2 * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
3 * 2000 Wim Taymans <wtay@chello.be>
5 * gstbuffer.c: Buffer operations
7 * This library is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Library General Public
9 * License as published by the Free Software Foundation; either
10 * version 2 of the License, or (at your option) any later version.
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Library General Public License for more details.
17 * You should have received a copy of the GNU Library General Public
18 * License along with this library; if not, write to the
19 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
20 * Boston, MA 02111-1307, USA.
25 * @short_description: Data-passing buffer type
26 * @see_also: #GstPad, #GstMiniObject, #GstMemory, #GstMeta, #GstBufferPool
28 * Buffers are the basic unit of data transfer in GStreamer. They contain the
29 * timing and offset along with other arbitrary metadata that is associated
30 * with the #GstMemory blocks that the buffer contains.
32 * Buffers are usually created with gst_buffer_new(). After a buffer has been
33 * created one will typically allocate memory for it and add it to the buffer.
34 * The following example creates a buffer that can hold a given video frame
35 * with a given width, height and bits per plane.
37 * <title>Creating a buffer for a video frame</title>
41 * gint size, width, height, bpp;
43 * size = width * height * bpp;
44 * buffer = gst_buffer_new ();
45 * memory = gst_allocator_alloc (NULL, size, NULL);
46 * gst_buffer_insert_memory (buffer, -1, memory);
51 * Alternatively, use gst_buffer_new_allocate()
52 * to create a buffer with preallocated data of a given size.
54 * Buffers can contain a list of #GstMemory objects. You can retrieve how many
55 * memory objects with gst_buffer_n_memory() and you can get a pointer
56 * to memory with gst_buffer_peek_memory()
58 * A buffer will usually have timestamps, and a duration, but neither of these
59 * are guaranteed (they may be set to #GST_CLOCK_TIME_NONE). Whenever a
60 * meaningful value can be given for these, they should be set. The timestamps
61 * and duration are measured in nanoseconds (they are #GstClockTime values).
63 * The buffer DTS refers to the timestamp when the buffer should be decoded and
64 * is usually monotonically increasing. The buffer PTS refers to the timestamp when
65 * the buffer content should be presented to the user and is not always
66 * monotonically increasing.
68 * A buffer can also have one or both of a start and an end offset. These are
69 * media-type specific. For video buffers, the start offset will generally be
70 * the frame number. For audio buffers, it will be the number of samples
71 * produced so far. For compressed data, it could be the byte offset in a
72 * source or destination file. Likewise, the end offset will be the offset of
73 * the end of the buffer. These can only be meaningfully interpreted if you
74 * know the media type of the buffer (the preceeding CAPS event). Either or both
75 * can be set to #GST_BUFFER_OFFSET_NONE.
77 * gst_buffer_ref() is used to increase the refcount of a buffer. This must be
78 * done when you want to keep a handle to the buffer after pushing it to the
79 * next element. The buffer refcount determines the writability of the buffer, a
80 * buffer is only writable when the refcount is exactly 1, i.e. when the caller
81 * has the only reference to the buffer.
83 * To efficiently create a smaller buffer out of an existing one, you can
84 * use gst_buffer_copy_region(). This method tries to share the memory objects
85 * between the two buffers.
87 * If a plug-in wants to modify the buffer data or metadata in-place, it should
88 * first obtain a buffer that is safe to modify by using
89 * gst_buffer_make_writable(). This function is optimized so that a copy will
90 * only be made when it is necessary.
92 * Several flags of the buffer can be set and unset with the
93 * GST_BUFFER_FLAG_SET() and GST_BUFFER_FLAG_UNSET() macros. Use
94 * GST_BUFFER_FLAG_IS_SET() to test if a certain #GstBufferFlag is set.
96 * Buffers can be efficiently merged into a larger buffer with
97 * gst_buffer_append(). Copying of memory will only be done when absolutely
100 * Arbitrary extra metadata can be set on a buffer with gst_buffer_add_meta().
101 * Metadata can be retrieved with gst_buffer_get_meta(). See also #GstMeta
103 * An element should either unref the buffer or push it out on a src pad
104 * using gst_pad_push() (see #GstPad).
106 * Buffers are usually freed by unreffing them with gst_buffer_unref(). When
107 * the refcount drops to 0, any memory and metadata pointed to by the buffer is
108 * unreffed as well. Buffers allocated from a #GstBufferPool will be returned to
109 * the pool when the refcount drops to 0.
111 * Last reviewed on 2012-03-28 (0.11.3)
113 #include "gst_private.h"
122 #include "gstbuffer.h"
123 #include "gstbufferpool.h"
125 #include "gstutils.h"
126 #include "gstversion.h"
128 GType _gst_buffer_type = 0;
130 typedef struct _GstMetaItem GstMetaItem;
137 #define ITEM_SIZE(info) ((info)->size + sizeof (GstMetaItem))
139 #define GST_BUFFER_MEM_MAX 16
141 #define GST_BUFFER_SLICE_SIZE(b) (((GstBufferImpl *)(b))->slice_size)
142 #define GST_BUFFER_MEM_LEN(b) (((GstBufferImpl *)(b))->len)
143 #define GST_BUFFER_MEM_ARRAY(b) (((GstBufferImpl *)(b))->mem)
144 #define GST_BUFFER_MEM_PTR(b,i) (((GstBufferImpl *)(b))->mem[i])
145 #define GST_BUFFER_BUFMEM(b) (((GstBufferImpl *)(b))->bufmem)
146 #define GST_BUFFER_META(b) (((GstBufferImpl *)(b))->item)
154 /* the memory blocks */
156 GstMemory *mem[GST_BUFFER_MEM_MAX];
158 /* memory of the buffer when allocated from 1 chunk */
161 /* FIXME, make metadata allocation more efficient by using part of the
168 _is_span (GstMemory ** mem, gsize len, gsize * poffset, GstMemory ** parent)
170 GstMemory *mcur, *mprv;
171 gboolean have_offset = FALSE;
176 for (i = 0; i < len; i++) {
184 /* check if memory is contiguous */
185 if (!gst_memory_is_span (mprv, mcur, &poffs))
