fecdec_filter.c

   1 /*
   2  * Copyright (C) 2009-2011 Andre Noll <maan@systemlinux.org>
   3  *
   4  * Licensed under the GPL v2. For licencing details see COPYING.
   5  */
   6
   7 /** \file fecdec_filter.c A filter that fec-decodes an audio stream. */
   8
   9 #include <regex.h>
  10 #include <stdbool.h>
  11
  12 #include "para.h"
  13 #include "error.h"
  14 #include "list.h"
  15 #include "sched.h"
  16 #include "ggo.h"
  17 #include "buffer_tree.h"
  18 #include "filter.h"
  19 #include "string.h"
  20 #include "portable_io.h"
  21 #include "fec.h"
  22 #include "fd.h"
  23
  24 /**
  25  * How many FEC groups to store in memory.
  26  *
  27  * Packet reordering requires to keep more than one FEC group in memory because
  28  * slices belonging to the next FEC group may arrive before the current FEC group
  29  * is complete.
  30  */
  31 #define NUM_FEC_GROUPS 3
  32
  33 /** Data read from the header of a slice. */
  34 struct fec_header {
  35         /** Total number of slices in this group. */
  36         uint8_t slices_per_group;
  37         /** Number of slices needed to start decoding. */
  38         uint8_t data_slices_per_group;
  39         /** Size of the ogg vorbis/wma header (zero for mp3, aac). */
  40         uint32_t audio_header_size;
  41         /** Number of the FEC group this slice belongs to. */
  42         uint32_t group_num;
  43         /** Size of the data in this FEC group. */
  44         uint32_t group_bytes;
  45         /** Number of this slice in the group. */
  46         uint8_t slice_num;
  47         /** Used data bytes of this slice. */
  48         uint16_t slice_bytes;
  49         /** Non-zero if this group is the beginning of the stream. */
  50         uint8_t bos;
  51         /** Non-zero if this stream embedds audio headers into fec groups. */
  52         uint8_t header_stream;
  53 };
  54
  55 /**
  56  * The status of one partially received FEC group.
  57  */
  58 struct fecdec_group {
  59         /** The header read from the last slice. */
  60         struct fec_header h;
  61         /** How many slices received so far. */
  62         int num_received_slices;
  63         /** Bitmap of received slices. */
  64         uint8_t received_slices[32];
  65         /** The size of the \a idx and the \a data arrays below. */
  66         int num_slices;
  67         /** Array of indices of the received slices. */
  68         int *idx;
  69         /** Content of the received slices. */
  70         unsigned char **data;
  71 };
  72
  73 /**
  74  * Data private to the fecdec filter.
  75  */
  76 struct private_fecdec_data {
  77         /** Used by the fec core code. */
  78         struct fec_parms *fec;
  79         /** Keeps track of what was received so far. */
  80         struct fecdec_group groups[NUM_FEC_GROUPS];
  81         /** Whether an audio file header was already received. */
  82         int have_header;
  83         /** Points to the first received group. */
  84         struct fecdec_group *first_complete_group;
  85         struct btr_pool *btrp;
  86 };
  87
  88 /** Iterate over all fecdec groups. */
  89 #define FOR_EACH_FECDEC_GROUP(g, d) for (g = (d)->groups; \
  90         (g) < (d)->groups + NUM_FEC_GROUPS; (g)++)
  91
  92 static int group_complete(struct fecdec_group *fg)
  93 {
  94         return fg->num_received_slices >= fg->h.data_slices_per_group;
  95 }
  96
  97 static int group_empty(struct fecdec_group *fg)
  98 {
  99         return fg->num_received_slices == 0;
 100 }
 101
 102 static void clear_group(struct fecdec_group *fg)
 103 {
 104         int i;
 105
 106         for (i = 0; i < fg->num_slices; i++)
 107                 free(fg->data[i]);
 108         free(fg->data);
 109         free(fg->idx);
 110         memset(fg, 0, sizeof(*fg));
 111 }
 112
 113 static int find_group(struct fec_header *h,
