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
28 * Buffers are the basic unit of data transfer in GStreamer. The #GstBuffer
29 * type provides all the state necessary to define a region of memory as part
30 * of a stream. Sub-buffers are also supported, allowing a smaller region of a
31 * buffer to become its own buffer, with mechanisms in place to ensure that
32 * 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 set the size of the
36 * buffer data. The following example creates a buffer that can hold a given
37 * video frame with a given width, height and bits per plane.
39 * <title>Creating a buffer for a video frame</title>
42 * gint size, width, height, bpp;
44 * size = width * height * bpp;
45 * buffer = gst_buffer_new ();
46 * GST_BUFFER_SIZE (buffer) = size;
47 * GST_BUFFER_MALLOCDATA (buffer) = g_malloc (size);
48 * GST_BUFFER_DATA (buffer) = GST_BUFFER_MALLOCDATA (buffer);
53 * Alternatively, use gst_buffer_new_and_alloc()
54 * to create a buffer with preallocated data of a given size.
56 * The data pointed to by the buffer can be retrieved with the GST_BUFFER_DATA()
57 * macro. The size of the data can be found with GST_BUFFER_SIZE(). For buffers
58 * of size 0, the data pointer is undefined (usually NULL) and should never be used.
60 * If an element knows what pad you will push the buffer out on, it should use
61 * gst_pad_alloc_buffer() instead to create a buffer. This allows downstream
62 * elements to provide special buffers to write in, like hardware buffers.
64 * A buffer has a pointer to a #GstCaps describing the media type of the data
65 * in the buffer. Attach caps to the buffer with gst_buffer_set_caps(); this
66 * is typically done before pushing out a buffer using gst_pad_push() so that
67 * the downstream element knows the type of the buffer.
69 * A buffer will usually have a timestamp, and a duration, but neither of these
70 * are guaranteed (they may be set to #GST_CLOCK_TIME_NONE). Whenever a
71 * meaningful value can be given for these, they should be set. The timestamp
72 * and duration are measured in nanoseconds (they are #GstClockTime values).
74 * A buffer can also have one or both of a start and an end offset. These are
75 * media-type specific. For video buffers, the start offset will generally be
76 * the frame number. For audio buffers, it will be the number of samples
77 * produced so far. For compressed data, it could be the byte offset in a
78 * source or destination file. Likewise, the end offset will be the offset of
79 * the end of the buffer. These can only be meaningfully interpreted if you
80 * know the media type of the buffer (the #GstCaps set on it). Either or both
81 * can be set to #GST_BUFFER_OFFSET_NONE.
83 * gst_buffer_ref() is used to increase the refcount of a buffer. This must be
84 * done when you want to keep a handle to the buffer after pushing it to the
87 * To efficiently create a smaller buffer out of an existing one, you can
88 * use gst_buffer_create_sub().
90 * If a plug-in wants to modify the buffer data in-place, it should first obtain
91 * a buffer that is safe to modify by using gst_buffer_make_writable(). This
92 * function is optimized so that a copy will only be made when it is necessary.
94 * A plugin that only wishes to modify the metadata of a buffer, such as the
95 * offset, timestamp or caps, should use gst_buffer_make_metadata_writable(),
96 * which will create a subbuffer of the original buffer to ensure the caller
97 * has sole ownership, and not copy the buffer data.
99 * Several flags of the buffer can be set and unset with the
100 * GST_BUFFER_FLAG_SET() and GST_BUFFER_FLAG_UNSET() macros. Use
101 * GST_BUFFER_FLAG_IS_SET() to test if a certain #GstBufferFlag is set.
103 * Buffers can be efficiently merged into a larger buffer with
104 * gst_buffer_merge() and gst_buffer_span() if the gst_buffer_is_span_fast()
105 * function returns TRUE.
107 * An element should either unref the buffer or push it out on a src pad
108 * using gst_pad_push() (see #GstPad).