192 *parent = mprv->parent;
202 _get_merged_memory (GstBuffer * buffer, guint idx, guint length)
204 GstMemory **mem, *result;
206 GST_LOG ("buffer %p, idx %u, length %u", buffer, idx, length);
208 mem = GST_BUFFER_MEM_ARRAY (buffer);
210 if (G_UNLIKELY (length == 0)) {
212 } else if (G_LIKELY (length == 1)) {
213 result = gst_memory_ref (mem[idx]);
215 GstMemory *parent = NULL;
216 gsize size, poffset = 0;
218 size = gst_buffer_get_size (buffer);
220 if (G_UNLIKELY (_is_span (mem + idx, length, &poffset, &parent))) {
221 if (GST_MEMORY_IS_NO_SHARE (parent)) {
222 GST_CAT_DEBUG (GST_CAT_PERFORMANCE, "copy for merge %p", parent);
223 result = gst_memory_copy (parent, poffset, size);
225 result = gst_memory_share (parent, poffset, size);
228 gsize i, tocopy, left;
229 GstMapInfo sinfo, dinfo;
232 result = gst_allocator_alloc (NULL, size, NULL);
233 gst_memory_map (result, &dinfo, GST_MAP_WRITE);
238 for (i = idx; i < length && left > 0; i++) {
239 gst_memory_map (mem[i], &sinfo, GST_MAP_READ);
240 tocopy = MIN (sinfo.size, left);
241 GST_CAT_DEBUG (GST_CAT_PERFORMANCE,
242 "memcpy %" G_GSIZE_FORMAT " bytes for merge %p from memory %p",
243 tocopy, result, mem[i]);
244 memcpy (ptr, (guint8 *) sinfo.data, tocopy);
247 gst_memory_unmap (mem[i], &sinfo);
249 gst_memory_unmap (result, &dinfo);
256 _replace_memory (GstBuffer * buffer, guint len, guint idx, guint length,
263 GST_LOG ("buffer %p replace %u-%" G_GSIZE_FORMAT " with memory %p", buffer,
266 /* unref old memory */
267 for (i = idx; i < end; i++) {
268 GstMemory *old = GST_BUFFER_MEM_PTR (buffer, i);
270 gst_memory_unlock (old, GST_LOCK_FLAG_EXCLUSIVE);
271 gst_memory_unref (old);
275 /* replace with single memory */
276 gst_memory_lock (mem, GST_LOCK_FLAG_EXCLUSIVE);
277 GST_BUFFER_MEM_PTR (buffer, idx) = mem;
283 g_memmove (&GST_BUFFER_MEM_PTR (buffer, idx),
284 &GST_BUFFER_MEM_PTR (buffer, end), (len - end) * sizeof (gpointer));
286 GST_BUFFER_MEM_LEN (buffer) = len - length;
290 _memory_add (GstBuffer * buffer, gint idx, GstMemory * mem, gboolean lock)
292 guint i, len = GST_BUFFER_MEM_LEN (buffer);
294 GST_LOG ("buffer %p, idx %d, mem %p, lock %d", buffer, idx, mem, lock);
296 if (G_UNLIKELY (len >= GST_BUFFER_MEM_MAX)) {
297 /* too many buffer, span them. */
298 /* FIXME, there is room for improvement here: We could only try to merge
299 * 2 buffers to make some room. If we can't efficiently merge 2 buffers we
300 * could try to only merge the two smallest buffers to avoid memcpy, etc. */
301 GST_CAT_DEBUG (GST_CAT_PERFORMANCE, "memory array overflow in buffer %p",
303 _replace_memory (buffer, len, 0, len, _get_merged_memory (buffer, 0, len));
304 /* we now have 1 single spanned buffer */
311 for (i = len; i > idx; i--) {
312 /* move buffers to insert, FIXME, we need to insert first and then merge */
313 GST_BUFFER_MEM_PTR (buffer, i) = GST_BUFFER_MEM_PTR (buffer, i - 1);
315 /* and insert the new buffer */
317 gst_memory_lock (mem, GST_LOCK_FLAG_EXCLUSIVE);
318 GST_BUFFER_MEM_PTR (buffer, idx) = mem;
319 GST_BUFFER_MEM_LEN (buffer) = len + 1;
322 GST_DEFINE_MINI_OBJECT_TYPE (GstBuffer, gst_buffer);
325 _priv_gst_buffer_initialize (void)
327 _gst_buffer_type = gst_buffer_get_type ();
331 * gst_buffer_copy_into:
332 * @dest: a destination #GstBuffer
333 * @src: a source #GstBuffer
334 * @flags: flags indicating what metadata fields should be copied.
335 * @offset: offset to copy from
336 * @size: total size to copy. If -1, all data is copied.
338 * Copies the information from @src into @dest.
340 * If @dest already contains memory and @flags contains GST_BUFFER_COPY_MEMORY,
341 * the memory from @src will be appended to @dest.
343 * @flags indicate which fields will be copied.
346 gst_buffer_copy_into (GstBuffer * dest, GstBuffer * src,
347 GstBufferCopyFlags flags, gsize offset, gsize size)
351 gboolean region = FALSE;
353 g_return_if_fail (dest != NULL);
354 g_return_if_fail (src != NULL);
356 /* nothing to copy if the buffers are the same */
357 if (G_UNLIKELY (dest == src))
360 g_return_if_fail (gst_buffer_is_writable (dest));
362 bufsize = gst_buffer_get_size (src);
363 g_return_if_fail (bufsize >= offset);
367 size = bufsize - offset;
370 g_return_if_fail (bufsize >= offset + size);
372 GST_CAT_LOG (GST_CAT_BUFFER, "copy %p to %p, offset %" G_GSIZE_FORMAT
373 "-%" G_GSIZE_FORMAT "/%" G_GSIZE_FORMAT, src, dest, offset, size,
376 if (flags & GST_BUFFER_COPY_FLAGS) {
378 GST_MINI_OBJECT_FLAGS (dest) = GST_MINI_OBJECT_FLAGS (src);
381 if (flags & GST_BUFFER_COPY_TIMESTAMPS) {
383 GST_BUFFER_PTS (dest) = GST_BUFFER_PTS (src);
384 GST_BUFFER_DTS (dest) = GST_BUFFER_DTS (src);
385 GST_BUFFER_OFFSET (dest) = GST_BUFFER_OFFSET (src);
386 if (size == bufsize) {
387 GST_BUFFER_DURATION (dest) = GST_BUFFER_DURATION (src);
388 GST_BUFFER_OFFSET_END (dest) = GST_BUFFER_OFFSET_END (src);
391 GST_BUFFER_PTS (dest) = GST_CLOCK_TIME_NONE;
392 GST_BUFFER_DTS (dest) = GST_CLOCK_TIME_NONE;
393 GST_BUFFER_DURATION (dest) = GST_CLOCK_TIME_NONE;
394 GST_BUFFER_OFFSET (dest) = GST_BUFFER_OFFSET_NONE;
395 GST_BUFFER_OFFSET_END (dest) = GST_BUFFER_OFFSET_NONE;
399 if (flags & GST_BUFFER_COPY_MEMORY) {
401 gsize skip, left, len, i, bsize;
403 len = GST_BUFFER_MEM_LEN (src);
407 /* copy and make regions of the memory */
408 for (i = 0; i < len && left > 0; i++) {
409 mem = GST_BUFFER_MEM_PTR (src, i);
410 bsize = gst_memory_get_sizes (mem, NULL, NULL);
413 /* don't copy buffer */
418 tocopy = MIN (bsize - skip, left);
419 if (GST_MEMORY_IS_NO_SHARE (mem)) {
420 /* no share, always copy then */
421 mem = gst_memory_copy (mem, skip, tocopy);
423 } else if (tocopy < bsize) {
424 /* we need to clip something */
425 mem = gst_memory_share (mem, skip, tocopy);
428 mem = gst_memory_ref (mem);
430 _memory_add (dest, -1, mem, TRUE);
434 if (flags & GST_BUFFER_COPY_MERGE) {
435 len = GST_BUFFER_MEM_LEN (dest);
436 _replace_memory (dest, len, 0, len, _get_merged_memory (dest, 0, len));
440 if (flags & GST_BUFFER_COPY_META) {
441 for (walk = GST_BUFFER_META (src); walk; walk = walk->next) {
