2 * Copyright (C) 2004 Benjamin Otte <otte@gnome.org>
3 * 2005 Wim Taymans <wim@fluendo.com>
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Library General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Library General Public License for more details.
15 * You should have received a copy of the GNU Library General Public
16 * License along with this library; if not, write to the
17 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 * Boston, MA 02111-1307, USA.
23 * @short_description: adapts incoming data on a sink pad into chunks of N bytes
25 * This class is for elements that receive buffers in an undesired size.
26 * While for example raw video contains one image per buffer, the same is not
27 * true for a lot of other formats, especially those that come directly from
28 * a file. So if you have undefined buffer sizes and require a specific size,
29 * this object is for you.
31 * An adapter is created with gst_adapter_new(). It can be freed again with
34 * The theory of operation is like this: All buffers received are put
35 * into the adapter using gst_adapter_push() and the data is then read back
36 * in chunks of the desired size using gst_adapter_map()/gst_adapter_unmap()
37 * and/or gst_adapter_copy(). After the data has been processed, it is freed
38 * using gst_adapter_unmap().
40 * Other methods such as gst_adapter_take() and gst_adapter_take_buffer()
41 * combine gst_adapter_map() and gst_adapter_unmap() in one method and are
42 * potentially more convenient for some use cases.
44 * For example, a sink pad's chain function that needs to pass data to a library
45 * in 512-byte chunks could be implemented like this:
47 * static GstFlowReturn
48 * sink_pad_chain (GstPad *pad, GstBuffer *buffer)
51 * GstAdapter *adapter;
52 * GstFlowReturn ret = GST_FLOW_OK;
54 * // will give the element an extra ref; remember to drop it
55 * this = MY_ELEMENT (gst_pad_get_parent (pad));
56 * adapter = this->adapter;
58 * // put buffer into adapter
59 * gst_adapter_push (adapter, buffer);
60 * // while we can read out 512 bytes, process them
61 * while (gst_adapter_available (adapter) >= 512 && ret == GST_FLOW_OK) {
62 * const guint8 *data = gst_adapter_map (adapter, 512);
63 * // use flowreturn as an error value
64 * ret = my_library_foo (data);
65 * gst_adapter_unmap (adapter);
66 * gst_adapter_flush (adapter, 512);
69 * gst_object_unref (this);
74 * For another example, a simple element inside GStreamer that uses GstAdapter
75 * is the libvisual element.
77 * An element using GstAdapter in its sink pad chain function should ensure that
78 * when the FLUSH_STOP event is received, that any queued data is cleared using
79 * gst_adapter_clear(). Data should also be cleared or processed on EOS and
80 * when changing state from #GST_STATE_PAUSED to #GST_STATE_READY.
82 * Also check the GST_BUFFER_FLAG_DISCONT flag on the buffer. Some elements might
83 * need to clear the adapter after a discontinuity.
85 * Since 0.10.24, the adapter will keep track of the timestamps of the buffers
86 * that were pushed. The last seen timestamp before the current position
87 * can be queried with gst_adapter_prev_timestamp(). This function can
88 * optionally return the amount of bytes between the start of the buffer that
89 * carried the timestamp and the current adapter position. The distance is
90 * useful when dealing with, for example, raw audio samples because it allows
91 * you to calculate the timestamp of the current adapter position by using the
92 * last seen timestamp and the amount of bytes since.
94 * A last thing to note is that while GstAdapter is pretty optimized,
95 * merging buffers still might be an operation that requires a malloc() and
96 * memcpy() operation, and these operations are not the fastest. Because of
97 * this, some functions like gst_adapter_available_fast() are provided to help
98 * speed up such cases should you want to. To avoid repeated memory allocations,
99 * gst_adapter_copy() can be used to copy data into a (statically allocated)
100 * user provided buffer.
102 * GstAdapter is not MT safe. All operations on an adapter must be serialized by
103 * the caller. This is not normally a problem, however, as the normal use case
104 * of GstAdapter is inside one pad's chain function, in which case access is
105 * serialized via the pad's STREAM_LOCK.
107 * Note that gst_adapter_push() takes ownership of the buffer passed. Use
108 * gst_buffer_ref() before pushing it into the adapter if you still want to
109 * access the buffer later. The adapter will never modify the data in the
110 * buffer pushed in it.
112 * Last reviewed on 2009-05-13 (0.10.24).
