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737 lines
23 KiB
C
737 lines
23 KiB
C
/* GStreamer
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* Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
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* 2000 Wim Taymans <wtay@chello.be>
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*
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* gstbuffer.c: Buffer operations
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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/**
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* SECTION:gstbuffer
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* @short_description: Data-passing buffer type, supporting sub-buffers.
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* @see_also: #GstPad, #GstMiniObject
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*
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* Buffers are the basic unit of data transfer in GStreamer. The #GstBuffer
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* type provides all the state necessary to define a region of memory as part
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* of a stream. Sub-buffers are also supported, allowing a smaller region of a
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* buffer to become its own buffer, with mechanisms in place to ensure that
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* neither memory space goes away prematurely.
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*
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* Buffers are usually created with gst_buffer_new(). After a buffer has been
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* created one will typically allocate memory for it and set the size of the
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* buffer data. The following example creates a buffer that can hold a given
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* video frame with a given width, height and bits per plane.
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* <example>
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* <title>Creating a buffer for a video frame</title>
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* <programlisting>
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* GstBuffer *buffer;
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* gint size, width, height, bpp;
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* ...
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* size = width * height * bpp;
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* buffer = gst_buffer_new ();
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* GST_BUFFER_SIZE (buffer) = size;
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* GST_BUFFER_MALLOCDATA (buffer) = g_malloc (size);
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* GST_BUFFER_DATA (buffer) = GST_BUFFER_MALLOCDATA (buffer);
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* ...
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* </programlisting>
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* </example>
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*
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* Alternatively, use gst_buffer_new_and_alloc()
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* to create a buffer with preallocated data of a given size.
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*
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* The data pointed to by the buffer can be retrieved with the GST_BUFFER_DATA()
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* macro. The size of the data can be found with GST_BUFFER_SIZE(). For buffers
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* of size 0, the data pointer is undefined (usually NULL) and should never be used.
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*
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* If an element knows what pad you will push the buffer out on, it should use
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* gst_pad_alloc_buffer() instead to create a buffer. This allows downstream
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* elements to provide special buffers to write in, like hardware buffers.
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*
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* A buffer has a pointer to a #GstCaps describing the media type of the data
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* in the buffer. Attach caps to the buffer with gst_buffer_set_caps(); this
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* is typically done before pushing out a buffer using gst_pad_push() so that
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* the downstream element knows the type of the buffer.
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*
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* A buffer will usually have a timestamp, and a duration, but neither of these
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* are guaranteed (they may be set to #GST_CLOCK_TIME_NONE). Whenever a
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* meaningful value can be given for these, they should be set. The timestamp
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* and duration are measured in nanoseconds (they are #GstClockTime values).
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*
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* A buffer can also have one or both of a start and an end offset. These are
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* media-type specific. For video buffers, the start offset will generally be
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* the frame number. For audio buffers, it will be the number of samples
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* produced so far. For compressed data, it could be the byte offset in a
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* source or destination file. Likewise, the end offset will be the offset of
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* the end of the buffer. These can only be meaningfully interpreted if you
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* know the media type of the buffer (the #GstCaps set on it). Either or both
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* can be set to #GST_BUFFER_OFFSET_NONE.
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*
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* gst_buffer_ref() is used to increase the refcount of a buffer. This must be
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* done when you want to keep a handle to the buffer after pushing it to the
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* next element.
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*
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* To efficiently create a smaller buffer out of an existing one, you can
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* use gst_buffer_create_sub().
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*
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* If a plug-in wants to modify the buffer data in-place, it should first obtain
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* a buffer that is safe to modify by using gst_buffer_make_writable(). This
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* function is optimized so that a copy will only be made when it is necessary.
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*
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* A plugin that only wishes to modify the metadata of a buffer, such as the
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* offset, timestamp or caps, should use gst_buffer_make_metadata_writable(),
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* which will create a subbuffer of the original buffer to ensure the caller
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* has sole ownership, and not copy the buffer data.