442 GstMeta *meta = &walk->meta;
443 const GstMetaInfo *info = meta->info;
445 if (info->transform_func) {
446 GstMetaTransformCopy copy_data;
448 copy_data.region = region;
449 copy_data.offset = offset;
450 copy_data.size = size;
452 info->transform_func (dest, meta, src,
453 _gst_meta_transform_copy, ©_data);
460 _gst_buffer_copy (GstBuffer * buffer)
464 g_return_val_if_fail (buffer != NULL, NULL);
466 /* create a fresh new buffer */
467 copy = gst_buffer_new ();
469 /* we simply copy everything from our parent */
470 gst_buffer_copy_into (copy, buffer, GST_BUFFER_COPY_ALL, 0, -1);
475 /* the default dispose function revives the buffer and returns it to the
476 * pool when there is a pool */
478 _gst_buffer_dispose (GstBuffer * buffer)
482 /* no pool, do free */
483 if ((pool = buffer->pool) == NULL)
486 /* keep the buffer alive */
487 gst_buffer_ref (buffer);
488 /* return the buffer to the pool */
489 GST_CAT_LOG (GST_CAT_BUFFER, "release %p to pool %p", buffer, pool);
490 gst_buffer_pool_release_buffer (pool, buffer);
496 _gst_buffer_free (GstBuffer * buffer)
498 GstMetaItem *walk, *next;
502 g_return_if_fail (buffer != NULL);
504 GST_CAT_LOG (GST_CAT_BUFFER, "finalize %p", buffer);
507 for (walk = GST_BUFFER_META (buffer); walk; walk = next) {
508 GstMeta *meta = &walk->meta;
509 const GstMetaInfo *info = meta->info;
511 /* call free_func if any */
513 info->free_func (meta, buffer);
516 /* and free the slice */
517 g_slice_free1 (ITEM_SIZE (info), walk);
520 /* get the size, when unreffing the memory, we could also unref the buffer
522 msize = GST_BUFFER_SLICE_SIZE (buffer);
524 /* free our memory */
525 len = GST_BUFFER_MEM_LEN (buffer);
526 for (i = 0; i < len; i++) {
527 gst_memory_unlock (GST_BUFFER_MEM_PTR (buffer, i), GST_LOCK_FLAG_EXCLUSIVE);
528 gst_memory_unref (GST_BUFFER_MEM_PTR (buffer, i));
531 /* we set msize to 0 when the buffer is part of the memory block */
533 g_slice_free1 (msize, buffer);
535 gst_memory_unref (GST_BUFFER_BUFMEM (buffer));
539 gst_buffer_init (GstBufferImpl * buffer, gsize size)
541 gst_mini_object_init (GST_MINI_OBJECT_CAST (buffer), 0, _gst_buffer_type,
542 (GstMiniObjectCopyFunction) _gst_buffer_copy,
543 (GstMiniObjectDisposeFunction) _gst_buffer_dispose,
544 (GstMiniObjectFreeFunction) _gst_buffer_free);
546 GST_BUFFER_SLICE_SIZE (buffer) = size;
548 GST_BUFFER (buffer)->pool = NULL;
549 GST_BUFFER_PTS (buffer) = GST_CLOCK_TIME_NONE;
550 GST_BUFFER_DTS (buffer) = GST_CLOCK_TIME_NONE;
551 GST_BUFFER_DURATION (buffer) = GST_CLOCK_TIME_NONE;
552 GST_BUFFER_OFFSET (buffer) = GST_BUFFER_OFFSET_NONE;
553 GST_BUFFER_OFFSET_END (buffer) = GST_BUFFER_OFFSET_NONE;
555 GST_BUFFER_MEM_LEN (buffer) = 0;
556 GST_BUFFER_META (buffer) = NULL;
562 * Creates a newly allocated buffer without any data.
566 * Returns: (transfer full): the new #GstBuffer.
569 gst_buffer_new (void)
571 GstBufferImpl *newbuf;
573 newbuf = g_slice_new (GstBufferImpl);
574 GST_CAT_LOG (GST_CAT_BUFFER, "new %p", newbuf);
576 gst_buffer_init (newbuf, sizeof (GstBufferImpl));
578 return GST_BUFFER_CAST (newbuf);
582 * gst_buffer_new_allocate:
583 * @allocator: (transfer none) (allow-none): the #GstAllocator to use, or NULL to use the
585 * @size: the size in bytes of the new buffer's data.
586 * @params: (transfer none) (allow-none): optional parameters
588 * Tries to create a newly allocated buffer with data of the given size and
589 * extra parameters from @allocator. If the requested amount of memory can't be
590 * allocated, NULL will be returned. The allocated buffer memory is not cleared.
592 * When @allocator is NULL, the default memory allocator will be used.
594 * Note that when @size == 0, the buffer will not have memory associated with it.
598 * Returns: (transfer full): a new #GstBuffer, or NULL if the memory couldn't
602 gst_buffer_new_allocate (GstAllocator * allocator, gsize size,
603 GstAllocationParams * params)
614 mem = gst_allocator_alloc (allocator, size, params);
615 if (G_UNLIKELY (mem == NULL))
621 newbuf = gst_buffer_new ();
624 _memory_add (newbuf, -1, mem, TRUE);
626 GST_CAT_LOG (GST_CAT_BUFFER,
627 "new buffer %p of size %" G_GSIZE_FORMAT " from allocator %p", newbuf,
632 asize = sizeof (GstBufferImpl) + size;
633 data = g_slice_alloc (asize);
634 if (G_UNLIKELY (data == NULL))
637 newbuf = GST_BUFFER_CAST (data);
639 gst_buffer_init ((GstBufferImpl *) data, asize);
641 mem = gst_memory_new_wrapped (0, data + sizeof (GstBufferImpl), NULL,
643 _memory_add (newbuf, -1, mem, TRUE);
648 /* allocate memory and buffer, it might be interesting to do this but there
649 * are many complications. We need to keep the memory mapped to access the
650 * buffer fields and the memory for the buffer might be just very slow. We
651 * also need to do some more magic to get the alignment right. */
652 asize = sizeof (GstBufferImpl) + size;
653 mem = gst_allocator_alloc (allocator, asize, align);
654 if (G_UNLIKELY (mem == NULL))
657 /* map the data part and init the buffer in it, set the buffer size to 0 so
658 * that a finalize won't free the buffer */
659 data = gst_memory_map (mem, &asize, NULL, GST_MAP_WRITE);
660 gst_buffer_init ((GstBufferImpl *) data, 0);
661 gst_memory_unmap (mem);
663 /* strip off the buffer */
664 gst_memory_resize (mem, sizeof (GstBufferImpl), size);
666 newbuf = GST_BUFFER_CAST (data);
667 GST_BUFFER_BUFMEM (newbuf) = mem;
670 _memory_add (newbuf, -1, gst_memory_ref (mem), TRUE);
678 GST_CAT_WARNING (GST_CAT_BUFFER,
679 "failed to allocate %" G_GSIZE_FORMAT " bytes", size);
685 * gst_buffer_new_wrapped_full:
686 * @flags: #GstMemoryFlags
687 * @data: data to wrap
688 * @maxsize: allocated size of @data
689 * @offset: offset in @data
690 * @size: size of valid data
691 * @user_data: user_data
692 * @notify: called with @user_data when the memory is freed
694 * Allocate a new buffer that wraps the given memory. @data must point to
695 * @maxsize of memory, the wrapped buffer will have the region from @offset and
698 * When the buffer is destroyed, @notify will be called with @user_data.
