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 <regex.h>
  10
  11 #include <dirent.h>
  12 #include "para.h"
  13 #include "error.h"
  14 #include "list.h"
  15 #include "sched.h"
  16 #include "ggo.h"
  17 #include "filter.h"
  18 #include "string.h"
  19 #include "portable_io.h"
  20 #include "fec.h"
  21 #include "fd.h"
  22
  23 /**
  24  * How many FEC groups to store in memory.
  25  *
  26  * Packet reordering requires to keep more than one FEC group in memory because
  27  * slices belonging to the next FEC group may arrive before the current FEC group
  28  * is complete.
  29  */
  30 #define NUM_FEC_GROUPS 3
  31
  32 /** Default size of the output buffer of the fecdec filter. */
  33 #define FECDEC_DEFAULT_OUTBUF_SIZE (3 * 1024)
  34 /** Maximal size of the output buffer of the fecdec filter. */
  35 #define FECDEC_MAX_OUTBUF_SIZE (1024 * 1024)
  36
  37 /** Data read from the header of a slice. */
  38 struct fec_header {
  39         /** Total number of slices in this group. */
  40         uint8_t slices_per_group;
  41         /** Number of slices needed to start decoding. */
  42         uint8_t data_slices_per_group;
  43         /** Size of the ogg vorbis header (zero for mp3, aac). */
  44         uint32_t audio_header_size;
  45         /** Number of the FEC group this slice belongs to. */
  46         uint32_t group_num;
  47         /** Size of the data in this FEC group. */
  48         uint32_t group_bytes;
  49         /** Number of this slice in the group. */
  50         uint8_t slice_num;
  51         /** Used data bytes of this slice. */
  52         uint16_t slice_bytes;
  53         /** Non-zero if this group is the beginning of the stream. */
  54         uint8_t bos;
  55         /** Non-zero if this stream embedds audio headers into fec groups. */
  56         uint8_t header_stream;
  57 };
  58
  59 /**
  60  * The status of one partially received FEC group.
  61  */
  62 struct fecdec_group {
  63         /** The header read from the last slice. */
  64         struct fec_header h;
  65         /** How many slices received so far. */
  66         int num_received_slices;
  67         /** The size of the \a idx and the \a data arrays below. */
  68         int num_slices;
  69         /** Array of indices of the received slices. */
  70         int *idx;
  71         /** Content of the received slices. */
  72         unsigned char **data;
  73 };
  74
  75 /**
  76  * The fecdec filter defers decoding of the first group until the first slice
  77  * of the next group was received. This avoids buffer underruns in subsequent
  78  * filters of the filter chain.
  79  */
  80 enum group_completion_status {
  81         /** No complete group received so far. */
  82         GCS_NO_COMPLETE_GROUP,
  83         /** First group received, but not yet decoded. */
  84         GCS_FIRST_GROUP_COMPLETE,
  85         /** At least one complete group decoded. */
  86         GCS_FIRST_GROUP_DECODED,
  87 };
  88
  89 /**
  90  * Data private to the fecdec filter.
