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, supporting sub-buffers.
26 * @see_also: #GstPad, #GstMiniObject, #GstBufferPool
28 * Buffers are the basic unit of data transfer in GStreamer. The #GstBuffer
29 * type provides all the state necessary to define the regions of memory as
30 * part of a stream. Region copies are also supported, allowing a smaller
31 * region of a buffer to become its own buffer, with mechanisms in place to
32 * ensure that neither memory space goes away prematurely.
34 * Buffers are usually created with gst_buffer_new(). After a buffer has been
35 * created one will typically allocate memory for it and add it to the buffer.
36 * The following example creates a buffer that can hold a given video frame
37 * with a given width, height and bits per plane.
39 * <title>Creating a buffer for a video frame</title>
43 * gint size, width, height, bpp;
45 * size = width * height * bpp;
46 * buffer = gst_buffer_new ();
47 * memory = gst_allocator_alloc (NULL, size, 0);
48 * gst_buffer_take_memory (buffer, -1, memory);
53 * Alternatively, use gst_buffer_new_allocate()
54 * to create a buffer with preallocated data of a given size.
56 * Buffers can contain a list of #GstMemory objects. You can retrieve how many
57 * memory objects with gst_buffer_n_memory() and you can get a pointer
58 * to memory with gst_buffer_peek_memory()
60 * A buffer will usually have timestamps, and a duration, but neither of these
61 * are guaranteed (they may be set to #GST_CLOCK_TIME_NONE). Whenever a
62 * meaningful value can be given for these, they should be set. The timestamps
63 * and duration are measured in nanoseconds (they are #GstClockTime values).
65 * A buffer can also have one or both of a start and an end offset. These are
66 * media-type specific. For video buffers, the start offset will generally be
67 * the frame number. For audio buffers, it will be the number of samples
68 * produced so far. For compressed data, it could be the byte offset in a
69 * source or destination file. Likewise, the end offset will be the offset of
70 * the end of the buffer. These can only be meaningfully interpreted if you
71 * know the media type of the buffer (the #GstCaps set on it). Either or both
72 * can be set to #GST_BUFFER_OFFSET_NONE.
74 * gst_buffer_ref() is used to increase the refcount of a buffer. This must be
75 * done when you want to keep a handle to the buffer after pushing it to the
78 * To efficiently create a smaller buffer out of an existing one, you can
79 * use gst_buffer_copy_region().
81 * If a plug-in wants to modify the buffer data or metadata in-place, it should
82 * first obtain a buffer that is safe to modify by using
83 * gst_buffer_make_writable(). This function is optimized so that a copy will
84 * only be made when it is necessary.
86 * Several flags of the buffer can be set and unset with the
87 * GST_BUFFER_FLAG_SET() and GST_BUFFER_FLAG_UNSET() macros. Use
88 * GST_BUFFER_FLAG_IS_SET() to test if a certain #GstBufferFlag is set.
90 * Buffers can be efficiently merged into a larger buffer with
91 * gst_buffer_span(), which avoids memory copies when the gst_buffer_is_span_fast()
92 * function returns TRUE.
94 * An element should either unref the buffer or push it out on a src pad
95 * using gst_pad_push() (see #GstPad).
97 * Buffers are usually freed by unreffing them with gst_buffer_unref(). When
98 * the refcount drops to 0, any data pointed to by the buffer is unreffed as
101 * Last reviewed on November 8, 2011 (0.11.2)
103 #include "gst_private.h"
112 #include "gstbuffer.h"
113 #include "gstbufferpool.h"
115 #include "gstutils.h"
116 #include "gstminiobject.h"
117 #include "gstversion.h"
119 GType _gst_buffer_type = 0;
121 static GstMemory *_gst_buffer_arr_span (GstMemory ** mem[], gsize len[],
122 guint n, gsize offset, gsize size, gboolean writable);
124 typedef struct _GstMetaItem GstMetaItem;
131 #define ITEM_SIZE(info) ((info)->size + sizeof (GstMetaItem))
133 #define GST_BUFFER_MEM_MAX 16
135 #define GST_BUFFER_MEM_LEN(b) (((GstBufferImpl *)(b))->len)
136 #define GST_BUFFER_MEM_ARRAY(b) (((GstBufferImpl *)(b))->mem)
137 #define GST_BUFFER_MEM_PTR(b,i) (((GstBufferImpl *)(b))->mem[i])
138 #define GST_BUFFER_BUFMEM(b) (((GstBufferImpl *)(b))->bufmem)
139 #define GST_BUFFER_META(b) (((GstBufferImpl *)(b))->item)
145 /* the memory blocks */
147 GstMemory *mem[GST_BUFFER_MEM_MAX];
149 /* memory of the buffer when allocated from 1 chunk */
152 /* FIXME, make metadata allocation more efficient by using part of the
158 _span_memory (GstBuffer * buffer, gsize offset, gsize size, gboolean writable)
160 GstMemory *span, **mem[1];
163 /* not enough room, span buffers */
164 mem[0] = GST_BUFFER_MEM_ARRAY (buffer);
165 len[0] = GST_BUFFER_MEM_LEN (buffer);
168 size = gst_buffer_get_size (buffer);
170 span = _gst_buffer_arr_span (mem, len, 1, offset, size, writable);
176 _replace_memory (GstBuffer * buffer, GstMemory * mem)
180 len = GST_BUFFER_MEM_LEN (buffer);
181 /* unref old buffers */
182 for (i = 0; i < len; i++)
183 gst_memory_unref (GST_BUFFER_MEM_PTR (buffer, i));
185 /* replace with single spanned buffer */
186 GST_BUFFER_MEM_PTR (buffer, 0) = mem;
187 GST_BUFFER_MEM_LEN (buffer) = 1;
191 _memory_add (GstBuffer * buffer, guint idx, GstMemory * mem)
193 guint i, len = GST_BUFFER_MEM_LEN (buffer);
195 if (G_UNLIKELY (len >= GST_BUFFER_MEM_MAX)) {
196 /* too many buffer, span them. */
197 /* FIXME, there is room for improvement here: We could only try to merge
198 * 2 buffers to make some room. If we can't efficiently merge 2 buffers we
199 * could try to only merge the two smallest buffers to avoid memcpy, etc. */
200 GST_CAT_DEBUG (GST_CAT_PERFORMANCE, "memory array overflow in buffer %p",
202 _replace_memory (buffer, _span_memory (buffer, 0, -1, FALSE));
203 /* we now have 1 single spanned buffer */
210 for (i = len; i > idx; i--) {
211 /* move buffers to insert, FIXME, we need to insert first and then merge */
212 GST_BUFFER_MEM_PTR (buffer, i) = GST_BUFFER_MEM_PTR (buffer, i - 1);
214 /* and insert the new buffer */
215 GST_BUFFER_MEM_PTR (buffer, idx) = mem;
216 GST_BUFFER_MEM_LEN (buffer) = len + 1;
219 GST_DEFINE_MINI_OBJECT_TYPE (GstBuffer, gst_buffer);
222 _priv_gst_buffer_initialize (void)
224 _gst_buffer_type = gst_buffer_get_type ();
228 * gst_buffer_copy_into:
229 * @dest: a destination #GstBuffer
230 * @src: a source #GstBuffer
231 * @flags: flags indicating what metadata fields should be copied.