110 * Buffers are usually freed by unreffing them with gst_buffer_unref(). When
111 * the refcount drops to 0, any data pointed to by GST_BUFFER_MALLOCDATA() will
114 * Last reviewed on August 11th, 2006 (0.10.10)
116 #include "gst_private.h"
125 #include "gstbuffer.h"
127 #include "gstutils.h"
128 #include "gstminiobject.h"
129 #include "gstversion.h"
131 struct _GstBufferPrivate
134 /* think about locking buffer->priv etc. when adding more fields */
137 static void gst_buffer_finalize (GstBuffer * buffer);
138 static GstBuffer *_gst_buffer_copy (GstBuffer * buffer);
140 static GType _gst_buffer_type = 0;
142 /* buffer alignment in bytes
143 * an alignment of 8 would be the same as malloc() guarantees
145 #ifdef HAVE_POSIX_MEMALIGN
146 #if defined(BUFFER_ALIGNMENT_MALLOC)
147 static size_t _gst_buffer_data_alignment = 8;
148 #elif defined(BUFFER_ALIGNMENT_PAGESIZE)
149 static size_t _gst_buffer_data_alignment = 0;
150 #elif defined(BUFFER_ALIGNMENT)
151 static size_t _gst_buffer_data_alignment = BUFFER_ALIGNMENT;
153 #error "No buffer alignment configured"
156 static inline gboolean
157 aligned_malloc (gpointer * memptr, guint size)
161 res = posix_memalign (memptr, _gst_buffer_data_alignment, size);
165 #endif /* HAVE_POSIX_MEMALIGN */
168 _gst_buffer_initialize (void)
170 /* the GstMiniObject types need to be class_ref'd once before it can be
171 * done from multiple threads;
172 * see http://bugzilla.gnome.org/show_bug.cgi?id=304551 */
173 g_type_class_ref (gst_buffer_get_type ());
174 #ifdef HAVE_GETPAGESIZE
175 #ifdef BUFFER_ALIGNMENT_PAGESIZE
176 _gst_buffer_data_alignment = getpagesize ();
183 _gst_buffer_type = g_define_type_id; \
186 G_DEFINE_TYPE_WITH_CODE (GstBuffer, gst_buffer, GST_TYPE_MINI_OBJECT, _do_init);
189 gst_buffer_class_init (GstBufferClass * klass)
191 klass->mini_object_class.copy = (GstMiniObjectCopyFunction) _gst_buffer_copy;
192 klass->mini_object_class.finalize =
193 (GstMiniObjectFinalizeFunction) gst_buffer_finalize;
195 g_type_class_add_private (klass, sizeof (GstBufferPrivate));
199 gst_buffer_finalize (GstBuffer * buffer)
201 g_return_if_fail (buffer != NULL);
203 GST_CAT_LOG (GST_CAT_BUFFER, "finalize %p", buffer);
206 if (G_LIKELY (buffer->malloc_data))
207 buffer->free_func (buffer->malloc_data);
209 gst_caps_replace (&GST_BUFFER_CAPS (buffer), NULL);
212 gst_buffer_unref (buffer->parent);
214 if (G_UNLIKELY (buffer->priv != NULL)) {
215 GstBufferPrivate *priv = buffer->priv;
217 while (priv->qdata != NULL) {
218 GstStructure *s = priv->qdata->data;
220 gst_structure_set_parent_refcount (s, NULL);
221 gst_structure_free (s);
222 priv->qdata = g_list_delete_link (priv->qdata, priv->qdata);
227 /* ((GstMiniObjectClass *) */
228 /* gst_buffer_parent_class)->finalize (GST_MINI_OBJECT_CAST (buffer)); */
231 static inline GstBufferPrivate *
232 gst_buffer_ensure_priv (GstBuffer * buf)
234 GstBufferPrivate *priv = buf->priv;
240 G_TYPE_INSTANCE_GET_PRIVATE (buf, GST_TYPE_BUFFER, GstBufferPrivate);
246 gst_buffer_copy_qdata (GstBuffer * dest, const GstBuffer * src)
248 GstBufferPrivate *priv;
249 GQueue qdata_copy = G_QUEUE_INIT;
252 if (G_LIKELY (src->priv == NULL))
255 for (l = src->priv->qdata; l != NULL; l = l->next) {
256 GstStructure *s = gst_structure_copy (l->data);
258 gst_structure_set_parent_refcount (s, &dest->mini_object.refcount);
259 g_queue_push_tail (&qdata_copy, s);
261 GST_CAT_TRACE (GST_CAT_BUFFER, "copying qdata '%s' from buffer %p to %p",
262 g_quark_to_string (s->name), src, dest);
265 priv = gst_buffer_ensure_priv (dest);
266 priv->qdata = qdata_copy.head;
270 * gst_buffer_copy_metadata:
271 * @dest: a destination #GstBuffer
272 * @src: a source #GstBuffer
273 * @flags: flags indicating what metadata fields should be copied.
