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., 51 Franklin St, Fifth Floor,
18 * Boston, MA 02110-1301, 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, GstObject *parent, GstBuffer *buffer)
51 * GstAdapter *adapter;
52 * GstFlowReturn ret = GST_FLOW_OK;
54 * this = MY_ELEMENT (parent);
56 * adapter = this->adapter;
58 * // put buffer into adapter
59 * gst_adapter_push (adapter, buffer);
61 * // while we can read out 512 bytes, process them
62 * while (gst_adapter_available (adapter) >= 512 && ret == GST_FLOW_OK) {
63 * const guint8 *data = gst_adapter_map (adapter, 512);
64 * // use flowreturn as an error value
65 * ret = my_library_foo (data);
66 * gst_adapter_unmap (adapter);
67 * gst_adapter_flush (adapter, 512);
73 * For another example, a simple element inside GStreamer that uses #GstAdapter
74 * is the libvisual element.
76 * An element using #GstAdapter in its sink pad chain function should ensure that
77 * when the FLUSH_STOP event is received, that any queued data is cleared using
78 * gst_adapter_clear(). Data should also be cleared or processed on EOS and
79 * when changing state from %GST_STATE_PAUSED to %GST_STATE_READY.
81 * Also check the GST_BUFFER_FLAG_DISCONT flag on the buffer. Some elements might
82 * need to clear the adapter after a discontinuity.
84 * The adapter will keep track of the timestamps of the buffers
85 * that were pushed. The last seen timestamp before the current position
86 * can be queried with gst_adapter_prev_pts(). This function can
87 * optionally return the number of bytes between the start of the buffer that
88 * carried the timestamp and the current adapter position. The distance is
89 * useful when dealing with, for example, raw audio samples because it allows
90 * you to calculate the timestamp of the current adapter position by using the
91 * last seen timestamp and the amount of bytes since. Additionally, the
92 * gst_adapter_prev_pts_at_offset() can be used to determine the last
93 * seen timestamp at a particular offset in the adapter.
95 * A last thing to note is that while #GstAdapter is pretty optimized,
96 * merging buffers still might be an operation that requires a malloc() and
97 * memcpy() operation, and these operations are not the fastest. Because of
98 * this, some functions like gst_adapter_available_fast() are provided to help
99 * speed up such cases should you want to. To avoid repeated memory allocations,
100 * gst_adapter_copy() can be used to copy data into a (statically allocated)
101 * user provided buffer.
103 * #GstAdapter is not MT safe. All operations on an adapter must be serialized by
104 * the caller. This is not normally a problem, however, as the normal use case
105 * of #GstAdapter is inside one pad's chain function, in which case access is
106 * serialized via the pad's STREAM_LOCK.
108 * Note that gst_adapter_push() takes ownership of the buffer passed. Use
109 * gst_buffer_ref() before pushing it into the adapter if you still want to
110 * access the buffer later. The adapter will never modify the data in the
111 * buffer pushed in it.
114 #include <gst/gst_private.h>
115 #include "gstadapter.h"
118 /* default size for the assembled data buffer */
119 #define DEFAULT_SIZE 4096
121 static void gst_adapter_flush_unchecked (GstAdapter * adapter, gsize flush);
123 GST_DEBUG_CATEGORY_STATIC (gst_adapter_debug);
124 #define GST_CAT_DEFAULT gst_adapter_debug
136 /* we keep state of assembled pieces */
137 gpointer assembled_data;
138 gsize assembled_size;
142 guint64 pts_distance;
144 guint64 dts_distance;
152 struct _GstAdapterClass
154 GObjectClass parent_class;
158 GST_DEBUG_CATEGORY_INIT (gst_adapter_debug, "adapter", 0, "object to splice and merge buffers to desired size")
159 #define gst_adapter_parent_class parent_class
160 G_DEFINE_TYPE_WITH_CODE (GstAdapter, gst_adapter, G_TYPE_OBJECT, _do_init);
162 static void gst_adapter_dispose (GObject * object);
163 static void gst_adapter_finalize (GObject * object);
166 gst_adapter_class_init (GstAdapterClass * klass)
168 GObjectClass *object = G_OBJECT_CLASS (klass);
170 object->dispose = gst_adapter_dispose;
171 object->finalize = gst_adapter_finalize;
175 gst_adapter_init (GstAdapter * adapter)
177 adapter->assembled_data = g_malloc (DEFAULT_SIZE);
178 adapter->assembled_size = DEFAULT_SIZE;
179 adapter->pts = GST_CLOCK_TIME_NONE;
180 adapter->pts_distance = 0;
181 adapter->dts = GST_CLOCK_TIME_NONE;
182 adapter->dts_distance = 0;
186 gst_adapter_dispose (GObject * object)
188 GstAdapter *adapter = GST_ADAPTER (object);
190 gst_adapter_clear (adapter);
192 GST_CALL_PARENT (G_OBJECT_CLASS, dispose, (object));
196 gst_adapter_finalize (GObject * object)
198 GstAdapter *adapter = GST_ADAPTER (object);
200 g_free (adapter->assembled_data);
202 GST_CALL_PARENT (G_OBJECT_CLASS, finalize, (object));
208 * Creates a new #GstAdapter. Free with g_object_unref().
