drivers/media/v4l2-core/v4l2-h264.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * V4L2 H264 helpers.
   4  *
   5  * Copyright (C) 2019 Collabora, Ltd.
   6  *
   7  * Author: Boris Brezillon <boris.brezillon@collabora.com>
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/sort.h>
  12
  13 #include <media/v4l2-h264.h>
  14
  15 /*
  16  * Size of the tempory buffer allocated when printing reference lists. The
  17  * output will be truncated if the size is too small.
  18  */
  19 static const int tmp_str_size = 1024;
  20
  21 /**
  22  * v4l2_h264_init_reflist_builder() - Initialize a P/B0/B1 reference list
  23  *                                    builder
  24  *
  25  * @b: the builder context to initialize
  26  * @dec_params: decode parameters control
  27  * @sps: SPS control
  28  * @dpb: DPB to use when creating the reference list
  29  */
  30 void
  31 v4l2_h264_init_reflist_builder(struct v4l2_h264_reflist_builder *b,
  32                 const struct v4l2_ctrl_h264_decode_params *dec_params,
  33                 const struct v4l2_ctrl_h264_sps *sps,
  34                 const struct v4l2_h264_dpb_entry dpb[V4L2_H264_NUM_DPB_ENTRIES])
  35 {
  36         int cur_frame_num, max_frame_num;
  37         unsigned int i;
  38
  39         max_frame_num = 1 << (sps->log2_max_frame_num_minus4 + 4);
  40         cur_frame_num = dec_params->frame_num;
  41
  42         memset(b, 0, sizeof(*b));
  43         if (!(dec_params->flags & V4L2_H264_DECODE_PARAM_FLAG_FIELD_PIC)) {
  44                 b->cur_pic_order_count = min(dec_params->bottom_field_order_cnt,
  45                                              dec_params->top_field_order_cnt);
  46                 b->cur_pic_fields = V4L2_H264_FRAME_REF;
  47         } else if (dec_params->flags & V4L2_H264_DECODE_PARAM_FLAG_BOTTOM_FIELD) {
  48                 b->cur_pic_order_count = dec_params->bottom_field_order_cnt;
  49                 b->cur_pic_fields = V4L2_H264_BOTTOM_FIELD_REF;
  50         } else {
  51                 b->cur_pic_order_count = dec_params->top_field_order_cnt;
  52                 b->cur_pic_fields = V4L2_H264_TOP_FIELD_REF;
  53         }
  54
  55         for (i = 0; i < V4L2_H264_NUM_DPB_ENTRIES; i++) {
  56                 if (!(dpb[i].flags & V4L2_H264_DPB_ENTRY_FLAG_ACTIVE))
  57                         continue;
  58
  59                 if (dpb[i].flags & V4L2_H264_DPB_ENTRY_FLAG_LONG_TERM)
  60                         b->refs[i].longterm = true;
  61
  62                 /*
  63                  * Handle frame_num wraparound as described in section
  64                  * '8.2.4.1 Decoding process for picture numbers' of the spec.
  65                  * For long term references, frame_num is set to
  66                  * long_term_frame_idx which requires no wrapping.