232 * @offset: offset to copy from
233 * @size: total size to copy. If -1, all data is copied.
235 * Copies the information from @src into @dest.
237 * @flags indicate which fields will be copied.
240 gst_buffer_copy_into (GstBuffer * dest, GstBuffer * src,
241 GstBufferCopyFlags flags, gsize offset, gsize size)
246 g_return_if_fail (dest != NULL);
247 g_return_if_fail (src != NULL);
249 /* nothing to copy if the buffers are the same */
250 if (G_UNLIKELY (dest == src))
253 g_return_if_fail (gst_buffer_is_writable (dest));
255 bufsize = gst_buffer_get_size (src);
256 g_return_if_fail (bufsize >= offset);
258 size = bufsize - offset;
259 g_return_if_fail (bufsize >= offset + size);
261 GST_CAT_LOG (GST_CAT_BUFFER, "copy %p to %p, offset %" G_GSIZE_FORMAT
262 "-%" G_GSIZE_FORMAT "/%" G_GSIZE_FORMAT, src, dest, offset, size,
265 if (flags & GST_BUFFER_COPY_FLAGS) {
267 GST_MINI_OBJECT_FLAGS (dest) = GST_MINI_OBJECT_FLAGS (src);
270 if (flags & GST_BUFFER_COPY_TIMESTAMPS) {
272 GST_BUFFER_PTS (dest) = GST_BUFFER_PTS (src);
273 GST_BUFFER_DTS (dest) = GST_BUFFER_DTS (src);
274 GST_BUFFER_OFFSET (dest) = GST_BUFFER_OFFSET (src);
275 if (size == bufsize) {
276 GST_BUFFER_DURATION (dest) = GST_BUFFER_DURATION (src);
277 GST_BUFFER_OFFSET_END (dest) = GST_BUFFER_OFFSET_END (src);
280 GST_BUFFER_PTS (dest) = GST_CLOCK_TIME_NONE;
281 GST_BUFFER_DTS (dest) = GST_CLOCK_TIME_NONE;
282 GST_BUFFER_DURATION (dest) = GST_CLOCK_TIME_NONE;
283 GST_BUFFER_OFFSET (dest) = GST_BUFFER_OFFSET_NONE;
284 GST_BUFFER_OFFSET_END (dest) = GST_BUFFER_OFFSET_NONE;
288 if (flags & GST_BUFFER_COPY_MEMORY) {
290 gsize skip, left, len, i, bsize;
292 len = GST_BUFFER_MEM_LEN (src);
296 /* copy and make regions of the memory */
297 for (i = 0; i < len && left > 0; i++) {
298 mem = GST_BUFFER_MEM_PTR (src, i);
299 bsize = gst_memory_get_sizes (mem, NULL, NULL);
302 /* don't copy buffer */
307 tocopy = MIN (bsize - skip, left);
308 if (mem->flags & GST_MEMORY_FLAG_NO_SHARE) {
309 /* no share, always copy then */
310 mem = gst_memory_copy (mem, skip, tocopy);
312 } else if (tocopy < bsize) {
313 /* we need to clip something */
314 mem = gst_memory_share (mem, skip, tocopy);
317 mem = gst_memory_ref (mem);
319 _memory_add (dest, -1, mem);
323 if (flags & GST_BUFFER_COPY_MERGE) {
324 _replace_memory (dest, _span_memory (dest, 0, size, FALSE));
328 if (flags & GST_BUFFER_COPY_META) {
329 for (walk = GST_BUFFER_META (src); walk; walk = walk->next) {
330 GstMeta *meta = &walk->meta;
331 const GstMetaInfo *info = meta->info;
334 info->copy_func (dest, meta, src, offset, size);
340 _gst_buffer_copy (GstBuffer * buffer)
344 g_return_val_if_fail (buffer != NULL, NULL);
346 /* create a fresh new buffer */
347 copy = gst_buffer_new ();
349 /* we simply copy everything from our parent */
350 gst_buffer_copy_into (copy, buffer, GST_BUFFER_COPY_ALL, 0, -1);
355 /* the default dispose function revives the buffer and returns it to the
356 * pool when there is a pool */
358 _gst_buffer_dispose (GstBuffer * buffer)
362 /* no pool, do free */
363 if ((pool = buffer->pool) == NULL)
366 /* keep the buffer alive */
367 gst_buffer_ref (buffer);
368 /* return the buffer to the pool */
369 GST_CAT_LOG (GST_CAT_BUFFER, "release %p to pool %p", buffer, pool);
370 gst_buffer_pool_release_buffer (pool, buffer);
376 _gst_buffer_free (GstBuffer * buffer)
378 GstMetaItem *walk, *next;
382 g_return_if_fail (buffer != NULL);
384 GST_CAT_LOG (GST_CAT_BUFFER, "finalize %p", buffer);
387 for (walk = GST_BUFFER_META (buffer); walk; walk = next) {
388 GstMeta *meta = &walk->meta;
389 const GstMetaInfo *info = meta->info;
391 /* call free_func if any */
393 info->free_func (meta, buffer);
396 /* and free the slice */
397 g_slice_free1 (ITEM_SIZE (info), walk);
400 /* get the size, when unreffing the memory, we could also unref the buffer
402 msize = GST_MINI_OBJECT_SIZE (buffer);
404 /* free our memory */
405 len = GST_BUFFER_MEM_LEN (buffer);
406 for (i = 0; i < len; i++)
407 gst_memory_unref (GST_BUFFER_MEM_PTR (buffer, i));
409 /* we set msize to 0 when the buffer is part of the memory block */
411 g_slice_free1 (msize, buffer);
413 gst_memory_unref (GST_BUFFER_BUFMEM (buffer));
417 gst_buffer_init (GstBufferImpl * buffer, gsize size)
419 gst_mini_object_init (GST_MINI_OBJECT_CAST (buffer), _gst_buffer_type, size);
421 buffer->buffer.mini_object.copy =