210 * Returns: (transfer full): a new #GstAdapter
213 gst_adapter_new (void)
215 return g_object_newv (GST_TYPE_ADAPTER, 0, NULL);
220 * @adapter: a #GstAdapter
222 * Removes all buffers from @adapter.
225 gst_adapter_clear (GstAdapter * adapter)
227 g_return_if_fail (GST_IS_ADAPTER (adapter));
229 if (adapter->info.memory)
230 gst_adapter_unmap (adapter);
232 g_slist_foreach (adapter->buflist, (GFunc) gst_mini_object_unref, NULL);
233 g_slist_free (adapter->buflist);
234 adapter->buflist = NULL;
235 adapter->buflist_end = NULL;
238 adapter->assembled_len = 0;
239 adapter->pts = GST_CLOCK_TIME_NONE;
240 adapter->pts_distance = 0;
241 adapter->dts = GST_CLOCK_TIME_NONE;
242 adapter->dts_distance = 0;
243 adapter->scan_offset = 0;
244 adapter->scan_entry = NULL;
248 update_timestamps (GstAdapter * adapter, GstBuffer * buf)
250 GstClockTime pts, dts;
252 pts = GST_BUFFER_PTS (buf);
253 if (GST_CLOCK_TIME_IS_VALID (pts)) {
254 GST_LOG_OBJECT (adapter, "new pts %" GST_TIME_FORMAT, GST_TIME_ARGS (pts));
256 adapter->pts_distance = 0;
258 dts = GST_BUFFER_DTS (buf);
259 if (GST_CLOCK_TIME_IS_VALID (dts)) {
260 GST_LOG_OBJECT (adapter, "new dts %" GST_TIME_FORMAT, GST_TIME_ARGS (dts));
262 adapter->dts_distance = 0;
266 /* copy data into @dest, skipping @skip bytes from the head buffers */
268 copy_into_unchecked (GstAdapter * adapter, guint8 * dest, gsize skip,
275 /* first step, do skipping */
276 /* we might well be copying where we were scanning */
277 if (adapter->scan_entry && (adapter->scan_offset <= skip)) {
278 g = adapter->scan_entry;
279 skip -= adapter->scan_offset;
281 g = adapter->buflist;
284 bsize = gst_buffer_get_size (buf);
285 while (G_UNLIKELY (skip >= bsize)) {
287 g = g_slist_next (g);
289 bsize = gst_buffer_get_size (buf);
291 /* copy partial buffer */
292 csize = MIN (bsize - skip, size);
293 GST_DEBUG ("bsize %" G_GSIZE_FORMAT ", skip %" G_GSIZE_FORMAT ", csize %"
294 G_GSIZE_FORMAT, bsize, skip, csize);
295 GST_CAT_LOG_OBJECT (GST_CAT_PERFORMANCE, adapter, "extract %" G_GSIZE_FORMAT
297 gst_buffer_extract (buf, skip, dest, csize);
301 /* second step, copy remainder */
303 g = g_slist_next (g);
305 bsize = gst_buffer_get_size (buf);
306 if (G_LIKELY (bsize > 0)) {
307 csize = MIN (bsize, size);
308 GST_CAT_LOG_OBJECT (GST_CAT_PERFORMANCE, adapter,
309 "extract %" G_GSIZE_FORMAT " bytes", csize);
310 gst_buffer_extract (buf, 0, dest, csize);
319 * @adapter: a #GstAdapter
320 * @buf: (transfer full): a #GstBuffer to add to queue in the adapter
322 * Adds the data from @buf to the data stored inside @adapter and takes
323 * ownership of the buffer.
326 gst_adapter_push (GstAdapter * adapter, GstBuffer * buf)
330 g_return_if_fail (GST_IS_ADAPTER (adapter));
331 g_return_if_fail (GST_IS_BUFFER (buf));
333 size = gst_buffer_get_size (buf);
334 adapter->size += size;
336 /* Note: merging buffers at this point is premature. */
337 if (G_UNLIKELY (adapter->buflist == NULL)) {
338 GST_LOG_OBJECT (adapter, "pushing %p first %" G_GSIZE_FORMAT " bytes",
340 adapter->buflist = adapter->buflist_end = g_slist_append (NULL, buf);
341 update_timestamps (adapter, buf);
343 /* Otherwise append to the end, and advance our end pointer */
344 GST_LOG_OBJECT (adapter, "pushing %p %" G_GSIZE_FORMAT " bytes at end, "
345 "size now %" G_GSIZE_FORMAT, buf, size, adapter->size);
346 adapter->buflist_end = g_slist_append (adapter->buflist_end, buf);
347 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);
411 * @adapter: a #GstAdapter
412 * @size: the number of bytes to map/peek
414 * Gets the first @size bytes stored in the @adapter. The returned pointer is
415 * valid until the next function is called on the adapter.