  67                  */
  68                 if (!b->refs[i].longterm && dpb[i].frame_num > cur_frame_num)
  69                         b->refs[i].frame_num = (int)dpb[i].frame_num -
  70                                                max_frame_num;
  71                 else
  72                         b->refs[i].frame_num = dpb[i].frame_num;
  73
  74                 b->refs[i].top_field_order_cnt = dpb[i].top_field_order_cnt;
  75                 b->refs[i].bottom_field_order_cnt = dpb[i].bottom_field_order_cnt;
  76
  77                 if (b->cur_pic_fields == V4L2_H264_FRAME_REF) {
  78                         u8 fields = V4L2_H264_FRAME_REF;
  79
  80                         b->unordered_reflist[b->num_valid].index = i;
  81                         b->unordered_reflist[b->num_valid].fields = fields;
  82                         b->num_valid++;
  83                         continue;
  84                 }
  85
  86                 if (dpb[i].fields & V4L2_H264_TOP_FIELD_REF) {
  87                         u8 fields = V4L2_H264_TOP_FIELD_REF;
  88
  89                         b->unordered_reflist[b->num_valid].index = i;
  90                         b->unordered_reflist[b->num_valid].fields = fields;
  91                         b->num_valid++;
  92                 }
  93
  94                 if (dpb[i].fields & V4L2_H264_BOTTOM_FIELD_REF) {
  95                         u8 fields = V4L2_H264_BOTTOM_FIELD_REF;
  96
  97                         b->unordered_reflist[b->num_valid].index = i;
  98                         b->unordered_reflist[b->num_valid].fields = fields;
  99                         b->num_valid++;
 100                 }
 101         }
 102
 103         for (i = b->num_valid; i < ARRAY_SIZE(b->unordered_reflist); i++)
 104                 b->unordered_reflist[i].index = i;
 105 }
 106 EXPORT_SYMBOL_GPL(v4l2_h264_init_reflist_builder);
 107
 108 static s32 v4l2_h264_get_poc(const struct v4l2_h264_reflist_builder *b,
 109                              const struct v4l2_h264_reference *ref)
 110 {
 111         switch (ref->fields) {
 112         case V4L2_H264_FRAME_REF:
 113                 return min(b->refs[ref->index].top_field_order_cnt,
 114                                 b->refs[ref->index].bottom_field_order_cnt);
 115         case V4L2_H264_TOP_FIELD_REF:
 116                 return b->refs[ref->index].top_field_order_cnt;
 117         case V4L2_H264_BOTTOM_FIELD_REF:
 118                 return b->refs[ref->index].bottom_field_order_cnt;
 119         }
 120
 121         /* not reached */
 122         return 0;
 123 }
 124
 125 static int v4l2_h264_p_ref_list_cmp(const void *ptra, const void *ptrb,
 126                                     const void *data)
 127 {
 128         const struct v4l2_h264_reflist_builder *builder = data;
 129         u8 idxa, idxb;
 130
 131         idxa = ((struct v4l2_h264_reference *)ptra)->index;
 132         idxb = ((struct v4l2_h264_reference *)ptrb)->index;
 133
 134         if (WARN_ON(idxa >= V4L2_H264_NUM_DPB_ENTRIES ||
 135                     idxb >= V4L2_H264_NUM_DPB_ENTRIES))
 136                 return 1;
 137
 138         if (builder->refs[idxa].longterm != builder->refs[idxb].longterm) {
 139                 /* Short term pics first. */
 140                 if (!builder->refs[idxa].longterm)
 141                         return -1;
 142                 else
 143                         return 1;
 144         }
 145
 146         /*
 147          * For frames, short term pics are in descending pic num order and long
 148          * term ones in ascending order. For fields, the same direction is used
 149          * but with frame_num (wrapped). For frames, the value of pic_num and
 150          * frame_num are the same (see formula (8-28) and (8-29)). For this
 151          * reason we can use frame_num only and share this function between
 152          * frames and fields reflist.
 153          */
 154         if (!builder->refs[idxa].longterm)
 155                 return builder->refs[idxb].frame_num <
 156                        builder->refs[idxa].frame_num ?
 157                        -1 : 1;
 158
 159         return builder->refs[idxa].frame_num < builder->refs[idxb].frame_num ?
 160                -1 : 1;
 161 }
 162
 163 static int v4l2_h264_b0_ref_list_cmp(const void *ptra, const void *ptrb,
 164                                      const void *data)
 165 {
 166         const struct v4l2_h264_reflist_builder *builder = data;
 167         s32 poca, pocb;
 168         u8 idxa, idxb;
 169
 170         idxa = ((struct v4l2_h264_reference *)ptra)->index;
 171         idxb = ((struct v4l2_h264_reference *)ptrb)->index;
 172
 173         if (WARN_ON(idxa >= V4L2_H264_NUM_DPB_ENTRIES ||
 174                     idxb >= V4L2_H264_NUM_DPB_ENTRIES))
 175                 return 1;
 176
 177         if (builder->refs[idxa].longterm != builder->refs[idxb].longterm) {
 178                 /* Short term pics first. */
 179                 if (!builder->refs[idxa].longterm)
 180                         return -1;
 181                 else
 182                         return 1;
 183         }
 184
 185         /* Long term pics in ascending frame num order. */
 186         if (builder->refs[idxa].longterm)
 187                 return builder->refs[idxa].frame_num <
 188                        builder->refs[idxb].frame_num ?