  91  */
  92 struct private_fecdec_data {
  93         /** Used by the fec core code. */
  94         struct fec_parms *fec;
  95         /** Keeps track of what was received so far. */
  96         struct fecdec_group groups[NUM_FEC_GROUPS];
  97         /** Whether an audio file header was already received. */
  98         int have_header;
  99         /** See \ref group_completion_status. */
 100         unsigned completion_status;
 101         /** Points to the first received group. */
 102         struct fecdec_group *first_complete_group;
 103 };
 104
 105 /** Iterate over all fecdec groups. */
 106 #define FOR_EACH_FECDEC_GROUP(g, d) for (g = (d)->groups; \
 107         (g) - (d)->groups < NUM_FEC_GROUPS; (g)++)
 108
 109 static int group_complete(struct fecdec_group *fg)
 110 {
 111         return fg->num_received_slices >= fg->h.data_slices_per_group;
 112 }
 113
 114 static int group_empty(struct fecdec_group *fg)
 115 {
 116         return fg->num_received_slices == 0;
 117 }
 118
 119 static void clear_group(struct fecdec_group *fg)
 120 {
 121         int i;
 122
 123         for (i = 0; i < fg->num_slices; i++) {
 124                 free(fg->data[i]);
 125                 fg->data[i] = NULL;
 126                 fg->idx[i] = -1;
 127         }
 128         free(fg->data);
 129         free(fg->idx);
 130         fg->num_slices = 0;
 131         memset(&fg->h, 0, sizeof(struct fec_header));
 132         fg->num_received_slices = 0;
 133 }
 134
 135 static int find_group(struct fec_header *h,
 136                 struct private_fecdec_data *pfd, struct fecdec_group **result)
 137 {
 138         struct fecdec_group *fg;
 139
 140         FOR_EACH_FECDEC_GROUP(fg, pfd) {
 141                 if (fg->h.group_num != h->group_num)
 142                         continue;
 143                 if (fg->num_received_slices == 0)
 144                         goto success;
 145                 if (fg->h.slices_per_group != h->slices_per_group)
 146                         return -E_BAD_FEC_HEADER;
 147                 if (fg->h.data_slices_per_group != h->data_slices_per_group)
 148                         return -E_BAD_FEC_HEADER;
 149                 if (fg->h.group_bytes != h->group_bytes)
 150                         return -E_BAD_FEC_HEADER;
 151 success:
 152                 *result = fg;
 153                 return 1;
 154         }
 155         return 0;
 156 }
 157
 158 static struct fecdec_group *find_unused_group(struct private_fecdec_data *pfd)
 159 {
 160         struct fecdec_group *fg;
 161
 162         FOR_EACH_FECDEC_GROUP(fg, pfd) {
 163                 if (fg->num_received_slices == 0)
 164                         return fg;
 165         }
 166         return NULL;
 167 }
 168
 169 static struct fecdec_group *try_to_free_group(struct private_fecdec_data *pfd)
 170 {
 171         struct fecdec_group *fg;
 172
 173         FOR_EACH_FECDEC_GROUP(fg, pfd) {
 174                 if (!group_complete(fg))
 175                         continue;
 176                 /*
 177                  * Don't clear the first complete group if it has not yet been
 178                  * decoded.
 179                  */
 180                 if (pfd->completion_status == GCS_FIRST_GROUP_COMPLETE
 181                                 && pfd->first_complete_group == fg)
 182                         continue;
 183                 clear_group(fg);
 184                 return fg;
 185         }
 186         return NULL;
 187 }
 188
 189 static struct fecdec_group *free_oldest_group(struct private_fecdec_data *pfd)
 190 {
 191         struct fecdec_group *fg, *oldest = NULL;
 192
 193         FOR_EACH_FECDEC_GROUP(fg, pfd) {
 194                 if (!oldest || oldest->h.group_num > fg->h.group_num)
 195                         oldest = fg;
 196         }
 197         if (!group_complete(oldest) && !group_empty(oldest))
 198                 PARA_WARNING_LOG("Clearing incomplete group %d "
 199                         "(contains %d slices)\n", oldest->h.group_num,
 200                         oldest->num_received_slices);
 201         assert(pfd->completion_status != GCS_FIRST_GROUP_COMPLETE
 202                 || oldest != pfd->first_complete_group);
 203         clear_group(oldest);
 204         return oldest;
 205 }
 206
 207 /* returns 1 if the group was found, 0 if not, negative on errors */
 208 static int get_group(struct fec_header *h, struct private_fecdec_data *pfd,
 209                 struct fecdec_group **result)
 210 {
 211         struct fecdec_group *fg;
 212         int ret = find_group(h, pfd, &fg);
 213
 214         if (ret < 0)
 215                 return ret;
 216         if (ret > 0) /* found group */
 217                 goto success;
 218         /* group not found */
 219         fg = find_unused_group(pfd);
 220         if (fg)
 221                 goto success;
 222         fg = try_to_free_group(pfd);
 223         if (fg)
 224                 goto success;
 225         fg = free_oldest_group(pfd);
 226         ret = 0;
 227 success:
 228         fg->h = *h;
 229         *result = fg;
 230         return ret;
 231 }
 232
 233 /*
 234  * returns 1 if slice was added, zero otherwise (because the group was already
 235  * complete). In any case the number of received slices is being increased by
 236  * one.
