1 /* GStreamer
2 * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
3 * Copyright (C) 2000,2005 Wim Taymans <wim@fluendo.com>
4 * Copyright (C) 2006 Tim-Philipp Müller <tim centricular net>
5 *
6 * gsttypefindhelper.c:
7 *
8 * This library is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Library General Public
10 * License as published by the Free Software Foundation; either
11 * version 2 of the License, or (at your option) any later version.
12 *
13 * This library is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Library General Public License for more details.
17 *
18 * You should have received a copy of the GNU Library General Public
19 * License along with this library; if not, write to the
20 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
21 * Boston, MA 02110-1301, USA.
22 */
23
24 /**
25 * SECTION:gsttypefindhelper
26 * @title: GstTypeFindHelper
27 * @short_description: Utility functions for typefinding
28 *
29 * Utility functions for elements doing typefinding:
30 * gst_type_find_helper() does typefinding in pull mode, while
31 * gst_type_find_helper_for_buffer() is useful for elements needing to do
32 * typefinding in push mode from a chain function.
33 */
34
35 #ifdef HAVE_CONFIG_H
36 # include "config.h"
37 #endif
38
39 #include <stdlib.h>
40 #include <string.h>
41
42 #include "gsttypefindhelper.h"
43
44 /* ********************** typefinding in pull mode ************************ */
45
46 static void
47 helper_find_suggest (gpointer data, guint probability, GstCaps * caps);
48
49 typedef struct
50 {
51 GstBuffer *buffer;
52 GstMapInfo map;
53 } GstMappedBuffer;
54
55 typedef struct
56 {
57 GSList *buffers; /* buffer cache */
58 guint64 size;
59 guint64 last_offset;
60 GstTypeFindHelperGetRangeFunction func;
61 GstTypeFindProbability best_probability;
62 GstCaps *caps;
63 GstTypeFindFactory *factory; /* for logging */
64 GstObject *obj; /* for logging */
65 GstObject *parent;
66 GstFlowReturn flow_ret;
67 } GstTypeFindHelper;
68
69 /*
70 * helper_find_peek:
71 * @data: helper data struct
72 * @off: stream offset
73 * @size: block size
74 *
75 * Get data pointer within a stream. Keeps a cache of read buffers (partly
76 * for performance reasons, but mostly because pointers returned by us need
77 * to stay valid until typefinding has finished)
78 *
79 * Returns: (nullable): address of the data or %NULL if buffer does not cover
80 * the requested range.
81 */
82 static const guint8 *
helper_find_peek(gpointer data,gint64 offset,guint size)83 helper_find_peek (gpointer data, gint64 offset, guint size)
84 {
85 GstTypeFindHelper *helper;
86 GstBuffer *buffer;
87 GSList *insert_pos = NULL;
88 gsize buf_size;
89 guint64 buf_offset;
90 GstMappedBuffer *bmap;
91 #if 0
92 GstCaps *caps;
93 #endif
94
95 helper = (GstTypeFindHelper *) data;
96
97 GST_LOG_OBJECT (helper->obj, "'%s' called peek (%" G_GINT64_FORMAT
98 ", %u)", GST_OBJECT_NAME (helper->factory), offset, size);
99
100 if (size == 0)
101 return NULL;
102
103 if (offset < 0) {
104 if (helper->size == -1 || helper->size < -offset)
105 return NULL;
106
107 offset += helper->size;
108 }
109
110 /* see if we have a matching buffer already in our list */
111 if (size > 0 && offset <= helper->last_offset) {
112 GSList *walk;
113
114 for (walk = helper->buffers; walk; walk = walk->next) {
115 GstMappedBuffer *bmp = (GstMappedBuffer *) walk->data;
116 GstBuffer *buf = GST_BUFFER_CAST (bmp->buffer);
117