115 #include <gst/gst_private.h>
116 #include "gstadapter.h"
119 /* default size for the assembled data buffer */
120 #define DEFAULT_SIZE 4096
122 static void gst_adapter_flush_unchecked (GstAdapter * adapter, gsize flush);
124 GST_DEBUG_CATEGORY_STATIC (gst_adapter_debug);
125 #define GST_CAT_DEFAULT gst_adapter_debug
137 /* we keep state of assembled pieces */
138 gpointer assembled_data;
139 gsize assembled_size;
143 guint64 pts_distance;
145 guint64 dts_distance;
153 struct _GstAdapterClass
155 GObjectClass parent_class;
159 GST_DEBUG_CATEGORY_INIT (gst_adapter_debug, "adapter", 0, "object to splice and merge buffers to desired size")
160 #define gst_adapter_parent_class parent_class
161 G_DEFINE_TYPE_WITH_CODE (GstAdapter, gst_adapter, G_TYPE_OBJECT, _do_init);
163 static void gst_adapter_dispose (GObject * object);
164 static void gst_adapter_finalize (GObject * object);
167 gst_adapter_class_init (GstAdapterClass * klass)
169 GObjectClass *object = G_OBJECT_CLASS (klass);
171 object->dispose = gst_adapter_dispose;
172 object->finalize = gst_adapter_finalize;
176 gst_adapter_init (GstAdapter * adapter)
178 adapter->assembled_data = g_malloc (DEFAULT_SIZE);
179 adapter->assembled_size = DEFAULT_SIZE;
180 adapter->pts = GST_CLOCK_TIME_NONE;
181 adapter->pts_distance = 0;
182 adapter->dts = GST_CLOCK_TIME_NONE;
183 adapter->dts_distance = 0;
187 gst_adapter_dispose (GObject * object)
189 GstAdapter *adapter = GST_ADAPTER (object);
191 gst_adapter_clear (adapter);
193 GST_CALL_PARENT (G_OBJECT_CLASS, dispose, (object));
197 gst_adapter_finalize (GObject * object)
199 GstAdapter *adapter = GST_ADAPTER (object);
201 g_free (adapter->assembled_data);
203 GST_CALL_PARENT (G_OBJECT_CLASS, finalize, (object));
209 * Creates a new #GstAdapter. Free with g_object_unref().
211 * Returns: (transfer full): a new #GstAdapter
214 gst_adapter_new (void)
216 return g_object_newv (GST_TYPE_ADAPTER, 0, NULL);
221 * @adapter: a #GstAdapter
223 * Removes all buffers from @adapter.
226 gst_adapter_clear (GstAdapter * adapter)
228 g_return_if_fail (GST_IS_ADAPTER (adapter));
230 if (adapter->info.memory)
231 gst_adapter_unmap (adapter);
233 g_slist_foreach (adapter->buflist, (GFunc) gst_mini_object_unref, NULL);
234 g_slist_free (adapter->buflist);
235 adapter->buflist = NULL;
236 adapter->buflist_end = NULL;
239 adapter->assembled_len = 0;
240 adapter->pts = GST_CLOCK_TIME_NONE;
241 adapter->pts_distance = 0;
242 adapter->dts = GST_CLOCK_TIME_NONE;
243 adapter->dts_distance = 0;
244 adapter->scan_offset = 0;
245 adapter->scan_entry = NULL;
249 update_timestamps (GstAdapter * adapter, GstBuffer * buf)
251 GstClockTime pts, dts;
253 pts = GST_BUFFER_PTS (buf);
254 if (GST_CLOCK_TIME_IS_VALID (pts)) {
255 GST_LOG_OBJECT (adapter, "new pts %" GST_TIME_FORMAT, GST_TIME_ARGS (pts));
257 adapter->pts_distance = 0;
259 dts = GST_BUFFER_DTS (buf);
260 if (GST_CLOCK_TIME_IS_VALID (dts)) {
261 GST_LOG_OBJECT (adapter, "new dts %" GST_TIME_FORMAT, GST_TIME_ARGS (dts));
263 adapter->dts_distance = 0;
267 /* copy data into @dest, skipping @skip bytes from the head buffers */
269 copy_into_unchecked (GstAdapter * adapter, guint8 * dest, gsize skip,
276 /* first step, do skipping */
277 /* we might well be copying where we were scanning */
278 if (adapter->scan_entry && (adapter->scan_offset <= skip)) {
279 g = adapter->scan_entry;