417 * Note that setting the returned pointer as the data of a #GstBuffer is
418 * incorrect for general-purpose plugins. The reason is that if a downstream
419 * element stores the buffer so that it has access to it outside of the bounds
420 * of its chain function, the buffer will have an invalid data pointer after
421 * your element flushes the bytes. In that case you should use
422 * gst_adapter_take(), which returns a freshly-allocated buffer that you can set
423 * as #GstBuffer memory or the potentially more performant
424 * gst_adapter_take_buffer().
426 * Returns %NULL if @size bytes are not available.
428 * Returns: (transfer none) (array length=size) (element-type guint8) (nullable):
429 * a pointer to the first @size bytes of data, or %NULL
432 gst_adapter_map (GstAdapter * adapter, gsize size)
436 gsize toreuse, tocopy;
439 g_return_val_if_fail (GST_IS_ADAPTER (adapter), NULL);
440 g_return_val_if_fail (size > 0, NULL);
442 if (adapter->info.memory)
443 gst_adapter_unmap (adapter);
445 /* we don't have enough data, return NULL. This is unlikely
446 * as one usually does an _available() first instead of peeking a
448 if (G_UNLIKELY (size > adapter->size))
451 /* we have enough assembled data, return it */
452 if (adapter->assembled_len >= size)
453 return adapter->assembled_data;
458 cur = adapter->buflist->data;
459 skip = adapter->skip;
461 csize = gst_buffer_get_size (cur);
462 if (csize >= size + skip) {
463 if (!gst_buffer_map (cur, &adapter->info, GST_MAP_READ))
466 return (guint8 *) adapter->info.data + skip;
468 /* We may be able to efficiently merge buffers in our pool to
469 * gather a big enough chunk to return it from the head buffer directly */
471 } while (gst_adapter_try_to_merge_up (adapter, size));
474 /* see how much data we can reuse from the assembled memory and how much
476 toreuse = adapter->assembled_len;
477 tocopy = size - toreuse;
479 /* Gonna need to copy stuff out */
480 if (G_UNLIKELY (adapter->assembled_size < size)) {
481 adapter->assembled_size = (size / DEFAULT_SIZE + 1) * DEFAULT_SIZE;
482 GST_DEBUG_OBJECT (adapter, "resizing internal buffer to %" G_GSIZE_FORMAT,
483 adapter->assembled_size);
485 GST_CAT_DEBUG (GST_CAT_PERFORMANCE, "alloc new buffer");
486 /* no g_realloc to avoid a memcpy that is not desired here since we are
487 * not going to reuse any data here */
488 g_free (adapter->assembled_data);
489 adapter->assembled_data = g_malloc (adapter->assembled_size);
491 /* we are going to reuse all data, realloc then */
492 GST_CAT_DEBUG (GST_CAT_PERFORMANCE, "reusing %" G_GSIZE_FORMAT " bytes",
494 adapter->assembled_data =
495 g_realloc (adapter->assembled_data, adapter->assembled_size);
498 GST_CAT_DEBUG (GST_CAT_PERFORMANCE, "copy remaining %" G_GSIZE_FORMAT
499 " bytes from adapter", tocopy);
500 data = adapter->assembled_data;
501 copy_into_unchecked (adapter, data + toreuse, skip + toreuse, tocopy);
502 adapter->assembled_len = size;
504 return adapter->assembled_data;
509 * @adapter: a #GstAdapter
511 * Releases the memory obtained with the last gst_adapter_map().
514 gst_adapter_unmap (GstAdapter * adapter)
516 g_return_if_fail (GST_IS_ADAPTER (adapter));
518 if (adapter->info.memory) {
519 GstBuffer *cur = adapter->buflist->data;
520 GST_LOG_OBJECT (adapter, "unmap memory buffer %p", cur);
521 gst_buffer_unmap (cur, &adapter->info);
522 adapter->info.memory = NULL;
527 * gst_adapter_copy: (skip)
528 * @adapter: a #GstAdapter
529 * @dest: (out caller-allocates) (array length=size) (element-type guint8):
530 * the memory to copy into
531 * @offset: the bytes offset in the adapter to start from
532 * @size: the number of bytes to copy
534 * Copies @size bytes of data starting at @offset out of the buffers
535 * contained in #GstAdapter into an array @dest provided by the caller.
537 * The array @dest should be large enough to contain @size bytes.
538 * The user should check that the adapter has (@offset + @size) bytes
539 * available before calling this function.