700 * The prefix/padding must be filled with 0 if @flags contains
701 * #GST_MEMORY_FLAG_ZERO_PREFIXED and #GST_MEMORY_FLAG_ZERO_PADDED respectively.
703 * Returns: (transfer full): a new #GstBuffer
706 gst_buffer_new_wrapped_full (GstMemoryFlags flags, gpointer data,
707 gsize maxsize, gsize offset, gsize size, gpointer user_data,
708 GDestroyNotify notify)
712 newbuf = gst_buffer_new ();
713 gst_buffer_append_memory (newbuf,
714 gst_memory_new_wrapped (flags, data, maxsize, offset, size,
721 * gst_buffer_new_wrapped:
722 * @data: data to wrap
723 * @size: allocated size of @data
725 * Creates a new buffer that wraps the given @data. The memory will be freed
726 * with g_free and will be marked writable.
730 * Returns: (transfer full): a new #GstBuffer
733 gst_buffer_new_wrapped (gpointer data, gsize size)
735 return gst_buffer_new_wrapped_full (0, data, size, 0, size, data, g_free);
739 * gst_buffer_n_memory:
740 * @buffer: a #GstBuffer.
742 * Get the amount of memory blocks that this buffer has.
744 * Returns: (transfer full): the amount of memory block in this buffer.
747 gst_buffer_n_memory (GstBuffer * buffer)
749 g_return_val_if_fail (GST_IS_BUFFER (buffer), 0);
751 return GST_BUFFER_MEM_LEN (buffer);
755 * gst_buffer_prepend_memory:
757 * @m: (transfer full): a #GstMemory.
759 * Prepend the memory block @m to @b. This function takes ownership
760 * of @m and thus doesn't increase its refcount.
763 * gst_buffer_append_memory:
765 * @m: (transfer full): a #GstMemory.
767 * Append the memory block @m to @b. This function takes ownership
768 * of @m and thus doesn't increase its refcount.
771 * gst_buffer_insert_memory:
772 * @buffer: a #GstBuffer.
773 * @idx: the index to add the memory at, or -1 to append it to the end
774 * @mem: (transfer full): a #GstMemory.
776 * Insert the memory block @mem to @buffer at @idx. This function takes ownership
777 * of @mem and thus doesn't increase its refcount.
780 gst_buffer_insert_memory (GstBuffer * buffer, gint idx, GstMemory * mem)
782 g_return_if_fail (GST_IS_BUFFER (buffer));
783 g_return_if_fail (gst_buffer_is_writable (buffer));
784 g_return_if_fail (mem != NULL);
785 g_return_if_fail (idx == -1 ||
786 (idx >= 0 && idx <= GST_BUFFER_MEM_LEN (buffer)));
788 _memory_add (buffer, idx, mem, TRUE);
792 _get_mapped (GstBuffer * buffer, guint idx, GstMapInfo * info,
795 GstMemory *mem, *mapped;
797 mem = gst_memory_ref (GST_BUFFER_MEM_PTR (buffer, idx));
799 mapped = gst_memory_make_mapped (mem, info, flags);
802 /* memory changed, lock new memory */
803 gst_memory_lock (mapped, GST_LOCK_FLAG_EXCLUSIVE);
804 GST_BUFFER_MEM_PTR (buffer, idx) = mapped;
805 /* unlock old memory */
806 gst_memory_unlock (mem, GST_LOCK_FLAG_EXCLUSIVE);
808 gst_memory_unref (mem);
814 * gst_buffer_peek_memory:
815 * @buffer: a #GstBuffer.
818 * Get the memory block at @idx in @buffer. The memory block stays valid until
819 * the memory block in @buffer is removed, replaced or merged, typically with
820 * any call that modifies the memory in @buffer.
822 * Since this call does not influence the refcount of the memory,
823 * gst_memory_is_writable() can be used to check if @buffer is the sole owner
824 * of the returned memory.
826 * Returns: (transfer none): the #GstMemory at @idx.
829 gst_buffer_peek_memory (GstBuffer * buffer, guint idx)
833 g_return_val_if_fail (GST_IS_BUFFER (buffer), NULL);
834 len = GST_BUFFER_MEM_LEN (buffer);
835 g_return_val_if_fail (idx < len, NULL);
837 return GST_BUFFER_MEM_PTR (buffer, idx);
841 * gst_buffer_get_memory:
845 * Get the memory block at index @i in @buffer.
847 * Returns: (transfer full): a #GstMemory that contains the data of the
848 * memory block at @idx. Use gst_memory_unref () after usage.
851 * gst_buffer_get_all_memory:
854 * Get all the memory block in @buffer. The memory blocks will be merged
855 * into one large #GstMemory.
857 * Returns: (transfer full): a #GstMemory that contains the merged memory.
858 * Use gst_memory_unref () after usage.
861 * gst_buffer_get_memory_range:
862 * @buffer: a #GstBuffer.
866 * Get @length memory blocks in @buffer starting at @idx. The memory blocks will
867 * be merged into one large #GstMemory.
869 * If @length is -1, all memory starting from @idx is merged.
871 * Returns: (transfer full): a #GstMemory that contains the merged data of @length
872 * blocks starting at @idx. Use gst_memory_unref () after usage.
875 gst_buffer_get_memory_range (GstBuffer * buffer, guint idx, gint length)
879 GST_DEBUG ("idx %u, length %d", idx, length);
881 g_return_val_if_fail (GST_IS_BUFFER (buffer), NULL);
882 len = GST_BUFFER_MEM_LEN (buffer);
883 g_return_val_if_fail ((len == 0 && idx == 0 && length == -1) ||
884 (length == -1 && idx < len) || (length > 0 && length + idx <= len), NULL);
889 return _get_merged_memory (buffer, idx, length);
893 * gst_buffer_replace_memory:
896 * @m: (transfer full): a #GstMemory
898 * Replaces the memory block at index @i in @b with @m.
901 * gst_buffer_replace_all_memory:
903 * @m: (transfer full): a #GstMemory
905 * Replaces all memory in @b with @m.
908 * gst_buffer_replace_memory_range:
909 * @buffer: a #GstBuffer.
911 * @length: a length should not be 0
912 * @mem: (transfer full): a #GstMemory
914 * Replaces @length memory blocks in @buffer starting at @idx with @mem.