118 buf_offset = GST_BUFFER_OFFSET (buf);
119 buf_size = bmp->map.size;
120
121 /* buffers are kept sorted by end offset (highest first) in the list, so
122 * at this point we save the current position and stop searching if
123 * we're after the searched end offset */
124 if (buf_offset <= offset) {
125 if ((offset + size) < (buf_offset + buf_size)) {
126 /* must already have been mapped before */
127 return (guint8 *) bmp->map.data + (offset - buf_offset);
128 }
129 } else if (offset + size >= buf_offset + buf_size) {
130 insert_pos = walk;
131 break;
132 }
133 }
134 }
135
136 buffer = NULL;
137 /* some typefinders go in 1 byte steps over 1k of data and request
138 * small buffers. It is really inefficient to pull each time, and pulling
139 * a larger chunk is almost free. Trying to pull a larger chunk at the end
140 * of the file is also not a problem here, we'll just get a truncated buffer
141 * in that case (and we'll have to double-check the size we actually get
142 * anyway, see below) */
143 helper->flow_ret =
144 helper->func (helper->obj, helper->parent, offset, MAX (size, 4096),
145 &buffer);
146
147 if (helper->flow_ret != GST_FLOW_OK)
148 goto error;
149
150 #if 0
151 caps = GST_BUFFER_CAPS (buffer);
152
153 if (caps && !gst_caps_is_empty (caps) && !gst_caps_is_any (caps)) {
154 GST_DEBUG ("buffer has caps %" GST_PTR_FORMAT ", suggest max probability",
155 caps);
156
157 gst_caps_replace (&helper->caps, caps);
158 helper->best_probability = GST_TYPE_FIND_MAXIMUM;
159
160 gst_buffer_unref (buffer);
161 return NULL;
162 }
163 #endif
164
165 /* getrange might silently return shortened buffers at the end of a file,
166 * we must, however, always return either the full requested data or %NULL */
167 buf_offset = GST_BUFFER_OFFSET (buffer);
168 buf_size = gst_buffer_get_size (buffer);
169
170 if (buf_size < size) {
171 GST_DEBUG ("dropping short buffer of size %" G_GSIZE_FORMAT ","
172 "requested size was %u", buf_size, size);
173 gst_buffer_unref (buffer);
174 return NULL;
175 }
176
177 if (buf_offset != -1 && buf_offset != offset) {
178 GST_DEBUG ("dropping buffer with unexpected offset %" G_GUINT64_FORMAT ", "
179 "expected offset was %" G_GUINT64_FORMAT, buf_offset, offset);
180 gst_buffer_unref (buffer);
181 return NULL;
182 }
183
184 bmap = g_slice_new0 (GstMappedBuffer);
185
186 if (!gst_buffer_map (buffer, &bmap->map, GST_MAP_READ))
187 goto map_failed;
188
189 bmap->buffer = buffer;
190
191 if (insert_pos) {
192 helper->buffers = g_slist_insert_before (helper->buffers, insert_pos, bmap);
193 } else {
194 /* if insert_pos is not set, our offset is bigger than the largest offset
195 * we have so far; since we keep the list sorted with highest offsets
196 * first, we need to prepend the buffer to the list */
197 helper->last_offset = GST_BUFFER_OFFSET (buffer) + buf_size;
198 helper->buffers = g_slist_prepend (helper->buffers, bmap);
199 }
200
201 return bmap->map.data;
202
203 error:
204 {
205 GST_INFO ("typefind function returned: %s",
206 gst_flow_get_name (helper->flow_ret));
207 return NULL;
208 }
209 map_failed:
210 {
211 GST_ERROR ("map failed");
212 gst_buffer_unref (buffer);
213 g_slice_free (GstMappedBuffer, bmap);
214 return NULL;
215 }
216 }
217
218 /*
219 * helper_find_suggest:
220 * @data: helper data struct
221 * @probability: probability of the match
222 * @caps: caps of the type
223 *
224 * If given @probability is higher, replace previously store caps.