275 * Copies the metadata from @src into @dest. The data, size and mallocdata
276 * fields are not copied.
278 * @flags indicate which fields will be copied. Use #GST_BUFFER_COPY_ALL to copy
279 * all the metadata fields.
281 * This function is typically called from a custom buffer copy function after
282 * creating @dest and setting the data, size, mallocdata.
287 gst_buffer_copy_metadata (GstBuffer * dest, const GstBuffer * src,
288 GstBufferCopyFlags flags)
290 g_return_if_fail (dest != NULL);
291 g_return_if_fail (src != NULL);
293 /* nothing to copy if the buffers are the same */
294 if (G_UNLIKELY (dest == src))
297 #if GST_VERSION_NANO == 1
298 /* we enable this extra debugging in git versions only for now */
299 g_warn_if_fail (gst_buffer_is_metadata_writable (dest));
302 GST_CAT_LOG (GST_CAT_BUFFER, "copy %p to %p", src, dest);
304 if (flags & GST_BUFFER_COPY_FLAGS) {
307 /* copy relevant flags */
308 mask = GST_BUFFER_FLAG_PREROLL | GST_BUFFER_FLAG_IN_CAPS |
309 GST_BUFFER_FLAG_DELTA_UNIT | GST_BUFFER_FLAG_DISCONT |
310 GST_BUFFER_FLAG_GAP | GST_BUFFER_FLAG_MEDIA1 |
311 GST_BUFFER_FLAG_MEDIA2 | GST_BUFFER_FLAG_MEDIA3;
312 GST_MINI_OBJECT_FLAGS (dest) |= GST_MINI_OBJECT_FLAGS (src) & mask;
315 if (flags & GST_BUFFER_COPY_TIMESTAMPS) {
316 GST_BUFFER_TIMESTAMP (dest) = GST_BUFFER_TIMESTAMP (src);
317 GST_BUFFER_DURATION (dest) = GST_BUFFER_DURATION (src);
318 GST_BUFFER_OFFSET (dest) = GST_BUFFER_OFFSET (src);
319 GST_BUFFER_OFFSET_END (dest) = GST_BUFFER_OFFSET_END (src);
322 if (flags & GST_BUFFER_COPY_CAPS) {
323 gst_caps_replace (&GST_BUFFER_CAPS (dest), GST_BUFFER_CAPS (src));
326 if ((flags & GST_BUFFER_COPY_QDATA)) {
327 GST_CAT_TRACE (GST_CAT_BUFFER, "copying qdata from %p to %p", src, dest);
328 gst_buffer_copy_qdata (dest, src);
333 * gst_buffer_set_qdata:
334 * @buffer: a #GstBuffer
335 * @quark: name quark of data structure to set or replace
336 * @data: (transfer full) (allow-none): a #GstStructure to store with the
337 * buffer, name must match @quark. Can be NULL to remove an existing
338 * structure. This function takes ownership of the structure passed.