 237  */
 238 static int add_slice(char *buf, struct fecdec_group *fg)
 239 {
 240         int r, slice_num;
 241
 242         if (group_complete(fg)) {
 243                 PARA_DEBUG_LOG("group %d complete, ignoring slice %d\n",
 244                         fg->h.group_num, fg->h.slice_num);
 245                 fg->num_received_slices++;
 246                 return 0;
 247         }
 248         slice_num = fg->h.slice_num;
 249         if (fg->num_slices == 0) {
 250                 fg->num_slices = fg->h.slices_per_group;
 251                 fg->idx = malloc(fg->num_slices * sizeof(int));
 252                 fg->data = malloc(fg->num_slices * sizeof(unsigned char *));
 253                 memset(fg->data, 0, fg->num_slices * sizeof(unsigned char *));
 254         }
 255         r = fg->num_received_slices;
 256         fg->idx[r] = slice_num;
 257         fg->data[r] = malloc(fg->h.slice_bytes);
 258         memcpy(fg->data[r], buf, fg->h.slice_bytes);
 259         fg->num_received_slices++;
 260         return 1;
 261 }
 262
 263 enum fec_group_usability {
 264         FEC_GROUP_UNUSABLE,
 265         FEC_GROUP_USABLE,
 266         FEC_GROUP_USABLE_SKIP_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;
 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 = 0, need;
 292         struct private_fecdec_data *pfd = fn->private_data;
 293         enum fec_group_usability u = group_is_usable(fg, pfd);
 294
 295         if (u == FEC_GROUP_UNUSABLE) {
 296                 PARA_INFO_LOG("dropping unusable group %d\n", fg->h.group_num);
 297                 return 0;
 298         }
 299         PARA_DEBUG_LOG("decoding group %d (%d slices)\n", fg->h.group_num,
 300                 fg->h.data_slices_per_group);
 301         ret = fec_decode(pfd->fec, fg->data, fg->idx, sb);
 302         if (ret < 0)
 303                 return ret;
 304         pfd->have_header = 1;
 305         i = 0;
 306         if (u == FEC_GROUP_USABLE_SKIP_HEADER) {
 307                 i = ROUND_UP(fg->h.audio_header_size, fg->h.slice_bytes)
 308                         / 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 = fn->loaded + (fg->h.data_slices_per_group - i)* sb;
 315         if (need > fn->bufsize) {
 316                 fn->bufsize = PARA_MAX(fn->bufsize * 2, need);
 317                 if (fn->bufsize > FECDEC_MAX_OUTBUF_SIZE)
 318                         return -E_FECDEC_OVERRUN;
 319                 PARA_INFO_LOG("increasing fec buf to %zu\n", fn->bufsize);
 320                 fn->buf = para_realloc(fn->buf, fn->bufsize);
 321         }
 322         for (; i < fg->h.data_slices_per_group; i++) {
 323                 size_t n = sb;
 324                 if (n + written > fg->h.group_bytes)
 325                         n = fg->h.group_bytes - written;
 326                 memcpy(fn->buf + fn->loaded, fg->data[i], n);
 327                 fn->loaded += n;
 328                 written += n;
 329         }
 330         return 0;
 331 }
 332
 333 /**
 334  * Read a fec header from a buffer.
 335  *
 336  * \param buf The buffer to write to.
 337  * \param h The fec header to write.