542 gst_adapter_copy (GstAdapter * adapter, gpointer dest, gsize offset, gsize size)
544 g_return_if_fail (GST_IS_ADAPTER (adapter));
545 g_return_if_fail (size > 0);
546 g_return_if_fail (offset + size <= adapter->size);
548 copy_into_unchecked (adapter, dest, offset + adapter->skip, size);
552 * gst_adapter_copy_bytes:
553 * @adapter: a #GstAdapter
554 * @offset: the bytes offset in the adapter to start from
555 * @size: the number of bytes to copy
557 * Similar to gst_adapter_copy, but more suitable for language bindings. @size
558 * bytes of data starting at @offset will be copied out of the buffers contained
559 * in @adapter and into a new #GBytes structure which is returned. Depending on
560 * the value of the @size argument an empty #GBytes structure may be returned.
562 * Returns: (transfer full): A new #GBytes structure containing the copied data.
564 * Rename to: gst_adapter_copy
569 gst_adapter_copy_bytes (GstAdapter * adapter, gsize offset, gsize size)
572 data = g_malloc (size);
573 gst_adapter_copy (adapter, data, offset, size);
574 return g_bytes_new_take (data, size);
577 /*Flushes the first @flush bytes in the @adapter*/
579 gst_adapter_flush_unchecked (GstAdapter * adapter, gsize flush)
585 GST_LOG_OBJECT (adapter, "flushing %" G_GSIZE_FORMAT " bytes", flush);
587 if (adapter->info.memory)
588 gst_adapter_unmap (adapter);
591 adapter->size -= flush;
592 adapter->assembled_len = 0;
594 /* take skip into account */
595 flush += adapter->skip;
596 /* distance is always at least the amount of skipped bytes */
597 adapter->pts_distance -= adapter->skip;
598 adapter->dts_distance -= adapter->skip;
600 g = adapter->buflist;
602 size = gst_buffer_get_size (cur);
603 while (flush >= size) {
604 /* can skip whole buffer */
605 GST_LOG_OBJECT (adapter, "flushing out head buffer");
606 adapter->pts_distance += size;
607 adapter->dts_distance += size;
610 gst_buffer_unref (cur);
611 g = g_slist_delete_link (g, g);
613 if (G_UNLIKELY (g == NULL)) {
614 GST_LOG_OBJECT (adapter, "adapter empty now");
615 adapter->buflist_end = NULL;
618 /* there is a new head buffer, update the timestamps */
620 update_timestamps (adapter, cur);
621 size = gst_buffer_get_size (cur);
623 adapter->buflist = g;
624 /* account for the remaining bytes */
625 adapter->skip = flush;
626 adapter->pts_distance += flush;
627 adapter->dts_distance += flush;
628 /* invalidate scan position */
629 adapter->scan_offset = 0;
630 adapter->scan_entry = NULL;
635 * @adapter: a #GstAdapter
636 * @flush: the number of bytes to flush
638 * Flushes the first @flush bytes in the @adapter. The caller must ensure that
639 * at least this many bytes are available.
641 * See also: gst_adapter_map(), gst_adapter_unmap()
644 gst_adapter_flush (GstAdapter * adapter, gsize flush)
646 g_return_if_fail (GST_IS_ADAPTER (adapter));
647 g_return_if_fail (flush <= adapter->size);
649 /* flushing out 0 bytes will do nothing */
650 if (G_UNLIKELY (flush == 0))
653 gst_adapter_flush_unchecked (adapter, flush);
656 /* internal function, nbytes should be flushed after calling this function */
658 gst_adapter_take_internal (GstAdapter * adapter, gsize nbytes)
661 gsize toreuse, tocopy;
663 /* see how much data we can reuse from the assembled memory and how much
665 toreuse = MIN (nbytes, adapter->assembled_len);
666 tocopy = nbytes - toreuse;
668 /* find memory to return */
669 if (adapter->assembled_size >= nbytes && toreuse > 0) {
670 /* we reuse already allocated memory but only when we're going to reuse
671 * something from it because else we are worse than the malloc and copy
673 GST_LOG_OBJECT (adapter, "reusing %" G_GSIZE_FORMAT " bytes of assembled"
675 /* we have enough free space in the assembled array */
676 data = adapter->assembled_data;
677 /* flush after this function should set the assembled_size to 0 */
678 adapter->assembled_data = g_malloc (adapter->assembled_size);
680 GST_LOG_OBJECT (adapter, "allocating %" G_GSIZE_FORMAT " bytes", nbytes);
681 /* not enough bytes in the assembled array, just allocate new space */
682 data = g_malloc (nbytes);
683 /* reuse what we can from the already assembled data */
685 GST_LOG_OBJECT (adapter, "reusing %" G_GSIZE_FORMAT " bytes", toreuse);
686 GST_CAT_LOG_OBJECT (GST_CAT_PERFORMANCE, adapter,
687 "memcpy %" G_GSIZE_FORMAT " bytes", toreuse);
688 memcpy (data, adapter->assembled_data, toreuse);
692 /* copy the remaining data */
693 copy_into_unchecked (adapter, toreuse + data, toreuse + adapter->skip,
701 * @adapter: a #GstAdapter
702 * @nbytes: the number of bytes to take
704 * Returns a freshly allocated buffer containing the first @nbytes bytes of the
705 * @adapter. The returned bytes will be flushed from the adapter.