 189                        -1 : 1;
 190
 191         poca = v4l2_h264_get_poc(builder, ptra);
 192         pocb = v4l2_h264_get_poc(builder, ptrb);
 193
 194         /*
 195          * Short term pics with POC < cur POC first in POC descending order
 196          * followed by short term pics with POC > cur POC in POC ascending
 197          * order.
 198          */
 199         if ((poca < builder->cur_pic_order_count) !=
 200              (pocb < builder->cur_pic_order_count))
 201                 return poca < pocb ? -1 : 1;
 202         else if (poca < builder->cur_pic_order_count)
 203                 return pocb < poca ? -1 : 1;
 204
 205         return poca < pocb ? -1 : 1;
 206 }
 207
 208 static int v4l2_h264_b1_ref_list_cmp(const void *ptra, const void *ptrb,
 209                                      const void *data)
 210 {
 211         const struct v4l2_h264_reflist_builder *builder = data;
 212         s32 poca, pocb;
 213         u8 idxa, idxb;
 214
 215         idxa = ((struct v4l2_h264_reference *)ptra)->index;
 216         idxb = ((struct v4l2_h264_reference *)ptrb)->index;
 217
 218         if (WARN_ON(idxa >= V4L2_H264_NUM_DPB_ENTRIES ||
 219                     idxb >= V4L2_H264_NUM_DPB_ENTRIES))
 220                 return 1;
 221
 222         if (builder->refs[idxa].longterm != builder->refs[idxb].longterm) {
 223                 /* Short term pics first. */
 224                 if (!builder->refs[idxa].longterm)
 225                         return -1;
 226                 else
 227                         return 1;
 228         }
 229
 230         /* Long term pics in ascending frame num order. */
 231         if (builder->refs[idxa].longterm)
 232                 return builder->refs[idxa].frame_num <
 233                        builder->refs[idxb].frame_num ?
 234                        -1 : 1;
 235
 236         poca = v4l2_h264_get_poc(builder, ptra);
 237         pocb = v4l2_h264_get_poc(builder, ptrb);
 238
 239         /*
 240          * Short term pics with POC > cur POC first in POC ascending order
 241          * followed by short term pics with POC < cur POC in POC descending
 242          * order.
 243          */
 244         if ((poca < builder->cur_pic_order_count) !=
 245             (pocb < builder->cur_pic_order_count))
 246                 return pocb < poca ? -1 : 1;
 247         else if (poca < builder->cur_pic_order_count)
 248                 return pocb < poca ? -1 : 1;
 249
 250         return poca < pocb ? -1 : 1;
 251 }
 252
 253 /*
 254  * The references need to be reordered so that references are alternating
 255  * between top and bottom field references starting with the current picture
 256  * parity. This has to be done for short term and long term references
 257  * separately.