 114                 struct private_fecdec_data *pfd, struct fecdec_group **result)
 115 {
 116         struct fecdec_group *fg;
 117
 118         FOR_EACH_FECDEC_GROUP(fg, pfd) {
 119                 if (fg->h.group_num != h->group_num)
 120                         continue;
 121                 if (fg->num_received_slices == 0)
 122                         goto success;
 123                 if (fg->h.slices_per_group != h->slices_per_group)
 124                         return -E_BAD_FEC_HEADER;
 125                 if (fg->h.data_slices_per_group != h->data_slices_per_group)
 126                         return -E_BAD_FEC_HEADER;
 127                 if (fg->h.group_bytes != h->group_bytes)
 128                         return -E_BAD_FEC_HEADER;
 129 success:
 130                 *result = fg;
 131                 return 1;
 132         }
 133         return 0;
 134 }
 135
 136 static struct fecdec_group *find_unused_group(struct private_fecdec_data *pfd)
 137 {
 138         struct fecdec_group *fg;
 139
 140         FOR_EACH_FECDEC_GROUP(fg, pfd) {
 141                 if (fg->num_received_slices == 0)
 142                         return fg;
 143         }
 144         return NULL;
 145 }
 146
 147 static struct fecdec_group *try_to_free_group(struct private_fecdec_data *pfd)
 148 {
 149         struct fecdec_group *fg;
 150
 151         FOR_EACH_FECDEC_GROUP(fg, pfd) {
 152                 if (!group_complete(fg))
 153                         continue;
 154                 /*
 155                  * Don't clear the first complete group if it has not yet been
 156                  * decoded.
 157                  */
 158                 if (fg == pfd->first_complete_group)
 159                         continue;
 160                 clear_group(fg);
 161                 return fg;
 162         }
 163         return NULL;
 164 }
 165
 166 static struct fecdec_group *free_oldest_group(struct private_fecdec_data *pfd)
 167 {
 168         struct fecdec_group *fg, *oldest = NULL;
 169
 170         FOR_EACH_FECDEC_GROUP(fg, pfd) {
 171                 if (!oldest || oldest->h.group_num > fg->h.group_num)
 172                         oldest = fg;
 173         }
 174         if (!group_complete(oldest) && !group_empty(oldest))
 175                 PARA_WARNING_LOG("Clearing incomplete group %d "
 176                         "(contains %d slices)\n", oldest->h.group_num,
 177                         oldest->num_received_slices);
 178         if (oldest == pfd->first_complete_group)
 179                 pfd->first_complete_group = NULL;
 180         clear_group(oldest);
 181         return oldest;
 182 }
 183
 184 /* returns 1 if the group was found, 0 if not, negative on errors */
 185 static int get_group(struct fec_header *h, struct private_fecdec_data *pfd,
 186                 struct fecdec_group **result)
 187 {
 188         struct fecdec_group *fg;
 189         int ret = find_group(h, pfd, &fg);
 190
 191         if (ret < 0)
 192                 return ret;
 193         if (ret > 0) /* found group */
 194                 goto success;
 195         /* group not found */
 196         fg = find_unused_group(pfd);
 197         if (fg)
 198                 goto success;
 199         fg = try_to_free_group(pfd);
 200         if (fg)
 201                 goto success;
 202         fg = free_oldest_group(pfd);
 203         ret = 0;
 204 success:
 205         fg->h = *h;
 206         *result = fg;
 207         return ret;
 208 }
 209
 210 static bool test_and_set_slice_bit(struct fecdec_group *fg, uint8_t slice_num)
 211 {
 212         uint8_t *p = fg->received_slices + slice_num / 8, old = *p;
 213
 214         *p |= 1 << (slice_num % 8);
 215         return old == *p;
 216 }
 217
 218 /*
 219  * returns 1 if slice was added, zero otherwise (because the group was already
 220  * complete or a slice has been received twice).
