Add some missing FEC documentation.
[paraslash.git] / 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 * Data private to the fecdec filter.
77 */
78 struct private_fecdec_data {
79 /** Used by the fec core code. */
80 struct fec_parms *fec;
81 /** Keeps track of what was received so far. */
82 struct fecdec_group groups[NUM_FEC_GROUPS];
83 /** Whether an audio file header was already received. */
84 int have_header;
85 /** Points to the first received group. */
86 struct fecdec_group *first_complete_group;
87 };
88
89 /** Iterate over all fecdec groups. */
90 #define FOR_EACH_FECDEC_GROUP(g, d) for (g = (d)->groups; \
91 (g) < (d)->groups + NUM_FEC_GROUPS; (g)++)
92
93 static int group_complete(struct fecdec_group *fg)
94 {
95 return fg->num_received_slices >= fg->h.data_slices_per_group;
96 }
97
98 static int group_empty(struct fecdec_group *fg)
99 {
100 return fg->num_received_slices == 0;
101 }
102
103 static void clear_group(struct fecdec_group *fg)
104 {
105 int i;
106
107 for (i = 0; i < fg->num_slices; i++) {
108 free(fg->data[i]);
109 fg->data[i] = NULL;
110 fg->idx[i] = -1;
111 }
112 free(fg->data);
113 fg->data = NULL;
114 free(fg->idx);
115 fg->idx = NULL;
116 fg->num_slices = 0;
117 memset(&fg->h, 0, sizeof(struct fec_header));
118 fg->num_received_slices = 0;
119 }
120
121 static int find_group(struct fec_header *h,
122 struct private_fecdec_data *pfd, struct fecdec_group **result)
123 {
124 struct fecdec_group *fg;
125
126 FOR_EACH_FECDEC_GROUP(fg, pfd) {
127 if (fg->h.group_num != h->group_num)
128 continue;
129 if (fg->num_received_slices == 0)
130 goto success;
131 if (fg->h.slices_per_group != h->slices_per_group)
132 return -E_BAD_FEC_HEADER;
133 if (fg->h.data_slices_per_group != h->data_slices_per_group)
134 return -E_BAD_FEC_HEADER;
135 if (fg->h.group_bytes != h->group_bytes)
136 return -E_BAD_FEC_HEADER;
137 success:
138 *result = fg;
139 return 1;
140 }
141 return 0;
142 }
143
144 static struct fecdec_group *find_unused_group(struct private_fecdec_data *pfd)
145 {
146 struct fecdec_group *fg;
147
148 FOR_EACH_FECDEC_GROUP(fg, pfd) {
149 if (fg->num_received_slices == 0)
150 return fg;
151 }
152 return NULL;
153 }
154
155 static struct fecdec_group *try_to_free_group(struct private_fecdec_data *pfd)
156 {
157 struct fecdec_group *fg;
158
159 FOR_EACH_FECDEC_GROUP(fg, pfd) {
160 if (!group_complete(fg))
161 continue;
162 /*
163 * Don't clear the first complete group if it has not yet been
164 * decoded.
165 */
166 if (fg == pfd->first_complete_group)
167 continue;
168 clear_group(fg);
169 return fg;
170 }
171 return NULL;
172 }
173
174 static struct fecdec_group *free_oldest_group(struct private_fecdec_data *pfd)
175 {
176 struct fecdec_group *fg, *oldest = NULL;
177
178 FOR_EACH_FECDEC_GROUP(fg, pfd) {
179 if (!oldest || oldest->h.group_num > fg->h.group_num)
180 oldest = fg;
181 }
182 if (!group_complete(oldest) && !group_empty(oldest))
183 PARA_WARNING_LOG("Clearing incomplete group %d "
184 "(contains %d slices)\n", oldest->h.group_num,
185 oldest->num_received_slices);
186 if (oldest == pfd->first_complete_group)
187 pfd->first_complete_group = NULL;
188 clear_group(oldest);
189 return oldest;
190 }
191
192 /* returns 1 if the group was found, 0 if not, negative on errors */
193 static int get_group(struct fec_header *h, struct private_fecdec_data *pfd,
194 struct fecdec_group **result)
195 {
196 struct fecdec_group *fg;
197 int ret = find_group(h, pfd, &fg);
198
199 if (ret < 0)
200 return ret;
201 if (ret > 0) /* found group */
202 goto success;
203 /* group not found */
204 fg = find_unused_group(pfd);
205 if (fg)
206 goto success;
207 fg = try_to_free_group(pfd);
208 if (fg)
209 goto success;
210 fg = free_oldest_group(pfd);
211 ret = 0;
212 success:
213 fg->h = *h;
214 *result = fg;
215 return ret;
216 }
217
218 /*
219 * returns 1 if slice was added, zero otherwise (because the group was already
220 * complete). In any case the number of received slices is being increased by
221 * one.
222 */
223 static int add_slice(char *buf, struct fecdec_group *fg)
224 {
225 int r, slice_num;
226
227 if (group_complete(fg)) {
228 PARA_DEBUG_LOG("group %d complete, ignoring slice %d\n",
229 fg->h.group_num, fg->h.slice_num);
230 fg->num_received_slices++;
231 return 0;
232 }
233 slice_num = fg->h.slice_num;
234 if (fg->num_slices == 0) {
235 fg->num_slices = fg->h.slices_per_group;
236 fg->idx = para_malloc(fg->num_slices * sizeof(int));
237 fg->data = para_malloc(fg->num_slices * sizeof(unsigned char *));
238 memset(fg->data, 0, fg->num_slices * sizeof(unsigned char *));
239 }
240 r = fg->num_received_slices;
241 fg->idx[r] = slice_num;
242 fg->data[r] = para_malloc(fg->h.slice_bytes);
243 memcpy(fg->data[r], buf, fg->h.slice_bytes);
244 fg->num_received_slices++;
245 return 1;
246 }
247
248 /**
249 * The different states of a complete FEC group.