 258  */
 259 static void reorder_field_reflist(const struct v4l2_h264_reflist_builder *b,
 260                                   struct v4l2_h264_reference *reflist)
 261 {
 262         struct v4l2_h264_reference tmplist[V4L2_H264_REF_LIST_LEN];
 263         u8 lt, i = 0, j = 0, k = 0;
 264
 265         memcpy(tmplist, reflist, sizeof(tmplist[0]) * b->num_valid);
 266
 267         for (lt = 0; lt <= 1; lt++) {
 268                 do {
 269                         for (; i < b->num_valid && b->refs[tmplist[i].index].longterm == lt; i++) {
 270                                 if (tmplist[i].fields == b->cur_pic_fields) {
 271                                         reflist[k++] = tmplist[i++];
 272                                         break;
 273                                 }
 274                         }
 275
 276                         for (; j < b->num_valid && b->refs[tmplist[j].index].longterm == lt; j++) {
 277                                 if (tmplist[j].fields != b->cur_pic_fields) {
 278                                         reflist[k++] = tmplist[j++];
 279                                         break;
 280                                 }
 281                         }
 282                 } while ((i < b->num_valid && b->refs[tmplist[i].index].longterm == lt) ||
 283                          (j < b->num_valid && b->refs[tmplist[j].index].longterm == lt));
 284         }
 285 }
 286
 287 static char ref_type_to_char(u8 ref_type)
 288 {
 289         switch (ref_type) {
 290         case V4L2_H264_FRAME_REF:
 291                 return 'f';
 292         case V4L2_H264_TOP_FIELD_REF:
 293                 return 't';
 294         case V4L2_H264_BOTTOM_FIELD_REF:
 295                 return 'b';
 296         }
 297
 298         return '?';
 299 }
 300
 301 static const char *format_ref_list_p(const struct v4l2_h264_reflist_builder *builder,
 302                                      struct v4l2_h264_reference *reflist,
 303                                      char **out_str)
 304 {
 305         int n = 0, i;
 306
 307         *out_str = kmalloc(tmp_str_size, GFP_KERNEL);
 308         if (!(*out_str))
 309                 return NULL;
 310
 311         n += snprintf(*out_str + n, tmp_str_size - n, "|");
 312
 313         for (i = 0; i < builder->num_valid; i++) {
 314                 /* this is pic_num for frame and frame_num (wrapped) for field,
 315                  * but for frame pic_num is equal to frame_num (wrapped).
 316                  */
 317                 int frame_num = builder->refs[reflist[i].index].frame_num;
 318                 bool longterm = builder->refs[reflist[i].index].longterm;
 319
 320                 n += scnprintf(*out_str + n, tmp_str_size - n, "%i%c%c|",
 321                                frame_num, longterm ? 'l' : 's',
 322                                ref_type_to_char(reflist[i].fields));
 323         }
 324
 325         return *out_str;
 326 }
 327
 328 static void print_ref_list_p(const struct v4l2_h264_reflist_builder *builder,
 329                              struct v4l2_h264_reference *reflist)
 330 {
 331         char *buf = NULL;
 332
 333         pr_debug("ref_pic_list_p (cur_poc %u%c) %s\n",
 334                  builder->cur_pic_order_count,
 335                  ref_type_to_char(builder->cur_pic_fields),
 336                  format_ref_list_p(builder, reflist, &buf));
 337
 338         kfree(buf);
 339 }
 340
 341 static const char *format_ref_list_b(const struct v4l2_h264_reflist_builder *builder,
 342                                      struct v4l2_h264_reference *reflist,
 343                                      char **out_str)
 344 {
 345         int n = 0, i;
 346
 347         *out_str = kmalloc(tmp_str_size, GFP_KERNEL);
 348         if (!(*out_str))
 349                 return NULL;
 350
 351         n += snprintf(*out_str + n, tmp_str_size - n, "|");
 352
 353         for (i = 0; i < builder->num_valid; i++) {
 354                 int frame_num = builder->refs[reflist[i].index].frame_num;
 355                 u32 poc = v4l2_h264_get_poc(builder, reflist + i);
 356                 bool longterm = builder->refs[reflist[i].index].longterm;
 357
 358                 n += scnprintf(*out_str + n, tmp_str_size - n, "%i%c%c|",
 359                                longterm ? frame_num : poc,
 360                                longterm ? 'l' : 's',
 361                                ref_type_to_char(reflist[i].fields));
 362         }
 363
 364         return *out_str;
 365 }
 366
 367 static void print_ref_list_b(const struct v4l2_h264_reflist_builder *builder,
 368                              struct v4l2_h264_reference *reflist, u8 list_num)
 369 {
 370         char *buf = NULL;
 371
 372         pr_debug("ref_pic_list_b%u (cur_poc %u%c) %s",
 373                  list_num, builder->cur_pic_order_count,
 374                  ref_type_to_char(builder->cur_pic_fields),
 375                  format_ref_list_b(builder, reflist, &buf));
 376
 377         kfree(buf);
 378 }
 379
 380 /**
 381  * v4l2_h264_build_p_ref_list() - Build the P reference list
 382  *
 383  * @builder: reference list builder context
 384  * @reflist: 32 sized array used to store the P reference list. Each entry
 385  *           is a v4l2_h264_reference structure
 386  *
 387  * This functions builds the P reference lists. This procedure is describe in
 388  * section '8.2.4 Decoding process for reference picture lists construction'
 389  * of the H264 spec. This function can be used by H264 decoder drivers that
 390  * need to pass a P reference list to the hardware.