280 skip -= adapter->scan_offset;
282 g = adapter->buflist;
285 bsize = gst_buffer_get_size (buf);
286 while (G_UNLIKELY (skip >= bsize)) {
288 g = g_slist_next (g);
290 bsize = gst_buffer_get_size (buf);
292 /* copy partial buffer */
293 csize = MIN (bsize - skip, size);
294 GST_DEBUG ("bsize %" G_GSIZE_FORMAT ", skip %" G_GSIZE_FORMAT ", csize %"
295 G_GSIZE_FORMAT, bsize, skip, csize);
296 GST_CAT_LOG_OBJECT (GST_CAT_PERFORMANCE, adapter, "extract %" G_GSIZE_FORMAT
298 gst_buffer_extract (buf, skip, dest, csize);
302 /* second step, copy remainder */
304 g = g_slist_next (g);
306 bsize = gst_buffer_get_size (buf);
307 if (G_LIKELY (bsize > 0)) {
308 csize = MIN (bsize, size);
309 GST_CAT_LOG_OBJECT (GST_CAT_PERFORMANCE, adapter,
310 "extract %" G_GSIZE_FORMAT " bytes", csize);
311 gst_buffer_extract (buf, 0, dest, csize);
320 * @adapter: a #GstAdapter
321 * @buf: (transfer full): a #GstBuffer to add to queue in the adapter
323 * Adds the data from @buf to the data stored inside @adapter and takes
324 * ownership of the buffer.
327 gst_adapter_push (GstAdapter * adapter, GstBuffer * buf)
331 g_return_if_fail (GST_IS_ADAPTER (adapter));
332 g_return_if_fail (GST_IS_BUFFER (buf));
334 size = gst_buffer_get_size (buf);
335 adapter->size += size;
337 /* Note: merging buffers at this point is premature. */
338 if (G_UNLIKELY (adapter->buflist == NULL)) {
339 GST_LOG_OBJECT (adapter, "pushing %p first %" G_GSIZE_FORMAT " bytes",
341 adapter->buflist = adapter->buflist_end = g_slist_append (NULL, buf);
342 update_timestamps (adapter, buf);
344 /* Otherwise append to the end, and advance our end pointer */
345 GST_LOG_OBJECT (adapter, "pushing %p %" G_GSIZE_FORMAT " bytes at end, "
346 "size now %" G_GSIZE_FORMAT, buf, size, adapter->size);
347 adapter->buflist_end = g_slist_append (adapter->buflist_end, buf);
348 adapter->buflist_end = g_slist_next (adapter->buflist_end);
352 /* Internal method only. Tries to merge buffers at the head of the queue
353 * to form a single larger buffer of size 'size'.
355 * Returns TRUE if it managed to merge anything.
358 gst_adapter_try_to_merge_up (GstAdapter * adapter, gsize size)
360 GstBuffer *cur, *head;
362 gboolean ret = FALSE;
365 g = adapter->buflist;
371 hsize = gst_buffer_get_size (head);
373 /* Remove skipped part from the buffer (otherwise the buffer might grow indefinitely) */
374 head = gst_buffer_make_writable (head);
375 gst_buffer_resize (head, adapter->skip, hsize - adapter->skip);
376 hsize -= adapter->skip;
380 g = g_slist_next (g);
382 while (g != NULL && hsize < size) {
384 /* Merge the head buffer and the next in line */
385 GST_LOG_OBJECT (adapter, "Merging buffers of size %" G_GSIZE_FORMAT " & %"
386 G_GSIZE_FORMAT " in search of target %" G_GSIZE_FORMAT,
387 hsize, gst_buffer_get_size (cur), size);
389 head = gst_buffer_append (head, cur);
390 hsize = gst_buffer_get_size (head);
393 /* Delete the front list item, and store our new buffer in the 2nd list
395 adapter->buflist = g_slist_delete_link (adapter->buflist, adapter->buflist);
398 /* invalidate scan position */
399 adapter->scan_offset = 0;
400 adapter->scan_entry = NULL;
402 g = g_slist_next (g);
410 * @adapter: a #GstAdapter
411 * @size: the number of bytes to map/peek
413 * Gets the first @size bytes stored in the @adapter. The returned pointer is
414 * valid until the next function is called on the adapter.
