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))) {
222 if (GST_MEMORY_IS_NO_SHARE (parent)) {
223 GST_CAT_DEBUG (GST_CAT_PERFORMANCE, "copy for merge %p", parent);
224 result = gst_memory_copy (parent, poffset, size);
226 result = gst_memory_share (parent, poffset, size);
229 gsize i, tocopy, left;
230 GstMapInfo sinfo, dinfo;
233 result = gst_allocator_alloc (NULL, size, NULL);
234 gst_memory_map (result, &dinfo, GST_MAP_WRITE);
239 for (i = idx; i < length && left > 0; i++) {
240 gst_memory_map (mem[i], &sinfo, GST_MAP_READ);
241 tocopy = MIN (sinfo.size, left);
242 GST_CAT_DEBUG (GST_CAT_PERFORMANCE,
243 "memcpy %" G_GSIZE_FORMAT " bytes for merge %p from memory %p",
244 tocopy, result, mem[i]);
245 memcpy (ptr, (guint8 *) sinfo.data, tocopy);
248 gst_memory_unmap (mem[i], &sinfo);
250 gst_memory_unmap (result, &dinfo);
257 _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 gst_memory_unref (GST_BUFFER_MEM_PTR (buffer, i));
271 /* replace with single memory */
272 GST_BUFFER_MEM_PTR (buffer, idx) = mem;
278 g_memmove (&GST_BUFFER_MEM_PTR (buffer, idx),
279 &GST_BUFFER_MEM_PTR (buffer, end), (len - end) * sizeof (gpointer));
281 GST_BUFFER_MEM_LEN (buffer) = len - length;
285 _memory_add (GstBuffer * buffer, gint idx, GstMemory * mem)
287 guint i, len = GST_BUFFER_MEM_LEN (buffer);
289 GST_LOG ("buffer %p, idx %d, mem %p", buffer, idx, mem);
291 if (G_UNLIKELY (len >= GST_BUFFER_MEM_MAX)) {
292 /* too many buffer, span them. */
293 /* FIXME, there is room for improvement here: We could only try to merge
294 * 2 buffers to make some room. If we can't efficiently merge 2 buffers we
295 * could try to only merge the two smallest buffers to avoid memcpy, etc. */
296 GST_CAT_DEBUG (GST_CAT_PERFORMANCE, "memory array overflow in buffer %p",
298 _replace_memory (buffer, len, 0, len, _get_merged_memory (buffer, 0, len));
299 /* we now have 1 single spanned buffer */
306 for (i = len; i > idx; i--) {
307 /* move buffers to insert, FIXME, we need to insert first and then merge */
308 GST_BUFFER_MEM_PTR (buffer, i) = GST_BUFFER_MEM_PTR (buffer, i - 1);
310 /* and insert the new buffer */
311 GST_BUFFER_MEM_PTR (buffer, idx) = mem;
312 GST_BUFFER_MEM_LEN (buffer) = len + 1;
315 GST_DEFINE_MINI_OBJECT_TYPE (GstBuffer, gst_buffer);
318 _priv_gst_buffer_initialize (void)
320 _gst_buffer_type = gst_buffer_get_type ();
324 * gst_buffer_copy_into:
325 * @dest: a destination #GstBuffer
326 * @src: a source #GstBuffer
327 * @flags: flags indicating what metadata fields should be copied.
328 * @offset: offset to copy from
329 * @size: total size to copy. If -1, all data is copied.
331 * Copies the information from @src into @dest.
333 * If @dest already contains memory and @flags contains GST_BUFFER_COPY_MEMORY,
334 * the memory from @src will be appended to @dest.
336 * @flags indicate which fields will be copied.
339 gst_buffer_copy_into (GstBuffer * dest, GstBuffer * src,
340 GstBufferCopyFlags flags, gsize offset, gsize size)
344 gboolean region = FALSE;
346 g_return_if_fail (dest != NULL);
347 g_return_if_fail (src != NULL);
349 /* nothing to copy if the buffers are the same */
350 if (G_UNLIKELY (dest == src))
353 g_return_if_fail (gst_buffer_is_writable (dest));
355 bufsize = gst_buffer_get_size (src);
356 g_return_if_fail (bufsize >= offset);
360 size = bufsize - offset;
363 g_return_if_fail (bufsize >= offset + size);
365 GST_CAT_LOG (GST_CAT_BUFFER, "copy %p to %p, offset %" G_GSIZE_FORMAT
366 "-%" G_GSIZE_FORMAT "/%" G_GSIZE_FORMAT, src, dest, offset, size,
369 if (flags & GST_BUFFER_COPY_FLAGS) {
371 GST_MINI_OBJECT_FLAGS (dest) = GST_MINI_OBJECT_FLAGS (src);
374 if (flags & GST_BUFFER_COPY_TIMESTAMPS) {
376 GST_BUFFER_PTS (dest) = GST_BUFFER_PTS (src);
377 GST_BUFFER_DTS (dest) = GST_BUFFER_DTS (src);
378 GST_BUFFER_OFFSET (dest) = GST_BUFFER_OFFSET (src);
379 if (size == bufsize) {
380 GST_BUFFER_DURATION (dest) = GST_BUFFER_DURATION (src);
381 GST_BUFFER_OFFSET_END (dest) = GST_BUFFER_OFFSET_END (src);
384 GST_BUFFER_PTS (dest) = GST_CLOCK_TIME_NONE;
385 GST_BUFFER_DTS (dest) = GST_CLOCK_TIME_NONE;
386 GST_BUFFER_DURATION (dest) = GST_CLOCK_TIME_NONE;
387 GST_BUFFER_OFFSET (dest) = GST_BUFFER_OFFSET_NONE;
388 GST_BUFFER_OFFSET_END (dest) = GST_BUFFER_OFFSET_NONE;
392 if (flags & GST_BUFFER_COPY_MEMORY) {
394 gsize skip, left, len, i, bsize;
396 len = GST_BUFFER_MEM_LEN (src);
400 /* copy and make regions of the memory */
