libavcodec/cbs_mpeg2.c

   1 /*
   2  * This file is part of FFmpeg.
   3  *
   4  * FFmpeg is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2.1 of the License, or (at your option) any later version.
   8  *
   9  * FFmpeg is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with FFmpeg; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  17  */
  18
  19 #include "libavutil/avassert.h"
  20
  21 #include "cbs.h"
  22 #include "cbs_internal.h"
  23 #include "cbs_mpeg2.h"
  24 #include "startcode.h"
  25
  26
  27 #define HEADER(name) do { \
  28         ff_cbs_trace_header(ctx, name); \
  29     } while (0)
  30
  31 #define CHECK(call) do { \
  32         err = (call); \
  33         if (err < 0) \
  34             return err; \
  35     } while (0)
  36
  37 #define FUNC_NAME(rw, codec, name) cbs_ ## codec ## _ ## rw ## _ ## name
  38 #define FUNC_MPEG2(rw, name) FUNC_NAME(rw, mpeg2, name)
  39 #define FUNC(name) FUNC_MPEG2(READWRITE, name)
  40
  41 #define SUBSCRIPTS(subs, ...) (subs > 0 ? ((int[subs + 1]){ subs, __VA_ARGS__ }) : NULL)
  42
  43 #define uir(width, name) \
  44         xui(width, name, current->name, 1, MAX_UINT_BITS(width), 0, )
  45 #define uis(width, name, subs, ...) \
  46         xui(width, name, current->name, 0, MAX_UINT_BITS(width), subs, __VA_ARGS__)
  47 #define uirs(width, name, subs, ...) \
  48         xui(width, name, current->name, 1, MAX_UINT_BITS(width), subs, __VA_ARGS__)
  49 #define xui(width, name, var, range_min, range_max, subs, ...) \
  50         xuia(width, #name, var, range_min, range_max, subs, __VA_ARGS__)
  51 #define sis(width, name, subs, ...) \
  52         xsi(width, name, current->name, subs, __VA_ARGS__)
  53
  54 #define marker_bit() \
  55         bit("marker_bit", 1)
  56 #define bit(string, value) do { \
  57         av_unused uint32_t bit = value; \
  58         xuia(1, string, bit, value, value, 0, ); \
  59     } while (0)
  60
  61
  62 #define READ
  63 #define READWRITE read
  64 #define RWContext GetBitContext
  65
  66 #define ui(width, name) do { \
  67         uint32_t value; \
  68         CHECK(ff_cbs_read_simple_unsigned(ctx, rw, width, #name, \
  69                                           &value)); \
  70         current->name = value; \
  71     } while (0)
  72 #define xuia(width, string, var, range_min, range_max, subs, ...) do { \
  73         uint32_t value; \
  74         CHECK(ff_cbs_read_unsigned(ctx, rw, width, string, \
  75                                    SUBSCRIPTS(subs, __VA_ARGS__), \
  76                                    &value, range_min, range_max)); \
  77         var = value; \
  78     } while (0)
  79
  80 #define xsi(width, name, var, subs, ...) do { \
  81         int32_t value; \
  82         CHECK(ff_cbs_read_signed(ctx, rw, width, #name, \
  83                                  SUBSCRIPTS(subs, __VA_ARGS__), &value, \
  84                                  MIN_INT_BITS(width), \
  85                                  MAX_INT_BITS(width))); \
  86         var = value; \
  87     } while (0)
  88
  89 #define nextbits(width, compare, var) \
  90     (get_bits_left(rw) >= width && \
  91      (var = show_bits(rw, width)) == (compare))
  92
  93 #define infer(name, value) do { \
  94         current->name = value; \
  95     } while (0)
  96
  97 #include "cbs_mpeg2_syntax_template.c"
  98
  99 #undef READ
 100 #undef READWRITE
 101 #undef RWContext
 102 #undef ui
 103 #undef xuia
 104 #undef xsi
 105 #undef nextbits
 106 #undef infer
 107
 108
 109 #define WRITE
 110 #define READWRITE write
 111 #define RWContext PutBitContext
 112
 113 #define ui(width, name) do { \