416 * Note that setting the returned pointer as the data of a #GstBuffer is
417 * incorrect for general-purpose plugins. The reason is that if a downstream
418 * element stores the buffer so that it has access to it outside of the bounds
419 * of its chain function, the buffer will have an invalid data pointer after
420 * your element flushes the bytes. In that case you should use
421 * gst_adapter_take(), which returns a freshly-allocated buffer that you can set
422 * as #GstBuffer malloc_data or the potentially more performant
423 * gst_adapter_take_buffer().
425 * Returns #NULL if @size bytes are not available.
427 * Returns: (transfer none) (array length=size): a pointer to the first
428 * @size bytes of data, or NULL
431 gst_adapter_map (GstAdapter * adapter, gsize size)
435 gsize toreuse, tocopy;
438 g_return_val_if_fail (GST_IS_ADAPTER (adapter), NULL);
439 g_return_val_if_fail (size > 0, NULL);
441 if (adapter->info.memory)
442 gst_adapter_unmap (adapter);
444 /* we don't have enough data, return NULL. This is unlikely
445 * as one usually does an _available() first instead of peeking a
447 if (G_UNLIKELY (size > adapter->size))
450 /* we have enough assembled data, return it */
451 if (adapter->assembled_len >= size)
452 return adapter->assembled_data;
455 cur = adapter->buflist->data;
456 skip = adapter->skip;
458 csize = gst_buffer_get_size (cur);
459 if (csize >= size + skip) {
460 if (!gst_buffer_map (cur, &adapter->info, GST_MAP_READ))
463 return (guint8 *) adapter->info.data + skip;
465 /* We may be able to efficiently merge buffers in our pool to
466 * gather a big enough chunk to return it from the head buffer directly */
467 } while (gst_adapter_try_to_merge_up (adapter, size));
469 /* see how much data we can reuse from the assembled memory and how much
471 toreuse = adapter->assembled_len;
472 tocopy = size - toreuse;
474 /* Gonna need to copy stuff out */
475 if (G_UNLIKELY (adapter->assembled_size < size)) {
476 adapter->assembled_size = (size / DEFAULT_SIZE + 1) * DEFAULT_SIZE;
477 GST_DEBUG_OBJECT (adapter, "resizing internal buffer to %" G_GSIZE_FORMAT,
478 adapter->assembled_size);
480 GST_CAT_DEBUG (GST_CAT_PERFORMANCE, "alloc new buffer");
481 /* no g_realloc to avoid a memcpy that is not desired here since we are
482 * not going to reuse any data here */
483 g_free (adapter->assembled_data);
484 adapter->assembled_data = g_malloc (adapter->assembled_size);
486 /* we are going to reuse all data, realloc then */
487 GST_CAT_DEBUG (GST_CAT_PERFORMANCE, "reusing %" G_GSIZE_FORMAT " bytes",
489 adapter->assembled_data =
490 g_realloc (adapter->assembled_data, adapter->assembled_size);
493 GST_CAT_DEBUG (GST_CAT_PERFORMANCE, "copy remaining %" G_GSIZE_FORMAT
494 " bytes from adapter", tocopy);
495 data = adapter->assembled_data;
496 copy_into_unchecked (adapter, data + toreuse, skip + toreuse, tocopy);
497 adapter->assembled_len = size;
499 return adapter->assembled_data;
504 * @adapter: a #GstAdapter
506 * Releases the memory obtained with the last gst_adapter_map().
509 gst_adapter_unmap (GstAdapter * adapter)
511 g_return_if_fail (GST_IS_ADAPTER (adapter));
513 if (adapter->info.memory) {
514 GstBuffer *cur = adapter->buflist->data;
515 GST_LOG_OBJECT (adapter, "unmap memory buffer %p", cur);
516 gst_buffer_unmap (cur, &adapter->info);
517 adapter->info.memory = NULL;
523 * @adapter: a #GstAdapter
524 * @dest: (out caller-allocates) (array length=size): the memory to copy into
525 * @offset: the bytes offset in the adapter to start from
526 * @size: the number of bytes to copy
528 * Copies @size bytes of data starting at @offset out of the buffers
529 * contained in @GstAdapter into an array @dest provided by the caller.
531 * The array @dest should be large enough to contain @size bytes.
532 * The user should check that the adapter has (@offset + @size) bytes
533 * available before calling this function.