225 */
226 static void
helper_find_suggest(gpointer data,guint probability,GstCaps * caps)227 helper_find_suggest (gpointer data, guint probability, GstCaps * caps)
228 {
229 GstTypeFindHelper *helper = (GstTypeFindHelper *) data;
230
231 GST_LOG_OBJECT (helper->obj,
232 "'%s' called suggest (%u, %" GST_PTR_FORMAT ")",
233 GST_OBJECT_NAME (helper->factory), probability, caps);
234
235 if (probability > helper->best_probability) {
236 gst_caps_replace (&helper->caps, caps);
237 helper->best_probability = probability;
238 }
239 }
240
241 static guint64
helper_find_get_length(gpointer data)242 helper_find_get_length (gpointer data)
243 {
244 GstTypeFindHelper *helper = (GstTypeFindHelper *) data;
245
246 GST_LOG_OBJECT (helper->obj, "'%s' called get_length, returning %"
247 G_GUINT64_FORMAT, GST_OBJECT_NAME (helper->factory), helper->size);
248
249 return helper->size;
250 }
251
252 static GList *
prioritize_extension(GstObject * obj,GList * type_list,const gchar * extension)253 prioritize_extension (GstObject * obj, GList * type_list,
254 const gchar * extension)
255 {
256 gint pos = 0;
257 GList *next, *l;
258
259 if (!extension)
260 return type_list;
261
262 /* move the typefinders for the extension first in the list. The idea is that
263 * when one of them returns MAX we don't need to search further as there is a
264 * very high chance we got the right type. */
265
266 GST_LOG_OBJECT (obj, "sorting typefind for extension %s to head", extension);
267
268 for (l = type_list; l; l = next) {
269 const gchar *const *ext;
270 GstTypeFindFactory *factory;
271
272 next = l->next;
273
274 factory = GST_TYPE_FIND_FACTORY (l->data);
275
276 ext = gst_type_find_factory_get_extensions (factory);
277 if (ext == NULL)
278 continue;
279
280 GST_LOG_OBJECT (obj, "testing factory %s for extension %s",
281 GST_OBJECT_NAME (factory), extension);
282
283 while (*ext != NULL) {
284 if (strcmp (*ext, extension) == 0) {
285 /* found extension, move in front */
286 GST_LOG_OBJECT (obj, "moving typefind for extension %s to head",
287 extension);
288 /* remove entry from list */
289 type_list = g_list_delete_link (type_list, l);
290 /* insert at the position */
291 type_list = g_list_insert (type_list, factory, pos);
292 /* next element will be inserted after this one */
293 pos++;
294 break;
295 }
296 ++ext;
297 }
298 }
299
300 return type_list;
301 }
302
303 /**
304 * gst_type_find_helper_get_range:
305 * @obj: A #GstObject that will be passed as first argument to @func
306 * @parent: (allow-none): the parent of @obj or %NULL
307 * @func: (scope call): A generic #GstTypeFindHelperGetRangeFunction that will
308 * be used to access data at random offsets when doing the typefinding
309 * @size: The length in bytes
310 * @extension: (allow-none): extension of the media, or %NULL
311 * @prob: (out) (allow-none): location to store the probability of the found
312 * caps, or %NULL
313 *
314 * Utility function to do pull-based typefinding. Unlike gst_type_find_helper()
315 * however, this function will use the specified function @func to obtain the
316 * data needed by the typefind functions, rather than operating on a given
317 * source pad. This is useful mostly for elements like tag demuxers which
318 * strip off data at the beginning and/or end of a file and want to typefind
319 * the stripped data stream before adding their own source pad (the specified
320 * callback can then call the upstream peer pad with offsets adjusted for the
321 * tag size, for example).
322 *
323 * When @extension is not %NULL, this function will first try the typefind
324 * functions for the given extension, which might speed up the typefinding
325 * in many cases.
326 *
327 * Free-function: gst_caps_unref
328 *
329 * Returns: (transfer full) (nullable): the #GstCaps corresponding to the data
330 * stream. Returns %NULL if no #GstCaps matches the data stream.