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*
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* Several flags of the buffer can be set and unset with the
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* GST_BUFFER_FLAG_SET() and GST_BUFFER_FLAG_UNSET() macros. Use
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* GST_BUFFER_FLAG_IS_SET() to test if a certain #GstBufferFlag is set.
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*
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* Buffers can be efficiently merged into a larger buffer with
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* gst_buffer_merge() and gst_buffer_span() if the gst_buffer_is_span_fast()
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* function returns TRUE.
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*
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* An element should either unref the buffer or push it out on a src pad
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* using gst_pad_push() (see #GstPad).
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*
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* Buffers are usually freed by unreffing them with gst_buffer_unref(). When
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* the refcount drops to 0, any data pointed to by GST_BUFFER_MALLOCDATA() will
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* also be freed.
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*
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* Last reviewed on August 11th, 2006 (0.10.10)
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*/
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#include "gst_private.h"
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#ifdef HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#ifdef HAVE_STDLIB_H
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#include <stdlib.h>
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#endif
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#include "gstbuffer.h"
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#include "gstinfo.h"
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#include "gstutils.h"
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#include "gstminiobject.h"
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#include "gstversion.h"
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static void gst_buffer_finalize (GstBuffer * buffer);
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static GstBuffer *_gst_buffer_copy (GstBuffer * buffer);
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static GType _gst_buffer_type = 0;
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/* buffer alignment in bytes
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* an alignment of 8 would be the same as malloc() guarantees
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*/
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#ifdef HAVE_POSIX_MEMALIGN
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#if defined(BUFFER_ALIGNMENT_MALLOC)
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static size_t _gst_buffer_data_alignment = 8;
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#elif defined(BUFFER_ALIGNMENT_PAGESIZE)
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static size_t _gst_buffer_data_alignment = 0;
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#elif defined(BUFFER_ALIGNMENT)
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static size_t _gst_buffer_data_alignment = BUFFER_ALIGNMENT;
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#else
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#error "No buffer alignment configured"
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#endif
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static inline gboolean
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aligned_malloc (gpointer * memptr, guint size)
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{
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gint res;
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res = posix_memalign (memptr, _gst_buffer_data_alignment, size);
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return (res == 0);
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}
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#endif /* HAVE_POSIX_MEMALIGN */
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void
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_gst_buffer_initialize (void)
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{
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/* the GstMiniObject types need to be class_ref'd once before it can be
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* done from multiple threads;
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* see http://bugzilla.gnome.org/show_bug.cgi?id=304551 */
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g_type_class_ref (gst_buffer_get_type ());
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#ifdef HAVE_GETPAGESIZE
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#ifdef BUFFER_ALIGNMENT_PAGESIZE
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_gst_buffer_data_alignment = getpagesize ();
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#endif
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#endif
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}
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#define _do_init \
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{ \
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_gst_buffer_type = g_define_type_id; \
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}
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G_DEFINE_TYPE_WITH_CODE (GstBuffer, gst_buffer, GST_TYPE_MINI_OBJECT, _do_init);
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static void
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gst_buffer_class_init (GstBufferClass * klass)
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{
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klass->mini_object_class.copy = (GstMiniObjectCopyFunction) _gst_buffer_copy;
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klass->mini_object_class.finalize =
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(GstMiniObjectFinalizeFunction) gst_buffer_finalize;
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}
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static void
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gst_buffer_finalize (GstBuffer * buffer)
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{
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g_return_if_fail (buffer != NULL);
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GST_CAT_LOG (GST_CAT_BUFFER, "finalize %p", buffer);
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/* free our data */
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if (G_LIKELY (buffer->malloc_data))
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buffer->free_func (buffer->malloc_data);
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gst_caps_replace (&GST_BUFFER_CAPS (buffer), NULL);
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if (buffer->parent)
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gst_buffer_unref (buffer->parent);
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/* ((GstMiniObjectClass *) */
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/* gst_buffer_parent_class)->finalize (GST_MINI_OBJECT_CAST (buffer)); */
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}
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/**
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* gst_buffer_copy_metadata:
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* @dest: a destination #GstBuffer
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* @src: a source #GstBuffer
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* @flags: flags indicating what metadata fields should be copied.