 391  */
 392 void
 393 v4l2_h264_build_p_ref_list(const struct v4l2_h264_reflist_builder *builder,
 394                            struct v4l2_h264_reference *reflist)
 395 {
 396         memcpy(reflist, builder->unordered_reflist,
 397                sizeof(builder->unordered_reflist[0]) * builder->num_valid);
 398         sort_r(reflist, builder->num_valid, sizeof(*reflist),
 399                v4l2_h264_p_ref_list_cmp, NULL, builder);
 400
 401         if (builder->cur_pic_fields != V4L2_H264_FRAME_REF)
 402                 reorder_field_reflist(builder, reflist);
 403
 404         print_ref_list_p(builder, reflist);
 405 }
 406 EXPORT_SYMBOL_GPL(v4l2_h264_build_p_ref_list);
 407
 408 /**
 409  * v4l2_h264_build_b_ref_lists() - Build the B0/B1 reference lists
 410  *
 411  * @builder: reference list builder context
 412  * @b0_reflist: 32 sized array used to store the B0 reference list. Each entry
 413  *              is a v4l2_h264_reference structure
 414  * @b1_reflist: 32 sized array used to store the B1 reference list. Each entry
 415  *              is a v4l2_h264_reference structure
 416  *
 417  * This functions builds the B0/B1 reference lists. This procedure is described
 418  * in section '8.2.4 Decoding process for reference picture lists construction'
 419  * of the H264 spec. This function can be used by H264 decoder drivers that
 420  * need to pass B0/B1 reference lists to the hardware.
 421  */
 422 void
 423 v4l2_h264_build_b_ref_lists(const struct v4l2_h264_reflist_builder *builder,
 424                             struct v4l2_h264_reference *b0_reflist,
 425                             struct v4l2_h264_reference *b1_reflist)
 426 {
 427         memcpy(b0_reflist, builder->unordered_reflist,
 428                sizeof(builder->unordered_reflist[0]) * builder->num_valid);
 429         sort_r(b0_reflist, builder->num_valid, sizeof(*b0_reflist),
 430                v4l2_h264_b0_ref_list_cmp, NULL, builder);
 431
 432         memcpy(b1_reflist, builder->unordered_reflist,
 433                sizeof(builder->unordered_reflist[0]) * builder->num_valid);
 434         sort_r(b1_reflist, builder->num_valid, sizeof(*b1_reflist),
 435                v4l2_h264_b1_ref_list_cmp, NULL, builder);
 436
 437         if (builder->cur_pic_fields != V4L2_H264_FRAME_REF) {
 438                 reorder_field_reflist(builder, b0_reflist);
 439                 reorder_field_reflist(builder, b1_reflist);
 440         }
 441
 442         if (builder->num_valid > 1 &&
 443             !memcmp(b1_reflist, b0_reflist, builder->num_valid))
 444                 swap(b1_reflist[0], b1_reflist[1]);
 445
 446         print_ref_list_b(builder, b0_reflist, 0);
 447         print_ref_list_b(builder, b1_reflist, 1);
 448 }
 449 EXPORT_SYMBOL_GPL(v4l2_h264_build_b_ref_lists);
 450
 451 MODULE_LICENSE("GPL");
 452 MODULE_DESCRIPTION("V4L2 H264 Helpers");
 453 MODULE_AUTHOR("Boris Brezillon <boris.brezillon@collabora.com>");