422 (GstMiniObjectCopyFunction) _gst_buffer_copy;
423 buffer->buffer.mini_object.dispose =
424 (GstMiniObjectDisposeFunction) _gst_buffer_dispose;
425 buffer->buffer.mini_object.free =
426 (GstMiniObjectFreeFunction) _gst_buffer_free;
428 GST_BUFFER (buffer)->pool = NULL;
429 GST_BUFFER_PTS (buffer) = GST_CLOCK_TIME_NONE;
430 GST_BUFFER_DTS (buffer) = GST_CLOCK_TIME_NONE;
431 GST_BUFFER_DURATION (buffer) = GST_CLOCK_TIME_NONE;
432 GST_BUFFER_OFFSET (buffer) = GST_BUFFER_OFFSET_NONE;
433 GST_BUFFER_OFFSET_END (buffer) = GST_BUFFER_OFFSET_NONE;
435 GST_BUFFER_MEM_LEN (buffer) = 0;
436 GST_BUFFER_META (buffer) = NULL;
442 * Creates a newly allocated buffer without any data.
446 * Returns: (transfer full): the new #GstBuffer.
449 gst_buffer_new (void)
451 GstBufferImpl *newbuf;
453 newbuf = g_slice_new (GstBufferImpl);
454 GST_CAT_LOG (GST_CAT_BUFFER, "new %p", newbuf);
456 gst_buffer_init (newbuf, sizeof (GstBufferImpl));
458 return GST_BUFFER_CAST (newbuf);
462 * gst_buffer_new_allocate:
463 * @allocator: (allow-none): the #GstAllocator to use, or NULL to use the
465 * @size: the size in bytes of the new buffer's data.
466 * @align: the alignment of the buffer memory
468 * Tries to create a newly allocated buffer with data of the given size and
469 * alignment from @allocator. If the requested amount of memory can't be
470 * allocated, NULL will be returned. The allocated buffer memory is not cleared.
472 * When @allocator is NULL, the default memory allocator will be used.
474 * Allocator buffer memory will be aligned to multiples of (@align + 1) bytes.
476 * Note that when @size == 0, the buffer will not have memory associated with it.
480 * Returns: (transfer full): a new #GstBuffer, or NULL if the memory couldn't
484 gst_buffer_new_allocate (GstAllocator * allocator, gsize size, gsize align)
495 mem = gst_allocator_alloc (allocator, size, align);
496 if (G_UNLIKELY (mem == NULL))
502 newbuf = gst_buffer_new ();
505 _memory_add (newbuf, -1, mem);
507 GST_CAT_LOG (GST_CAT_BUFFER,
508 "new buffer %p of size %" G_GSIZE_FORMAT " from allocator %p", newbuf,
513 asize = sizeof (GstBufferImpl) + size;
514 data = g_slice_alloc (asize);
515 if (G_UNLIKELY (data == NULL))
518 newbuf = GST_BUFFER_CAST (data);
520 gst_buffer_init ((GstBufferImpl *) data, asize);
522 mem = gst_memory_new_wrapped (0, data + sizeof (GstBufferImpl), NULL,
524 _memory_add (newbuf, -1, mem);
529 /* allocate memory and buffer, it might be interesting to do this but there
530 * are many complications. We need to keep the memory mapped to access the
531 * buffer fields and the memory for the buffer might be just very slow. We
532 * also need to do some more magic to get the alignment right. */
533 asize = sizeof (GstBufferImpl) + size;
534 mem = gst_allocator_alloc (allocator, asize, align);
535 if (G_UNLIKELY (mem == NULL))
538 /* map the data part and init the buffer in it, set the buffer size to 0 so
539 * that a finalize won't free the buffer */
540 data = gst_memory_map (mem, &asize, NULL, GST_MAP_WRITE);
541 gst_buffer_init ((GstBufferImpl *) data, 0);
542 gst_memory_unmap (mem);
544 /* strip off the buffer */
545 gst_memory_resize (mem, sizeof (GstBufferImpl), size);
547 newbuf = GST_BUFFER_CAST (data);
548 GST_BUFFER_BUFMEM (newbuf) = mem;
551 _memory_add (newbuf, -1, gst_memory_ref (mem));
559 GST_CAT_WARNING (GST_CAT_BUFFER,
560 "failed to allocate %" G_GSIZE_FORMAT " bytes", size);
566 * gst_buffer_new_wrapped_full:
567 * @data: data to wrap
568 * @free_func: function to free @data
569 * @offset: offset in @data of valid data
570 * @size: size of valid data in @data starting at @offset
572 * Creates a new buffer that wraps the given @data. Valid data is set
573 * to start at @offset and up to @size. If no @free_func is provided,
574 * buffer memory is marked READONLY.
578 * Returns: (transfer full): a new #GstBuffer
581 gst_buffer_new_wrapped_full (gpointer data, GFreeFunc free_func, gsize offset,
586 newbuf = gst_buffer_new ();
587 gst_buffer_take_memory (newbuf, -1,
588 gst_memory_new_wrapped (free_func ? 0 : GST_MEMORY_FLAG_READONLY,
589 data, free_func, offset + size, offset, size));
595 * gst_buffer_new_wrapped:
596 * @data: data to wrap
597 * @size: allocated size of @data
599 * Creates a new buffer that wraps the given @data. The memory will be freed
600 * with g_free and will be marked writable.