331 */
332 GstCaps *
gst_type_find_helper_get_range(GstObject * obj,GstObject * parent,GstTypeFindHelperGetRangeFunction func,guint64 size,const gchar * extension,GstTypeFindProbability * prob)333 gst_type_find_helper_get_range (GstObject * obj, GstObject * parent,
334 GstTypeFindHelperGetRangeFunction func, guint64 size,
335 const gchar * extension, GstTypeFindProbability * prob)
336 {
337 GstCaps *caps = NULL;
338
339 gst_type_find_helper_get_range_full (obj, parent, func, size, extension,
340 &caps, prob);
341
342 return caps;
343 }
344
345 /**
346 * gst_type_find_helper_get_range_full:
347 * @obj: A #GstObject that will be passed as first argument to @func
348 * @parent: (allow-none): the parent of @obj or %NULL
349 * @func: (scope call): A generic #GstTypeFindHelperGetRangeFunction that will
350 * be used to access data at random offsets when doing the typefinding
351 * @size: The length in bytes
352 * @extension: (allow-none): extension of the media, or %NULL
353 * @caps: (out) (transfer full): returned caps
354 * @prob: (out) (allow-none): location to store the probability of the found
355 * caps, or %NULL
356 *
357 * Utility function to do pull-based typefinding. Unlike gst_type_find_helper()
358 * however, this function will use the specified function @func to obtain the
359 * data needed by the typefind functions, rather than operating on a given
360 * source pad. This is useful mostly for elements like tag demuxers which
361 * strip off data at the beginning and/or end of a file and want to typefind
362 * the stripped data stream before adding their own source pad (the specified
363 * callback can then call the upstream peer pad with offsets adjusted for the
364 * tag size, for example).
365 *
366 * When @extension is not %NULL, this function will first try the typefind
367 * functions for the given extension, which might speed up the typefinding
368 * in many cases.
369 *
370 * Returns: the last %GstFlowReturn from pulling a buffer or %GST_FLOW_OK if
371 * typefinding was successful.
372 *
373 * Since: 1.14.3
374 */
375 GstFlowReturn
gst_type_find_helper_get_range_full(GstObject * obj,GstObject * parent,GstTypeFindHelperGetRangeFunction func,guint64 size,const gchar * extension,GstCaps ** caps,GstTypeFindProbability * prob)376 gst_type_find_helper_get_range_full (GstObject * obj, GstObject * parent,
377 GstTypeFindHelperGetRangeFunction func, guint64 size,
378 const gchar * extension, GstCaps ** caps, GstTypeFindProbability * prob)
379 {
380 GstTypeFindHelper helper;
381 GstTypeFind find;
382 GSList *walk;
383 GList *l, *type_list;
384 GstCaps *result = NULL;
385
386 g_return_val_if_fail (GST_IS_OBJECT (obj), GST_FLOW_ERROR);
387 g_return_val_if_fail (func != NULL, GST_FLOW_ERROR);
388 g_return_val_if_fail (caps != NULL, GST_FLOW_ERROR);
389
390 *caps = NULL;
391
392 helper.buffers = NULL;
393 helper.size = size;
394 helper.last_offset = 0;
395 helper.func = func;
396 helper.best_probability = GST_TYPE_FIND_NONE;
397 helper.caps = NULL;
398 helper.obj = obj;
399 helper.parent = parent;
400 helper.flow_ret = GST_FLOW_OK;
401
402 find.data = &helper;
403 find.peek = helper_find_peek;
404 find.suggest = helper_find_suggest;
405
406 if (size == 0 || size == (guint64) - 1) {
407 find.get_length = NULL;
408 } else {
409 find.get_length = helper_find_get_length;
410 }
411
412 type_list = gst_type_find_factory_get_list ();
413 type_list = prioritize_extension (obj, type_list, extension);
414
415 for (l = type_list; l; l = l->next) {
416 helper.factory = GST_TYPE_FIND_FACTORY (l->data);
417 gst_type_find_factory_call_function (helper.factory, &find);
418 if (helper.best_probability >= GST_TYPE_FIND_MAXIMUM) {
419 /* Any other flow return can be ignored here, we found