916 * If @length is -1, all memory starting from @idx will be removed and
917 * replaced with @mem.
919 * @buffer should be writable.
922 gst_buffer_replace_memory_range (GstBuffer * buffer, guint idx, gint length,
927 g_return_if_fail (GST_IS_BUFFER (buffer));
928 g_return_if_fail (gst_buffer_is_writable (buffer));
930 len = GST_BUFFER_MEM_LEN (buffer);
931 g_return_if_fail ((len == 0 && idx == 0 && length == -1) ||
932 (length == -1 && idx < len) || (length > 0 && length + idx <= len));
937 _replace_memory (buffer, len, idx, length, mem);
941 * gst_buffer_remove_memory:
945 * Remove the memory block in @b at index @i.
948 * gst_buffer_remove_all_memory:
951 * Remove all the memory blocks in @b.
954 * gst_buffer_remove_memory_range:
955 * @buffer: a #GstBuffer.
959 * Remove @length memory blocks in @buffer starting from @idx.
961 * @length can be -1, in which case all memory starting from @idx is removed.
964 gst_buffer_remove_memory_range (GstBuffer * buffer, guint idx, gint length)
968 g_return_if_fail (GST_IS_BUFFER (buffer));
969 g_return_if_fail (gst_buffer_is_writable (buffer));
971 len = GST_BUFFER_MEM_LEN (buffer);
972 g_return_if_fail ((len == 0 && idx == 0 && length == -1) ||
973 (length == -1 && idx < len) || length + idx <= len);
978 _replace_memory (buffer, len, idx, length, NULL);
982 * gst_buffer_find_memory:
983 * @buffer: a #GstBuffer.
986 * @idx: (out): pointer to index
987 * @length: (out): pointer to length
988 * @skip: (out): pointer to skip
990 * Find the memory blocks that span @size bytes starting from @offset
993 * When this function returns %TRUE, @idx will contain the index of the first
994 * memory bock where the byte for @offset can be found and @length contains the
995 * number of memory blocks containing the @size remaining bytes. @skip contains
996 * the number of bytes to skip in the memory bock at @idx to get to the byte
999 * @size can be -1 to get all the memory blocks after @idx.
1001 * Returns: %TRUE when @size bytes starting from @offset could be found in
1002 * @buffer and @idx, @length and @skip will be filled.
1005 gst_buffer_find_memory (GstBuffer * buffer, gsize offset, gsize size,
1006 guint * idx, guint * length, gsize * skip)
1008 guint i, len, found;
1010 g_return_val_if_fail (GST_IS_BUFFER (buffer), FALSE);
1011 g_return_val_if_fail (idx != NULL, FALSE);
1012 g_return_val_if_fail (length != NULL, FALSE);
1013 g_return_val_if_fail (skip != NULL, FALSE);
1015 len = GST_BUFFER_MEM_LEN (buffer);
1018 for (i = 0; i < len; i++) {
1022 mem = GST_BUFFER_MEM_PTR (buffer, i);
1023 s = gst_memory_get_sizes (mem, NULL, NULL);
1026 /* block before offset, or empty block, skip */
1029 /* block after offset */
1031 /* first block, remember index and offset */
1035 /* return remaining blocks */
1042 /* count the amount of found bytes */
1044 if (found >= size) {
1045 /* we have enough bytes */
1046 *length = i - *idx + 1;
1055 * gst_buffer_get_sizes:
1057 * @of: a pointer to the offset
1058 * @ms: a pointer to the maxsize
1060 * Get the total size of the memory blocks in @b.
1062 * When not %NULL, @of will contain the offset of the data in the first
1063 * memory block in @buffer and @maxsize will contain the sum of the size
1064 * and @of and the amount of extra padding on the last memory block.
1065 * @of and @ms can be used to resize the buffer memory blocks with
1066 * gst_buffer_resize().
1068 * Returns: total size of the memory blocks in @b.
1071 * gst_buffer_get_size:
1074 * Get the total size of the memory blocks in @b.
1076 * Returns: total size of the memory blocks in @b.
1079 * gst_buffer_get_sizes_range:
1080 * @buffer: a #GstBuffer.
1083 * @offset: a pointer to the offset
1084 * @maxsize: a pointer to the maxsize
1086 * Get the total size of @length memory blocks stating from @idx in @buffer.
1088 * When not %NULL, @offset will contain the offset of the data in the
1089 * memory block in @buffer at @idx and @maxsize will contain the sum of the size
1090 * and @offset and the amount of extra padding on the memory block at @idx +
1092 * @offset and @maxsize can be used to resize the buffer memory blocks with
1093 * gst_buffer_resize_range().
1095 * Returns: total size of @length memory blocks starting at @idx in @buffer.
1098 gst_buffer_get_sizes_range (GstBuffer * buffer, guint idx, gint length,
1099 gsize * offset, gsize * maxsize)
1105 g_return_val_if_fail (GST_IS_BUFFER (buffer), 0);
1106 len = GST_BUFFER_MEM_LEN (buffer);
1107 g_return_val_if_fail ((len == 0 && idx == 0 && length == -1) ||
1108 (length == -1 && idx < len) || (length + idx <= len), 0);
1113 if (G_LIKELY (length == 1)) {
1115 mem = GST_BUFFER_MEM_PTR (buffer, idx);
1116 size = gst_memory_get_sizes (mem, offset, maxsize);
1122 size = offs = extra = 0;
1123 for (i = idx; i < end; i++) {
1126 mem = GST_BUFFER_MEM_PTR (buffer, i);
1127 s = gst_memory_get_sizes (mem, &o, &ms);
1131 /* first size, take accumulated data before as the offset */
1135 /* save the amount of data after this block */
1136 extra = ms - (o + s);
1138 /* empty block, add as extra */
1145 *maxsize = offs + size + extra;
1151 * gst_buffer_resize:
1153 * @of: the offset adjustement
1154 * @s: the new size or -1 to just adjust the offset
1156 * Set the offset and total size of the memory blocks in @b.
1159 * gst_buffer_set_size:
1163 * Set the total size of the memory blocks in @b.
1166 * gst_buffer_resize_range:
1167 * @buffer: a #GstBuffer.