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*
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* Copies the metadata from @src into @dest. The data, size and mallocdata
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* fields are not copied.
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*
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* @flags indicate which fields will be copied. Use #GST_BUFFER_COPY_ALL to copy
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* all the metadata fields.
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*
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* This function is typically called from a custom buffer copy function after
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* creating @dest and setting the data, size, mallocdata.
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*
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* Since: 0.10.13
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*/
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void
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gst_buffer_copy_metadata (GstBuffer * dest, const GstBuffer * src,
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GstBufferCopyFlags flags)
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{
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g_return_if_fail (dest != NULL);
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g_return_if_fail (src != NULL);
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/* nothing to copy if the buffers are the same */
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if (G_UNLIKELY (dest == src))
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return;
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#if GST_VERSION_NANO == 1
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/* we enable this extra debugging in git versions only for now */
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g_return_if_fail (gst_buffer_is_metadata_writable (dest));
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#endif
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GST_CAT_LOG (GST_CAT_BUFFER, "copy %p to %p", src, dest);
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if (flags & GST_BUFFER_COPY_FLAGS) {
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guint mask;
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/* copy relevant flags */
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mask = GST_BUFFER_FLAG_PREROLL | GST_BUFFER_FLAG_IN_CAPS |
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GST_BUFFER_FLAG_DELTA_UNIT | GST_BUFFER_FLAG_DISCONT |
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GST_BUFFER_FLAG_GAP | GST_BUFFER_FLAG_MEDIA1 |
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GST_BUFFER_FLAG_MEDIA2 | GST_BUFFER_FLAG_MEDIA3;
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GST_MINI_OBJECT_FLAGS (dest) |= GST_MINI_OBJECT_FLAGS (src) & mask;
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}
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if (flags & GST_BUFFER_COPY_TIMESTAMPS) {
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GST_BUFFER_TIMESTAMP (dest) = GST_BUFFER_TIMESTAMP (src);
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GST_BUFFER_DURATION (dest) = GST_BUFFER_DURATION (src);
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GST_BUFFER_OFFSET (dest) = GST_BUFFER_OFFSET (src);
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GST_BUFFER_OFFSET_END (dest) = GST_BUFFER_OFFSET_END (src);
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}
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if (flags & GST_BUFFER_COPY_CAPS) {
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gst_caps_replace (&GST_BUFFER_CAPS (dest), GST_BUFFER_CAPS (src));
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}
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}
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static GstBuffer *
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_gst_buffer_copy (GstBuffer * buffer)
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{
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GstBuffer *copy;
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g_return_val_if_fail (buffer != NULL, NULL);
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/* create a fresh new buffer */
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copy = gst_buffer_new ();
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/* we simply copy everything from our parent */
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#ifdef HAVE_POSIX_MEMALIGN
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{
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gpointer memptr = NULL;
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if (G_LIKELY (buffer->size)) {
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if (G_UNLIKELY (!aligned_malloc (&memptr, buffer->size))) {
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/* terminate on error like g_memdup() would */
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g_error ("%s: failed to allocate %u bytes", G_STRLOC, buffer->size);
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} else {
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memcpy (memptr, buffer->data, buffer->size);
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}
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}
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copy->data = (guint8 *) memptr;
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GST_BUFFER_FREE_FUNC (copy) = free;
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}
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#else
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copy->data = g_memdup (buffer->data, buffer->size);
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#endif
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/* make sure it gets freed (even if the parent is subclassed, we return a
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normal buffer) */
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copy->malloc_data = copy->data;
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copy->size = buffer->size;
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gst_buffer_copy_metadata (copy, buffer, GST_BUFFER_COPY_ALL);
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return copy;
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}
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static void
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gst_buffer_init (GstBuffer * buffer)
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{
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GST_CAT_LOG (GST_CAT_BUFFER, "init %p", buffer);
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GST_BUFFER_TIMESTAMP (buffer) = GST_CLOCK_TIME_NONE;
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GST_BUFFER_DURATION (buffer) = GST_CLOCK_TIME_NONE;
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GST_BUFFER_OFFSET (buffer) = GST_BUFFER_OFFSET_NONE;
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GST_BUFFER_OFFSET_END (buffer) = GST_BUFFER_OFFSET_NONE;
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GST_BUFFER_FREE_FUNC (buffer) = g_free;
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}
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/**
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* gst_buffer_new:
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*
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* Creates a newly allocated buffer without any data.