 338  */
 339 static int read_fec_header(char *buf, size_t len, struct fec_header *h)
 340 {
 341         uint32_t magic;
 342
 343         if (len < FEC_HEADER_SIZE)
 344                 return 0;
 345         magic = read_u32(buf);
 346         if (magic != FEC_MAGIC)
 347                 return -E_BAD_FEC_HEADER;
 348         h->slices_per_group = read_u8(buf + 4);
 349         h->data_slices_per_group = read_u8(buf + 5);
 350         h->audio_header_size = read_u32(buf + 6);
 351
 352         h->group_num = read_u32(buf + 10);
 353         h->group_bytes = read_u32(buf + 14);
 354
 355         h->slice_num = read_u8(buf + 18);
 356         h->slice_bytes = read_u16(buf + 20);
 357         h->bos = read_u8(buf + 22);
 358         h->header_stream = read_u8(buf + 23);
 359         if (!memcmp(buf, FEC_EOF_PACKET, FEC_EOF_PACKET_LEN))
 360                 return -E_FECDEC_EOF;
 361 //      PARA_DEBUG_LOG("group %u, slize %u, slices per group: %u\n",
 362 //              h->group_num, h->slice_num, h->slices_per_group);
 363         return 1;
 364 }
 365
 366 /* returns 1 if we used the buffer, 0 if we didn't, negative on errors */
 367 static int dispatch_slice(char *buf, size_t len, struct fec_header *h,
 368                 struct filter_node *fn)
 369 {
 370         struct fecdec_group *fg;
 371         int ret, k, n;
 372         struct private_fecdec_data *pfd = fn->private_data;
 373
 374         if (h->slice_bytes > len) /* can not use the thing, try to read more */
 375                 return 0;
 376         ret = get_group(h, pfd, &fg);
 377         if (ret < 0)
 378                 return ret;
 379         if (!add_slice(buf, fg))
 380                 return 1;
 381         if (group_complete(fg)) {
 382                 if (pfd->completion_status == GCS_NO_COMPLETE_GROUP) {
 383                         pfd->completion_status = GCS_FIRST_GROUP_COMPLETE;
 384                         pfd->first_complete_group = fg;
 385                         return 1;
 386                 }
 387                 assert(pfd->fec);
 388                 ret = decode_group(fg, fn);
 389                 if (ret < 0)
 390                         return ret;
 391                 return 1;
 392         }
 393         if (pfd->completion_status == GCS_NO_COMPLETE_GROUP)
 394                 return 1;
 395         if (pfd->completion_status == GCS_FIRST_GROUP_DECODED)
 396                 return 1;
 397         if (fg == pfd->first_complete_group)
 398                 return 1;
 399         assert(!pfd->fec);
 400         k = h->data_slices_per_group;
 401         n = h->slices_per_group;
 402         PARA_NOTICE_LOG("init fec (%d, %d)\n", k, n);
 403         ret = fec_new(k, n, &pfd->fec);
 404         if (ret < 0)
 405                 return ret;
 406         ret = decode_group(pfd->first_complete_group, fn);
 407         if (ret < 0)
 408                 return ret;
 409         pfd->completion_status = GCS_FIRST_GROUP_DECODED;
 410         return 1;
 411 }
 412
 413 static ssize_t fecdec(char *buf, size_t len, struct filter_node *fn)
 414 {
 415         int ret;
 416         struct fec_header h;
 417
 418         ret = read_fec_header(buf, len, &h);
 419         if (ret <= 0)
 420                 return ret;
 421         if (!h.slice_bytes)
 422                 return -E_BAD_SLICE_SIZE;
 423         if (h.slice_num > h.slices_per_group)
 424                 return -E_BAD_SLICE_NUM;
 425         ret = dispatch_slice(buf + FEC_HEADER_SIZE, len - FEC_HEADER_SIZE,
 426                 &h, fn);
 427         //PARA_INFO_LOG("ret: %d, len: %d, slice_bytes: %d\n", ret, len, h.slice_bytes);
 428         if (ret <= 0)
 429                 return ret;
 430         return FEC_HEADER_SIZE + h.slice_bytes;
 431 }
 432
 433 static void fecdec_close(struct filter_node *fn)
 434 {
 435         struct private_fecdec_data *pfd = fn->private_data;
 436         struct fecdec_group *fg;
 437
 438         FOR_EACH_FECDEC_GROUP(fg, pfd)
 439                 clear_group(fg);
 440         free(fn->buf);
 441         fn->buf = NULL;
 442         fec_free(pfd->fec);
 443         free(fn->private_data);
 444         fn->private_data = NULL;
 445 }
 446
 447 static void fecdec_open(struct filter_node *fn)
 448 {
 449         struct private_fecdec_data *pfd;
 450         fn->bufsize = FECDEC_DEFAULT_OUTBUF_SIZE;
 451         fn->buf = para_malloc(fn->bufsize);
 452         pfd = para_calloc(sizeof(*pfd));
 453         pfd->completion_status = GCS_NO_COMPLETE_GROUP;
 454         fn->private_data = pfd;
 455         fn->loaded = 0;
 456 }
 457
 458 /**
 459  * The init function of the fecdec filter.
 460  *
 461  * \param f struct to initialize.
 462  */
 463 void fecdec_filter_init(struct filter *f)
 464 {
 465         f->convert = fecdec;
 466         f->close = fecdec_close;
 467         f->open = fecdec_open;
 468 }