707 * Caller owns returned value. g_free after usage.
709 * Free-function: g_free
711 * Returns: (transfer full) (array length=nbytes) (element-type guint8) (nullable):
712 * oven-fresh hot data, or %NULL if @nbytes bytes are not available
715 gst_adapter_take (GstAdapter * adapter, gsize nbytes)
719 g_return_val_if_fail (GST_IS_ADAPTER (adapter), NULL);
720 g_return_val_if_fail (nbytes > 0, NULL);
722 /* we don't have enough data, return NULL. This is unlikely
723 * as one usually does an _available() first instead of peeking a
725 if (G_UNLIKELY (nbytes > adapter->size))
728 data = gst_adapter_take_internal (adapter, nbytes);
730 gst_adapter_flush_unchecked (adapter, nbytes);
736 * gst_adapter_take_buffer_fast:
737 * @adapter: a #GstAdapter
738 * @nbytes: the number of bytes to take
740 * Returns a #GstBuffer containing the first @nbytes of the @adapter.
741 * The returned bytes will be flushed from the adapter. This function
742 * is potentially more performant than gst_adapter_take_buffer() since
743 * it can reuse the memory in pushed buffers by subbuffering or
744 * merging. Unlike gst_adapter_take_buffer(), the returned buffer may
745 * be composed of multiple non-contiguous #GstMemory objects, no
748 * Note that no assumptions should be made as to whether certain buffer
749 * flags such as the DISCONT flag are set on the returned buffer, or not.
750 * The caller needs to explicitly set or unset flags that should be set or
753 * This function can return buffer up to the return value of
754 * gst_adapter_available() without making copies if possible.
756 * Caller owns a reference to the returned buffer. gst_buffer_unref() after
759 * Free-function: gst_buffer_unref
761 * Returns: (transfer full) (nullable): a #GstBuffer containing the first
762 * @nbytes of the adapter, or %NULL if @nbytes bytes are not available.
763 * gst_buffer_unref() when no longer needed.
769 gst_adapter_take_buffer_fast (GstAdapter * adapter, gsize nbytes)
771 GstBuffer *buffer = NULL;
777 g_return_val_if_fail (GST_IS_ADAPTER (adapter), NULL);
778 g_return_val_if_fail (nbytes > 0, NULL);
780 GST_LOG_OBJECT (adapter, "taking buffer of %" G_GSIZE_FORMAT " bytes",
783 /* we don't have enough data, return NULL. This is unlikely
784 * as one usually does an _available() first instead of grabbing a
786 if (G_UNLIKELY (nbytes > adapter->size))
789 skip = adapter->skip;
790 cur = adapter->buflist->data;
792 if (skip == 0 && gst_buffer_get_size (cur) == nbytes) {
793 GST_LOG_OBJECT (adapter, "providing buffer of %" G_GSIZE_FORMAT " bytes"
794 " as head buffer", nbytes);
795 buffer = gst_buffer_ref (cur);
799 for (item = adapter->buflist; item && left > 0; item = item->next) {
803 size = MIN (gst_buffer_get_size (cur) - skip, left);
805 GST_LOG_OBJECT (adapter, "appending %" G_GSIZE_FORMAT " bytes"
806 " via region copy", size);
808 gst_buffer_copy_into (buffer, cur, GST_BUFFER_COPY_MEMORY, skip, size);
810 buffer = gst_buffer_copy_region (cur, GST_BUFFER_COPY_ALL, skip, size);
816 gst_adapter_flush_unchecked (adapter, nbytes);
822 * gst_adapter_take_buffer:
823 * @adapter: a #GstAdapter
824 * @nbytes: the number of bytes to take
826 * Returns a #GstBuffer containing the first @nbytes bytes of the
827 * @adapter. The returned bytes will be flushed from the adapter.
828 * This function is potentially more performant than
829 * gst_adapter_take() since it can reuse the memory in pushed buffers
830 * by subbuffering or merging. This function will always return a
831 * buffer with a single memory region.
833 * Note that no assumptions should be made as to whether certain buffer
834 * flags such as the DISCONT flag are set on the returned buffer, or not.
835 * The caller needs to explicitly set or unset flags that should be set or
838 * Caller owns a reference to the returned buffer. gst_buffer_unref() after
841 * Free-function: gst_buffer_unref
843 * Returns: (transfer full) (nullable): a #GstBuffer containing the first
844 * @nbytes of the adapter, or %NULL if @nbytes bytes are not available.
845 * gst_buffer_unref() when no longer needed.