604 * Returns: (transfer full): a new #GstBuffer
607 gst_buffer_new_wrapped (gpointer data, gsize size)
609 return gst_buffer_new_wrapped_full (data, g_free, 0, size);
613 * gst_buffer_n_memory:
614 * @buffer: a #GstBuffer.
616 * Get the amount of memory blocks that this buffer has.
618 * Returns: (transfer full): the amount of memory block in this buffer.
621 gst_buffer_n_memory (GstBuffer * buffer)
623 g_return_val_if_fail (GST_IS_BUFFER (buffer), 0);
625 return GST_BUFFER_MEM_LEN (buffer);
629 * gst_buffer_take_memory:
630 * @buffer: a #GstBuffer.
631 * @idx: the index to add the memory at, or -1 to append it to the end
632 * @mem: (transfer full): a #GstMemory.
634 * Add the memory block @mem to @buffer at @idx. This function takes ownership
635 * of @mem and thus doesn't increase its refcount.
638 gst_buffer_take_memory (GstBuffer * buffer, gint idx, GstMemory * mem)
640 g_return_if_fail (GST_IS_BUFFER (buffer));
641 g_return_if_fail (gst_buffer_is_writable (buffer));
642 g_return_if_fail (mem != NULL);
643 g_return_if_fail (idx == -1 ||
644 (idx >= 0 && idx <= GST_BUFFER_MEM_LEN (buffer)));
646 _memory_add (buffer, idx, mem);
650 _get_memory (GstBuffer * buffer, guint idx, gboolean write)
654 mem = GST_BUFFER_MEM_PTR (buffer, idx);
656 if (G_UNLIKELY (write && !gst_memory_is_writable (mem))) {
658 GST_CAT_LOG (GST_CAT_BUFFER,
659 "making writable copy of memory %p in buffer %p", mem, buffer);
660 /* replace with a writable copy */
661 copy = gst_memory_copy (mem, 0, -1);
662 GST_BUFFER_MEM_PTR (buffer, idx) = copy;
663 gst_memory_unref (mem);
670 * gst_buffer_peek_memory:
671 * @buffer: a #GstBuffer.
673 * @flags: #GstMapFlags
675 * Get the memory block in @buffer at @idx for memory access in @flags.
676 * This function does not return a refcount to the memory block. The memory
677 * block stays valid for as long as the caller has a valid reference to @buffer
678 * and as long as no operations that modify the memory blocks are called, such
679 * as gst_buffer_remove_memory_range(), gst_buffer_take_memory() and gst_buffer_resize().
681 * @buffer should be writable when @flags contains #GST_MAP_WRITE. If the memory
682 * at @idx is not writable, a new writable copy will be installed in @buffer and
685 * Returns: a #GstMemory at @idx.
688 gst_buffer_peek_memory (GstBuffer * buffer, guint idx, GstMapFlags flags)
693 write = (flags & GST_MAP_WRITE) != 0;
695 g_return_val_if_fail (GST_IS_BUFFER (buffer), NULL);
696 g_return_val_if_fail (idx < GST_BUFFER_MEM_LEN (buffer), NULL);
698 /* check if we can write when asked for write access */
699 if (G_UNLIKELY (write && !gst_buffer_is_writable (buffer)))
702 mem = _get_memory (buffer, idx, write);
709 g_return_val_if_fail (gst_buffer_is_writable (buffer), NULL);
715 * gst_buffer_remove_memory_range:
716 * @buffer: a #GstBuffer.
720 * Remove @len memory blocks in @buffer starting from @idx.
722 * @length can be -1, in which case all memory starting from @idx is removed.
725 gst_buffer_remove_memory_range (GstBuffer * buffer, guint idx, guint length)
729 g_return_if_fail (GST_IS_BUFFER (buffer));
730 g_return_if_fail (gst_buffer_is_writable (buffer));
732 len = GST_BUFFER_MEM_LEN (buffer);
734 g_return_if_fail (idx < len);
739 for (i = idx; i < end; i++)
740 gst_memory_unref (GST_BUFFER_MEM_PTR (buffer, i));
743 g_memmove (&GST_BUFFER_MEM_PTR (buffer, idx),
744 &GST_BUFFER_MEM_PTR (buffer, end), (len - end) * sizeof (gpointer));
746 GST_BUFFER_MEM_LEN (buffer) = len - length;
750 * gst_buffer_get_merged_memory:
751 * @buffer: a #GstBuffer.
753 * Return a #GstMemory object that contains all the memory in @buffer. If there
754 * was only one memory in @buffer, it will be returned directly, otherwise all
755 * memory objects will be merged into one object that will be returned.
757 * Returns: a #GstMemory with the merged memory in @buffer. This function can
758 * return %NULL if there is no memory in @buffer. Use gst_memory_unref() after
762 gst_buffer_get_merged_memory (GstBuffer * buffer)
767 g_return_val_if_fail (GST_IS_BUFFER (buffer), NULL);
769 len = GST_BUFFER_MEM_LEN (buffer);
771 if (G_UNLIKELY (len == 0)) {
774 } else if (G_LIKELY (len == 1)) {
775 /* we can take the first one */
776 mem = GST_BUFFER_MEM_PTR (buffer, 0);
777 gst_memory_ref (mem);
779 /* we need to span memory */
780 mem = _span_memory (buffer, 0, -1, FALSE);
786 * gst_buffer_get_sizes:
787 * @buffer: a #GstBuffer.
788 * @offset: a pointer to the offset
789 * @maxsize: a pointer to the maxsize
791 * Get the total size of all memory blocks in @buffer.
793 * When not %NULL, @offset will contain the offset of the data in the first
794 * memory block in @buffer and @maxsize will contain the sum of the size
795 * and @offset and the amount of extra padding on the last memory block.
796 * @offset and @maxsize can be used to resize the buffer with
797 * gst_buffer_resize().
799 * Returns: the total size of the memory in @buffer.