 114         CHECK(ff_cbs_write_simple_unsigned(ctx, rw, width, #name, \
 115                                            current->name)); \
 116     } while (0)
 117
 118 #define xuia(width, string, var, range_min, range_max, subs, ...) do { \
 119         CHECK(ff_cbs_write_unsigned(ctx, rw, width, string, \
 120                                     SUBSCRIPTS(subs, __VA_ARGS__), \
 121                                     var, range_min, range_max)); \
 122     } while (0)
 123
 124 #define xsi(width, name, var, subs, ...) do { \
 125         CHECK(ff_cbs_write_signed(ctx, rw, width, #name, \
 126                                   SUBSCRIPTS(subs, __VA_ARGS__), var, \
 127                                   MIN_INT_BITS(width), \
 128                                   MAX_INT_BITS(width))); \
 129     } while (0)
 130
 131 #define nextbits(width, compare, var) (var)
 132
 133 #define infer(name, value) do { \
 134         if (current->name != (value)) { \
 135             av_log(ctx->log_ctx, AV_LOG_WARNING, "Warning: " \
 136                    "%s does not match inferred value: " \
 137                    "%"PRId64", but should be %"PRId64".\n", \
 138                    #name, (int64_t)current->name, (int64_t)(value)); \
 139         } \
 140     } while (0)
 141
 142 #include "cbs_mpeg2_syntax_template.c"
 143
 144 #undef WRITE
 145 #undef READWRITE
 146 #undef RWContext
 147 #undef ui
 148 #undef xuia
 149 #undef xsi
 150 #undef nextbits
 151 #undef infer
 152
 153
 154 static int cbs_mpeg2_split_fragment(CodedBitstreamContext *ctx,
 155                                     CodedBitstreamFragment *frag,
 156                                     int header)
 157 {
 158     const uint8_t *start;
 159     uint32_t start_code = -1;
 160     int err;
 161
 162     start = avpriv_find_start_code(frag->data, frag->data + frag->data_size,
 163                                    &start_code);
 164     if (start_code >> 8 != 0x000001) {
 165         // No start code found.
 166         return AVERROR_INVALIDDATA;
 167     }
 168
 169     do {
 170         CodedBitstreamUnitType unit_type = start_code & 0xff;
 171         const uint8_t *end;
 172         size_t unit_size;
 173
 174         // Reset start_code to ensure that avpriv_find_start_code()
 175         // really reads a new start code and does not reuse the old
 176         // start code in any way (as e.g. happens when there is a
 177         // Sequence End unit at the very end of a packet).
 178         start_code = UINT32_MAX;
 179         end = avpriv_find_start_code(start--, frag->data + frag->data_size,
 180                                      &start_code);
 181
 182         // start points to the byte containing the start_code_identifier
 183         // (may be the last byte of fragment->data); end points to the byte
 184         // following the byte containing the start code identifier (or to
 185         // the end of fragment->data).
 186         if (start_code >> 8 == 0x000001) {
 187             // Unit runs from start to the beginning of the start code
 188             // pointed to by end (including any padding zeroes).
 189             unit_size = (end - 4) - start;
 190         } else {
 191            // We didn't find a start code, so this is the final unit.
 192            unit_size = end - start;
 193         }
 194
 195         err = ff_cbs_append_unit_data(frag, unit_type, (uint8_t*)start,
 196                                       unit_size, frag->data_ref);
 197         if (err < 0)
 198             return err;
 199
 200         start = end;
 201
 202         // Do we have a further unit to add to the fragment?