420 * something before any error with highest probability */
421 helper.flow_ret = GST_FLOW_OK;
422 break;
423 } else if (helper.flow_ret != GST_FLOW_OK
424 && helper.flow_ret != GST_FLOW_EOS) {
425 /* We had less than maximum probability and an error, don't return
426 * any caps as they might be with a lower probability than what
427 * we would've gotten when continuing if there was no error */
428 gst_caps_replace (&helper.caps, NULL);
429 break;
430 }
431 }
432 gst_plugin_feature_list_free (type_list);
433
434 for (walk = helper.buffers; walk; walk = walk->next) {
435 GstMappedBuffer *bmap = (GstMappedBuffer *) walk->data;
436
437 gst_buffer_unmap (bmap->buffer, &bmap->map);
438 gst_buffer_unref (bmap->buffer);
439 g_slice_free (GstMappedBuffer, bmap);
440 }
441 g_slist_free (helper.buffers);
442
443 if (helper.best_probability > 0)
444 result = helper.caps;
445
446 if (prob)
447 *prob = helper.best_probability;
448
449 *caps = result;
450 if (helper.flow_ret == GST_FLOW_EOS) {
451 /* Some typefinder might've tried to read too much, if we
452 * didn't get any meaningful caps because of that this is
453 * just a normal error */
454 helper.flow_ret = GST_FLOW_ERROR;
455 }
456
457 GST_LOG_OBJECT (obj, "Returning %" GST_PTR_FORMAT " (probability = %u)",
458 result, (guint) helper.best_probability);
459
460 return helper.flow_ret;
461 }
462
463 /**
464 * gst_type_find_helper:
465 * @src: A source #GstPad
466 * @size: The length in bytes
467 *
468 * Tries to find what type of data is flowing from the given source #GstPad.
469 *
470 * Free-function: gst_caps_unref
471 *
472 * Returns: (transfer full) (nullable): the #GstCaps corresponding to the data
473 * stream. Returns %NULL if no #GstCaps matches the data stream.
474 */
475
476 GstCaps *
gst_type_find_helper(GstPad * src,guint64 size)477 gst_type_find_helper (GstPad * src, guint64 size)
478 {
479 GstTypeFindHelperGetRangeFunction func;
480
481 g_return_val_if_fail (GST_IS_OBJECT (src), NULL);
482 g_return_val_if_fail (GST_PAD_GETRANGEFUNC (src) != NULL, NULL);
483
484 func = (GstTypeFindHelperGetRangeFunction) (GST_PAD_GETRANGEFUNC (src));
485
486 return gst_type_find_helper_get_range (GST_OBJECT (src),
487 GST_OBJECT_PARENT (src), func, size, NULL, NULL);
488 }
489
490 /* ********************** typefinding for buffers ************************* */
491
492 typedef struct
493 {
494 const guint8 *data; /* buffer data */
495 gsize size;
496 GstTypeFindProbability best_probability;
497 GstCaps *caps;
498 GstTypeFindFactory *factory; /* for logging */
499 GstObject *obj; /* for logging */
500 } GstTypeFindBufHelper;
501
502 /*
503 * buf_helper_find_peek:
504 * @data: helper data struct
505 * @off: stream offset
506 * @size: block size
507 *
508 * Get data pointer within a buffer.
509 *
510 * Returns: (nullable): address inside the buffer or %NULL if buffer does not
511 * cover the requested range.
512 */
513 static const guint8 *
buf_helper_find_peek(gpointer data,gint64 off,guint size)514 buf_helper_find_peek (gpointer data, gint64 off, guint size)
515 {
516 GstTypeFindBufHelper *helper;
517
518 helper = (GstTypeFindBufHelper *) data;
519 GST_LOG_OBJECT (helper->obj, "'%s' called peek (%" G_GINT64_FORMAT ", %u)",
520 GST_OBJECT_NAME (helper->factory), off, size);
521
522 if (size == 0)
523 return NULL;
524
525 if (off < 0) {
526 GST_LOG_OBJECT (helper->obj, "'%s' wanted to peek at end; not supported",
527 GST_OBJECT_NAME (helper->factory));
528 return NULL;
529 }
530
531 /* If we request beyond the available size, we're sure we can't return
532 * anything regardless of the requested offset */
533 if (size > helper->size)
534 return NULL;
535
536 /* Only return data if there's enough room left for the given offset.