250 *
251 * Even if a FEC group has been received successfully, it probably can not be
252 * used right away because some streams (ogg, wma) need to receive an audio
253 * file header before decoding can start.
254 */
255 enum fec_group_usability {
256 /** Drop the group (because we did not receive the header yet). */
257 FEC_GROUP_UNUSABLE,
258 /** Use all data in the group. */
259 FEC_GROUP_USABLE,
260 /** Use the group, but drop its audio file header. */
261 FEC_GROUP_USABLE_SKIP_HEADER,
262 /** Use the group, including its header. */
263 FEC_GROUP_USABLE_WITH_HEADER
264 };
265
266 static enum fec_group_usability group_is_usable(struct fecdec_group *fg,
267 struct private_fecdec_data *pfd)
268 {
269 struct fec_header *h = &fg->h;
270
271 if (!h->header_stream)
272 return FEC_GROUP_USABLE;
273 if (pfd->have_header) {
274 if (h->audio_header_size)
275 return FEC_GROUP_USABLE_SKIP_HEADER;
276 return FEC_GROUP_USABLE;
277 }
278 if (fg->h.bos)
279 return FEC_GROUP_USABLE;
280 if (fg->h.audio_header_size)
281 return FEC_GROUP_USABLE_WITH_HEADER;
282 return FEC_GROUP_UNUSABLE;
283 }
284
285 static int decode_group(struct fecdec_group *fg, struct filter_node *fn)
286 {
287 int i, ret, sb = fg->h.slice_bytes;
288 size_t written, need;
289 struct private_fecdec_data *pfd = fn->private_data;
290 enum fec_group_usability u = group_is_usable(fg, pfd);
291
292 if (u == FEC_GROUP_UNUSABLE) {
293 PARA_INFO_LOG("dropping unusable group %d\n", fg->h.group_num);
294 return 0;
295 }
296 PARA_DEBUG_LOG("decoding group %d (%d slices)\n", fg->h.group_num,
297 fg->h.data_slices_per_group);
298 ret = fec_decode(pfd->fec, fg->data, fg->idx, sb);
299 if (ret < 0)
300 return ret;
301 pfd->have_header = 1;
302 i = 0;
303 if (u == FEC_GROUP_USABLE_SKIP_HEADER) {
304 i = ROUND_UP(fg->h.audio_header_size, fg->h.slice_bytes)
305 / fg->h.slice_bytes;
306 PARA_DEBUG_LOG("skipping %d header slices\n", i);
307 }
308 PARA_DEBUG_LOG("writing group %d (%d/%d decoded data bytes)\n",
309 fg->h.group_num, fg->h.group_bytes,
310 fg->h.data_slices_per_group * sb);
311 need = fn->loaded + (fg->h.data_slices_per_group - i)* sb;
312 if (need > fn->bufsize) {
313 fn->bufsize = PARA_MAX(fn->bufsize * 2, need);
314 if (fn->bufsize > FECDEC_MAX_OUTBUF_SIZE)
315 return -E_FECDEC_OVERRUN;
316 PARA_INFO_LOG("increasing fec buf to %zu\n", fn->bufsize);
317 fn->buf = para_realloc(fn->buf, fn->bufsize);
318 }
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 memcpy(fn->buf + fn->loaded, fg->data[i], n);
329 fn->loaded += n;
330 written += n;
331 }
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 memcpy(fn->buf + fn->loaded, fg->data[i], n);
339 fn->loaded += n;
340 written += n;
341 }
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 return 0;
388 ret = get_group(h, pfd, &fg);
389 if (ret < 0)
390 return ret;
391 if (!add_slice(buf, fg)) /* group already complete */
392 return 1;
393 if (!group_complete(fg))
394 return 1;
395 /* this slice completed the group */
396 if (pfd->fec)
397 goto decode;
398 /* it's either the first or the second complete group */
399 if (!pfd->first_complete_group) { /* it's the first group */
400 enum fec_group_usability u = group_is_usable(fg, pfd);
401 assert(u != FEC_GROUP_USABLE_SKIP_HEADER);
402 if (u == FEC_GROUP_UNUSABLE) /* forget it */
403 return 1;
404 pfd->first_complete_group = fg; /* remember it */
405 return 1;
406 }
407 /* we have two complete groups, let's go */
408 k = h->data_slices_per_group;
409 n = h->slices_per_group;
410 PARA_NOTICE_LOG("init fec (%d, %d)\n", k, n);
411 ret = fec_new(k, n, &pfd->fec);
412 if (ret < 0)
413 return ret;
414 /* decode and clear the first group */
415 ret = decode_group(pfd->first_complete_group, fn);
416 if (ret < 0)
417 return ret;
418 clear_group(pfd->first_complete_group);
419 pfd->first_complete_group = NULL;
420 decode:
421 ret = decode_group(fg, fn);
422 if (ret < 0)
423 return ret;
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 fn->private_data = pfd;
468 fn->loaded = 0;
469 }
470
471 /**
472 * The init function of the fecdec filter.
473 *
474 * \param f struct to initialize.
475 */
476 void fecdec_filter_init(struct filter *f)
477 {
478 f->convert = fecdec;
479 f->close = fecdec_close;
480 f->open = fecdec_open;
481 }