340 * Set metadata structure for name quark @quark to @data, or remove the
341 * existing metadata structure by that name in case @data is NULL.
343 * Takes ownership of @data.
348 gst_buffer_set_qdata (GstBuffer * buffer, GQuark quark, GstStructure * data)
350 GstBufferPrivate *priv;
353 g_return_if_fail (GST_IS_BUFFER (buffer));
354 g_return_if_fail (gst_buffer_is_metadata_writable (buffer));
355 g_return_if_fail (data == NULL || quark == gst_structure_get_name_id (data));
357 /* locking should not really be required, since the metadata_writable
358 * check ensures that the caller is the only one holding a ref, so as
359 * as a second ref is added everything turns read-only */
360 priv = gst_buffer_ensure_priv (buffer);
363 gst_structure_set_parent_refcount (data, &buffer->mini_object.refcount);
366 for (l = priv->qdata; l != NULL; l = l->next) {
367 GstStructure *s = l->data;
369 if (s->name == quark) {
370 GST_CAT_LOG (GST_CAT_BUFFER, "Replacing qdata '%s' on buffer %p: "
371 "%" GST_PTR_FORMAT " => %" GST_PTR_FORMAT, g_quark_to_string (quark),
373 gst_structure_set_parent_refcount (s, NULL);
374 gst_structure_free (s);
377 priv->qdata = g_list_delete_link (priv->qdata, l);
385 GST_CAT_LOG (GST_CAT_BUFFER, "Set qdata '%s' on buffer %p: %" GST_PTR_FORMAT,
386 g_quark_to_string (quark), buffer, data);
388 priv->qdata = g_list_prepend (priv->qdata, data);
396 * gst_buffer_get_qdata:
397 * @buffer: a #GstBuffer
398 * @quark: name quark of data structure to find
400 * Get metadata structure for name quark @quark.
402 * Returns: (transfer none): a #GstStructure, or NULL if not found
407 gst_buffer_get_qdata (GstBuffer * buffer, GQuark quark)
409 GstStructure *ret = NULL;
411 /* no need for locking: if the caller has the only ref, we're safe, and
412 * if the buffer has multiple refs, it's not metadata-writable any longer
413 * and the data can't change */
415 GST_CAT_LOG (GST_CAT_BUFFER, "Looking for qdata '%s' on buffer %p",
416 g_quark_to_string (quark), buffer);
418 if (buffer->priv != NULL) {
421 for (l = buffer->priv->qdata; l != NULL; l = l->next) {
422 GstStructure *s = l->data;
424 GST_CAT_LOG (GST_CAT_BUFFER, "checking qdata '%s' on buffer %p",
425 g_quark_to_string (s->name), buffer);
427 if (s->name == quark) {
438 _gst_buffer_copy (GstBuffer * buffer)
442 g_return_val_if_fail (buffer != NULL, NULL);
444 /* create a fresh new buffer */
445 copy = gst_buffer_new ();
447 /* we simply copy everything from our parent */
448 #ifdef HAVE_POSIX_MEMALIGN
450 gpointer memptr = NULL;
452 if (G_LIKELY (buffer->size)) {
453 if (G_UNLIKELY (!aligned_malloc (&memptr, buffer->size))) {
454 /* terminate on error like g_memdup() would */
455 g_error ("%s: failed to allocate %u bytes", G_STRLOC, buffer->size);
457 memcpy (memptr, buffer->data, buffer->size);
460 copy->data = (guint8 *) memptr;
461 GST_BUFFER_FREE_FUNC (copy) = free;
464 copy->data = g_memdup (buffer->data, buffer->size);
467 /* make sure it gets freed (even if the parent is subclassed, we return a
469 copy->malloc_data = copy->data;
470 copy->size = buffer->size;
472 gst_buffer_copy_metadata (copy, buffer, GST_BUFFER_COPY_ALL);
478 gst_buffer_init (GstBuffer * buffer)
480 GST_CAT_LOG (GST_CAT_BUFFER, "init %p", buffer);
482 GST_BUFFER_TIMESTAMP (buffer) = GST_CLOCK_TIME_NONE;
483 GST_BUFFER_DURATION (buffer) = GST_CLOCK_TIME_NONE;
484 GST_BUFFER_OFFSET (buffer) = GST_BUFFER_OFFSET_NONE;
485 GST_BUFFER_OFFSET_END (buffer) = GST_BUFFER_OFFSET_NONE;
486 GST_BUFFER_FREE_FUNC (buffer) = g_free;
492 * Creates a newly allocated buffer without any data.