 221  */
 222 static int add_slice(char *buf, struct fecdec_group *fg)
 223 {
 224         int r;
 225         uint8_t slice_num = fg->h.slice_num;
 226
 227         if (group_complete(fg)) {
 228                 PARA_DEBUG_LOG("group %d complete, ignoring slice %d\n",
 229                         fg->h.group_num, slice_num);
 230                 return 0;
 231         }
 232         if (fg->num_slices == 0) {
 233                 fg->num_slices = fg->h.slices_per_group;
 234                 fg->idx = para_malloc(fg->num_slices * sizeof(int));
 235                 fg->data = para_calloc(fg->num_slices * sizeof(unsigned char *));
 236         }
 237         r = fg->num_received_slices;
 238         /* Check if we already have this slice. */
 239         if (test_and_set_slice_bit(fg, slice_num)) {
 240                 PARA_INFO_LOG("ignoring duplicate slice %d:%d\n", fg->h.group_num,
 241                         slice_num);
 242                 return 0;
 243         }
 244         fg->idx[r] = slice_num;
 245         fg->data[r] = para_malloc(fg->h.slice_bytes);
 246         memcpy(fg->data[r], buf, fg->h.slice_bytes);
 247         fg->num_received_slices++;
 248         return 1;
 249 }
 250
 251 /**
 252  * The different states of a complete FEC group.
 253  *
 254  * Even if a FEC group has been received successfully, it probably can not be
 255  * used right away because some streams (ogg, wma) need to receive an audio
 256  * file header before decoding can start.
 257  */
 258 enum fec_group_usability {
 259         /** Drop the group (because we did not receive the header yet). */
 260         FEC_GROUP_UNUSABLE,
 261         /** Use all data in the group. */
 262         FEC_GROUP_USABLE,
 263         /** Use the group, but drop its audio file header. */
 264         FEC_GROUP_USABLE_SKIP_HEADER,
 265         /** Use the group, including its header. */
 266         FEC_GROUP_USABLE_WITH_HEADER
 267 };
 268
 269 static enum fec_group_usability group_is_usable(struct fecdec_group *fg,
 270                 struct private_fecdec_data *pfd)
 271 {
 272         struct fec_header *h = &fg->h;
 273
 274         if (!h->header_stream)
 275                 return FEC_GROUP_USABLE;
 276         if (pfd->have_header) {
 277                 if (h->audio_header_size)
 278                         return FEC_GROUP_USABLE_SKIP_HEADER;
 279                 return FEC_GROUP_USABLE;
 280         }
 281         if (fg->h.bos)
 282                 return FEC_GROUP_USABLE;
 283         if (fg->h.audio_header_size)
 284                 return FEC_GROUP_USABLE_WITH_HEADER;
 285         return FEC_GROUP_UNUSABLE;
 286 }
 287
 288 static int decode_group(struct fecdec_group *fg, struct filter_node *fn)
 289 {
 290         int i, ret, sb = fg->h.slice_bytes;
 291         size_t written, need;
 292         struct private_fecdec_data *pfd = fn->private_data;
 293         enum fec_group_usability u = group_is_usable(fg, pfd);
 294         char *buf = NULL, *p;
 295
 296         if (u == FEC_GROUP_UNUSABLE) {
 297                 PARA_INFO_LOG("dropping unusable group %d\n", fg->h.group_num);
 298                 return 0;
 299         }
 300         PARA_DEBUG_LOG("decoding group %d (%d slices)\n", fg->h.group_num,
 301                 fg->h.data_slices_per_group);
 302         ret = fec_decode(pfd->fec, fg->data, fg->idx, sb);
 303         if (ret < 0)
 304                 return ret;
 305         pfd->have_header = 1;
 306         i = 0;
 307         if (u == FEC_GROUP_USABLE_SKIP_HEADER) {
 308                 i = DIV_ROUND_UP(fg->h.audio_header_size, fg->h.slice_bytes);
 309                 PARA_DEBUG_LOG("skipping %d header slices\n", i);