848 gst_adapter_take_buffer (GstAdapter * adapter, gsize nbytes)
855 g_return_val_if_fail (GST_IS_ADAPTER (adapter), NULL);
856 g_return_val_if_fail (nbytes > 0, NULL);
858 GST_LOG_OBJECT (adapter, "taking buffer of %" G_GSIZE_FORMAT " bytes",
861 /* we don't have enough data, return NULL. This is unlikely
862 * as one usually does an _available() first instead of grabbing a
864 if (G_UNLIKELY (nbytes > adapter->size))
867 cur = adapter->buflist->data;
868 skip = adapter->skip;
869 hsize = gst_buffer_get_size (cur);
871 /* our head buffer has enough data left, return it */
872 if (skip == 0 && hsize == nbytes) {
873 GST_LOG_OBJECT (adapter, "providing buffer of %" G_GSIZE_FORMAT " bytes"
874 " as head buffer", nbytes);
875 buffer = gst_buffer_ref (cur);
877 } else if (hsize >= nbytes + skip) {
878 GST_LOG_OBJECT (adapter, "providing buffer of %" G_GSIZE_FORMAT " bytes"
879 " via region copy", nbytes);
880 buffer = gst_buffer_copy_region (cur, GST_BUFFER_COPY_ALL, skip, nbytes);
884 if (gst_adapter_try_to_merge_up (adapter, nbytes)) {
885 /* Merged something, let's try again for sub-buffering */
886 cur = adapter->buflist->data;
887 skip = adapter->skip;
888 if (gst_buffer_get_size (cur) >= nbytes + skip) {
889 GST_LOG_OBJECT (adapter, "providing buffer of %" G_GSIZE_FORMAT " bytes"
890 " via sub-buffer", nbytes);
891 buffer = gst_buffer_copy_region (cur, GST_BUFFER_COPY_ALL, skip, nbytes);
897 data = gst_adapter_take_internal (adapter, nbytes);
899 buffer = gst_buffer_new_wrapped (data, nbytes);
902 gst_adapter_flush_unchecked (adapter, nbytes);
908 * gst_adapter_take_list:
909 * @adapter: a #GstAdapter
910 * @nbytes: the number of bytes to take
912 * Returns a #GList of buffers containing the first @nbytes bytes of the
913 * @adapter. The returned bytes will be flushed from the adapter.
914 * When the caller can deal with individual buffers, this function is more
915 * performant because no memory should be copied.
917 * Caller owns returned list and contained buffers. gst_buffer_unref() each
918 * buffer in the list before freeing the list after usage.
920 * Returns: (element-type Gst.Buffer) (transfer full) (nullable): a #GList of
921 * buffers containing the first @nbytes of the adapter, or %NULL if @nbytes
922 * bytes are not available
925 gst_adapter_take_list (GstAdapter * adapter, gsize nbytes)
927 GQueue queue = G_QUEUE_INIT;
931 g_return_val_if_fail (GST_IS_ADAPTER (adapter), NULL);
932 g_return_val_if_fail (nbytes <= adapter->size, NULL);
934 GST_LOG_OBJECT (adapter, "taking %" G_GSIZE_FORMAT " bytes", nbytes);
937 cur = adapter->buflist->data;
938 skip = adapter->skip;
939 hsize = MIN (nbytes, gst_buffer_get_size (cur) - skip);
941 cur = gst_adapter_take_buffer (adapter, hsize);
943 g_queue_push_tail (&queue, cur);
951 * gst_adapter_available:
952 * @adapter: a #GstAdapter
954 * Gets the maximum amount of bytes available, that is it returns the maximum
955 * value that can be supplied to gst_adapter_map() without that function
958 * Returns: number of bytes available in @adapter
961 gst_adapter_available (GstAdapter * adapter)
963 g_return_val_if_fail (GST_IS_ADAPTER (adapter), 0);
965 return adapter->size;
969 * gst_adapter_available_fast:
970 * @adapter: a #GstAdapter
972 * Gets the maximum number of bytes that are immediately available without
973 * requiring any expensive operations (like copying the data into a
976 * Returns: number of bytes that are available in @adapter without expensive
980 gst_adapter_available_fast (GstAdapter * adapter)
986 g_return_val_if_fail (GST_IS_ADAPTER (adapter), 0);
989 if (adapter->size == 0)
992 /* some stuff we already assembled */
993 if (adapter->assembled_len)
994 return adapter->assembled_len;
996 /* take the first non-zero buffer */
997 g = adapter->buflist;
1000 size = gst_buffer_get_size (cur);
1003 g = g_slist_next (g);
1006 /* we can quickly get the (remaining) data of the first buffer */
1007 return size - adapter->skip;
1011 * gst_adapter_prev_pts:
1012 * @adapter: a #GstAdapter
1013 * @distance: (out) (allow-none): pointer to location for distance, or %NULL
1015 * Get the pts that was before the current byte in the adapter. When
1016 * @distance is given, the amount of bytes between the pts and the current
1017 * position is returned.
1019 * The pts is reset to GST_CLOCK_TIME_NONE and the distance is set to 0 when
1020 * the adapter is first created or when it is cleared. This also means that before
1021 * the first byte with a pts is removed from the adapter, the pts
1022 * and distance returned are GST_CLOCK_TIME_NONE and 0 respectively.