1170 * @offset: the offset adjustement
1171 * @size: the new size or -1 to just adjust the offset
1173 * Set the total size of the @length memory blocks starting at @idx in
1177 gst_buffer_resize_range (GstBuffer * buffer, guint idx, gint length,
1178 gssize offset, gssize size)
1181 gsize bsize, bufsize, bufoffs, bufmax;
1183 g_return_if_fail (gst_buffer_is_writable (buffer));
1184 g_return_if_fail (size >= -1);
1185 len = GST_BUFFER_MEM_LEN (buffer);
1186 g_return_if_fail ((len == 0 && idx == 0 && length == -1) ||
1187 (length == -1 && idx < len) || (length + idx <= len));
1192 bufsize = gst_buffer_get_sizes_range (buffer, idx, length, &bufoffs, &bufmax);
1194 GST_CAT_LOG (GST_CAT_BUFFER, "trim %p %" G_GSSIZE_FORMAT "-%" G_GSSIZE_FORMAT
1195 " size:%" G_GSIZE_FORMAT " offs:%" G_GSIZE_FORMAT " max:%"
1196 G_GSIZE_FORMAT, buffer, offset, size, bufsize, bufoffs, bufmax);
1198 /* we can't go back further than the current offset or past the end of the
1200 g_return_if_fail ((offset < 0 && bufoffs >= -offset) || (offset >= 0
1201 && bufoffs + offset <= bufmax));
1203 g_return_if_fail (bufsize >= offset);
1204 size = bufsize - offset;
1206 g_return_if_fail (bufmax >= bufoffs + offset + size);
1209 if (offset == 0 && size == bufsize)
1214 for (i = idx; i < end; i++) {
1218 mem = GST_BUFFER_MEM_PTR (buffer, i);
1219 bsize = gst_memory_get_sizes (mem, NULL, NULL);
1222 /* last buffer always gets resized to the remaining size */
1225 /* shrink buffers before the offset */
1226 else if ((gssize) bsize <= offset) {
1228 noffs = offset - bsize;
1231 /* clip other buffers */
1233 left = MIN (bsize - offset, size);
1235 if (offset != 0 || left != bsize) {
1236 if (gst_memory_is_writable (mem)) {
1237 gst_memory_resize (mem, offset, left);
1241 if (GST_MEMORY_IS_NO_SHARE (mem))
1242 newmem = gst_memory_copy (mem, offset, left);
1244 newmem = gst_memory_share (mem, offset, left);
1246 gst_memory_lock (newmem, GST_LOCK_FLAG_EXCLUSIVE);
1247 GST_BUFFER_MEM_PTR (buffer, i) = newmem;
1248 gst_memory_unlock (mem, GST_LOCK_FLAG_EXCLUSIVE);
1249 gst_memory_unref (mem);
1261 * @i: (out): info about the mapping
1262 * @f: flags for the mapping
1264 * This function fills @i with the #GstMapInfo of all merged memory blocks
1267 * @flags describe the desired access of the memory. When @flags is
1268 * #GST_MAP_WRITE, @buffer should be writable (as returned from
1269 * gst_buffer_is_writable()).
1271 * When @buffer is writable but the memory isn't, a writable copy will
1272 * automatically be created and returned. The readonly copy of the buffer memory
1273 * will then also be replaced with this writable copy.
1275 * The memory in @i should be unmapped with gst_buffer_unmap() after usage.
1277 * Returns: %TRUE if the map succeeded and @i contains valid data.
1280 * gst_buffer_map_range:
1281 * @buffer: a #GstBuffer.
1284 * @info: (out): info about the mapping
1285 * @flags: flags for the mapping
1287 * This function fills @info with the #GstMapInfo of @length merged memory blocks
1288 * starting at @idx in @buffer. When @length is -1, all memory blocks starting
1289 * from @idx are merged and mapped.
1291 * @flags describe the desired access of the memory. When @flags is
1292 * #GST_MAP_WRITE, @buffer should be writable (as returned from
1293 * gst_buffer_is_writable()).
1295 * When @buffer is writable but the memory isn't, a writable copy will
1296 * automatically be created and returned. The readonly copy of the buffer memory
1297 * will then also be replaced with this writable copy.
1299 * The memory in @info should be unmapped with gst_buffer_unmap() after usage.
1301 * Returns: %TRUE if the map succeeded and @info contains valid
1305 gst_buffer_map_range (GstBuffer * buffer, guint idx, gint length,
1306 GstMapInfo * info, GstMapFlags flags)
1308 GstMemory *mem, *nmem;
1309 gboolean write, writable;
1312 g_return_val_if_fail (GST_IS_BUFFER (buffer), FALSE);
1313 g_return_val_if_fail (info != NULL, FALSE);
1314 len = GST_BUFFER_MEM_LEN (buffer);
1315 g_return_val_if_fail ((len == 0 && idx == 0 && length == -1) ||
1316 (length == -1 && idx < len) || (length > 0
1317 && length + idx <= len), FALSE);
1319 GST_LOG ("buffer %p, idx %u, length %d, flags %04x", buffer, idx, length,
1322 write = (flags & GST_MAP_WRITE) != 0;
1323 writable = gst_buffer_is_writable (buffer);
1325 /* check if we can write when asked for write access */
1326 if (G_UNLIKELY (write && !writable))
1332 mem = _get_merged_memory (buffer, idx, length);
1333 if (G_UNLIKELY (mem == NULL))
1336 /* now try to map */
1337 nmem = gst_memory_make_mapped (mem, info, flags);
1338 if (G_UNLIKELY (nmem == NULL))
1341 /* if we merged or when the map returned a different memory, we try to replace
1342 * the memory in the buffer */
1343 if (G_UNLIKELY (length > 1 || nmem != mem)) {
1344 /* if the buffer is writable, replace the memory */
1346 _replace_memory (buffer, len, idx, length, gst_memory_ref (nmem));
1349 GST_CAT_DEBUG (GST_CAT_PERFORMANCE,
1350 "temporary mapping for memory %p in buffer %p", nmem, buffer);
1359 GST_WARNING_OBJECT (buffer, "write map requested on non-writable buffer");
1360 g_critical ("write map requested on non-writable buffer");
1365 /* empty buffer, we need to return NULL */
1366 GST_DEBUG_OBJECT (buffer, "can't get buffer memory");
1367 info->memory = NULL;
1375 GST_DEBUG_OBJECT (buffer, "cannot map memory");
1382 * @buffer: a #GstBuffer.
1383 * @info: a #GstMapInfo
1385 * Release the memory previously mapped with gst_buffer_map().
1388 gst_buffer_unmap (GstBuffer * buffer, GstMapInfo * info)
1390 g_return_if_fail (GST_IS_BUFFER (buffer));
1391 g_return_if_fail (info != NULL);
1393 /* we need to check for NULL, it is possible that we tried to map a buffer
1394 * without memory and we should be able to unmap that fine */
1395 if (G_LIKELY (info->memory)) {
1396 gst_memory_unmap (info->memory, info);
1397 gst_memory_unref (info->memory);
1403 * @buffer: a #GstBuffer.
1404 * @offset: the offset to fill
1405 * @src: the source address
1406 * @size: the size to fill
1408 * Copy @size bytes from @src to @buffer at @offset.
1410 * Returns: The amount of bytes copied. This value can be lower than @size
1411 * when @buffer did not contain enough data.