537 * This is the same as "if (off + size <= helper->size)" except that
538 * it doesn't exceed type limits */
539 if (off <= helper->size - size)
540 return helper->data + off;
541
542 return NULL;
543 }
544
545 /*
546 * buf_helper_find_suggest:
547 * @data: helper data struct
548 * @probability: probability of the match
549 * @caps: caps of the type
550 *
551 * If given @probability is higher, replace previously store caps.
552 */
553 static void
buf_helper_find_suggest(gpointer data,guint probability,GstCaps * caps)554 buf_helper_find_suggest (gpointer data, guint probability, GstCaps * caps)
555 {
556 GstTypeFindBufHelper *helper = (GstTypeFindBufHelper *) data;
557
558 GST_LOG_OBJECT (helper->obj,
559 "'%s' called suggest (%u, %" GST_PTR_FORMAT ")",
560 GST_OBJECT_NAME (helper->factory), probability, caps);
561
562 /* Note: not >= as we call typefinders in order of rank, highest first */
563 if (probability > helper->best_probability) {
564 gst_caps_replace (&helper->caps, caps);
565 helper->best_probability = probability;
566 }
567 }
568
569 /**
570 * gst_type_find_helper_for_data:
571 * @obj: (allow-none): object doing the typefinding, or %NULL (used for logging)
572 * @data: (transfer none) (array length=size): * a pointer with data to typefind
573 * @size: the size of @data
574 * @prob: (out) (allow-none): location to store the probability of the found
575 * caps, or %NULL
576 *
577 * Tries to find what type of data is contained in the given @data, the
578 * assumption being that the data represents the beginning of the stream or
579 * file.
580 *
581 * All available typefinders will be called on the data in order of rank. If
582 * a typefinding function returns a probability of %GST_TYPE_FIND_MAXIMUM,
583 * typefinding is stopped immediately and the found caps will be returned
584 * right away. Otherwise, all available typefind functions will the tried,
585 * and the caps with the highest probability will be returned, or %NULL if
586 * the content of @data could not be identified.
587 *
588 * Free-function: gst_caps_unref
589 *
590 * Returns: (transfer full) (nullable): the #GstCaps corresponding to the data,
591 * or %NULL if no type could be found. The caller should free the caps
592 * returned with gst_caps_unref().
593 */
594 GstCaps *
gst_type_find_helper_for_data(GstObject * obj,const guint8 * data,gsize size,GstTypeFindProbability * prob)595 gst_type_find_helper_for_data (GstObject * obj, const guint8 * data, gsize size,
596 GstTypeFindProbability * prob)
597 {
598 return gst_type_find_helper_for_data_with_extension (obj, data, size, NULL,
599 prob);
600 }
601
602 /**
603 * gst_type_find_helper_for_data_with_extension:
604 * @obj: (allow-none): object doing the typefinding, or %NULL (used for logging)
605 * @data: (transfer none) (array length=size): * a pointer with data to typefind
606 * @size: the size of @data
607 * @extension: (allow-none): extension of the media, or %NULL
608 * @prob: (out) (allow-none): location to store the probability of the found
609 * caps, or %NULL
610 *
611 * Tries to find what type of data is contained in the given @data, the
612 * assumption being that the data represents the beginning of the stream or
613 * file.
614 *
615 * All available typefinders will be called on the data in order of rank. If
616 * a typefinding function returns a probability of %GST_TYPE_FIND_MAXIMUM,
617 * typefinding is stopped immediately and the found caps will be returned
618 * right away. Otherwise, all available typefind functions will the tried,
619 * and the caps with the highest probability will be returned, or %NULL if
620 * the content of @data could not be identified.
621 *
622 * When @extension is not %NULL, this function will first try the typefind
623 * functions for the given extension, which might speed up the typefinding
624 * in many cases.
625 *
626 * Free-function: gst_caps_unref
627 *
628 * Returns: (transfer full) (nullable): the #GstCaps corresponding to the data,
629 * or %NULL if no type could be found. The caller should free the caps
630 * returned with gst_caps_unref().