401 for (i = 0; i < len && left > 0; i++) {
402 mem = GST_BUFFER_MEM_PTR (src, i);
403 bsize = gst_memory_get_sizes (mem, NULL, NULL);
406 /* don't copy buffer */
411 tocopy = MIN (bsize - skip, left);
412 if (GST_MEMORY_IS_NO_SHARE (mem)) {
413 /* no share, always copy then */
414 mem = gst_memory_copy (mem, skip, tocopy);
416 } else if (tocopy < bsize) {
417 /* we need to clip something */
418 mem = gst_memory_share (mem, skip, tocopy);
421 mem = gst_memory_ref (mem);
423 _memory_add (dest, -1, mem);
427 if (flags & GST_BUFFER_COPY_MERGE) {
428 len = GST_BUFFER_MEM_LEN (dest);
429 _replace_memory (dest, len, 0, len, _get_merged_memory (dest, 0, len));
433 if (flags & GST_BUFFER_COPY_META) {
434 for (walk = GST_BUFFER_META (src); walk; walk = walk->next) {
435 GstMeta *meta = &walk->meta;
436 const GstMetaInfo *info = meta->info;
438 if (info->transform_func) {
439 GstMetaTransformCopy copy_data;
441 copy_data.region = region;
442 copy_data.offset = offset;
443 copy_data.size = size;
445 info->transform_func (dest, meta, src,
446 _gst_meta_transform_copy, ©_data);
453 _gst_buffer_copy (GstBuffer * buffer)
457 g_return_val_if_fail (buffer != NULL, NULL);
459 /* create a fresh new buffer */
460 copy = gst_buffer_new ();
462 /* we simply copy everything from our parent */
463 gst_buffer_copy_into (copy, buffer, GST_BUFFER_COPY_ALL, 0, -1);
468 /* the default dispose function revives the buffer and returns it to the
469 * pool when there is a pool */
471 _gst_buffer_dispose (GstBuffer * buffer)
475 /* no pool, do free */
476 if ((pool = buffer->pool) == NULL)
479 /* keep the buffer alive */
480 gst_buffer_ref (buffer);
481 /* return the buffer to the pool */
482 GST_CAT_LOG (GST_CAT_BUFFER, "release %p to pool %p", buffer, pool);
483 gst_buffer_pool_release_buffer (pool, buffer);
489 _gst_buffer_free (GstBuffer * buffer)
491 GstMetaItem *walk, *next;
495 g_return_if_fail (buffer != NULL);
497 GST_CAT_LOG (GST_CAT_BUFFER, "finalize %p", buffer);
500 for (walk = GST_BUFFER_META (buffer); walk; walk = next) {
501 GstMeta *meta = &walk->meta;
502 const GstMetaInfo *info = meta->info;
504 /* call free_func if any */
506 info->free_func (meta, buffer);
509 /* and free the slice */
510 g_slice_free1 (ITEM_SIZE (info), walk);
513 /* get the size, when unreffing the memory, we could also unref the buffer
515 msize = GST_BUFFER_SLICE_SIZE (buffer);
517 /* free our memory */
518 len = GST_BUFFER_MEM_LEN (buffer);
519 for (i = 0; i < len; i++)
520 gst_memory_unref (GST_BUFFER_MEM_PTR (buffer, i));
522 /* we set msize to 0 when the buffer is part of the memory block */
524 g_slice_free1 (msize, buffer);
526 gst_memory_unref (GST_BUFFER_BUFMEM (buffer));
530 gst_buffer_init (GstBufferImpl * buffer, gsize size)
532 gst_mini_object_init (GST_MINI_OBJECT_CAST (buffer), _gst_buffer_type,
533 (GstMiniObjectCopyFunction) _gst_buffer_copy,
534 (GstMiniObjectDisposeFunction) _gst_buffer_dispose,
535 (GstMiniObjectFreeFunction) _gst_buffer_free);
537 GST_BUFFER_SLICE_SIZE (buffer) = size;
539 GST_BUFFER (buffer)->pool = NULL;
540 GST_BUFFER_PTS (buffer) = GST_CLOCK_TIME_NONE;
541 GST_BUFFER_DTS (buffer) = GST_CLOCK_TIME_NONE;
542 GST_BUFFER_DURATION (buffer) = GST_CLOCK_TIME_NONE;
543 GST_BUFFER_OFFSET (buffer) = GST_BUFFER_OFFSET_NONE;
544 GST_BUFFER_OFFSET_END (buffer) = GST_BUFFER_OFFSET_NONE;
546 GST_BUFFER_MEM_LEN (buffer) = 0;
547 GST_BUFFER_META (buffer) = NULL;
553 * Creates a newly allocated buffer without any data.
557 * Returns: (transfer full): the new #GstBuffer.
560 gst_buffer_new (void)
562 GstBufferImpl *newbuf;
564 newbuf = g_slice_new (GstBufferImpl);
565 GST_CAT_LOG (GST_CAT_BUFFER, "new %p", newbuf);
567 gst_buffer_init (newbuf, sizeof (GstBufferImpl));
569 return GST_BUFFER_CAST (newbuf);
573 * gst_buffer_new_allocate:
574 * @allocator: (transfer none) (allow-none): the #GstAllocator to use, or NULL to use the
576 * @size: the size in bytes of the new buffer's data.
577 * @params: (transfer none) (allow-none): optional parameters
579 * Tries to create a newly allocated buffer with data of the given size and
580 * extra parameters from @allocator. If the requested amount of memory can't be
581 * allocated, NULL will be returned. The allocated buffer memory is not cleared.
583 * When @allocator is NULL, the default memory allocator will be used.
585 * Note that when @size == 0, the buffer will not have memory associated with it.