 203     } while ((start_code >> 8) == 0x000001);
 204
 205     return 0;
 206 }
 207
 208 static int cbs_mpeg2_read_unit(CodedBitstreamContext *ctx,
 209                                CodedBitstreamUnit *unit)
 210 {
 211     GetBitContext gbc;
 212     int err;
 213
 214     err = init_get_bits(&gbc, unit->data, 8 * unit->data_size);
 215     if (err < 0)
 216         return err;
 217
 218     err = ff_cbs_alloc_unit_content(ctx, unit);
 219     if (err < 0)
 220         return err;
 221
 222     if (MPEG2_START_IS_SLICE(unit->type)) {
 223         MPEG2RawSlice *slice = unit->content;
 224         int pos, len;
 225
 226         err = cbs_mpeg2_read_slice_header(ctx, &gbc, &slice->header);
 227         if (err < 0)
 228             return err;
 229
 230         if (!get_bits_left(&gbc))
 231             return AVERROR_INVALIDDATA;
 232
 233         pos = get_bits_count(&gbc);
 234         len = unit->data_size;
 235
 236         slice->data_size = len - pos / 8;
 237         slice->data_ref  = av_buffer_ref(unit->data_ref);
 238         if (!slice->data_ref)
 239             return AVERROR(ENOMEM);
 240         slice->data = unit->data + pos / 8;
 241
 242         slice->data_bit_start = pos % 8;
 243
 244     } else {
 245         switch (unit->type) {
 246 #define START(start_code, type, read_func, free_func) \
 247         case start_code: \
 248             { \
 249                 type *header = unit->content; \
 250                 err = cbs_mpeg2_read_ ## read_func(ctx, &gbc, header); \
 251                 if (err < 0) \
 252                     return err; \
 253             } \
 254             break;
 255             START(MPEG2_START_PICTURE,   MPEG2RawPictureHeader,
 256                   picture_header,           &cbs_mpeg2_free_picture_header);
 257             START(MPEG2_START_USER_DATA, MPEG2RawUserData,
 258                   user_data,                &cbs_mpeg2_free_user_data);
 259             START(MPEG2_START_SEQUENCE_HEADER, MPEG2RawSequenceHeader,
 260                   sequence_header,          NULL);
 261             START(MPEG2_START_EXTENSION, MPEG2RawExtensionData,
 262                   extension_data,           NULL);
 263             START(MPEG2_START_GROUP,     MPEG2RawGroupOfPicturesHeader,
 264                   group_of_pictures_header, NULL);
 265             START(MPEG2_START_SEQUENCE_END, MPEG2RawSequenceEnd,
 266                   sequence_end,             NULL);
 267 #undef START
 268         default:
 269             return AVERROR(ENOSYS);
 270         }
 271     }
 272
 273     return 0;
 274 }
 275
 276 static int cbs_mpeg2_write_header(CodedBitstreamContext *ctx,
 277                                   CodedBitstreamUnit *unit,
 278                                   PutBitContext *pbc)
 279 {
 280     int err;
 281
 282     switch (unit->type) {
 283 #define START(start_code, type, func) \
 284     case start_code: \
 285         err = cbs_mpeg2_write_ ## func(ctx, pbc, unit->content); \
 286         break;
 287         START(MPEG2_START_PICTURE,         MPEG2RawPictureHeader,  picture_header);
 288         START(MPEG2_START_USER_DATA,       MPEG2RawUserData,       user_data);
 289         START(MPEG2_START_SEQUENCE_HEADER, MPEG2RawSequenceHeader, sequence_header);
 290         START(MPEG2_START_EXTENSION,       MPEG2RawExtensionData,  extension_data);
 291         START(MPEG2_START_GROUP,           MPEG2RawGroupOfPicturesHeader,
 292                                                          group_of_pictures_header);
 293         START(MPEG2_START_SEQUENCE_END,    MPEG2RawSequenceEnd,    sequence_end);
 294 #undef START
 295     default:
 296         av_log(ctx->log_ctx, AV_LOG_ERROR, "Write unimplemented for start "
 297                "code %02"PRIx32".\n", unit->type);
 298         return AVERROR_PATCHWELCOME;
 299     }
 300
 301     return err;
 302 }
 303
 304 static int cbs_mpeg2_write_slice(CodedBitstreamContext *ctx,
 305                                  CodedBitstreamUnit *unit,
 306                                  PutBitContext *pbc)
 307 {
 308     MPEG2RawSlice *slice = unit->content;
 309     int err;
 310
 311     err = cbs_mpeg2_write_slice_header(ctx, pbc, &slice->header);
 312     if (err < 0)
 313         return err;
 314
 315     if (slice->data) {
 316         size_t rest = slice->data_size - (slice->data_bit_start + 7) / 8;
 317         uint8_t *pos = slice->data + slice->data_bit_start / 8;
 318
 319         av_assert0(slice->data_bit_start >= 0 &&
 320                    slice->data_size > slice->data_bit_start / 8);
 321
 322         if (slice->data_size * 8 + 8 > put_bits_left(pbc))
 323             return AVERROR(ENOSPC);
 324
 325         // First copy the remaining bits of the first byte
 326         if (slice->data_bit_start % 8)
 327             put_bits(pbc, 8 - slice->data_bit_start % 8,
 328                      *pos++ & MAX_UINT_BITS(8 - slice->data_bit_start % 8));
 329
 330         if (put_bits_count(pbc) % 8 == 0) {
 331             // If the writer is aligned at this point,
 332             // memcpy can be used to improve performance.
 333             // This is the normal case.