 310         }
 311         PARA_DEBUG_LOG("writing group %d (%d/%d decoded data bytes)\n",
 312                 fg->h.group_num, fg->h.group_bytes,
 313                 fg->h.data_slices_per_group * sb);
 314         need = (fg->h.data_slices_per_group - i) * sb;
 315         if (need > btr_pool_unused(pfd->btrp))
 316                 return -E_FECDEC_OVERRUN;
 317         btr_pool_get_buffer(pfd->btrp, &buf);
 318         p = buf;
 319         if (u == FEC_GROUP_USABLE_WITH_HEADER) {
 320                 PARA_INFO_LOG("writing audio file header\n");
 321                 written = 0;
 322                 for (i = 0; i < fg->h.data_slices_per_group; i++) {
 323                         size_t n = sb;
 324                         if (written >= fg->h.audio_header_size)
 325                                 break;
 326                         if (sb + written > fg->h.audio_header_size)
 327                                 n = fg->h.audio_header_size - written;
 328                         btr_copy(fg->data[i], n, pfd->btrp, fn->btrn);
 329                         written += n;
 330                 }
 331                 p += written;
 332         }
 333         written = 0;
 334         for (; i < fg->h.data_slices_per_group; i++) {
 335                 size_t n = sb;
 336                 if (n + written > fg->h.group_bytes)
 337                         n = fg->h.group_bytes - written;
 338                 btr_copy(fg->data[i], n, pfd->btrp, fn->btrn);
 339                 written += n;
 340         }
 341         p += written;
 342         return 0;
 343 }
 344
 345 /**
 346  * Read a fec header from a buffer.
 347  *
 348  * \param buf The buffer to write to.
 349  * \param h The fec header to write.
 350  */
 351 static int read_fec_header(char *buf, size_t len, struct fec_header *h)
 352 {
 353         uint32_t magic;
 354
 355         if (len < FEC_HEADER_SIZE)
 356                 return 0;
 357         magic = read_u32(buf);
 358         if (magic != FEC_MAGIC)
 359                 return -E_BAD_FEC_HEADER;
 360         h->slices_per_group = read_u8(buf + 4);
 361         h->data_slices_per_group = read_u8(buf + 5);
 362         h->audio_header_size = read_u32(buf + 6);
 363
 364         h->group_num = read_u32(buf + 10);
 365         h->group_bytes = read_u32(buf + 14);
 366
 367         h->slice_num = read_u8(buf + 18);
 368         h->slice_bytes = read_u16(buf + 20);
 369         h->bos = read_u8(buf + 22);
 370         h->header_stream = read_u8(buf + 23);
 371         if (!memcmp(buf, FEC_EOF_PACKET, FEC_EOF_PACKET_LEN))
 372                 return -E_FECDEC_EOF;
 373 //      PARA_DEBUG_LOG("group %u, slize %u, slices per group: %u\n",
 374 //              h->group_num, h->slice_num, h->slices_per_group);
 375         return 1;
 376 }
 377
 378 /* returns 1 if we used the buffer, 0 if we didn't, negative on errors */
 379 static int dispatch_slice(char *buf, size_t len, struct fec_header *h,
 380                 struct filter_node *fn)
 381 {
 382         struct fecdec_group *fg;
 383         int ret, k, n;
 384         struct private_fecdec_data *pfd = fn->private_data;
 385
 386         if (h->slice_bytes > len) { /* can not use the thing, try to read more */
 387                 fn->min_iqs = h->slice_bytes + FEC_HEADER_SIZE;
 388                 return 0;
 389         }
 390         ret = get_group(h, pfd, &fg);
 391         if (ret < 0)
 392                 return ret;
 393         if (!add_slice(buf, fg)) /* group already complete */
 394                 return 1;
 395         if (!group_complete(fg))
 396                 return 1;
 397         /* this slice completed the group */
 398         if (pfd->fec)