1024 * Returns: The previously seen pts.
1027 gst_adapter_prev_pts (GstAdapter * adapter, guint64 * distance)
1029 g_return_val_if_fail (GST_IS_ADAPTER (adapter), GST_CLOCK_TIME_NONE);
1032 *distance = adapter->pts_distance;
1034 return adapter->pts;
1038 * gst_adapter_prev_dts:
1039 * @adapter: a #GstAdapter
1040 * @distance: (out) (allow-none): pointer to location for distance, or %NULL
1042 * Get the dts that was before the current byte in the adapter. When
1043 * @distance is given, the amount of bytes between the dts and the current
1044 * position is returned.
1046 * The dts is reset to GST_CLOCK_TIME_NONE and the distance is set to 0 when
1047 * the adapter is first created or when it is cleared. This also means that before
1048 * the first byte with a dts is removed from the adapter, the dts
1049 * and distance returned are GST_CLOCK_TIME_NONE and 0 respectively.
1051 * Returns: The previously seen dts.
1054 gst_adapter_prev_dts (GstAdapter * adapter, guint64 * distance)
1056 g_return_val_if_fail (GST_IS_ADAPTER (adapter), GST_CLOCK_TIME_NONE);
1059 *distance = adapter->dts_distance;
1061 return adapter->dts;
1065 * gst_adapter_prev_pts_at_offset:
1066 * @adapter: a #GstAdapter
1067 * @offset: the offset in the adapter at which to get timestamp
1068 * @distance: (out) (allow-none): pointer to location for distance, or %NULL
1070 * Get the pts that was before the byte at offset @offset in the adapter. When
1071 * @distance is given, the amount of bytes between the pts and the current
1072 * position is returned.
1074 * The pts is reset to GST_CLOCK_TIME_NONE and the distance is set to 0 when
1075 * the adapter is first created or when it is cleared. This also means that before
1076 * the first byte with a pts is removed from the adapter, the pts
1077 * and distance returned are GST_CLOCK_TIME_NONE and 0 respectively.
1080 * Returns: The previously seen pts at given offset.
1083 gst_adapter_prev_pts_at_offset (GstAdapter * adapter, gsize offset,
1088 gsize read_offset = 0;
1089 GstClockTime pts = adapter->pts;
1091 g_return_val_if_fail (GST_IS_ADAPTER (adapter), GST_CLOCK_TIME_NONE);
1093 g = adapter->buflist;
1095 while (g && read_offset < offset + adapter->skip) {
1098 read_offset += gst_buffer_get_size (cur);
1099 if (GST_CLOCK_TIME_IS_VALID (GST_BUFFER_PTS (cur))) {
1100 pts = GST_BUFFER_PTS (cur);
1103 g = g_slist_next (g);
1107 *distance = adapter->dts_distance + offset;
1113 * gst_adapter_prev_dts_at_offset:
1114 * @adapter: a #GstAdapter
1115 * @offset: the offset in the adapter at which to get timestamp
1116 * @distance: (out) (allow-none): pointer to location for distance, or %NULL
1118 * Get the dts that was before the byte at offset @offset in the adapter. When
1119 * @distance is given, the amount of bytes between the dts and the current
1120 * position is returned.
1122 * The dts is reset to GST_CLOCK_TIME_NONE and the distance is set to 0 when
1123 * the adapter is first created or when it is cleared. This also means that before
1124 * the first byte with a dts is removed from the adapter, the dts
1125 * and distance returned are GST_CLOCK_TIME_NONE and 0 respectively.
1128 * Returns: The previously seen dts at given offset.
1131 gst_adapter_prev_dts_at_offset (GstAdapter * adapter, gsize offset,
1136 gsize read_offset = 0;
1137 GstClockTime dts = adapter->dts;
1139 g_return_val_if_fail (GST_IS_ADAPTER (adapter), GST_CLOCK_TIME_NONE);
1141 g = adapter->buflist;
1143 while (g && read_offset < offset + adapter->skip) {
1146 read_offset += gst_buffer_get_size (cur);
1147 if (GST_CLOCK_TIME_IS_VALID (GST_BUFFER_DTS (cur))) {
1148 dts = GST_BUFFER_DTS (cur);
1151 g = g_slist_next (g);
1155 *distance = adapter->dts_distance + offset;
1161 * gst_adapter_masked_scan_uint32_peek:
1162 * @adapter: a #GstAdapter
1163 * @mask: mask to apply to data before matching against @pattern
1164 * @pattern: pattern to match (after mask is applied)
1165 * @offset: offset into the adapter data from which to start scanning, returns
1166 * the last scanned position.
1167 * @size: number of bytes to scan from offset
1168 * @value: pointer to uint32 to return matching data
1170 * Scan for pattern @pattern with applied mask @mask in the adapter data,
1171 * starting from offset @offset. If a match is found, the value that matched
1172 * is returned through @value, otherwise @value is left untouched.