538 gst_adapter_copy (GstAdapter * adapter, gpointer dest, gsize offset, gsize size)
540 g_return_if_fail (GST_IS_ADAPTER (adapter));
541 g_return_if_fail (size > 0);
542 g_return_if_fail (offset + size <= adapter->size);
544 copy_into_unchecked (adapter, dest, offset + adapter->skip, size);
549 * @adapter: a #GstAdapter
550 * @flush: the number of bytes to flush
552 * Flushes the first @flush bytes in the @adapter. The caller must ensure that
553 * at least this many bytes are available.
555 * See also: gst_adapter_map(), gst_adapter_unmap()
558 gst_adapter_flush_unchecked (GstAdapter * adapter, gsize flush)
564 GST_LOG_OBJECT (adapter, "flushing %" G_GSIZE_FORMAT " bytes", flush);
566 if (adapter->info.memory)
567 gst_adapter_unmap (adapter);
570 adapter->size -= flush;
571 adapter->assembled_len = 0;
573 /* take skip into account */
574 flush += adapter->skip;
575 /* distance is always at least the amount of skipped bytes */
576 adapter->pts_distance -= adapter->skip;
577 adapter->dts_distance -= adapter->skip;
579 g = adapter->buflist;
581 size = gst_buffer_get_size (cur);
582 while (flush >= size) {
583 /* can skip whole buffer */
584 GST_LOG_OBJECT (adapter, "flushing out head buffer");
585 adapter->pts_distance += size;
586 adapter->dts_distance += size;
589 gst_buffer_unref (cur);
590 g = g_slist_delete_link (g, g);
592 if (G_UNLIKELY (g == NULL)) {
593 GST_LOG_OBJECT (adapter, "adapter empty now");
594 adapter->buflist_end = NULL;
597 /* there is a new head buffer, update the timestamps */
599 update_timestamps (adapter, cur);
600 size = gst_buffer_get_size (cur);
602 adapter->buflist = g;
603 /* account for the remaining bytes */
604 adapter->skip = flush;
605 adapter->pts_distance += flush;
606 adapter->dts_distance += flush;
607 /* invalidate scan position */
608 adapter->scan_offset = 0;
609 adapter->scan_entry = NULL;
613 gst_adapter_flush (GstAdapter * adapter, gsize flush)
615 g_return_if_fail (GST_IS_ADAPTER (adapter));
616 g_return_if_fail (flush <= adapter->size);
618 /* flushing out 0 bytes will do nothing */
619 if (G_UNLIKELY (flush == 0))
622 gst_adapter_flush_unchecked (adapter, flush);
625 /* internal function, nbytes should be flushed after calling this function */
627 gst_adapter_take_internal (GstAdapter * adapter, gsize nbytes)
630 gsize toreuse, tocopy;
632 /* see how much data we can reuse from the assembled memory and how much
634 toreuse = MIN (nbytes, adapter->assembled_len);
635 tocopy = nbytes - toreuse;
637 /* find memory to return */
638 if (adapter->assembled_size >= nbytes && toreuse > 0) {
639 /* we reuse already allocated memory but only when we're going to reuse
640 * something from it because else we are worse than the malloc and copy
642 GST_LOG_OBJECT (adapter, "reusing %" G_GSIZE_FORMAT " bytes of assembled"
644 /* we have enough free space in the assembled array */
645 data = adapter->assembled_data;
646 /* flush after this function should set the assembled_size to 0 */
647 adapter->assembled_data = g_malloc (adapter->assembled_size);
649 GST_LOG_OBJECT (adapter, "allocating %" G_GSIZE_FORMAT " bytes", nbytes);
650 /* not enough bytes in the assembled array, just allocate new space */
651 data = g_malloc (nbytes);
652 /* reuse what we can from the already assembled data */
654 GST_LOG_OBJECT (adapter, "reusing %" G_GSIZE_FORMAT " bytes", toreuse);
655 GST_CAT_LOG_OBJECT (GST_CAT_PERFORMANCE, adapter,
656 "memcpy %" G_GSIZE_FORMAT " bytes", toreuse);
657 memcpy (data, adapter->assembled_data, toreuse);
661 /* copy the remaining data */
662 copy_into_unchecked (adapter, toreuse + data, toreuse + adapter->skip,
670 * @adapter: a #GstAdapter
671 * @nbytes: the number of bytes to take
673 * Returns a freshly allocated buffer containing the first @nbytes bytes of the
674 * @adapter. The returned bytes will be flushed from the adapter.
676 * Caller owns returned value. g_free after usage.