1414 gst_buffer_fill (GstBuffer * buffer, gsize offset, gconstpointer src,
1418 const guint8 *ptr = src;
1420 g_return_val_if_fail (GST_IS_BUFFER (buffer), 0);
1421 g_return_val_if_fail (gst_buffer_is_writable (buffer), 0);
1422 g_return_val_if_fail (src != NULL, 0);
1424 GST_LOG ("buffer %p, offset %" G_GSIZE_FORMAT ", size %" G_GSIZE_FORMAT,
1425 buffer, offset, size);
1427 len = GST_BUFFER_MEM_LEN (buffer);
1430 for (i = 0; i < len && left > 0; i++) {
1435 mem = _get_mapped (buffer, i, &info, GST_MAP_WRITE);
1436 if (info.size > offset) {
1437 /* we have enough */
1438 tocopy = MIN (info.size - offset, left);
1439 memcpy ((guint8 *) info.data + offset, ptr, tocopy);
1444 /* offset past buffer, skip */
1445 offset -= info.size;
1447 gst_memory_unmap (mem, &info);
1453 * gst_buffer_extract:
1454 * @buffer: a #GstBuffer.
1455 * @offset: the offset to extract
1456 * @dest: the destination address
1457 * @size: the size to extract
1459 * Copy @size bytes starting from @offset in @buffer to @dest.
1461 * Returns: The amount of bytes extracted. This value can be lower than @size
1462 * when @buffer did not contain enough data.
1465 gst_buffer_extract (GstBuffer * buffer, gsize offset, gpointer dest, gsize size)
1470 g_return_val_if_fail (GST_IS_BUFFER (buffer), 0);
1471 g_return_val_if_fail (dest != NULL, 0);
1473 GST_LOG ("buffer %p, offset %" G_GSIZE_FORMAT ", size %" G_GSIZE_FORMAT,
1474 buffer, offset, size);
1476 len = GST_BUFFER_MEM_LEN (buffer);
1479 for (i = 0; i < len && left > 0; i++) {
1484 mem = _get_mapped (buffer, i, &info, GST_MAP_READ);
1485 if (info.size > offset) {
1486 /* we have enough */
1487 tocopy = MIN (info.size - offset, left);
1488 memcpy (ptr, (guint8 *) info.data + offset, tocopy);
1493 /* offset past buffer, skip */
1494 offset -= info.size;
1496 gst_memory_unmap (mem, &info);
1502 * gst_buffer_memcmp:
1503 * @buffer: a #GstBuffer.
1504 * @offset: the offset in @buffer
1505 * @mem: the memory to compare
1506 * @size: the size to compare
1508 * Compare @size bytes starting from @offset in @buffer with the memory in @mem.
1510 * Returns: 0 if the memory is equal.
1513 gst_buffer_memcmp (GstBuffer * buffer, gsize offset, gconstpointer mem,
1517 const guint8 *ptr = mem;
1520 g_return_val_if_fail (GST_IS_BUFFER (buffer), 0);
1521 g_return_val_if_fail (mem != NULL, 0);
1523 GST_LOG ("buffer %p, offset %" G_GSIZE_FORMAT ", size %" G_GSIZE_FORMAT,
1524 buffer, offset, size);
1526 len = GST_BUFFER_MEM_LEN (buffer);
1528 for (i = 0; i < len && size > 0 && res == 0; i++) {
1533 mem = _get_mapped (buffer, i, &info, GST_MAP_READ);
1534 if (info.size > offset) {
1535 /* we have enough */
1536 tocmp = MIN (info.size - offset, size);
1537 res = memcmp (ptr, (guint8 *) info.data + offset, tocmp);
1542 /* offset past buffer, skip */
1543 offset -= info.size;
1545 gst_memory_unmap (mem, &info);
1551 * gst_buffer_memset:
1552 * @buffer: a #GstBuffer.
1553 * @offset: the offset in @buffer
1554 * @val: the value to set
1555 * @size: the size to set
1557 * Fill @buf with @size bytes with @val starting from @offset.
1559 * Returns: The amount of bytes filled. This value can be lower than @size
1560 * when @buffer did not contain enough data.
1563 gst_buffer_memset (GstBuffer * buffer, gsize offset, guint8 val, gsize size)
1567 g_return_val_if_fail (GST_IS_BUFFER (buffer), 0);
1568 g_return_val_if_fail (gst_buffer_is_writable (buffer), 0);
1570 GST_LOG ("buffer %p, offset %" G_GSIZE_FORMAT ", val %02x, size %"
1571 G_GSIZE_FORMAT, buffer, offset, val, size);
1573 len = GST_BUFFER_MEM_LEN (buffer);
1576 for (i = 0; i < len && left > 0; i++) {
1581 mem = _get_mapped (buffer, i, &info, GST_MAP_WRITE);
1582 if (info.size > offset) {
1583 /* we have enough */
1584 toset = MIN (info.size - offset, left);
1585 memset ((guint8 *) info.data + offset, val, toset);
1589 /* offset past buffer, skip */
1590 offset -= info.size;
1592 gst_memory_unmap (mem, &info);
1598 * gst_buffer_copy_region:
1599 * @parent: a #GstBuffer.
1600 * @flags: the #GstBufferCopyFlags
1601 * @offset: the offset into parent #GstBuffer at which the new sub-buffer
1603 * @size: the size of the new #GstBuffer sub-buffer, in bytes.
1605 * Creates a sub-buffer from @parent at @offset and @size.
1606 * This sub-buffer uses the actual memory space of the parent buffer.
1607 * This function will copy the offset and timestamp fields when the
1608 * offset is 0. If not, they will be set to #GST_CLOCK_TIME_NONE and
1609 * #GST_BUFFER_OFFSET_NONE.
1610 * If @offset equals 0 and @size equals the total size of @buffer, the
1611 * duration and offset end fields are also copied. If not they will be set
1612 * to #GST_CLOCK_TIME_NONE and #GST_BUFFER_OFFSET_NONE.
1616 * Returns: (transfer full): the new #GstBuffer or NULL if the arguments were
1620 gst_buffer_copy_region (GstBuffer * buffer, GstBufferCopyFlags flags,
1621 gsize offset, gsize size)
1625 g_return_val_if_fail (buffer != NULL, NULL);
1627 /* create the new buffer */
1628 copy = gst_buffer_new ();
1630 GST_CAT_LOG (GST_CAT_BUFFER, "new region copy %p of %p %" G_GSIZE_FORMAT
1631 "-%" G_GSIZE_FORMAT, copy, buffer, offset, size);
1633 gst_buffer_copy_into (copy, buffer, flags, offset, size);
1639 * gst_buffer_append:
1640 * @buf1: (transfer full): the first source #GstBuffer to append.
1641 * @buf2: (transfer full): the second source #GstBuffer to append.
1643 * Append all the memory from @buf2 to @buf1. The result buffer will contain a
1644 * concatenation of the memory of @buf1 and @buf2.
1646 * Returns: (transfer full): the new #GstBuffer that contains the memory
1647 * of the two source buffers.
1650 * gst_buffer_append_region:
1651 * @buf1: (transfer full): the first source #GstBuffer to append.
1652 * @buf2: (transfer full): the second source #GstBuffer to append.
1653 * @offset: the offset in @buf2
1654 * @size: the size or -1 of @buf2
1656 * Append @size bytes at @offset from @buf2 to @buf1. The result buffer will
1657 * contain a concatenation of the memory of @buf1 and the requested region of
1660 * Returns: (transfer full): the new #GstBuffer that contains the memory
1661 * of the two source buffers.