496 * Returns: (transfer full): the new #GstBuffer.
499 gst_buffer_new (void)
503 newbuf = (GstBuffer *) gst_mini_object_new (_gst_buffer_type);
505 GST_CAT_LOG (GST_CAT_BUFFER, "new %p", newbuf);
511 * gst_buffer_new_and_alloc:
512 * @size: the size in bytes of the new buffer's data.
514 * Creates a newly allocated buffer with data of the given size.
515 * The buffer memory is not cleared. If the requested amount of
516 * memory can't be allocated, the program will abort. Use
517 * gst_buffer_try_new_and_alloc() if you want to handle this case
518 * gracefully or have gotten the size to allocate from an untrusted
519 * source such as a media stream.
522 * Note that when @size == 0, the buffer data pointer will be NULL.
526 * Returns: (transfer full): the new #GstBuffer.
529 gst_buffer_new_and_alloc (guint size)
533 newbuf = gst_buffer_new ();
535 #ifdef HAVE_POSIX_MEMALIGN
537 gpointer memptr = NULL;
539 if (G_LIKELY (size)) {
540 if (G_UNLIKELY (!aligned_malloc (&memptr, size))) {
541 /* terminate on error like g_memdup() would */
542 g_error ("%s: failed to allocate %u bytes", G_STRLOC, size);
545 newbuf->malloc_data = (guint8 *) memptr;
546 GST_BUFFER_FREE_FUNC (newbuf) = free;
549 newbuf->malloc_data = g_malloc (size);
551 GST_BUFFER_DATA (newbuf) = newbuf->malloc_data;
552 GST_BUFFER_SIZE (newbuf) = size;
554 GST_CAT_LOG (GST_CAT_BUFFER, "new %p of size %d", newbuf, size);
560 * gst_buffer_try_new_and_alloc:
561 * @size: the size in bytes of the new buffer's data.
563 * Tries to create a newly allocated buffer with data of the given size. If
564 * the requested amount of memory can't be allocated, NULL will be returned.
565 * The buffer memory is not cleared.
567 * Note that when @size == 0, the buffer data pointer will be NULL.
571 * Returns: (transfer full): a new #GstBuffer, or NULL if the memory couldn't
577 gst_buffer_try_new_and_alloc (guint size)
581 #ifdef HAVE_POSIX_MEMALIGN
582 gpointer memptr = NULL;
584 if (G_LIKELY (size)) {
585 if (G_UNLIKELY (!aligned_malloc (&memptr, size))) {
586 GST_CAT_WARNING (GST_CAT_BUFFER, "failed to allocate %d bytes", size);
590 malloc_data = (guint8 *) memptr;
592 malloc_data = g_try_malloc (size);
594 if (G_UNLIKELY (malloc_data == NULL && size != 0)) {
595 GST_CAT_WARNING (GST_CAT_BUFFER, "failed to allocate %d bytes", size);
600 /* FIXME: there's no g_type_try_create_instance() in GObject yet, so this
601 * will still abort if a new GstBuffer structure can't be allocated */
602 newbuf = gst_buffer_new ();
604 GST_BUFFER_MALLOCDATA (newbuf) = malloc_data;
605 GST_BUFFER_DATA (newbuf) = malloc_data;
606 GST_BUFFER_SIZE (newbuf) = size;
607 #ifdef HAVE_POSIX_MEMALIGN
608 GST_BUFFER_FREE_FUNC (newbuf) = free;
611 GST_CAT_LOG (GST_CAT_BUFFER, "new %p of size %d", newbuf, size);
617 * gst_buffer_get_caps:
618 * @buffer: a #GstBuffer.