802 gst_buffer_get_sizes (GstBuffer * buffer, gsize * offset, gsize * maxsize)
808 g_return_val_if_fail (GST_IS_BUFFER (buffer), 0);
810 len = GST_BUFFER_MEM_LEN (buffer);
812 if (G_LIKELY (len == 1)) {
814 mem = GST_BUFFER_MEM_PTR (buffer, 0);
815 size = gst_memory_get_sizes (mem, offset, maxsize);
820 size = offs = extra = 0;
821 for (i = 0; i < len; i++) {
824 mem = GST_BUFFER_MEM_PTR (buffer, i);
825 s = gst_memory_get_sizes (mem, &o, &ms);
829 /* first size, take accumulated data before as the offset */
833 /* save the amount of data after this block */
834 extra = ms - (o + s);
836 /* empty block, add as extra */
843 *maxsize = offs + size + extra;
850 * @buffer: a #GstBuffer.
851 * @offset: the offset adjustement
852 * @size: the new size or -1 to just adjust the offset
854 * Set the total size of the buffer
857 gst_buffer_resize (GstBuffer * buffer, gssize offset, gssize size)
861 gsize bsize, bufsize, bufoffs, bufmax;
864 g_return_if_fail (gst_buffer_is_writable (buffer));
865 g_return_if_fail (size >= -1);
867 bufsize = gst_buffer_get_sizes (buffer, &bufoffs, &bufmax);
869 GST_CAT_LOG (GST_CAT_BUFFER, "trim %p %" G_GSSIZE_FORMAT "-%" G_GSSIZE_FORMAT
870 " size:%" G_GSIZE_FORMAT " offs:%" G_GSIZE_FORMAT " max:%"
871 G_GSIZE_FORMAT, buffer, offset, size, bufsize, bufoffs, bufmax);
873 /* we can't go back further than the current offset or past the end of the
875 g_return_if_fail ((offset < 0 && bufoffs >= -offset) || (offset >= 0
876 && bufoffs + offset <= bufmax));
878 g_return_if_fail (bufsize >= offset);
879 size = bufsize - offset;
881 g_return_if_fail (bufmax >= bufoffs + offset + size);
883 len = GST_BUFFER_MEM_LEN (buffer);
886 for (i = 0; i < len; i++) {
889 mem = GST_BUFFER_MEM_PTR (buffer, i);
890 bsize = gst_memory_get_sizes (mem, NULL, NULL);
893 /* last buffer always gets resized to the remaining size */
896 /* shrink buffers before the offset */
897 else if ((gssize) bsize <= offset) {
899 noffs = offset - bsize;
902 /* clip other buffers */
904 left = MIN (bsize - offset, size);
906 if (offset != 0 || left != bsize) {
907 /* we need to clip something */
908 if (gst_memory_is_writable (mem)) {
909 gst_memory_resize (mem, offset, left);
913 if (mem->flags & GST_MEMORY_FLAG_NO_SHARE)
914 tmp = gst_memory_copy (mem, offset, left);
916 tmp = gst_memory_share (mem, offset, left);
918 gst_memory_unref (mem);
925 GST_BUFFER_MEM_PTR (buffer, i) = mem;
931 * @buffer: a #GstBuffer.
932 * @info: (out): info about the mapping
933 * @flags: flags for the mapping
935 * This function fills @info with a pointer to the merged memory in @buffer.
936 * @flags describe the desired access of the memory. When @flags is
937 * #GST_MAP_WRITE, @buffer should be writable (as returned from
938 * gst_buffer_is_writable()).
940 * When @buffer is writable but the memory isn't, a writable copy will
941 * automatically be created and returned. The readonly copy of the buffer memory
942 * will then also be replaced with this writable copy.
944 * When the buffer contains multiple memory blocks, the returned pointer will be
945 * a concatenation of the memory blocks.
947 * Returns: (transfer full): %TRUE if the map succeeded and @info contains valid
951 gst_buffer_map (GstBuffer * buffer, GstMapInfo * info, GstMapFlags flags)
954 gboolean write, writable;
956 g_return_val_if_fail (GST_IS_BUFFER (buffer), FALSE);
957 g_return_val_if_fail (info != NULL, FALSE);
959 write = (flags & GST_MAP_WRITE) != 0;
960 writable = gst_buffer_is_writable (buffer);
962 /* check if we can write when asked for write access */
963 if (G_UNLIKELY (write && !writable))
966 mem = gst_buffer_get_merged_memory (buffer);
967 if (G_UNLIKELY (mem == NULL))
971 mem = gst_memory_make_mapped (mem, info, flags);
972 if (G_UNLIKELY (mem == NULL))
975 /* if the buffer is writable, replace the memory */
977 _replace_memory (buffer, gst_memory_ref (mem));
978 else if (GST_BUFFER_MEM_LEN (buffer) > 1) {
979 GST_CAT_DEBUG (GST_CAT_PERFORMANCE,
980 "temporary mapping for memory %p in buffer %p", mem, buffer);
988 g_critical ("write map requested on non-writable buffer");
993 /* empty buffer, we need to return NULL */
994 GST_DEBUG_OBJECT (buffer, "can't get buffer memory");
1003 GST_DEBUG_OBJECT (buffer, "cannot map memory");
1010 * @buffer: a #GstBuffer.
1011 * @info: a #GstMapInfo
1013 * Release the memory previously mapped with gst_buffer_map().
1016 gst_buffer_unmap (GstBuffer * buffer, GstMapInfo * info)
1018 g_return_if_fail (GST_IS_BUFFER (buffer));
1019 g_return_if_fail (info != NULL);
1022 gst_memory_unmap (info->memory, info);
1023 gst_memory_unref (info->memory);
1029 * @buffer: a #GstBuffer.
1030 * @offset: the offset to fill
1031 * @src: the source address
1032 * @size: the size to fill
1034 * Copy @size bytes from @src to @buffer at @offset.
1036 * Returns: The amount of bytes copied. This value can be lower than @size
1037 * when @buffer did not contain enough data.