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*
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* MT safe.
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* Returns: the new #GstBuffer.
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*/
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GstBuffer *
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gst_buffer_new (void)
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{
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GstBuffer *newbuf;
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newbuf = (GstBuffer *) gst_mini_object_new (_gst_buffer_type);
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GST_CAT_LOG (GST_CAT_BUFFER, "new %p", newbuf);
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return newbuf;
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}
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/**
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* gst_buffer_new_and_alloc:
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* @size: the size of the new buffer's data.
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*
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* Creates a newly allocated buffer with data of the given size.
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* The buffer memory is not cleared. If the requested amount of
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* memory can't be allocated, the program will abort. Use
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* gst_buffer_try_new_and_alloc() if you want to handle this case
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* gracefully or have gotten the size to allocate from an untrusted
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* source such as a media stream.
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*
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*
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* Note that when @size == 0, the buffer data pointer will be NULL.
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*
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* MT safe.
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* Returns: the new #GstBuffer.
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*/
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GstBuffer *
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gst_buffer_new_and_alloc (guint size)
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{
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GstBuffer *newbuf;
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newbuf = gst_buffer_new ();
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#ifdef HAVE_POSIX_MEMALIGN
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{
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gpointer memptr = NULL;
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if (G_LIKELY (size)) {
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if (G_UNLIKELY (!aligned_malloc (&memptr, size))) {
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/* terminate on error like g_memdup() would */
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g_error ("%s: failed to allocate %u bytes", G_STRLOC, size);
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}
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}
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newbuf->malloc_data = (guint8 *) memptr;
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GST_BUFFER_FREE_FUNC (newbuf) = free;
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}
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#else
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newbuf->malloc_data = g_malloc (size);
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#endif
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GST_BUFFER_DATA (newbuf) = newbuf->malloc_data;
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GST_BUFFER_SIZE (newbuf) = size;
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GST_CAT_LOG (GST_CAT_BUFFER, "new %p of size %d", newbuf, size);
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return newbuf;
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}
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/**
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* gst_buffer_try_new_and_alloc:
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* @size: the size of the new buffer's data.
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*
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* Tries to create a newly allocated buffer with data of the given size. If
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* the requested amount of memory can't be allocated, NULL will be returned.
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* The buffer memory is not cleared.
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*
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* Note that when @size == 0, the buffer data pointer will be NULL.
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*
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* MT safe.
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*
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* Returns: a new #GstBuffer, or NULL if the memory couldn't be allocated.
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*
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* Since: 0.10.13
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*/
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GstBuffer *
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gst_buffer_try_new_and_alloc (guint size)
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{
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GstBuffer *newbuf;
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guint8 *malloc_data;
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#ifdef HAVE_POSIX_MEMALIGN
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gpointer memptr = NULL;
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if (G_LIKELY (size)) {
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if (G_UNLIKELY (!aligned_malloc (&memptr, size))) {
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GST_CAT_WARNING (GST_CAT_BUFFER, "failed to allocate %d bytes", size);
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return NULL;
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}
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}
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malloc_data = (guint8 *) memptr;
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#else
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malloc_data = g_try_malloc (size);
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if (G_UNLIKELY (malloc_data == NULL && size != 0)) {
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GST_CAT_WARNING (GST_CAT_BUFFER, "failed to allocate %d bytes", size);
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return NULL;
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}
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#endif
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/* FIXME: there's no g_type_try_create_instance() in GObject yet, so this
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* will still abort if a new GstBuffer structure can't be allocated */
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newbuf = gst_buffer_new ();
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GST_BUFFER_MALLOCDATA (newbuf) = malloc_data;
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GST_BUFFER_DATA (newbuf) = malloc_data;
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GST_BUFFER_SIZE (newbuf) = size;
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#ifdef HAVE_POSIX_MEMALIGN
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GST_BUFFER_FREE_FUNC (newbuf) = free;
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#endif
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GST_CAT_LOG (GST_CAT_BUFFER, "new %p of size %d", newbuf, size);
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return newbuf;
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}
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/**
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* gst_buffer_get_caps:
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* @buffer: a #GstBuffer.