1174 * The bytes in @pattern and @mask are interpreted left-to-right, regardless
1175 * of endianness. All four bytes of the pattern must be present in the
1176 * adapter for it to match, even if the first or last bytes are masked out.
1178 * It is an error to call this function without making sure that there is
1179 * enough data (offset+size bytes) in the adapter.
1181 * Returns: offset of the first match, or -1 if no match was found.
1184 gst_adapter_masked_scan_uint32_peek (GstAdapter * adapter, guint32 mask,
1185 guint32 pattern, gsize offset, gsize size, guint32 * value)
1188 gsize skip, bsize, i;
1194 g_return_val_if_fail (size > 0, -1);
1195 g_return_val_if_fail (offset + size <= adapter->size, -1);
1196 g_return_val_if_fail (((~mask) & pattern) == 0, -1);
1198 /* we can't find the pattern with less than 4 bytes */
1199 if (G_UNLIKELY (size < 4))
1202 skip = offset + adapter->skip;
1204 /* first step, do skipping and position on the first buffer */
1205 /* optimistically assume scanning continues sequentially */
1206 if (adapter->scan_entry && (adapter->scan_offset <= skip)) {
1207 g = adapter->scan_entry;
1208 skip -= adapter->scan_offset;
1210 g = adapter->buflist;
1211 adapter->scan_offset = 0;
1212 adapter->scan_entry = NULL;
1215 bsize = gst_buffer_get_size (buf);
1216 while (G_UNLIKELY (skip >= bsize)) {
1218 g = g_slist_next (g);
1219 adapter->scan_offset += bsize;
1220 adapter->scan_entry = g;
1222 bsize = gst_buffer_get_size (buf);
1224 /* get the data now */
1225 if (!gst_buffer_map (buf, &info, GST_MAP_READ))
1228 bdata = (guint8 *) info.data + skip;
1229 bsize = info.size - skip;
1232 /* set the state to something that does not match */
1237 bsize = MIN (bsize, size);
1238 for (i = 0; i < bsize; i++) {
1239 state = ((state << 8) | bdata[i]);
1240 if (G_UNLIKELY ((state & mask) == pattern)) {
1241 /* we have a match but we need to have skipped at
1242 * least 4 bytes to fill the state. */
1243 if (G_LIKELY (skip + i >= 3)) {
1244 if (G_LIKELY (value))
1246 gst_buffer_unmap (buf, &info);
1247 return offset + skip + i - 3;
1255 /* nothing found yet, go to next buffer */
1257 g = g_slist_next (g);
1258 adapter->scan_offset += info.size;
1259 adapter->scan_entry = g;
1260 gst_buffer_unmap (buf, &info);
1263 if (!gst_buffer_map (buf, &info, GST_MAP_READ))
1270 gst_buffer_unmap (buf, &info);
1277 * gst_adapter_masked_scan_uint32:
1278 * @adapter: a #GstAdapter
1279 * @mask: mask to apply to data before matching against @pattern
1280 * @pattern: pattern to match (after mask is applied)
1281 * @offset: offset into the adapter data from which to start scanning, returns
1282 * the last scanned position.
1283 * @size: number of bytes to scan from offset
1285 * Scan for pattern @pattern with applied mask @mask in the adapter data,
1286 * starting from offset @offset.
1288 * The bytes in @pattern and @mask are interpreted left-to-right, regardless
1289 * of endianness. All four bytes of the pattern must be present in the
1290 * adapter for it to match, even if the first or last bytes are masked out.
1292 * It is an error to call this function without making sure that there is
1293 * enough data (offset+size bytes) in the adapter.
1295 * This function calls gst_adapter_masked_scan_uint32_peek() passing %NULL
1298 * Returns: offset of the first match, or -1 if no match was found.
1302 * // Assume the adapter contains 0x00 0x01 0x02 ... 0xfe 0xff
1304 * gst_adapter_masked_scan_uint32 (adapter, 0xffffffff, 0x00010203, 0, 256);
1306 * gst_adapter_masked_scan_uint32 (adapter, 0xffffffff, 0x00010203, 1, 255);
1308 * gst_adapter_masked_scan_uint32 (adapter, 0xffffffff, 0x01020304, 1, 255);
1310 * gst_adapter_masked_scan_uint32 (adapter, 0xffff, 0x0001, 0, 256);
1312 * gst_adapter_masked_scan_uint32 (adapter, 0xffff, 0x0203, 0, 256);
1314 * gst_adapter_masked_scan_uint32 (adapter, 0xffff0000, 0x02030000, 0, 256);
1316 * gst_adapter_masked_scan_uint32 (adapter, 0xffff0000, 0x02030000, 0, 4);
1321 gst_adapter_masked_scan_uint32 (GstAdapter * adapter, guint32 mask,
1322 guint32 pattern, gsize offset, gsize size)
1324 return gst_adapter_masked_scan_uint32_peek (adapter, mask, pattern, offset,