589 * Returns: (transfer full): a new #GstBuffer, or NULL if the memory couldn't
593 gst_buffer_new_allocate (GstAllocator * allocator, gsize size,
594 GstAllocationParams * params)
605 mem = gst_allocator_alloc (allocator, size, params);
606 if (G_UNLIKELY (mem == NULL))
612 newbuf = gst_buffer_new ();
615 _memory_add (newbuf, -1, mem);
617 GST_CAT_LOG (GST_CAT_BUFFER,
618 "new buffer %p of size %" G_GSIZE_FORMAT " from allocator %p", newbuf,
623 asize = sizeof (GstBufferImpl) + size;
624 data = g_slice_alloc (asize);
625 if (G_UNLIKELY (data == NULL))
628 newbuf = GST_BUFFER_CAST (data);
630 gst_buffer_init ((GstBufferImpl *) data, asize);
632 mem = gst_memory_new_wrapped (0, data + sizeof (GstBufferImpl), NULL,
634 _memory_add (newbuf, -1, mem);
639 /* allocate memory and buffer, it might be interesting to do this but there
640 * are many complications. We need to keep the memory mapped to access the
641 * buffer fields and the memory for the buffer might be just very slow. We
642 * also need to do some more magic to get the alignment right. */
643 asize = sizeof (GstBufferImpl) + size;
644 mem = gst_allocator_alloc (allocator, asize, align);
645 if (G_UNLIKELY (mem == NULL))
648 /* map the data part and init the buffer in it, set the buffer size to 0 so
649 * that a finalize won't free the buffer */
650 data = gst_memory_map (mem, &asize, NULL, GST_MAP_WRITE);
651 gst_buffer_init ((GstBufferImpl *) data, 0);
652 gst_memory_unmap (mem);
654 /* strip off the buffer */
655 gst_memory_resize (mem, sizeof (GstBufferImpl), size);
657 newbuf = GST_BUFFER_CAST (data);
658 GST_BUFFER_BUFMEM (newbuf) = mem;
661 _memory_add (newbuf, -1, gst_memory_ref (mem));
669 GST_CAT_WARNING (GST_CAT_BUFFER,
670 "failed to allocate %" G_GSIZE_FORMAT " bytes", size);
676 * gst_buffer_new_wrapped_full:
677 * @flags: #GstMemoryFlags
678 * @data: data to wrap
679 * @maxsize: allocated size of @data
680 * @offset: offset in @data
681 * @size: size of valid data
682 * @user_data: user_data
683 * @notify: called with @user_data when the memory is freed
685 * Allocate a new buffer that wraps the given memory. @data must point to
686 * @maxsize of memory, the wrapped buffer will have the region from @offset and
689 * When the buffer is destroyed, @notify will be called with @user_data.
691 * The prefix/padding must be filled with 0 if @flags contains
692 * #GST_MEMORY_FLAG_ZERO_PREFIXED and #GST_MEMORY_FLAG_ZERO_PADDED respectively.
694 * Returns: (transfer full): a new #GstBuffer
697 gst_buffer_new_wrapped_full (GstMemoryFlags flags, gpointer data,
698 gsize maxsize, gsize offset, gsize size, gpointer user_data,
699 GDestroyNotify notify)
703 newbuf = gst_buffer_new ();
704 gst_buffer_append_memory (newbuf,
705 gst_memory_new_wrapped (flags, data, maxsize, offset, size,
712 * gst_buffer_new_wrapped:
713 * @data: data to wrap
714 * @size: allocated size of @data
716 * Creates a new buffer that wraps the given @data. The memory will be freed
717 * with g_free and will be marked writable.
721 * Returns: (transfer full): a new #GstBuffer
724 gst_buffer_new_wrapped (gpointer data, gsize size)
726 return gst_buffer_new_wrapped_full (0, data, size, 0, size, data, g_free);
730 * gst_buffer_n_memory:
731 * @buffer: a #GstBuffer.
733 * Get the amount of memory blocks that this buffer has.
735 * Returns: (transfer full): the amount of memory block in this buffer.
738 gst_buffer_n_memory (GstBuffer * buffer)
740 g_return_val_if_fail (GST_IS_BUFFER (buffer), 0);
742 return GST_BUFFER_MEM_LEN (buffer);
746 * gst_buffer_prepend_memory:
748 * @m: (transfer full): a #GstMemory.
750 * Prepend the memory block @m to @b. This function takes ownership
751 * of @m and thus doesn't increase its refcount.
754 * gst_buffer_append_memory:
756 * @m: (transfer full): a #GstMemory.
758 * Append the memory block @m to @b. This function takes ownership
759 * of @m and thus doesn't increase its refcount.
762 * gst_buffer_insert_memory:
763 * @buffer: a #GstBuffer.
764 * @idx: the index to add the memory at, or -1 to append it to the end
765 * @mem: (transfer full): a #GstMemory.
767 * Insert the memory block @mem to @buffer at @idx. This function takes ownership
768 * of @mem and thus doesn't increase its refcount.
771 gst_buffer_insert_memory (GstBuffer * buffer, gint idx, GstMemory * mem)
773 g_return_if_fail (GST_IS_BUFFER (buffer));
774 g_return_if_fail (gst_buffer_is_writable (buffer));
775 g_return_if_fail (mem != NULL);
776 g_return_if_fail (idx == -1 ||
777 (idx >= 0 && idx <= GST_BUFFER_MEM_LEN (buffer)));
779 _memory_add (buffer, idx, mem);
783 _get_mapped (GstBuffer * buffer, guint idx, GstMapInfo * info,
786 GstMemory *mem, *mapped;
788 mem = gst_memory_ref (GST_BUFFER_MEM_PTR (buffer, idx));
790 mapped = gst_memory_make_mapped (mem, info, flags);
792 if (mapped && mapped != mem) {
793 /* new memory, replace old memory */
794 GST_BUFFER_MEM_PTR (buffer, idx) = mapped;
796 gst_memory_unref (mem);
802 * gst_buffer_peek_memory:
803 * @buffer: a #GstBuffer.
806 * Get the memory block at @idx in @buffer. The memory block stays valid until
807 * the memory block in @buffer is removed, replaced or merged, typically with
808 * any call that modifies the memory in @buffer.
810 * Since this call does not influence the refcount of the memory,
811 * gst_memory_is_exclusive() can be used to check if @buffer is the sole owner
812 * of the returned memory.
814 * Returns: (transfer none): the #GstMemory at @idx.