678 * Free-function: g_free
680 * Returns: (transfer full) (array length=nbytes): oven-fresh hot data, or
681 * #NULL if @nbytes bytes are not available
684 gst_adapter_take (GstAdapter * adapter, gsize nbytes)
688 g_return_val_if_fail (GST_IS_ADAPTER (adapter), NULL);
689 g_return_val_if_fail (nbytes > 0, NULL);
691 /* we don't have enough data, return NULL. This is unlikely
692 * as one usually does an _available() first instead of peeking a
694 if (G_UNLIKELY (nbytes > adapter->size))
697 data = gst_adapter_take_internal (adapter, nbytes);
699 gst_adapter_flush_unchecked (adapter, nbytes);
705 * gst_adapter_take_buffer:
706 * @adapter: a #GstAdapter
707 * @nbytes: the number of bytes to take
709 * Returns a #GstBuffer containing the first @nbytes bytes of the
710 * @adapter. The returned bytes will be flushed from the adapter.
711 * This function is potentially more performant than gst_adapter_take()
712 * since it can reuse the memory in pushed buffers by subbuffering
715 * Caller owns returned value. gst_buffer_unref() after usage.
717 * Free-function: gst_buffer_unref
719 * Returns: (transfer full): a #GstBuffer containing the first @nbytes of
720 * the adapter, or #NULL if @nbytes bytes are not available
725 gst_adapter_take_buffer (GstAdapter * adapter, gsize nbytes)
732 g_return_val_if_fail (GST_IS_ADAPTER (adapter), NULL);
733 g_return_val_if_fail (nbytes > 0, NULL);
735 GST_LOG_OBJECT (adapter, "taking buffer of %" G_GSIZE_FORMAT " bytes",
738 /* we don't have enough data, return NULL. This is unlikely
739 * as one usually does an _available() first instead of grabbing a
741 if (G_UNLIKELY (nbytes > adapter->size))
744 cur = adapter->buflist->data;
745 skip = adapter->skip;
746 hsize = gst_buffer_get_size (cur);
748 /* our head buffer has enough data left, return it */
749 if (skip == 0 && hsize == nbytes) {
750 GST_LOG_OBJECT (adapter, "providing buffer of %" G_GSIZE_FORMAT " bytes"
751 " as head buffer", nbytes);
752 buffer = gst_buffer_ref (cur);
754 } else if (hsize >= nbytes + skip) {
755 GST_LOG_OBJECT (adapter, "providing buffer of %" G_GSIZE_FORMAT " bytes"
756 " via region copy", nbytes);
757 buffer = gst_buffer_copy_region (cur, GST_BUFFER_COPY_ALL, skip, nbytes);
761 if (gst_adapter_try_to_merge_up (adapter, nbytes)) {
762 /* Merged something, let's try again for sub-buffering */
763 cur = adapter->buflist->data;
764 skip = adapter->skip;
765 if (gst_buffer_get_size (cur) >= nbytes + skip) {
766 GST_LOG_OBJECT (adapter, "providing buffer of %" G_GSIZE_FORMAT " bytes"
767 " via sub-buffer", nbytes);
768 buffer = gst_buffer_copy_region (cur, GST_BUFFER_COPY_ALL, skip, nbytes);
773 data = gst_adapter_take_internal (adapter, nbytes);
775 buffer = gst_buffer_new_wrapped (data, nbytes);
778 gst_adapter_flush_unchecked (adapter, nbytes);
784 * gst_adapter_take_list:
785 * @adapter: a #GstAdapter
786 * @nbytes: the number of bytes to take
788 * Returns a #GList of buffers containing the first @nbytes bytes of the
789 * @adapter. The returned bytes will be flushed from the adapter.
790 * When the caller can deal with individual buffers, this function is more
791 * performant because no memory should be copied.
793 * Caller owns returned list and contained buffers. gst_buffer_unref() each
794 * buffer in the list before freeing the list after usage.