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*
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* Gets the media type of the buffer. This can be NULL if there
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* is no media type attached to this buffer.
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*
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* Returns: a reference to the #GstCaps. unref after usage.
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* Returns NULL if there were no caps on this buffer.
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*/
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/* this is not made atomic because if the buffer were reffed from multiple
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* threads, it would have a refcount > 2 and thus be immutable.
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*/
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GstCaps *
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gst_buffer_get_caps (GstBuffer * buffer)
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{
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GstCaps *ret;
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g_return_val_if_fail (buffer != NULL, NULL);
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ret = GST_BUFFER_CAPS (buffer);
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if (ret)
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gst_caps_ref (ret);
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return ret;
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}
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/**
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* gst_buffer_set_caps:
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* @buffer: a #GstBuffer.
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* @caps: a #GstCaps.
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*
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* Sets the media type on the buffer. The refcount of the caps will
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* be increased and any previous caps on the buffer will be
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* unreffed.
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*/
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/* this is not made atomic because if the buffer were reffed from multiple
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* threads, it would have a refcount > 2 and thus be immutable.
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*/
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void
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gst_buffer_set_caps (GstBuffer * buffer, GstCaps * caps)
|
|
{
|
|
g_return_if_fail (buffer != NULL);
|
|
#if GST_VERSION_NANO == 1
|
|
/* we enable this extra debugging in git versions only for now */
|
|
g_return_if_fail (gst_buffer_is_metadata_writable (buffer));
|
|
#endif
|
|
|
|
gst_caps_replace (&GST_BUFFER_CAPS (buffer), caps);
|
|
}
|
|
|
|
/**
|
|
* gst_buffer_is_metadata_writable:
|
|
* @buf: a #GstBuffer
|
|
*
|
|
* Similar to gst_buffer_is_writable, but this only ensures that the
|
|
* refcount of the buffer is 1, indicating that the caller is the sole
|
|
* owner and can change the buffer metadata, such as caps and timestamps.
|
|
*
|
|
* Returns: TRUE if the metadata is writable.
|
|
*/
|
|
gboolean
|
|
gst_buffer_is_metadata_writable (GstBuffer * buf)
|
|
{
|
|
return (GST_MINI_OBJECT_REFCOUNT_VALUE (GST_MINI_OBJECT_CAST (buf)) == 1);
|
|
}
|
|
|
|
/**
|
|
* gst_buffer_make_metadata_writable:
|
|
* @buf: a #GstBuffer
|
|
*
|
|
* Similar to gst_buffer_make_writable, but does not ensure that the buffer
|
|
* data array is writable. Instead, this just ensures that the returned buffer
|
|
* is solely owned by the caller, by creating a subbuffer of the original
|
|
* buffer if necessary.
|
|
*
|
|
* After calling this function, @buf should not be referenced anymore. The
|
|
* result of this function has guaranteed writable metadata.
|
|
*
|
|
* Returns: A new #GstBuffer with writable metadata.
|
|
*/
|
|
GstBuffer *
|
|
gst_buffer_make_metadata_writable (GstBuffer * buf)
|
|
{
|
|
GstBuffer *ret;
|
|
|
|
if (gst_buffer_is_metadata_writable (buf)) {
|
|
ret = buf;
|
|
} else {
|
|
ret = gst_buffer_create_sub (buf, 0, GST_BUFFER_SIZE (buf));
|
|
|
|
gst_buffer_unref (buf);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
#define GST_IS_SUBBUFFER(obj) (GST_BUFFER_CAST(obj)->parent != NULL)
|
|
|
|
/**
|
|
* gst_buffer_create_sub:
|
|
* @parent: a #GstBuffer.