1040 gst_buffer_fill (GstBuffer * buffer, gsize offset, gconstpointer src,
1044 const guint8 *ptr = src;
1046 g_return_val_if_fail (GST_IS_BUFFER (buffer), 0);
1047 g_return_val_if_fail (gst_buffer_is_writable (buffer), 0);
1048 g_return_val_if_fail (src != NULL, 0);
1050 len = GST_BUFFER_MEM_LEN (buffer);
1053 for (i = 0; i < len && left > 0; i++) {
1058 mem = _get_memory (buffer, i, TRUE);
1060 gst_memory_map (mem, &info, GST_MAP_WRITE);
1061 if (info.size > offset) {
1062 /* we have enough */
1063 tocopy = MIN (info.size - offset, left);
1064 memcpy ((guint8 *) info.data + offset, ptr, tocopy);
1069 /* offset past buffer, skip */
1070 offset -= info.size;
1072 gst_memory_unmap (mem, &info);
1078 * gst_buffer_extract:
1079 * @buffer: a #GstBuffer.
1080 * @offset: the offset to extract
1081 * @dest: the destination address
1082 * @size: the size to extract
1084 * Copy @size bytes starting from @offset in @buffer to @dest.
1086 * Returns: The amount of bytes extracted. This value can be lower than @size
1087 * when @buffer did not contain enough data.
1090 gst_buffer_extract (GstBuffer * buffer, gsize offset, gpointer dest, gsize size)
1095 g_return_val_if_fail (GST_IS_BUFFER (buffer), 0);
1096 g_return_val_if_fail (dest != NULL, 0);
1098 len = GST_BUFFER_MEM_LEN (buffer);
1101 for (i = 0; i < len && left > 0; i++) {
1106 mem = GST_BUFFER_MEM_PTR (buffer, i);
1108 gst_memory_map (mem, &info, GST_MAP_READ);
1109 if (info.size > offset) {
1110 /* we have enough */
1111 tocopy = MIN (info.size - offset, left);
1112 memcpy (ptr, (guint8 *) info.data + offset, tocopy);
1117 /* offset past buffer, skip */
1118 offset -= info.size;
1120 gst_memory_unmap (mem, &info);
1126 * gst_buffer_memcmp:
1127 * @buffer: a #GstBuffer.
1128 * @offset: the offset in @buffer
1129 * @mem: the memory to compare
1130 * @size: the size to compare
1132 * Compare @size bytes starting from @offset in @buffer with the memory in @mem.
1134 * Returns: 0 if the memory is equal.
1137 gst_buffer_memcmp (GstBuffer * buffer, gsize offset, gconstpointer mem,
1141 const guint8 *ptr = mem;
1144 g_return_val_if_fail (GST_IS_BUFFER (buffer), 0);
1145 g_return_val_if_fail (mem != NULL, 0);
1147 len = GST_BUFFER_MEM_LEN (buffer);
1149 for (i = 0; i < len && size > 0 && res == 0; i++) {
1154 mem = GST_BUFFER_MEM_PTR (buffer, i);
1156 gst_memory_map (mem, &info, GST_MAP_READ);
1157 if (info.size > offset) {
1158 /* we have enough */
1159 tocmp = MIN (info.size - offset, size);
1160 res = memcmp (ptr, (guint8 *) info.data + offset, tocmp);
1165 /* offset past buffer, skip */
1166 offset -= info.size;
1168 gst_memory_unmap (mem, &info);
1174 * gst_buffer_memset:
1175 * @buffer: a #GstBuffer.
1176 * @offset: the offset in @buffer
1177 * @val: the value to set
1178 * @size: the size to set
1180 * Fill @buf with @size bytes with @val starting from @offset.
1182 * Returns: The amount of bytes filled. This value can be lower than @size
1183 * when @buffer did not contain enough data.
1186 gst_buffer_memset (GstBuffer * buffer, gsize offset, guint8 val, gsize size)
1190 g_return_val_if_fail (GST_IS_BUFFER (buffer), 0);
1191 g_return_val_if_fail (gst_buffer_is_writable (buffer), 0);
1193 len = GST_BUFFER_MEM_LEN (buffer);
1196 for (i = 0; i < len && left > 0; i++) {
1201 mem = _get_memory (buffer, i, TRUE);
1203 gst_memory_map (mem, &info, GST_MAP_WRITE);
1204 if (info.size > offset) {
1205 /* we have enough */
1206 toset = MIN (info.size - offset, left);
1207 memset ((guint8 *) info.data + offset, val, toset);
1211 /* offset past buffer, skip */
1212 offset -= info.size;
1214 gst_memory_unmap (mem, &info);
1220 * gst_buffer_copy_region:
1221 * @parent: a #GstBuffer.
1222 * @flags: the #GstBufferCopyFlags
1223 * @offset: the offset into parent #GstBuffer at which the new sub-buffer
1225 * @size: the size of the new #GstBuffer sub-buffer, in bytes.
1227 * Creates a sub-buffer from @parent at @offset and @size.
1228 * This sub-buffer uses the actual memory space of the parent buffer.
1229 * This function will copy the offset and timestamp fields when the
1230 * offset is 0. If not, they will be set to #GST_CLOCK_TIME_NONE and
1231 * #GST_BUFFER_OFFSET_NONE.
1232 * If @offset equals 0 and @size equals the total size of @buffer, the
1233 * duration and offset end fields are also copied. If not they will be set
1234 * to #GST_CLOCK_TIME_NONE and #GST_BUFFER_OFFSET_NONE.