796 * Returns: (element-type Gst.Buffer) (transfer full): a #GList of buffers
797 * containing the first @nbytes of the adapter, or #NULL if @nbytes bytes
803 gst_adapter_take_list (GstAdapter * adapter, gsize nbytes)
805 GQueue queue = G_QUEUE_INIT;
809 g_return_val_if_fail (GST_IS_ADAPTER (adapter), NULL);
810 g_return_val_if_fail (nbytes <= adapter->size, NULL);
812 GST_LOG_OBJECT (adapter, "taking %" G_GSIZE_FORMAT " bytes", nbytes);
815 cur = adapter->buflist->data;
816 skip = adapter->skip;
817 hsize = MIN (nbytes, gst_buffer_get_size (cur) - skip);
819 cur = gst_adapter_take_buffer (adapter, hsize);
821 g_queue_push_tail (&queue, cur);
829 * gst_adapter_available:
830 * @adapter: a #GstAdapter
832 * Gets the maximum amount of bytes available, that is it returns the maximum
833 * value that can be supplied to gst_adapter_map() without that function
836 * Returns: number of bytes available in @adapter
839 gst_adapter_available (GstAdapter * adapter)
841 g_return_val_if_fail (GST_IS_ADAPTER (adapter), 0);
843 return adapter->size;
847 * gst_adapter_available_fast:
848 * @adapter: a #GstAdapter
850 * Gets the maximum number of bytes that are immediately available without
851 * requiring any expensive operations (like copying the data into a
854 * Returns: number of bytes that are available in @adapter without expensive
858 gst_adapter_available_fast (GstAdapter * adapter)
864 g_return_val_if_fail (GST_IS_ADAPTER (adapter), 0);
867 if (adapter->size == 0)
870 /* some stuff we already assembled */
871 if (adapter->assembled_len)
872 return adapter->assembled_len;
874 /* take the first non-zero buffer */
875 g = adapter->buflist;
878 size = gst_buffer_get_size (cur);
881 g = g_slist_next (g);
884 /* we can quickly get the (remaining) data of the first buffer */
885 return size - adapter->skip;
889 * gst_adapter_prev_pts:
890 * @adapter: a #GstAdapter
891 * @distance: (out) (allow-none): pointer to location for distance, or NULL
893 * Get the pts that was before the current byte in the adapter. When
894 * @distance is given, the amount of bytes between the pts and the current
895 * position is returned.
897 * The pts is reset to GST_CLOCK_TIME_NONE and the distance is set to 0 when
898 * the adapter is first created or when it is cleared. This also means that before
899 * the first byte with a pts is removed from the adapter, the pts
900 * and distance returned are GST_CLOCK_TIME_NONE and 0 respectively.
902 * Returns: The previously seen pts.
905 gst_adapter_prev_pts (GstAdapter * adapter, guint64 * distance)
907 g_return_val_if_fail (GST_IS_ADAPTER (adapter), GST_CLOCK_TIME_NONE);
910 *distance = adapter->pts_distance;
916 * gst_adapter_prev_dts:
917 * @adapter: a #GstAdapter
918 * @distance: (out) (allow-none): pointer to location for distance, or NULL
920 * Get the dts that was before the current byte in the adapter. When
921 * @distance is given, the amount of bytes between the dts and the current
922 * position is returned.
924 * The dts is reset to GST_CLOCK_TIME_NONE and the distance is set to 0 when
925 * the adapter is first created or when it is cleared. This also means that before
926 * the first byte with a dts is removed from the adapter, the dts
927 * and distance returned are GST_CLOCK_TIME_NONE and 0 respectively.
929 * Returns: The previously seen dts.
932 gst_adapter_prev_dts (GstAdapter * adapter, guint64 * distance)
934 g_return_val_if_fail (GST_IS_ADAPTER (adapter), GST_CLOCK_TIME_NONE);
937 *distance = adapter->dts_distance;
943 * gst_adapter_masked_scan_uint32_peek:
944 * @adapter: a #GstAdapter
945 * @mask: mask to apply to data before matching against @pattern
946 * @pattern: pattern to match (after mask is applied)
947 * @offset: offset into the adapter data from which to start scanning, returns
948 * the last scanned position.
949 * @size: number of bytes to scan from offset
950 * @value: pointer to uint32 to return matching data
952 * Scan for pattern @pattern with applied mask @mask in the adapter data,
953 * starting from offset @offset. If a match is found, the value that matched
954 * is returned through @value, otherwise @value is left untouched.
956 * The bytes in @pattern and @mask are interpreted left-to-right, regardless
957 * of endianness. All four bytes of the pattern must be present in the
958 * adapter for it to match, even if the first or last bytes are masked out.
960 * It is an error to call this function without making sure that there is
961 * enough data (offset+size bytes) in the adapter.
963 * Returns: offset of the first match, or -1 if no match was found.