817 gst_buffer_peek_memory (GstBuffer * buffer, guint idx)
821 g_return_val_if_fail (GST_IS_BUFFER (buffer), NULL);
822 len = GST_BUFFER_MEM_LEN (buffer);
823 g_return_val_if_fail (idx < len, NULL);
825 return GST_BUFFER_MEM_PTR (buffer, idx);
829 * gst_buffer_get_memory:
833 * Get the memory block at index @i in @buffer.
835 * Returns: (transfer full): a #GstMemory that contains the data of the
836 * memory block at @idx. Use gst_memory_unref () after usage.
839 * gst_buffer_get_all_memory:
842 * Get all the memory block in @buffer. The memory blocks will be merged
843 * into one large #GstMemory.
845 * Returns: (transfer full): a #GstMemory that contains the merged memory.
846 * Use gst_memory_unref () after usage.
849 * gst_buffer_get_memory_range:
850 * @buffer: a #GstBuffer.
854 * Get @length memory blocks in @buffer starting at @idx. The memory blocks will
855 * be merged into one large #GstMemory.
857 * If @length is -1, all memory starting from @idx is merged.
859 * Returns: (transfer full): a #GstMemory that contains the merged data of @length
860 * blocks starting at @idx. Use gst_memory_unref () after usage.
863 gst_buffer_get_memory_range (GstBuffer * buffer, guint idx, gint length)
867 GST_DEBUG ("idx %u, length %d", idx, length);
869 g_return_val_if_fail (GST_IS_BUFFER (buffer), NULL);
870 len = GST_BUFFER_MEM_LEN (buffer);
871 g_return_val_if_fail ((len == 0 && idx == 0 && length == -1) ||
872 (length == -1 && idx < len) || (length > 0 && length + idx <= len), NULL);
877 return _get_merged_memory (buffer, idx, length);
881 * gst_buffer_replace_memory:
884 * @m: (transfer full): a #GstMemory
886 * Replaces the memory block at index @i in @b with @m.
889 * gst_buffer_replace_all_memory:
891 * @m: (transfer full): a #GstMemory
893 * Replaces all memory in @b with @m.
896 * gst_buffer_replace_memory_range:
897 * @buffer: a #GstBuffer.
899 * @length: a length should not be 0
900 * @mem: (transfer full): a #GstMemory
902 * Replaces @length memory blocks in @buffer starting at @idx with @mem.
904 * If @length is -1, all memory starting from @idx will be removed and
905 * replaced with @mem.
907 * @buffer should be writable.
910 gst_buffer_replace_memory_range (GstBuffer * buffer, guint idx, gint length,
915 g_return_if_fail (GST_IS_BUFFER (buffer));
916 g_return_if_fail (gst_buffer_is_writable (buffer));
917 len = GST_BUFFER_MEM_LEN (buffer);
918 g_return_if_fail ((len == 0 && idx == 0 && length == -1) ||
919 (length == -1 && idx < len) || (length > 0 && length + idx <= len));
924 _replace_memory (buffer, len, idx, length, mem);
928 * gst_buffer_remove_memory:
932 * Remove the memory block in @b at index @i.
935 * gst_buffer_remove_all_memory:
938 * Remove all the memory blocks in @b.
941 * gst_buffer_remove_memory_range:
942 * @buffer: a #GstBuffer.
946 * Remove @length memory blocks in @buffer starting from @idx.
948 * @length can be -1, in which case all memory starting from @idx is removed.
951 gst_buffer_remove_memory_range (GstBuffer * buffer, guint idx, gint length)
955 g_return_if_fail (GST_IS_BUFFER (buffer));
956 g_return_if_fail (gst_buffer_is_writable (buffer));
958 len = GST_BUFFER_MEM_LEN (buffer);
959 g_return_if_fail ((len == 0 && idx == 0 && length == -1) ||
960 (length == -1 && idx < len) || length + idx <= len);
965 _replace_memory (buffer, len, idx, length, NULL);
969 * gst_buffer_find_memory:
970 * @buffer: a #GstBuffer.
973 * @idx: (out): pointer to index
974 * @length: (out): pointer to length
975 * @skip: (out): pointer to skip
977 * Find the memory blocks that span @size bytes starting from @offset
980 * When this function returns %TRUE, @idx will contain the index of the first
981 * memory bock where the byte for @offset can be found and @length contains the
982 * number of memory blocks containing the @size remaining bytes. @skip contains
983 * the number of bytes to skip in the memory bock at @idx to get to the byte
986 * @size can be -1 to get all the memory blocks after @idx.
988 * Returns: %TRUE when @size bytes starting from @offset could be found in
989 * @buffer and @idx, @length and @skip will be filled.
992 gst_buffer_find_memory (GstBuffer * buffer, gsize offset, gsize size,
993 guint * idx, guint * length, gsize * skip)
997 g_return_val_if_fail (GST_IS_BUFFER (buffer), FALSE);
998 g_return_val_if_fail (idx != NULL, FALSE);
999 g_return_val_if_fail (length != NULL, FALSE);
1000 g_return_val_if_fail (skip != NULL, FALSE);
1002 len = GST_BUFFER_MEM_LEN (buffer);
1005 for (i = 0; i < len; i++) {
1009 mem = GST_BUFFER_MEM_PTR (buffer, i);
1010 s = gst_memory_get_sizes (mem, NULL, NULL);
1013 /* block before offset, or empty block, skip */
1016 /* block after offset */
1018 /* first block, remember index and offset */
1022 /* return remaining blocks */
1029 /* count the amount of found bytes */
1031 if (found >= size) {
1032 /* we have enough bytes */
1033 *length = i - *idx + 1;
1042 * gst_buffer_get_sizes:
1044 * @of: a pointer to the offset
1045 * @ms: a pointer to the maxsize
1047 * Get the total size of the memory blocks in @b.
1049 * When not %NULL, @of will contain the offset of the data in the first
1050 * memory block in @buffer and @maxsize will contain the sum of the size
1051 * and @of and the amount of extra padding on the last memory block.
1052 * @of and @ms can be used to resize the buffer memory blocks with
1053 * gst_buffer_resize().