631 *
632 * Since: 1.16
633 *
634 */
635 GstCaps *
gst_type_find_helper_for_data_with_extension(GstObject * obj,const guint8 * data,gsize size,const gchar * extension,GstTypeFindProbability * prob)636 gst_type_find_helper_for_data_with_extension (GstObject * obj,
637 const guint8 * data, gsize size, const gchar * extension,
638 GstTypeFindProbability * prob)
639 {
640 GstTypeFindBufHelper helper;
641 GstTypeFind find;
642 GList *l, *type_list;
643 GstCaps *result = NULL;
644
645 g_return_val_if_fail (data != NULL, NULL);
646
647 helper.data = data;
648 helper.size = size;
649 helper.best_probability = GST_TYPE_FIND_NONE;
650 helper.caps = NULL;
651 helper.obj = obj;
652
653 if (helper.data == NULL || helper.size == 0)
654 return NULL;
655
656 find.data = &helper;
657 find.peek = buf_helper_find_peek;
658 find.suggest = buf_helper_find_suggest;
659 find.get_length = NULL;
660
661 type_list = gst_type_find_factory_get_list ();
662 type_list = prioritize_extension (obj, type_list, extension);
663
664 for (l = type_list; l; l = l->next) {
665 helper.factory = GST_TYPE_FIND_FACTORY (l->data);
666 gst_type_find_factory_call_function (helper.factory, &find);
667 if (helper.best_probability >= GST_TYPE_FIND_MAXIMUM)
668 break;
669 }
670 gst_plugin_feature_list_free (type_list);
671
672 if (helper.best_probability > 0)
673 result = helper.caps;
674
675 if (prob)
676 *prob = helper.best_probability;
677
678 GST_LOG_OBJECT (obj, "Returning %" GST_PTR_FORMAT " (probability = %u)",
679 result, (guint) helper.best_probability);
680
681 return result;
682 }
683
684 /**
685 * gst_type_find_helper_for_buffer:
686 * @obj: (allow-none): object doing the typefinding, or %NULL (used for logging)
687 * @buf: (in) (transfer none): a #GstBuffer with data to typefind
688 * @prob: (out) (allow-none): location to store the probability of the found
689 * caps, or %NULL
690 *
691 * Tries to find what type of data is contained in the given #GstBuffer, the
692 * assumption being that the buffer represents the beginning of the stream or
693 * file.
694 *
695 * All available typefinders will be called on the data in order of rank. If
696 * a typefinding function returns a probability of %GST_TYPE_FIND_MAXIMUM,
697 * typefinding is stopped immediately and the found caps will be returned
698 * right away. Otherwise, all available typefind functions will the tried,
699 * and the caps with the highest probability will be returned, or %NULL if
700 * the content of the buffer could not be identified.
701 *
702 * Free-function: gst_caps_unref
703 *
704 * Returns: (transfer full) (nullable): the #GstCaps corresponding to the data,
705 * or %NULL if no type could be found. The caller should free the caps
706 * returned with gst_caps_unref().
707 */
708 GstCaps *
gst_type_find_helper_for_buffer(GstObject * obj,GstBuffer * buf,GstTypeFindProbability * prob)709 gst_type_find_helper_for_buffer (GstObject * obj, GstBuffer * buf,
710 GstTypeFindProbability * prob)
711 {
712 return gst_type_find_helper_for_buffer_with_extension (obj, buf, NULL, prob);
713 }
714
715 /**
716 * gst_type_find_helper_for_buffer_with_extension:
717 * @obj: (allow-none): object doing the typefinding, or %NULL (used for logging)
718 * @buf: (in) (transfer none): a #GstBuffer with data to typefind
719 * @extension: (allow-none): extension of the media, or %NULL
720 * @prob: (out) (allow-none): location to store the probability of the found
721 * caps, or %NULL
722 *
723 * Tries to find what type of data is contained in the given #GstBuffer, the
724 * assumption being that the buffer represents the beginning of the stream or
725 * file.