620 * Gets the media type of the buffer. This can be NULL if there
621 * is no media type attached to this buffer.
623 * Returns: (transfer full): a reference to the #GstCaps. unref after usage.
624 * Returns NULL if there were no caps on this buffer.
626 /* this is not made atomic because if the buffer were reffed from multiple
627 * threads, it would have a refcount > 2 and thus be immutable.
630 gst_buffer_get_caps (GstBuffer * buffer)
634 g_return_val_if_fail (buffer != NULL, NULL);
636 ret = GST_BUFFER_CAPS (buffer);
645 * gst_buffer_set_caps:
646 * @buffer: a #GstBuffer.
647 * @caps: (transfer none): a #GstCaps.
649 * Sets the media type on the buffer. The refcount of the caps will
650 * be increased and any previous caps on the buffer will be
653 /* this is not made atomic because if the buffer were reffed from multiple
654 * threads, it would have a refcount > 2 and thus be immutable.
657 gst_buffer_set_caps (GstBuffer * buffer, GstCaps * caps)
659 g_return_if_fail (buffer != NULL);
660 g_return_if_fail (caps == NULL || GST_CAPS_IS_SIMPLE (caps));
662 #if GST_VERSION_NANO == 1
663 /* we enable this extra debugging in git versions only for now */
664 g_warn_if_fail (gst_buffer_is_metadata_writable (buffer));
665 /* FIXME: would be nice to also check if caps are fixed here, but expensive */
668 gst_caps_replace (&GST_BUFFER_CAPS (buffer), caps);
672 * gst_buffer_is_metadata_writable:
675 * Similar to gst_buffer_is_writable, but this only ensures that the
676 * refcount of the buffer is 1, indicating that the caller is the sole
677 * owner and can change the buffer metadata, such as caps and timestamps.
679 * Returns: TRUE if the metadata is writable.
682 gst_buffer_is_metadata_writable (GstBuffer * buf)
684 return (GST_MINI_OBJECT_REFCOUNT_VALUE (GST_MINI_OBJECT_CAST (buf)) == 1);
688 * gst_buffer_make_metadata_writable:
689 * @buf: (transfer full): a #GstBuffer
691 * Similar to gst_buffer_make_writable, but does not ensure that the buffer
692 * data array is writable. Instead, this just ensures that the returned buffer
693 * is solely owned by the caller, by creating a subbuffer of the original
694 * buffer if necessary.
696 * After calling this function, @buf should not be referenced anymore. The
697 * result of this function has guaranteed writable metadata.
699 * Returns: (transfer full): a new #GstBuffer with writable metadata, which
700 * may or may not be the same as @buf.
703 gst_buffer_make_metadata_writable (GstBuffer * buf)
707 if (gst_buffer_is_metadata_writable (buf)) {
710 ret = gst_buffer_create_sub (buf, 0, GST_BUFFER_SIZE (buf));
712 gst_buffer_unref (buf);
718 #define GST_IS_SUBBUFFER(obj) (GST_BUFFER_CAST(obj)->parent != NULL)
721 * gst_buffer_create_sub:
722 * @parent: a #GstBuffer.
723 * @offset: the offset into parent #GstBuffer at which the new sub-buffer
725 * @size: the size of the new #GstBuffer sub-buffer, in bytes.
727 * Creates a sub-buffer from @parent at @offset and @size.
728 * This sub-buffer uses the actual memory space of the parent buffer.
729 * This function will copy the offset and timestamp fields when the
730 * offset is 0. If not, they will be set to #GST_CLOCK_TIME_NONE and
731 * #GST_BUFFER_OFFSET_NONE.