1055 * Returns: total size of the memory blocks in @b.
1058 * gst_buffer_get_size:
1061 * Get the total size of the memory blocks in @b.
1063 * Returns: total size of the memory blocks in @b.
1066 * gst_buffer_get_sizes_range:
1067 * @buffer: a #GstBuffer.
1070 * @offset: a pointer to the offset
1071 * @maxsize: a pointer to the maxsize
1073 * Get the total size of @length memory blocks stating from @idx in @buffer.
1075 * When not %NULL, @offset will contain the offset of the data in the
1076 * memory block in @buffer at @idx and @maxsize will contain the sum of the size
1077 * and @offset and the amount of extra padding on the memory block at @idx +
1079 * @offset and @maxsize can be used to resize the buffer memory blocks with
1080 * gst_buffer_resize_range().
1082 * Returns: total size of @length memory blocks starting at @idx in @buffer.
1085 gst_buffer_get_sizes_range (GstBuffer * buffer, guint idx, gint length,
1086 gsize * offset, gsize * maxsize)
1092 g_return_val_if_fail (GST_IS_BUFFER (buffer), 0);
1093 len = GST_BUFFER_MEM_LEN (buffer);
1094 g_return_val_if_fail ((len == 0 && idx == 0 && length == -1) ||
1095 (length == -1 && idx < len) || (length + idx <= len), 0);
1100 if (G_LIKELY (length == 1)) {
1102 mem = GST_BUFFER_MEM_PTR (buffer, idx);
1103 size = gst_memory_get_sizes (mem, offset, maxsize);
1109 size = offs = extra = 0;
1110 for (i = idx; i < end; i++) {
1113 mem = GST_BUFFER_MEM_PTR (buffer, i);
1114 s = gst_memory_get_sizes (mem, &o, &ms);
1118 /* first size, take accumulated data before as the offset */
1122 /* save the amount of data after this block */
1123 extra = ms - (o + s);
1125 /* empty block, add as extra */
1132 *maxsize = offs + size + extra;
1138 * gst_buffer_resize:
1140 * @of: the offset adjustement
1141 * @s: the new size or -1 to just adjust the offset
1143 * Set the offset and total size of the memory blocks in @b.
1146 * gst_buffer_set_size:
1150 * Set the total size of the memory blocks in @b.
1153 * gst_buffer_resize_range:
1154 * @buffer: a #GstBuffer.
1157 * @offset: the offset adjustement
1158 * @size: the new size or -1 to just adjust the offset
1160 * Set the total size of the @length memory blocks starting at @idx in
1164 gst_buffer_resize_range (GstBuffer * buffer, guint idx, gint length,
1165 gssize offset, gssize size)
1168 gsize bsize, bufsize, bufoffs, bufmax;
1171 g_return_if_fail (gst_buffer_is_writable (buffer));
1172 g_return_if_fail (size >= -1);
1173 len = GST_BUFFER_MEM_LEN (buffer);
1174 g_return_if_fail ((len == 0 && idx == 0 && length == -1) ||
1175 (length == -1 && idx < len) || (length + idx <= len));
1180 bufsize = gst_buffer_get_sizes_range (buffer, idx, length, &bufoffs, &bufmax);
1182 GST_CAT_LOG (GST_CAT_BUFFER, "trim %p %" G_GSSIZE_FORMAT "-%" G_GSSIZE_FORMAT
1183 " size:%" G_GSIZE_FORMAT " offs:%" G_GSIZE_FORMAT " max:%"
1184 G_GSIZE_FORMAT, buffer, offset, size, bufsize, bufoffs, bufmax);
1186 /* we can't go back further than the current offset or past the end of the
1188 g_return_if_fail ((offset < 0 && bufoffs >= -offset) || (offset >= 0
1189 && bufoffs + offset <= bufmax));
1191 g_return_if_fail (bufsize >= offset);
1192 size = bufsize - offset;
1194 g_return_if_fail (bufmax >= bufoffs + offset + size);
1197 if (offset == 0 && size == bufsize)
1202 for (i = idx; i < end; i++) {
1205 mem = GST_BUFFER_MEM_PTR (buffer, i);
1206 bsize = gst_memory_get_sizes (mem, NULL, NULL);
1209 /* last buffer always gets resized to the remaining size */
1212 /* shrink buffers before the offset */
1213 else if ((gssize) bsize <= offset) {
1215 noffs = offset - bsize;
1218 /* clip other buffers */
1220 left = MIN (bsize - offset, size);
1222 if (offset != 0 || left != bsize) {
1223 if (gst_memory_is_exclusive (mem)) {
1224 gst_memory_resize (mem, offset, left);
1228 if (GST_MEMORY_IS_NO_SHARE (mem))
1229 tmp = gst_memory_copy (mem, offset, left);
1231 tmp = gst_memory_share (mem, offset, left);
1233 gst_memory_unref (mem);
1240 GST_BUFFER_MEM_PTR (buffer, i) = mem;
1247 * @i: (out): info about the mapping
1248 * @f: flags for the mapping
1250 * This function fills @i with the #GstMapInfo of all merged memory blocks
1253 * @flags describe the desired access of the memory. When @flags is
1254 * #GST_MAP_WRITE, @buffer should be writable (as returned from
1255 * gst_buffer_is_writable()).
1257 * When @buffer is writable but the memory isn't, a writable copy will
1258 * automatically be created and returned. The readonly copy of the buffer memory
1259 * will then also be replaced with this writable copy.
1261 * The memory in @i should be unmapped with gst_buffer_unmap() after usage.
1263 * Returns: %TRUE if the map succeeded and @i contains valid data.
1266 * gst_buffer_map_range:
1267 * @buffer: a #GstBuffer.
1270 * @info: (out): info about the mapping
1271 * @flags: flags for the mapping
1273 * This function fills @info with the #GstMapInfo of @length merged memory blocks
1274 * starting at @idx in @buffer. When @length is -1, all memory blocks starting
1275 * from @idx are merged and mapped.