|
|
* @offset: the offset into parent #GstBuffer at which the new sub-buffer
|
|
* begins.
|
|
* @size: the size of the new #GstBuffer sub-buffer, in bytes.
|
|
*
|
|
* Creates a sub-buffer from @parent at @offset and @size.
|
|
* This sub-buffer uses the actual memory space of the parent buffer.
|
|
* This function will copy the offset and timestamp fields when the
|
|
* offset is 0. If not, they will be set to #GST_CLOCK_TIME_NONE and
|
|
* #GST_BUFFER_OFFSET_NONE.
|
|
* If @offset equals 0 and @size equals the total size of @buffer, the
|
|
* duration and offset end fields are also copied. If not they will be set
|
|
* to #GST_CLOCK_TIME_NONE and #GST_BUFFER_OFFSET_NONE.
|
|
*
|
|
* MT safe.
|
|
* Returns: the new #GstBuffer.
|
|
* Returns NULL if the arguments were invalid.
|
|
*/
|
|
GstBuffer *
|
|
gst_buffer_create_sub (GstBuffer * buffer, guint offset, guint size)
|
|
{
|
|
GstBuffer *subbuffer;
|
|
GstBuffer *parent;
|
|
gboolean complete;
|
|
|
|
g_return_val_if_fail (buffer != NULL, NULL);
|
|
g_return_val_if_fail (buffer->mini_object.refcount > 0, NULL);
|
|
g_return_val_if_fail (buffer->size >= offset + size, NULL);
|
|
|
|
/* find real parent */
|
|
if (GST_IS_SUBBUFFER (buffer)) {
|
|
parent = buffer->parent;
|
|
} else {
|
|
parent = buffer;
|
|
}
|
|
gst_buffer_ref (parent);
|
|
|
|
/* create the new buffer */
|
|
subbuffer = gst_buffer_new ();
|
|
subbuffer->parent = parent;
|
|
GST_BUFFER_FLAG_SET (subbuffer, GST_BUFFER_FLAG_READONLY);
|
|
|
|
GST_CAT_LOG (GST_CAT_BUFFER, "new subbuffer %p (parent %p)", subbuffer,
|
|
parent);
|
|
|
|
/* set the right values in the child */
|
|
GST_BUFFER_DATA (subbuffer) = buffer->data + offset;
|
|
GST_BUFFER_SIZE (subbuffer) = size;
|
|
|
|
if ((offset == 0) && (size == GST_BUFFER_SIZE (buffer))) {
|
|
/* copy all the flags except IN_CAPS */
|
|
GST_BUFFER_FLAG_SET (subbuffer, GST_BUFFER_FLAGS (buffer));
|
|
GST_BUFFER_FLAG_UNSET (subbuffer, GST_BUFFER_FLAG_IN_CAPS);
|
|
} else {
|
|
/* copy only PREROLL & GAP flags */
|
|
GST_BUFFER_FLAG_SET (subbuffer, (GST_BUFFER_FLAGS (buffer) &
|
|
(GST_BUFFER_FLAG_PREROLL | GST_BUFFER_FLAG_GAP)));
|
|
}
|
|
|
|
/* we can copy the timestamp and offset if the new buffer starts at
|
|
* offset 0 */
|
|
if (offset == 0) {
|
|
GST_BUFFER_TIMESTAMP (subbuffer) = GST_BUFFER_TIMESTAMP (buffer);
|
|
GST_BUFFER_OFFSET (subbuffer) = GST_BUFFER_OFFSET (buffer);
|
|
complete = (buffer->size == size);
|
|
} else {
|
|
GST_BUFFER_TIMESTAMP (subbuffer) = GST_CLOCK_TIME_NONE;
|
|
GST_BUFFER_OFFSET (subbuffer) = GST_BUFFER_OFFSET_NONE;
|
|
complete = FALSE;
|
|
}
|
|
|
|
if (complete) {
|
|
GstCaps *caps;
|
|
|
|
/* if we copied the complete buffer we can copy the duration,
|
|
* offset_end and caps as well */
|
|
GST_BUFFER_DURATION (subbuffer) = GST_BUFFER_DURATION (buffer);
|
|
GST_BUFFER_OFFSET_END (subbuffer) = GST_BUFFER_OFFSET_END (buffer);
|
|
if ((caps = GST_BUFFER_CAPS (buffer)))
|
|
gst_caps_ref (caps);
|
|
GST_BUFFER_CAPS (subbuffer) = caps;
|
|
} else {
|
|
GST_BUFFER_DURATION (subbuffer) = GST_CLOCK_TIME_NONE;
|
|
GST_BUFFER_OFFSET_END (subbuffer) = GST_BUFFER_OFFSET_NONE;
|
|
GST_BUFFER_CAPS (subbuffer) = NULL;
|
|
}
|
|
return subbuffer;
|
|
}
|
|
|
|
/**
|
|
* gst_buffer_is_span_fast:
|
|
* @buf1: the first #GstBuffer.