732 * If @offset equals 0 and @size equals the total size of @buffer, the
733 * duration and offset end fields are also copied. If not they will be set
734 * to #GST_CLOCK_TIME_NONE and #GST_BUFFER_OFFSET_NONE.
738 * Returns: (transfer full): the new #GstBuffer or NULL if the arguments were
742 gst_buffer_create_sub (GstBuffer * buffer, guint offset, guint size)
744 GstBuffer *subbuffer;
748 g_return_val_if_fail (buffer != NULL, NULL);
749 g_return_val_if_fail (buffer->mini_object.refcount > 0, NULL);
750 g_return_val_if_fail (buffer->size >= offset + size, NULL);
752 /* find real parent */
753 if (GST_IS_SUBBUFFER (buffer)) {
754 parent = buffer->parent;
758 gst_buffer_ref (parent);
760 /* create the new buffer */
761 subbuffer = gst_buffer_new ();
762 subbuffer->parent = parent;
763 GST_BUFFER_FLAG_SET (subbuffer, GST_BUFFER_FLAG_READONLY);
765 GST_CAT_LOG (GST_CAT_BUFFER, "new subbuffer %p (parent %p)", subbuffer,
768 /* set the right values in the child */
769 GST_BUFFER_DATA (subbuffer) = buffer->data + offset;
770 GST_BUFFER_SIZE (subbuffer) = size;
772 if ((offset == 0) && (size == GST_BUFFER_SIZE (buffer))) {
773 /* copy all the flags except IN_CAPS */
774 GST_BUFFER_FLAG_SET (subbuffer, GST_BUFFER_FLAGS (buffer));
775 GST_BUFFER_FLAG_UNSET (subbuffer, GST_BUFFER_FLAG_IN_CAPS);
777 /* copy only PREROLL & GAP flags */
778 GST_BUFFER_FLAG_SET (subbuffer, (GST_BUFFER_FLAGS (buffer) &
779 (GST_BUFFER_FLAG_PREROLL | GST_BUFFER_FLAG_GAP)));
782 /* we can copy the timestamp and offset if the new buffer starts at
785 GST_BUFFER_TIMESTAMP (subbuffer) = GST_BUFFER_TIMESTAMP (buffer);
786 GST_BUFFER_OFFSET (subbuffer) = GST_BUFFER_OFFSET (buffer);
787 complete = (buffer->size == size);
789 GST_BUFFER_TIMESTAMP (subbuffer) = GST_CLOCK_TIME_NONE;
790 GST_BUFFER_OFFSET (subbuffer) = GST_BUFFER_OFFSET_NONE;
797 /* if we copied the complete buffer we can copy the duration,
798 * offset_end and caps as well */
799 GST_BUFFER_DURATION (subbuffer) = GST_BUFFER_DURATION (buffer);
800 GST_BUFFER_OFFSET_END (subbuffer) = GST_BUFFER_OFFSET_END (buffer);
801 if ((caps = GST_BUFFER_CAPS (buffer)))
803 GST_BUFFER_CAPS (subbuffer) = caps;
805 /* and also the attached qdata */
806 gst_buffer_copy_qdata (subbuffer, buffer);
808 GST_BUFFER_DURATION (subbuffer) = GST_CLOCK_TIME_NONE;
809 GST_BUFFER_OFFSET_END (subbuffer) = GST_BUFFER_OFFSET_NONE;
810 GST_BUFFER_CAPS (subbuffer) = NULL;
816 * gst_buffer_is_span_fast:
817 * @buf1: the first #GstBuffer.
818 * @buf2: the second #GstBuffer.
820 * Determines whether a gst_buffer_span() can be done without copying
821 * the contents, that is, whether the data areas are contiguous sub-buffers of
825 * Returns: TRUE if the buffers are contiguous,
826 * FALSE if a copy would be required.