1277 * @flags describe the desired access of the memory. When @flags is
1278 * #GST_MAP_WRITE, @buffer should be writable (as returned from
1279 * gst_buffer_is_writable()).
1281 * When @buffer is writable but the memory isn't, a writable copy will
1282 * automatically be created and returned. The readonly copy of the buffer memory
1283 * will then also be replaced with this writable copy.
1285 * The memory in @info should be unmapped with gst_buffer_unmap() after usage.
1287 * Returns: %TRUE if the map succeeded and @info contains valid
1291 gst_buffer_map_range (GstBuffer * buffer, guint idx, gint length,
1292 GstMapInfo * info, GstMapFlags flags)
1294 GstMemory *mem, *nmem;
1295 gboolean write, writable;
1298 g_return_val_if_fail (GST_IS_BUFFER (buffer), FALSE);
1299 g_return_val_if_fail (info != NULL, FALSE);
1300 len = GST_BUFFER_MEM_LEN (buffer);
1301 g_return_val_if_fail ((len == 0 && idx == 0 && length == -1) ||
1302 (length == -1 && idx < len) || (length > 0
1303 && length + idx <= len), FALSE);
1305 GST_LOG ("buffer %p, idx %u, length %d, flags %04x", buffer, idx, length,
1308 write = (flags & GST_MAP_WRITE) != 0;
1309 writable = gst_buffer_is_writable (buffer);
1311 /* check if we can write when asked for write access */
1312 if (G_UNLIKELY (write && !writable))
1318 mem = _get_merged_memory (buffer, idx, length);
1319 if (G_UNLIKELY (mem == NULL))
1322 /* now try to map */
1323 nmem = gst_memory_make_mapped (mem, info, flags);
1324 if (G_UNLIKELY (nmem == NULL))
1327 /* if we merged or when the map returned a different memory, we try to replace
1328 * the memory in the buffer */
1329 if (G_UNLIKELY (length > 1 || nmem != mem)) {
1330 /* if the buffer is writable, replace the memory */
1332 _replace_memory (buffer, len, idx, length, gst_memory_ref (nmem));
1335 GST_CAT_DEBUG (GST_CAT_PERFORMANCE,
1336 "temporary mapping for memory %p in buffer %p", nmem, buffer);
1345 GST_WARNING_OBJECT (buffer, "write map requested on non-writable buffer");
1346 g_critical ("write map requested on non-writable buffer");
1351 /* empty buffer, we need to return NULL */
1352 GST_DEBUG_OBJECT (buffer, "can't get buffer memory");
1353 info->memory = NULL;
1361 GST_DEBUG_OBJECT (buffer, "cannot map memory");
1368 * @buffer: a #GstBuffer.
1369 * @info: a #GstMapInfo
1371 * Release the memory previously mapped with gst_buffer_map().
1374 gst_buffer_unmap (GstBuffer * buffer, GstMapInfo * info)
1376 g_return_if_fail (GST_IS_BUFFER (buffer));
1377 g_return_if_fail (info != NULL);
1379 /* we need to check for NULL, it is possible that we tried to map a buffer
1380 * without memory and we should be able to unmap that fine */
1381 if (G_LIKELY (info->memory)) {
1382 gst_memory_unmap (info->memory, info);
1383 gst_memory_unref (info->memory);
1389 * @buffer: a #GstBuffer.
1390 * @offset: the offset to fill
1391 * @src: the source address
1392 * @size: the size to fill
1394 * Copy @size bytes from @src to @buffer at @offset.
1396 * Returns: The amount of bytes copied. This value can be lower than @size
1397 * when @buffer did not contain enough data.
1400 gst_buffer_fill (GstBuffer * buffer, gsize offset, gconstpointer src,
1404 const guint8 *ptr = src;
1406 g_return_val_if_fail (GST_IS_BUFFER (buffer), 0);
1407 g_return_val_if_fail (gst_buffer_is_writable (buffer), 0);
1408 g_return_val_if_fail (src != NULL, 0);
1410 GST_LOG ("buffer %p, offset %" G_GSIZE_FORMAT ", size %" G_GSIZE_FORMAT,
1411 buffer, offset, size);
1413 len = GST_BUFFER_MEM_LEN (buffer);
1416 for (i = 0; i < len && left > 0; i++) {
1421 mem = _get_mapped (buffer, i, &info, GST_MAP_WRITE);
1422 if (info.size > offset) {
1423 /* we have enough */
1424 tocopy = MIN (info.size - offset, left);
1425 memcpy ((guint8 *) info.data + offset, ptr, tocopy);
1430 /* offset past buffer, skip */
1431 offset -= info.size;
1433 gst_memory_unmap (mem, &info);
1439 * gst_buffer_extract:
1440 * @buffer: a #GstBuffer.
1441 * @offset: the offset to extract
1442 * @dest: the destination address
1443 * @size: the size to extract
1445 * Copy @size bytes starting from @offset in @buffer to @dest.
1447 * Returns: The amount of bytes extracted. This value can be lower than @size
1448 * when @buffer did not contain enough data.
1451 gst_buffer_extract (GstBuffer * buffer, gsize offset, gpointer dest, gsize size)
1456 g_return_val_if_fail (GST_IS_BUFFER (buffer), 0);
1457 g_return_val_if_fail (dest != NULL, 0);
1459 GST_LOG ("buffer %p, offset %" G_GSIZE_FORMAT ", size %" G_GSIZE_FORMAT,
1460 buffer, offset, size);
1462 len = GST_BUFFER_MEM_LEN (buffer);
1465 for (i = 0; i < len && left > 0; i++) {
1470 mem = _get_mapped (buffer, i, &info, GST_MAP_READ);
1471 if (info.size > offset) {
1472 /* we have enough */
1473 tocopy = MIN (info.size - offset, left);
1474 memcpy (ptr, (guint8 *) info.data + offset, tocopy);
1479 /* offset past buffer, skip */
1480 offset -= info.size;
1482 gst_memory_unmap (mem, &info);
1488 * gst_buffer_memcmp:
1489 * @buffer: a #GstBuffer.