 399                 goto decode;
 400         /* it's either the first or the second complete group */
 401         if (!pfd->first_complete_group) { /* it's the first group */
 402                 enum fec_group_usability u = group_is_usable(fg, pfd);
 403                 assert(u != FEC_GROUP_USABLE_SKIP_HEADER);
 404                 if (u == FEC_GROUP_UNUSABLE) /* forget it */
 405                         return 1;
 406                 pfd->first_complete_group = fg; /* remember it */
 407                 return 1;
 408         }
 409         /* we have two complete groups, let's go */
 410         k = h->data_slices_per_group;
 411         n = h->slices_per_group;
 412         PARA_NOTICE_LOG("init fec (%d, %d)\n", k, n);
 413         ret = fec_new(k, n, &pfd->fec);
 414         if (ret < 0)
 415                 return ret;
 416         pfd->btrp = btr_pool_new("fecdec", 64 * 1024);
 417         /* decode and clear the first group */
 418         ret = decode_group(pfd->first_complete_group, fn);
 419         if (ret < 0)
 420                 return ret;
 421         clear_group(pfd->first_complete_group);
 422         pfd->first_complete_group = NULL;
 423 decode:
 424         ret = decode_group(fg, fn);
 425         if (ret < 0)
 426                 return ret;
 427         return 1;
 428 }
 429
 430 static void fecdec_close(struct filter_node *fn)
 431 {
 432         struct private_fecdec_data *pfd = fn->private_data;
 433         struct fecdec_group *fg;
 434
 435         FOR_EACH_FECDEC_GROUP(fg, pfd)
 436                 clear_group(fg);
 437         fec_free(pfd->fec);
 438         btr_pool_free(pfd->btrp);
 439         free(fn->private_data);
 440         fn->private_data = NULL;
 441 }
 442
 443 static void fecdec_post_select(__a_unused struct sched *s, struct task *t)
 444 {
 445         struct filter_node *fn = container_of(t, struct filter_node, task);
 446         struct btr_node *btrn = fn->btrn;
 447         int ret;
 448         struct fec_header h;
 449         char *buf;
 450         size_t len;
 451
 452 next_buffer:
 453         ret = btr_node_status(btrn, fn->min_iqs, BTR_NT_INTERNAL);
 454         if (ret <= 0)
 455                 goto out;
 456         btr_merge(btrn, fn->min_iqs);
 457         len = btr_next_buffer(btrn, &buf);
 458         ret = read_fec_header(buf, len, &h);
 459         if (ret <= 0)
 460                 goto out;
 461         ret = -E_BAD_SLICE_SIZE;
 462         if (!h.slice_bytes)
 463                 goto out;
 464         ret = -E_BAD_SLICE_NUM;
 465         if (h.slice_num > h.slices_per_group)
 466                 goto out;
 467         ret = dispatch_slice(buf + FEC_HEADER_SIZE, len - FEC_HEADER_SIZE,
 468                 &h, fn);
 469         //PARA_INFO_LOG("ret: %d, len: %d, slice_bytes: %d\n", ret, len, h.slice_bytes);
 470         if (ret <= 0)
 471                 goto out;
 472         btr_consume(btrn, FEC_HEADER_SIZE + h.slice_bytes);
 473         goto next_buffer;
 474 out:
 475         t->error = ret;
 476         if (ret < 0)
 477                 btr_remove_node(btrn);
 478 }
 479
 480 static void fecdec_open(struct filter_node *fn)
 481 {
 482         struct private_fecdec_data *pfd;
 483         pfd = para_calloc(sizeof(*pfd));
 484         fn->private_data = pfd;
 485         fn->min_iqs = FEC_HEADER_SIZE;
 486 }
 487
 488 /**
 489  * The init function of the fecdec filter.
 490  *
 491  * \param f Struct to initialize.
 492  */
 493 void fecdec_filter_init(struct filter *f)
 494 {
 495         f->close = fecdec_close;
 496         f->open = fecdec_open;
 497         f->pre_select = generic_filter_pre_select;
 498         f->post_select = fecdec_post_select;
 499 }