mvx_diff, mvy_diff) *mv_scale Intra DC Prediction block[y][x] dc[1]
#define i(width, name, range_min, range_max)
static void FUNC() pred_angular_0(uint8_t *src, const uint8_t *top, const uint8_t *left, ptrdiff_t stride, int c_idx, int mode)
The reader does not expect b to be semantically here and if the code is changed by maybe adding a a division or other the signedness will almost certainly be mistaken To avoid this confusion a new type was SUINT is the C unsigned type but it holds a signed int to use the same example SUINT a
static double fact(double i)
static void FUNC() pred_dc(uint8_t *_src, const uint8_t *_top, const uint8_t *_left, ptrdiff_t stride, int log2_size, int c_idx)
static int FUNC() sps(CodedBitstreamContext *ctx, RWContext *rw, H264RawSPS *current)
Tag MUST be and< 10hcoeff half pel interpolation filter coefficients, hcoeff[0] are the 2 middle coefficients[1] are the next outer ones and so on, resulting in a filter like:...eff[2], hcoeff[1], hcoeff[0], hcoeff[0], hcoeff[1], hcoeff[2] ... the sign of the coefficients is not explicitly stored but alternates after each coeff and coeff[0] is positive, so ...,+,-,+,-,+,+,-,+,-,+,... hcoeff[0] is not explicitly stored but found by subtracting the sum of all stored coefficients with signs from 32 hcoeff[0]=32 - hcoeff[1] - hcoeff[2] - ... a good choice for hcoeff and htaps is htaps=6 hcoeff={40,-10, 2} an alternative which requires more computations at both encoder and decoder side and may or may not be better is htaps=8 hcoeff={42,-14, 6,-2}ref_frames minimum of the number of available reference frames and max_ref_frames for example the first frame after a key frame always has ref_frames=1spatial_decomposition_type wavelet type 0 is a 9/7 symmetric compact integer wavelet 1 is a 5/3 symmetric compact integer wavelet others are reserved stored as delta from last, last is reset to 0 if always_reset||keyframeqlog quality(logarithmic quantizer scale) stored as delta from last, last is reset to 0 if always_reset||keyframemv_scale stored as delta from last, last is reset to 0 if always_reset||keyframe FIXME check that everything works fine if this changes between framesqbias dequantization bias stored as delta from last, last is reset to 0 if always_reset||keyframeblock_max_depth maximum depth of the block tree stored as delta from last, last is reset to 0 if always_reset||keyframequant_table quantization tableHighlevel bitstream structure:==============================--------------------------------------------|Header|--------------------------------------------|------------------------------------|||Block0||||split?||||yes no||||......... intra?||||:Block01 :yes no||||:Block02 :....... ..........||||:Block03 ::y DC ::ref index:||||:Block04 ::cb DC ::motion x :||||......... :cr DC ::motion y :||||....... ..........|||------------------------------------||------------------------------------|||Block1|||...|--------------------------------------------|------------ ------------ ------------|||Y subbands||Cb subbands||Cr subbands||||--- ---||--- ---||--- ---|||||LL0||HL0||||LL0||HL0||||LL0||HL0|||||--- ---||--- ---||--- ---||||--- ---||--- ---||--- ---|||||LH0||HH0||||LH0||HH0||||LH0||HH0|||||--- ---||--- ---||--- ---||||--- ---||--- ---||--- ---|||||HL1||LH1||||HL1||LH1||||HL1||LH1|||||--- ---||--- ---||--- ---||||--- ---||--- ---||--- ---|||||HH1||HL2||||HH1||HL2||||HH1||HL2|||||...||...||...|||------------ ------------ ------------|--------------------------------------------Decoding process:=================------------|||Subbands|------------||||------------|Intra DC||||LL0 subband prediction ------------|\ Dequantization ------------------- \||Reference frames|\ IDWT|------- -------|Motion \|||Frame 0||Frame 1||Compensation . OBMC v -------|------- -------|--------------. \------> Frame n output Frame Frame<----------------------------------/|...|------------------- Range Coder:============Binary Range Coder:------------------- The implemented range coder is an adapted version based upon "Range encoding: an algorithm for removing redundancy from a digitised message." by G. N. N. Martin. The symbols encoded by the Snow range coder are bits(0|1). The associated probabilities are not fix but change depending on the symbol mix seen so far. bit seen|new state ---------+----------------------------------------------- 0|256 - state_transition_table[256 - old_state];1|state_transition_table[old_state];state_transition_table={ 0, 0, 0, 0, 0, 0, 0, 0, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 190, 191, 192, 194, 194, 195, 196, 197, 198, 199, 200, 201, 202, 202, 204, 205, 206, 207, 208, 209, 209, 210, 211, 212, 213, 215, 215, 216, 217, 218, 219, 220, 220, 222, 223, 224, 225, 226, 227, 227, 229, 229, 230, 231, 232, 234, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 248, 0, 0, 0, 0, 0, 0, 0};FIXME Range Coding of integers:------------------------- FIXME Neighboring Blocks:===================left and top are set to the respective blocks unless they are outside of the image in which case they are set to the Null block top-left is set to the top left block unless it is outside of the image in which case it is set to the left block if this block has no larger parent block or it is at the left side of its parent block and the top right block is not outside of the image then the top right block is used for top-right else the top-left block is used Null block y, cb, cr are 128 level, ref, mx and my are 0 Motion Vector Prediction:=========================1. the motion vectors of all the neighboring blocks are scaled to compensate for the difference of reference frames scaled_mv=(mv *(256 *(current_reference+1)/(mv.reference+1))+128)> the median of the scaled left
static void FUNC() pred_angular_1(uint8_t *src, const uint8_t *top, const uint8_t *left, ptrdiff_t stride, int c_idx, int mode)
static int ref[MAX_W *MAX_W]
#define EXTEND(ptr, val, len)
static av_always_inline void FUNC() pred_planar(uint8_t *_src, const uint8_t *_top, const uint8_t *_left, ptrdiff_t stride, int trafo_size)