1664 gst_buffer_append_region (GstBuffer * buf1, GstBuffer * buf2, gssize offset,
1669 g_return_val_if_fail (GST_IS_BUFFER (buf1), NULL);
1670 g_return_val_if_fail (GST_IS_BUFFER (buf2), NULL);
1672 buf1 = gst_buffer_make_writable (buf1);
1673 buf2 = gst_buffer_make_writable (buf2);
1675 gst_buffer_resize (buf2, offset, size);
1677 len = GST_BUFFER_MEM_LEN (buf2);
1678 for (i = 0; i < len; i++) {
1681 mem = GST_BUFFER_MEM_PTR (buf2, i);
1682 GST_BUFFER_MEM_PTR (buf2, i) = NULL;
1683 _memory_add (buf1, -1, mem, FALSE);
1686 GST_BUFFER_MEM_LEN (buf2) = 0;
1687 gst_buffer_unref (buf2);
1693 * gst_buffer_get_meta:
1694 * @buffer: a #GstBuffer
1695 * @api: the #GType of an API
1697 * Get the metadata for @api on buffer. When there is no such
1698 * metadata, NULL is returned.
1700 * Returns: (transfer none): the metadata for @api on @buffer.
1703 gst_buffer_get_meta (GstBuffer * buffer, GType api)
1706 GstMeta *result = NULL;
1708 g_return_val_if_fail (buffer != NULL, NULL);
1709 g_return_val_if_fail (api != 0, NULL);
1711 /* find GstMeta of the requested API */
1712 for (item = GST_BUFFER_META (buffer); item; item = item->next) {
1713 GstMeta *meta = &item->meta;
1714 if (meta->info->api == api) {
1723 * gst_buffer_add_meta:
1724 * @buffer: a #GstBuffer
1725 * @info: a #GstMetaInfo
1726 * @params: params for @info
1728 * Add metadata for @info to @buffer using the parameters in @params.
1730 * Returns: (transfer none): the metadata for the api in @info on @buffer.
1733 gst_buffer_add_meta (GstBuffer * buffer, const GstMetaInfo * info,
1737 GstMeta *result = NULL;
1740 g_return_val_if_fail (buffer != NULL, NULL);
1741 g_return_val_if_fail (info != NULL, NULL);
1742 g_return_val_if_fail (gst_buffer_is_writable (buffer), NULL);
1744 /* create a new slice */
1745 size = ITEM_SIZE (info);
1746 item = g_slice_alloc (size);
1747 result = &item->meta;
1748 result->info = info;
1749 result->flags = GST_META_FLAG_NONE;
1751 GST_CAT_DEBUG (GST_CAT_BUFFER,
1752 "alloc metadata %p (%s) of size %" G_GSIZE_FORMAT, result,
1753 g_type_name (info->type), info->size);
1755 /* call the init_func when needed */
1756 if (info->init_func)
1757 if (!info->init_func (result, params, buffer))
1760 /* and add to the list of metadata */
1761 item->next = GST_BUFFER_META (buffer);
1762 GST_BUFFER_META (buffer) = item;
1768 g_slice_free1 (size, item);
1774 * gst_buffer_remove_meta:
1775 * @buffer: a #GstBuffer
1778 * Remove the metadata for @meta on @buffer.
1780 * Returns: %TRUE if the metadata existed and was removed, %FALSE if no such
1781 * metadata was on @buffer.
1784 gst_buffer_remove_meta (GstBuffer * buffer, GstMeta * meta)
1786 GstMetaItem *walk, *prev;
1788 g_return_val_if_fail (buffer != NULL, FALSE);
1789 g_return_val_if_fail (meta != NULL, FALSE);
1790 g_return_val_if_fail (gst_buffer_is_writable (buffer), FALSE);
1791 g_return_val_if_fail (!GST_META_FLAG_IS_SET (meta, GST_META_FLAG_LOCKED),
1794 /* find the metadata and delete */
1795 prev = GST_BUFFER_META (buffer);
1796 for (walk = prev; walk; walk = walk->next) {
1797 GstMeta *m = &walk->meta;
1799 const GstMetaInfo *info = meta->info;
1801 /* remove from list */
1802 if (GST_BUFFER_META (buffer) == walk)
1803 GST_BUFFER_META (buffer) = walk->next;
1805 prev->next = walk->next;
1806 /* call free_func if any */
1807 if (info->free_func)
1808 info->free_func (m, buffer);
1810 /* and free the slice */
1811 g_slice_free1 (ITEM_SIZE (info), walk);
1816 return walk != NULL;
1820 * gst_buffer_iterate_meta:
1821 * @buffer: a #GstBuffer
1822 * @state: an opaque state pointer
1824 * Retrieve the next #GstMeta after @current. If @state points
1825 * to %NULL, the first metadata is returned.
1827 * @state will be updated with an opage state pointer
1829 * Returns: (transfer none): The next #GstMeta or %NULL when there are
1833 gst_buffer_iterate_meta (GstBuffer * buffer, gpointer * state)
1837 g_return_val_if_fail (buffer != NULL, NULL);
1838 g_return_val_if_fail (state != NULL, NULL);
1840 meta = (GstMetaItem **) state;
1842 /* state NULL, move to first item */
1843 *meta = GST_BUFFER_META (buffer);
1845 /* state !NULL, move to next item in list */
1846 *meta = (*meta)->next;
1849 return &(*meta)->meta;
1855 * gst_buffer_foreach_meta:
1856 * @buffer: a #GstBuffer
1857 * @func: (scope call): a #GstBufferForeachMetaFunc to call
1858 * @user_data: (closure): user data passed to @func
1860 * Call @func with @user_data for each meta in @buffer.
1862 * @func can modify the passed meta pointer or its contents. The return value
1863 * of @func define if this function returns or if the remaining metadata items
1864 * in the buffer should be skipped.
1867 gst_buffer_foreach_meta (GstBuffer * buffer, GstBufferForeachMetaFunc func,
1870 GstMetaItem *walk, *prev, *next;
1872 g_return_if_fail (buffer != NULL);
1873 g_return_if_fail (func != NULL);
1875 /* find the metadata and delete */
1876 prev = GST_BUFFER_META (buffer);
1877 for (walk = prev; walk; walk = next) {
1881 m = new = &walk->meta;
1884 res = func (buffer, &new, user_data);
1887 const GstMetaInfo *info = m->info;
1889 GST_CAT_DEBUG (GST_CAT_BUFFER, "remove metadata %p (%s)", m,
1890 g_type_name (info->type));
1892 g_return_if_fail (gst_buffer_is_writable (buffer));
1893 g_return_if_fail (!GST_META_FLAG_IS_SET (m, GST_META_FLAG_LOCKED));
1895 /* remove from list */
1896 if (GST_BUFFER_META (buffer) == walk)
1897 GST_BUFFER_META (buffer) = next;
1901 /* call free_func if any */
1902 if (info->free_func)
1903 info->free_func (m, buffer);
1905 /* and free the slice */
1906 g_slice_free1 (ITEM_SIZE (info), walk);