1490 * @offset: the offset in @buffer
1491 * @mem: the memory to compare
1492 * @size: the size to compare
1494 * Compare @size bytes starting from @offset in @buffer with the memory in @mem.
1496 * Returns: 0 if the memory is equal.
1499 gst_buffer_memcmp (GstBuffer * buffer, gsize offset, gconstpointer mem,
1503 const guint8 *ptr = mem;
1506 g_return_val_if_fail (GST_IS_BUFFER (buffer), 0);
1507 g_return_val_if_fail (mem != NULL, 0);
1509 GST_LOG ("buffer %p, offset %" G_GSIZE_FORMAT ", size %" G_GSIZE_FORMAT,
1510 buffer, offset, size);
1512 len = GST_BUFFER_MEM_LEN (buffer);
1514 for (i = 0; i < len && size > 0 && res == 0; i++) {
1519 mem = _get_mapped (buffer, i, &info, GST_MAP_READ);
1520 if (info.size > offset) {
1521 /* we have enough */
1522 tocmp = MIN (info.size - offset, size);
1523 res = memcmp (ptr, (guint8 *) info.data + offset, tocmp);
1528 /* offset past buffer, skip */
1529 offset -= info.size;
1531 gst_memory_unmap (mem, &info);
1537 * gst_buffer_memset:
1538 * @buffer: a #GstBuffer.
1539 * @offset: the offset in @buffer
1540 * @val: the value to set
1541 * @size: the size to set
1543 * Fill @buf with @size bytes with @val starting from @offset.
1545 * Returns: The amount of bytes filled. This value can be lower than @size
1546 * when @buffer did not contain enough data.
1549 gst_buffer_memset (GstBuffer * buffer, gsize offset, guint8 val, gsize size)
1553 g_return_val_if_fail (GST_IS_BUFFER (buffer), 0);
1554 g_return_val_if_fail (gst_buffer_is_writable (buffer), 0);
1556 GST_LOG ("buffer %p, offset %" G_GSIZE_FORMAT ", val %02x, size %"
1557 G_GSIZE_FORMAT, buffer, offset, val, size);
1559 len = GST_BUFFER_MEM_LEN (buffer);
1562 for (i = 0; i < len && left > 0; i++) {
1567 mem = _get_mapped (buffer, i, &info, GST_MAP_WRITE);
1568 if (info.size > offset) {
1569 /* we have enough */
1570 toset = MIN (info.size - offset, left);
1571 memset ((guint8 *) info.data + offset, val, toset);
1575 /* offset past buffer, skip */
1576 offset -= info.size;
1578 gst_memory_unmap (mem, &info);
1584 * gst_buffer_copy_region:
1585 * @parent: a #GstBuffer.
1586 * @flags: the #GstBufferCopyFlags
1587 * @offset: the offset into parent #GstBuffer at which the new sub-buffer
1589 * @size: the size of the new #GstBuffer sub-buffer, in bytes.
1591 * Creates a sub-buffer from @parent at @offset and @size.
1592 * This sub-buffer uses the actual memory space of the parent buffer.
1593 * This function will copy the offset and timestamp fields when the
1594 * offset is 0. If not, they will be set to #GST_CLOCK_TIME_NONE and
1595 * #GST_BUFFER_OFFSET_NONE.
1596 * If @offset equals 0 and @size equals the total size of @buffer, the
1597 * duration and offset end fields are also copied. If not they will be set
1598 * to #GST_CLOCK_TIME_NONE and #GST_BUFFER_OFFSET_NONE.
1602 * Returns: (transfer full): the new #GstBuffer or NULL if the arguments were
1606 gst_buffer_copy_region (GstBuffer * buffer, GstBufferCopyFlags flags,
1607 gsize offset, gsize size)
1611 g_return_val_if_fail (buffer != NULL, NULL);
1613 /* create the new buffer */
1614 copy = gst_buffer_new ();
1616 GST_CAT_LOG (GST_CAT_BUFFER, "new region copy %p of %p %" G_GSIZE_FORMAT
1617 "-%" G_GSIZE_FORMAT, copy, buffer, offset, size);
1619 gst_buffer_copy_into (copy, buffer, flags, offset, size);
1625 * gst_buffer_append:
1626 * @buf1: (transfer full): the first source #GstBuffer to append.
1627 * @buf2: (transfer full): the second source #GstBuffer to append.
1629 * Append all the memory from @buf2 to @buf1. The result buffer will contain a
1630 * concatenation of the memory of @buf1 and @buf2.
1632 * Returns: (transfer full): the new #GstBuffer that contains the memory
1633 * of the two source buffers.
1636 * gst_buffer_append_region:
1637 * @buf1: (transfer full): the first source #GstBuffer to append.
1638 * @buf2: (transfer full): the second source #GstBuffer to append.
1639 * @offset: the offset in @buf2
1640 * @size: the size or -1 of @buf2
1642 * Append @size bytes at @offset from @buf2 to @buf1. The result buffer will
1643 * contain a concatenation of the memory of @buf1 and the requested region of
1646 * Returns: (transfer full): the new #GstBuffer that contains the memory
1647 * of the two source buffers.
1650 gst_buffer_append_region (GstBuffer * buf1, GstBuffer * buf2, gssize offset,
1655 g_return_val_if_fail (GST_IS_BUFFER (buf1), NULL);
1656 g_return_val_if_fail (GST_IS_BUFFER (buf2), NULL);
1658 buf1 = gst_buffer_make_writable (buf1);
1659 buf2 = gst_buffer_make_writable (buf2);
1661 gst_buffer_resize (buf2, offset, size);
1663 len = GST_BUFFER_MEM_LEN (buf2);
1664 for (i = 0; i < len; i++) {
1667 mem = GST_BUFFER_MEM_PTR (buf2, i);
1668 GST_BUFFER_MEM_PTR (buf2, i) = NULL;
1669 _memory_add (buf1, -1, mem);
1672 GST_BUFFER_MEM_LEN (buf2) = 0;
1673 gst_buffer_unref (buf2);
1679 * gst_buffer_get_meta:
1680 * @buffer: a #GstBuffer
1681 * @api: the #GType of an API
1683 * Get the metadata for @api on buffer. When there is no such
1684 * metadata, NULL is returned.