829 gst_buffer_is_span_fast (GstBuffer * buf1, GstBuffer * buf2)
831 g_return_val_if_fail (buf1 != NULL && buf2 != NULL, FALSE);
832 g_return_val_if_fail (buf1->mini_object.refcount > 0, FALSE);
833 g_return_val_if_fail (buf2->mini_object.refcount > 0, FALSE);
835 /* it's only fast if we have subbuffers of the same parent */
836 return (GST_IS_SUBBUFFER (buf1) &&
837 GST_IS_SUBBUFFER (buf2) && (buf1->parent == buf2->parent)
838 && ((buf1->data + buf1->size) == buf2->data));
843 * @buf1: the first source #GstBuffer to merge.
844 * @offset: the offset in the first buffer from where the new
845 * buffer should start.
846 * @buf2: the second source #GstBuffer to merge.
847 * @len: the total length of the new buffer.
849 * Creates a new buffer that consists of part of buf1 and buf2.
850 * Logically, buf1 and buf2 are concatenated into a single larger
851 * buffer, and a new buffer is created at the given offset inside
852 * this space, with a given length.
854 * If the two source buffers are children of the same larger buffer,
855 * and are contiguous, the new buffer will be a child of the shared
856 * parent, and thus no copying is necessary. you can use
857 * gst_buffer_is_span_fast() to determine if a memcpy will be needed.
861 * Returns: (transfer full): the new #GstBuffer that spans the two source
862 * buffers, or NULL if the arguments are invalid.
865 gst_buffer_span (GstBuffer * buf1, guint32 offset, GstBuffer * buf2,
870 g_return_val_if_fail (buf1 != NULL && buf2 != NULL, NULL);
871 g_return_val_if_fail (buf1->mini_object.refcount > 0, NULL);
872 g_return_val_if_fail (buf2->mini_object.refcount > 0, NULL);
873 g_return_val_if_fail (len > 0, NULL);
874 g_return_val_if_fail (len <= buf1->size + buf2->size - offset, NULL);
876 /* if the two buffers have the same parent and are adjacent */
877 if (gst_buffer_is_span_fast (buf1, buf2)) {
878 GstBuffer *parent = buf1->parent;
880 /* we simply create a subbuffer of the common parent */
881 newbuf = gst_buffer_create_sub (parent,
882 buf1->data - parent->data + offset, len);
884 GST_CAT_DEBUG (GST_CAT_BUFFER,
885 "slow path taken while spanning buffers %p and %p", buf1, buf2);
886 /* otherwise we simply have to brute-force copy the buffers */
887 newbuf = gst_buffer_new_and_alloc (len);
889 /* copy the first buffer's data across */
890 memcpy (newbuf->data, buf1->data + offset, buf1->size - offset);
891 /* copy the second buffer's data across */
892 memcpy (newbuf->data + (buf1->size - offset), buf2->data,
893 len - (buf1->size - offset));
895 /* if the offset is 0, the new buffer has the same timestamp as buf1 */
897 GST_BUFFER_OFFSET (newbuf) = GST_BUFFER_OFFSET (buf1);
898 GST_BUFFER_TIMESTAMP (newbuf) = GST_BUFFER_TIMESTAMP (buf1);
900 /* if we completely merged the two buffers (appended), we can
901 * calculate the duration too. Also make sure we's not messing with
902 * invalid DURATIONS */
903 if (buf1->size + buf2->size == len) {
904 if (GST_BUFFER_DURATION_IS_VALID (buf1) &&
905 GST_BUFFER_DURATION_IS_VALID (buf2)) {
907 GST_BUFFER_DURATION (newbuf) = GST_BUFFER_DURATION (buf1) +
908 GST_BUFFER_DURATION (buf2);
910 if (GST_BUFFER_OFFSET_END_IS_VALID (buf2)) {
912 GST_BUFFER_OFFSET_END (newbuf) = GST_BUFFER_OFFSET_END (buf2);