726 *
727 * All available typefinders will be called on the data in order of rank. If
728 * a typefinding function returns a probability of %GST_TYPE_FIND_MAXIMUM,
729 * typefinding is stopped immediately and the found caps will be returned
730 * right away. Otherwise, all available typefind functions will the tried,
731 * and the caps with the highest probability will be returned, or %NULL if
732 * the content of the buffer could not be identified.
733 *
734 * When @extension is not %NULL, this function will first try the typefind
735 * functions for the given extension, which might speed up the typefinding
736 * in many cases.
737 *
738 * Free-function: gst_caps_unref
739 *
740 * Returns: (transfer full) (nullable): the #GstCaps corresponding to the data,
741 * or %NULL if no type could be found. The caller should free the caps
742 * returned with gst_caps_unref().
743 *
744 * Since: 1.16
745 *
746 */
747 GstCaps *
gst_type_find_helper_for_buffer_with_extension(GstObject * obj,GstBuffer * buf,const gchar * extension,GstTypeFindProbability * prob)748 gst_type_find_helper_for_buffer_with_extension (GstObject * obj,
749 GstBuffer * buf, const gchar * extension, GstTypeFindProbability * prob)
750 {
751 GstCaps *result;
752 GstMapInfo info;
753
754 g_return_val_if_fail (buf != NULL, NULL);
755 g_return_val_if_fail (GST_IS_BUFFER (buf), NULL);
756 g_return_val_if_fail (GST_BUFFER_OFFSET (buf) == 0 ||
757 GST_BUFFER_OFFSET (buf) == GST_BUFFER_OFFSET_NONE, NULL);
758
759 if (!gst_buffer_map (buf, &info, GST_MAP_READ))
760 return NULL;
761 result =
762 gst_type_find_helper_for_data_with_extension (obj, info.data, info.size,
763 extension, prob);
764 gst_buffer_unmap (buf, &info);
765
766 return result;
767 }
768
769 /**
770 * gst_type_find_helper_for_extension:
771 * @obj: (allow-none): object doing the typefinding, or %NULL (used for logging)
772 * @extension: an extension
773 *
774 * Tries to find the best #GstCaps associated with @extension.
775 *
776 * All available typefinders will be checked against the extension in order
777 * of rank. The caps of the first typefinder that can handle @extension will be
778 * returned.
779 *
780 * Free-function: gst_caps_unref
781 *
782 * Returns: (transfer full) (nullable): the #GstCaps corresponding to
783 * @extension, or %NULL if no type could be found. The caller should free
784 * the caps returned with gst_caps_unref().
785 */
786 GstCaps *
gst_type_find_helper_for_extension(GstObject * obj,const gchar * extension)787 gst_type_find_helper_for_extension (GstObject * obj, const gchar * extension)
788 {
789 GList *l, *type_list;
790 GstCaps *result = NULL;
791
792 g_return_val_if_fail (extension != NULL, NULL);
793
794 GST_LOG_OBJECT (obj, "finding caps for extension %s", extension);
795
796 type_list = gst_type_find_factory_get_list ();
797
798 for (l = type_list; l; l = g_list_next (l)) {
799 GstTypeFindFactory *factory;
800 const gchar *const *ext;
801
802 factory = GST_TYPE_FIND_FACTORY (l->data);
803
804 /* we only want to check those factories without a function */
805 if (gst_type_find_factory_has_function (factory))
806 continue;
807
808 /* get the extension that this typefind factory can handle */
809 ext = gst_type_find_factory_get_extensions (factory);
810 if (ext == NULL)
811 continue;
812
813 /* there are extension, see if one of them matches the requested
814 * extension */
815 while (*ext != NULL) {
816 if (strcmp (*ext, extension) == 0) {
817 /* we found a matching extension, take the caps */
818 if ((result = gst_type_find_factory_get_caps (factory))) {
819 gst_caps_ref (result);
820 goto done;
821 }
822 }
823 ++ext;
824 }
825 }
826 done:
827 gst_plugin_feature_list_free (type_list);
828
829 GST_LOG_OBJECT (obj, "Returning %" GST_PTR_FORMAT, result);
830
831 return result;
832 }
833