1686 * Returns: (transfer none): the metadata for @api on @buffer.
1689 gst_buffer_get_meta (GstBuffer * buffer, GType api)
1692 GstMeta *result = NULL;
1694 g_return_val_if_fail (buffer != NULL, NULL);
1695 g_return_val_if_fail (api != 0, NULL);
1697 /* find GstMeta of the requested API */
1698 for (item = GST_BUFFER_META (buffer); item; item = item->next) {
1699 GstMeta *meta = &item->meta;
1700 if (meta->info->api == api) {
1709 * gst_buffer_add_meta:
1710 * @buffer: a #GstBuffer
1711 * @info: a #GstMetaInfo
1712 * @params: params for @info
1714 * Add metadata for @info to @buffer using the parameters in @params.
1716 * Returns: (transfer none): the metadata for the api in @info on @buffer.
1719 gst_buffer_add_meta (GstBuffer * buffer, const GstMetaInfo * info,
1723 GstMeta *result = NULL;
1726 g_return_val_if_fail (buffer != NULL, NULL);
1727 g_return_val_if_fail (info != NULL, NULL);
1728 g_return_val_if_fail (gst_buffer_is_writable (buffer), NULL);
1730 /* create a new slice */
1731 size = ITEM_SIZE (info);
1732 item = g_slice_alloc (size);
1733 result = &item->meta;
1734 result->info = info;
1735 result->flags = GST_META_FLAG_NONE;
1737 GST_CAT_DEBUG (GST_CAT_BUFFER,
1738 "alloc metadata %p (%s) of size %" G_GSIZE_FORMAT, result,
1739 g_type_name (info->type), info->size);
1741 /* call the init_func when needed */
1742 if (info->init_func)
1743 if (!info->init_func (result, params, buffer))
1746 /* and add to the list of metadata */
1747 item->next = GST_BUFFER_META (buffer);
1748 GST_BUFFER_META (buffer) = item;
1754 g_slice_free1 (size, item);
1760 * gst_buffer_remove_meta:
1761 * @buffer: a #GstBuffer
1764 * Remove the metadata for @meta on @buffer.
1766 * Returns: %TRUE if the metadata existed and was removed, %FALSE if no such
1767 * metadata was on @buffer.
1770 gst_buffer_remove_meta (GstBuffer * buffer, GstMeta * meta)
1772 GstMetaItem *walk, *prev;
1774 g_return_val_if_fail (buffer != NULL, FALSE);
1775 g_return_val_if_fail (meta != NULL, FALSE);
1776 g_return_val_if_fail (gst_buffer_is_writable (buffer), FALSE);
1777 g_return_val_if_fail (!GST_META_FLAG_IS_SET (meta, GST_META_FLAG_LOCKED),
1780 /* find the metadata and delete */
1781 prev = GST_BUFFER_META (buffer);
1782 for (walk = prev; walk; walk = walk->next) {
1783 GstMeta *m = &walk->meta;
1785 const GstMetaInfo *info = meta->info;
1787 /* remove from list */
1788 if (GST_BUFFER_META (buffer) == walk)
1789 GST_BUFFER_META (buffer) = walk->next;
1791 prev->next = walk->next;
1792 /* call free_func if any */
1793 if (info->free_func)
1794 info->free_func (m, buffer);
1796 /* and free the slice */
1797 g_slice_free1 (ITEM_SIZE (info), walk);
1802 return walk != NULL;
1806 * gst_buffer_iterate_meta:
1807 * @buffer: a #GstBuffer
1808 * @state: an opaque state pointer
1810 * Retrieve the next #GstMeta after @current. If @state points
1811 * to %NULL, the first metadata is returned.
1813 * @state will be updated with an opage state pointer
1815 * Returns: (transfer none): The next #GstMeta or %NULL when there are
1819 gst_buffer_iterate_meta (GstBuffer * buffer, gpointer * state)
1823 g_return_val_if_fail (buffer != NULL, NULL);
1824 g_return_val_if_fail (state != NULL, NULL);
1826 meta = (GstMetaItem **) state;
1828 /* state NULL, move to first item */
1829 *meta = GST_BUFFER_META (buffer);
1831 /* state !NULL, move to next item in list */
1832 *meta = (*meta)->next;
1835 return &(*meta)->meta;
1841 * gst_buffer_foreach_meta:
1842 * @buffer: a #GstBuffer
1843 * @func: (scope call): a #GstBufferForeachMetaFunc to call
1844 * @user_data: (closure): user data passed to @func
1846 * Call @func with @user_data for each meta in @buffer.
1848 * @func can modify the passed meta pointer or its contents. The return value
1849 * of @func define if this function returns or if the remaining metadata items
1850 * in the buffer should be skipped.
1853 gst_buffer_foreach_meta (GstBuffer * buffer, GstBufferForeachMetaFunc func,
1856 GstMetaItem *walk, *prev, *next;
1858 g_return_if_fail (buffer != NULL);
1859 g_return_if_fail (func != NULL);
1861 /* find the metadata and delete */
1862 prev = GST_BUFFER_META (buffer);
1863 for (walk = prev; walk; walk = next) {
1867 m = new = &walk->meta;
1870 res = func (buffer, &new, user_data);
1873 const GstMetaInfo *info = m->info;
1875 GST_CAT_DEBUG (GST_CAT_BUFFER, "remove metadata %p (%s)", m,
1876 g_type_name (info->type));
1878 g_return_if_fail (gst_buffer_is_writable (buffer));
1879 g_return_if_fail (!GST_META_FLAG_IS_SET (m, GST_META_FLAG_LOCKED));
1881 /* remove from list */
1882 if (GST_BUFFER_META (buffer) == walk)
1883 GST_BUFFER_META (buffer) = next;
1887 /* call free_func if any */
1888 if (info->free_func)
1889 info->free_func (m, buffer);
1891 /* and free the slice */
1892 g_slice_free1 (ITEM_SIZE (info), walk);