1238 * Returns: (transfer full): the new #GstBuffer or NULL if the arguments were
1242 gst_buffer_copy_region (GstBuffer * buffer, GstBufferCopyFlags flags,
1243 gsize offset, gsize size)
1247 g_return_val_if_fail (buffer != NULL, NULL);
1249 /* create the new buffer */
1250 copy = gst_buffer_new ();
1252 GST_CAT_LOG (GST_CAT_BUFFER, "new region copy %p of %p %" G_GSIZE_FORMAT
1253 "-%" G_GSIZE_FORMAT, copy, buffer, offset, size);
1255 gst_buffer_copy_into (copy, buffer, flags, offset, size);
1261 _gst_buffer_arr_is_span_fast (GstMemory ** mem[], gsize len[], guint n,
1262 gsize * offset, GstMemory ** parent)
1264 GstMemory *mcur, *mprv;
1265 gboolean have_offset = FALSE;
1269 for (count = 0; count < n; count++) {
1276 for (i = 0; i < clen; i++) {
1282 /* check is memory is contiguous */
1283 if (!gst_memory_is_span (mprv, mcur, &offs))
1290 *parent = mprv->parent;
1301 _gst_buffer_arr_span (GstMemory ** mem[], gsize len[], guint n, gsize offset,
1302 gsize size, gboolean writable)
1304 GstMemory *span, *parent = NULL;
1308 && _gst_buffer_arr_is_span_fast (mem, len, n, &poffset, &parent)) {
1309 if (parent->flags & GST_MEMORY_FLAG_NO_SHARE) {
1310 GST_CAT_DEBUG (GST_CAT_PERFORMANCE, "copy for span %p", parent);
1311 span = gst_memory_copy (parent, offset + poffset, size);
1313 span = gst_memory_share (parent, offset + poffset, size);
1320 span = gst_allocator_alloc (NULL, size, 0);
1321 gst_memory_map (span, &dinfo, GST_MAP_WRITE);
1326 for (count = 0; count < n; count++) {
1328 gsize i, tocopy, clen;
1334 for (i = 0; i < clen && left > 0; i++) {
1335 gst_memory_map (cmem[i], &sinfo, GST_MAP_READ);
1336 tocopy = MIN (sinfo.size, left);
1337 if (tocopy > offset) {
1338 GST_CAT_DEBUG (GST_CAT_PERFORMANCE,
1339 "memcpy for span %p from memory %p", span, cmem[i]);
1340 memcpy (ptr, (guint8 *) sinfo.data + offset, tocopy - offset);
1347 gst_memory_unmap (cmem[i], &sinfo);
1350 gst_memory_unmap (span, &dinfo);
1356 * gst_buffer_is_span_fast:
1357 * @buf1: the first #GstBuffer.
1358 * @buf2: the second #GstBuffer.
1360 * Determines whether a gst_buffer_span() can be done without copying
1361 * the contents, that is, whether the data areas are contiguous sub-buffers of
1365 * Returns: TRUE if the buffers are contiguous,
1366 * FALSE if a copy would be required.
1369 gst_buffer_is_span_fast (GstBuffer * buf1, GstBuffer * buf2)
1374 g_return_val_if_fail (GST_IS_BUFFER (buf1), FALSE);
1375 g_return_val_if_fail (GST_IS_BUFFER (buf2), FALSE);
1376 g_return_val_if_fail (buf1->mini_object.refcount > 0, FALSE);
1377 g_return_val_if_fail (buf2->mini_object.refcount > 0, FALSE);
1379 mem[0] = GST_BUFFER_MEM_ARRAY (buf1);
1380 len[0] = GST_BUFFER_MEM_LEN (buf1);
1381 mem[1] = GST_BUFFER_MEM_ARRAY (buf2);
1382 len[1] = GST_BUFFER_MEM_LEN (buf2);
1384 return _gst_buffer_arr_is_span_fast (mem, len, 2, NULL, NULL);
1389 * @buf1: the first source #GstBuffer to merge.
1390 * @offset: the offset in the first buffer from where the new
1391 * buffer should start.
1392 * @buf2: the second source #GstBuffer to merge.
1393 * @size: the total size of the new buffer.
1395 * Creates a new buffer that consists of part of buf1 and buf2.
1396 * Logically, buf1 and buf2 are concatenated into a single larger
1397 * buffer, and a new buffer is created at the given offset inside
1398 * this space, with a given length.
1400 * If the two source buffers are children of the same larger buffer,
1401 * and are contiguous, the new buffer will be a child of the shared
1402 * parent, and thus no copying is necessary. you can use
1403 * gst_buffer_is_span_fast() to determine if a memcpy will be needed.
1407 * Returns: (transfer full): the new #GstBuffer that spans the two source
1408 * buffers, or NULL if the arguments are invalid.
1411 gst_buffer_span (GstBuffer * buf1, gsize offset, GstBuffer * buf2, gsize size)
1416 gsize len[2], len1, len2;
1418 g_return_val_if_fail (GST_IS_BUFFER (buf1), NULL);
1419 g_return_val_if_fail (GST_IS_BUFFER (buf2), NULL);
1420 g_return_val_if_fail (buf1->mini_object.refcount > 0, NULL);
1421 g_return_val_if_fail (buf2->mini_object.refcount > 0, NULL);
1422 len1 = gst_buffer_get_size (buf1);
1423 len2 = gst_buffer_get_size (buf2);
1424 g_return_val_if_fail (len1 + len2 > offset, NULL);
1426 size = len1 + len2 - offset;
1428 g_return_val_if_fail (size <= len1 + len2 - offset, NULL);
1430 mem[0] = GST_BUFFER_MEM_ARRAY (buf1);
1431 len[0] = GST_BUFFER_MEM_LEN (buf1);
1432 mem[1] = GST_BUFFER_MEM_ARRAY (buf2);
1433 len[1] = GST_BUFFER_MEM_LEN (buf2);
1435 span = _gst_buffer_arr_span (mem, len, 2, offset, size, FALSE);
1437 newbuf = gst_buffer_new ();
1438 _memory_add (newbuf, -1, span);
1441 /* if the offset is 0, the new buffer has the same timestamp as buf1 */
1443 GST_BUFFER_OFFSET (newbuf) = GST_BUFFER_OFFSET (buf1);
1444 GST_BUFFER_PTS (newbuf) = GST_BUFFER_PTS (buf1);
1445 GST_BUFFER_DTS (newbuf) = GST_BUFFER_DTS (buf1);
1447 /* if we completely merged the two buffers (appended), we can
1448 * calculate the duration too. Also make sure we's not messing with
1449 * invalid DURATIONS */
1450 if (buf1->size + buf2->size == len) {
1451 if (GST_BUFFER_DURATION_IS_VALID (buf1) &&
1452 GST_BUFFER_DURATION_IS_VALID (buf2)) {
1454 GST_BUFFER_DURATION (newbuf) = GST_BUFFER_DURATION (buf1) +
1455 GST_BUFFER_DURATION (buf2);
1457 if (GST_BUFFER_OFFSET_END_IS_VALID (buf2)) {
1458 /* add offset_end */
1459 GST_BUFFER_OFFSET_END (newbuf) = GST_BUFFER_OFFSET_END (buf2);
1469 * gst_buffer_get_meta:
1470 * @buffer: a #GstBuffer
1471 * @info: a #GstMetaInfo
1473 * Get the metadata for the api in @info on buffer. When there is no such
1474 * metadata, NULL is returned.