968 gst_adapter_masked_scan_uint32_peek (GstAdapter * adapter, guint32 mask,
969 guint32 pattern, gsize offset, gsize size, guint32 * value)
972 gsize skip, bsize, i;
978 g_return_val_if_fail (size > 0, -1);
979 g_return_val_if_fail (offset + size <= adapter->size, -1);
980 g_return_val_if_fail (((~mask) & pattern) == 0, -1);
982 /* we can't find the pattern with less than 4 bytes */
983 if (G_UNLIKELY (size < 4))
986 skip = offset + adapter->skip;
988 /* first step, do skipping and position on the first buffer */
989 /* optimistically assume scanning continues sequentially */
990 if (adapter->scan_entry && (adapter->scan_offset <= skip)) {
991 g = adapter->scan_entry;
992 skip -= adapter->scan_offset;
994 g = adapter->buflist;
995 adapter->scan_offset = 0;
996 adapter->scan_entry = NULL;
999 bsize = gst_buffer_get_size (buf);
1000 while (G_UNLIKELY (skip >= bsize)) {
1002 g = g_slist_next (g);
1003 adapter->scan_offset += bsize;
1004 adapter->scan_entry = g;
1006 bsize = gst_buffer_get_size (buf);
1008 /* get the data now */
1009 if (!gst_buffer_map (buf, &info, GST_MAP_READ))
1012 bdata = (guint8 *) info.data + skip;
1013 bsize = info.size - skip;
1016 /* set the state to something that does not match */
1021 bsize = MIN (bsize, size);
1022 for (i = 0; i < bsize; i++) {
1023 state = ((state << 8) | bdata[i]);
1024 if (G_UNLIKELY ((state & mask) == pattern)) {
1025 /* we have a match but we need to have skipped at
1026 * least 4 bytes to fill the state. */
1027 if (G_LIKELY (skip + i >= 3)) {
1028 if (G_LIKELY (value))
1030 gst_buffer_unmap (buf, &info);
1031 return offset + skip + i - 3;
1039 /* nothing found yet, go to next buffer */
1041 g = g_slist_next (g);
1042 adapter->scan_offset += info.size;
1043 adapter->scan_entry = g;
1044 gst_buffer_unmap (buf, &info);
1047 gst_buffer_map (buf, &info, GST_MAP_READ);
1052 gst_buffer_unmap (buf, &info);
1059 * gst_adapter_masked_scan_uint32:
1060 * @adapter: a #GstAdapter
1061 * @mask: mask to apply to data before matching against @pattern
1062 * @pattern: pattern to match (after mask is applied)
1063 * @offset: offset into the adapter data from which to start scanning, returns
1064 * the last scanned position.
1065 * @size: number of bytes to scan from offset
1067 * Scan for pattern @pattern with applied mask @mask in the adapter data,
1068 * starting from offset @offset.
1070 * The bytes in @pattern and @mask are interpreted left-to-right, regardless
1071 * of endianness. All four bytes of the pattern must be present in the
1072 * adapter for it to match, even if the first or last bytes are masked out.
1074 * It is an error to call this function without making sure that there is
1075 * enough data (offset+size bytes) in the adapter.
1077 * This function calls gst_adapter_masked_scan_uint32_peek() passing NULL
1080 * Returns: offset of the first match, or -1 if no match was found.
1084 * // Assume the adapter contains 0x00 0x01 0x02 ... 0xfe 0xff
1086 * gst_adapter_masked_scan_uint32 (adapter, 0xffffffff, 0x00010203, 0, 256);
1088 * gst_adapter_masked_scan_uint32 (adapter, 0xffffffff, 0x00010203, 1, 255);
1090 * gst_adapter_masked_scan_uint32 (adapter, 0xffffffff, 0x01020304, 1, 255);
1092 * gst_adapter_masked_scan_uint32 (adapter, 0xffff, 0x0001, 0, 256);
1094 * gst_adapter_masked_scan_uint32 (adapter, 0xffff, 0x0203, 0, 256);
1096 * gst_adapter_masked_scan_uint32 (adapter, 0xffff0000, 0x02030000, 0, 256);
1098 * gst_adapter_masked_scan_uint32 (adapter, 0xffff0000, 0x02030000, 0, 4);
1105 gst_adapter_masked_scan_uint32 (GstAdapter * adapter, guint32 mask,
1106 guint32 pattern, gsize offset, gsize size)
1108 return gst_adapter_masked_scan_uint32_peek (adapter, mask, pattern, offset,