 334             flush_put_bits(pbc);
 335             memcpy(put_bits_ptr(pbc), pos, rest);
 336             skip_put_bytes(pbc, rest);
 337         } else {
 338             // If not, we have to copy manually:
 339             for (; rest > 3; rest -= 4, pos += 4)
 340                 put_bits32(pbc, AV_RB32(pos));
 341
 342             for (; rest; rest--, pos++)
 343                 put_bits(pbc, 8, *pos);
 344
 345             // Align with zeros
 346             put_bits(pbc, 8 - put_bits_count(pbc) % 8, 0);
 347         }
 348     }
 349
 350     return 0;
 351 }
 352
 353 static int cbs_mpeg2_write_unit(CodedBitstreamContext *ctx,
 354                                 CodedBitstreamUnit *unit,
 355                                 PutBitContext *pbc)
 356 {
 357     if (MPEG2_START_IS_SLICE(unit->type))
 358         return cbs_mpeg2_write_slice (ctx, unit, pbc);
 359     else
 360         return cbs_mpeg2_write_header(ctx, unit, pbc);
 361 }
 362
 363 static int cbs_mpeg2_assemble_fragment(CodedBitstreamContext *ctx,
 364                                        CodedBitstreamFragment *frag)
 365 {
 366     uint8_t *data;
 367     size_t size, dp;
 368     int i;
 369
 370     size = 0;
 371     for (i = 0; i < frag->nb_units; i++)
 372         size += 3 + frag->units[i].data_size;
 373
 374     frag->data_ref = av_buffer_alloc(size + AV_INPUT_BUFFER_PADDING_SIZE);
 375     if (!frag->data_ref)
 376         return AVERROR(ENOMEM);
 377     data = frag->data_ref->data;
 378
 379     dp = 0;
 380     for (i = 0; i < frag->nb_units; i++) {
 381         CodedBitstreamUnit *unit = &frag->units[i];
 382
 383         data[dp++] = 0;
 384         data[dp++] = 0;
 385         data[dp++] = 1;
 386
 387         memcpy(data + dp, unit->data, unit->data_size);
 388         dp += unit->data_size;
 389     }
 390
 391     av_assert0(dp == size);
 392
 393     memset(data + size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
 394     frag->data      = data;
 395     frag->data_size = size;
 396
 397     return 0;
 398 }
 399
 400 static CodedBitstreamUnitTypeDescriptor cbs_mpeg2_unit_types[] = {
 401     CBS_UNIT_TYPE_INTERNAL_REF(MPEG2_START_PICTURE, MPEG2RawPictureHeader,
 402                                extra_information_picture.extra_information),
 403
 404     {
 405         .nb_unit_types         = CBS_UNIT_TYPE_RANGE,
 406         .unit_type.range.start = 0x01,
 407         .unit_type.range.end   = 0xaf,
 408
 409         .content_type   = CBS_CONTENT_TYPE_INTERNAL_REFS,
 410         .content_size   = sizeof(MPEG2RawSlice),
 411         .type.ref = { .nb_offsets = 2,
 412                       .offsets    = { offsetof(MPEG2RawSlice, header.extra_information_slice.extra_information),
 413                                       offsetof(MPEG2RawSlice, data) } },
 414     },
 415
 416     CBS_UNIT_TYPE_INTERNAL_REF(MPEG2_START_USER_DATA, MPEG2RawUserData,
 417                                user_data),
 418
 419     CBS_UNIT_TYPE_POD(MPEG2_START_SEQUENCE_HEADER, MPEG2RawSequenceHeader),
 420     CBS_UNIT_TYPE_POD(MPEG2_START_EXTENSION,       MPEG2RawExtensionData),
 421     CBS_UNIT_TYPE_POD(MPEG2_START_SEQUENCE_END,    MPEG2RawSequenceEnd),
 422     CBS_UNIT_TYPE_POD(MPEG2_START_GROUP,           MPEG2RawGroupOfPicturesHeader),
 423
 424     CBS_UNIT_TYPE_END_OF_LIST
 425 };
 426
 427 const CodedBitstreamType ff_cbs_type_mpeg2 = {
 428     .codec_id          = AV_CODEC_ID_MPEG2VIDEO,
 429
 430     .priv_data_size    = sizeof(CodedBitstreamMPEG2Context),
 431
 432     .unit_types        = cbs_mpeg2_unit_types,
 433
 434     .split_fragment    = &cbs_mpeg2_split_fragment,
 435     .read_unit         = &cbs_mpeg2_read_unit,
 436     .write_unit        = &cbs_mpeg2_write_unit,
 437     .assemble_fragment = &cbs_mpeg2_assemble_fragment,
 438 };