1476 * Note that the result metadata might not be of the implementation @info.
1478 * Returns: the metadata for the api in @info on @buffer.
1481 gst_buffer_get_meta (GstBuffer * buffer, const GstMetaInfo * info)
1484 GstMeta *result = NULL;
1486 g_return_val_if_fail (buffer != NULL, NULL);
1487 g_return_val_if_fail (info != NULL, NULL);
1489 /* find GstMeta of the requested API */
1490 for (item = GST_BUFFER_META (buffer); item; item = item->next) {
1491 GstMeta *meta = &item->meta;
1492 if (meta->info->api == info->api) {
1501 * gst_buffer_add_meta:
1502 * @buffer: a #GstBuffer
1503 * @info: a #GstMetaInfo
1504 * @params: params for @info
1506 * Add metadata for @info to @buffer using the parameters in @params.
1508 * Returns: (transfer none): the metadata for the api in @info on @buffer.
1511 gst_buffer_add_meta (GstBuffer * buffer, const GstMetaInfo * info,
1515 GstMeta *result = NULL;
1518 g_return_val_if_fail (buffer != NULL, NULL);
1519 g_return_val_if_fail (info != NULL, NULL);
1521 /* create a new slice */
1522 size = ITEM_SIZE (info);
1523 item = g_slice_alloc (size);
1524 result = &item->meta;
1525 result->info = info;
1526 result->flags = GST_META_FLAG_NONE;
1528 GST_CAT_DEBUG (GST_CAT_BUFFER,
1529 "alloc metadata %p (%s) of size %" G_GSIZE_FORMAT, result,
1530 g_type_name (info->type), info->size);
1532 /* call the init_func when needed */
1533 if (info->init_func)
1534 if (!info->init_func (result, params, buffer))
1537 /* and add to the list of metadata */
1538 item->next = GST_BUFFER_META (buffer);
1539 GST_BUFFER_META (buffer) = item;
1545 g_slice_free1 (size, item);
1551 * gst_buffer_remove_meta:
1552 * @buffer: a #GstBuffer
1555 * Remove the metadata for @meta on @buffer.
1557 * Returns: %TRUE if the metadata existed and was removed, %FALSE if no such
1558 * metadata was on @buffer.
1561 gst_buffer_remove_meta (GstBuffer * buffer, GstMeta * meta)
1563 GstMetaItem *walk, *prev;
1565 g_return_val_if_fail (buffer != NULL, FALSE);
1566 g_return_val_if_fail (meta != NULL, FALSE);
1568 /* find the metadata and delete */
1569 prev = GST_BUFFER_META (buffer);
1570 for (walk = prev; walk; walk = walk->next) {
1571 GstMeta *m = &walk->meta;
1573 const GstMetaInfo *info = meta->info;
1575 /* remove from list */
1576 if (GST_BUFFER_META (buffer) == walk)
1577 GST_BUFFER_META (buffer) = walk->next;
1579 prev->next = walk->next;
1580 /* call free_func if any */
1581 if (info->free_func)
1582 info->free_func (m, buffer);
1584 /* and free the slice */
1585 g_slice_free1 (ITEM_SIZE (info), walk);
1590 return walk != NULL;
1594 * gst_buffer_iterate_meta:
1595 * @buffer: a #GstBuffer
1596 * @state: an opaque state pointer
1598 * Retrieve the next #GstMeta after @current. If @state points
1599 * to %NULL, the first metadata is returned.
1601 * @state will be updated with an opage state pointer
1603 * Returns: The next #GstMeta or %NULL when there are no more items.
1606 gst_buffer_iterate_meta (GstBuffer * buffer, gpointer * state)
1610 g_return_val_if_fail (buffer != NULL, NULL);
1611 g_return_val_if_fail (state != NULL, NULL);
1613 meta = (GstMetaItem **) state;
1615 /* state NULL, move to first item */
1616 *meta = GST_BUFFER_META (buffer);
1618 /* state !NULL, move to next item in list */
1619 *meta = (*meta)->next;
1622 return &(*meta)->meta;
1628 * gst_buffer_foreach_meta:
1629 * @buffer: a #GstBuffer
1630 * @func: (scope call): a #GstBufferForeachMetaFunc to call
1631 * @user_data: (closure): user data passed to @func
1633 * Call @func with @user_data for each meta in @buffer.
1635 * @func can modify the passed meta pointer or its contents. The return value
1636 * of @func define if this function returns or if the remaining metadata items
1637 * in the buffer should be skipped.
1640 gst_buffer_foreach_meta (GstBuffer * buffer, GstBufferForeachMetaFunc func,
1643 GstMetaItem *walk, *prev, *next;
1645 g_return_if_fail (buffer != NULL);
1646 g_return_if_fail (func != NULL);
1648 /* find the metadata and delete */
1649 prev = GST_BUFFER_META (buffer);
1650 for (walk = prev; walk; walk = next) {
1654 m = new = &walk->meta;
1657 res = func (buffer, &new, user_data);
1660 const GstMetaInfo *info = m->info;
1662 GST_CAT_DEBUG (GST_CAT_BUFFER, "remove metadata %p (%s)", m,
1663 g_type_name (info->type));
1665 /* remove from list */
1666 if (GST_BUFFER_META (buffer) == walk)
1667 GST_BUFFER_META (buffer) = next;
1671 /* call free_func if any */
1672 if (info->free_func)
1673 info->free_func (m, buffer);
1675 /* and free the slice */
1676 g_slice_free1 (ITEM_SIZE (info), walk);