fecdec_filter.c

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