|
|
* @buf2: the second #GstBuffer.
|
|
*
|
|
* Determines whether a gst_buffer_span() can be done without copying
|
|
* the contents, that is, whether the data areas are contiguous sub-buffers of
|
|
* the same buffer.
|
|
*
|
|
* MT safe.
|
|
* Returns: TRUE if the buffers are contiguous,
|
|
* FALSE if a copy would be required.
|
|
*/
|
|
gboolean
|
|
gst_buffer_is_span_fast (GstBuffer * buf1, GstBuffer * buf2)
|
|
{
|
|
g_return_val_if_fail (buf1 != NULL && buf2 != NULL, FALSE);
|
|
g_return_val_if_fail (buf1->mini_object.refcount > 0, FALSE);
|
|
g_return_val_if_fail (buf2->mini_object.refcount > 0, FALSE);
|
|
|
|
/* it's only fast if we have subbuffers of the same parent */
|
|
return (GST_IS_SUBBUFFER (buf1) &&
|
|
GST_IS_SUBBUFFER (buf2) && (buf1->parent == buf2->parent)
|
|
&& ((buf1->data + buf1->size) == buf2->data));
|
|
}
|
|
|
|
/**
|
|
* gst_buffer_span:
|
|
* @buf1: the first source #GstBuffer to merge.
|
|
* @offset: the offset in the first buffer from where the new
|
|
* buffer should start.
|
|
* @buf2: the second source #GstBuffer to merge.
|
|
* @len: the total length of the new buffer.
|
|
*
|
|
* Creates a new buffer that consists of part of buf1 and buf2.
|
|
* Logically, buf1 and buf2 are concatenated into a single larger
|
|
* buffer, and a new buffer is created at the given offset inside
|
|
* this space, with a given length.
|
|
*
|
|
* If the two source buffers are children of the same larger buffer,
|
|
* and are contiguous, the new buffer will be a child of the shared
|
|
* parent, and thus no copying is necessary. you can use
|
|
* gst_buffer_is_span_fast() to determine if a memcpy will be needed.
|
|
*
|
|
* MT safe.
|
|
* Returns: the new #GstBuffer that spans the two source buffers.
|
|
* Returns NULL if the arguments are invalid.
|
|
*/
|
|
GstBuffer *
|
|
gst_buffer_span (GstBuffer * buf1, guint32 offset, GstBuffer * buf2,
|
|
guint32 len)
|
|
{
|
|
GstBuffer *newbuf;
|
|
|
|
g_return_val_if_fail (buf1 != NULL && buf2 != NULL, NULL);
|
|
g_return_val_if_fail (buf1->mini_object.refcount > 0, NULL);
|
|
g_return_val_if_fail (buf2->mini_object.refcount > 0, NULL);
|
|
g_return_val_if_fail (len > 0, NULL);
|
|
g_return_val_if_fail (len <= buf1->size + buf2->size - offset, NULL);
|
|
|
|
/* if the two buffers have the same parent and are adjacent */
|
|
if (gst_buffer_is_span_fast (buf1, buf2)) {
|
|
GstBuffer *parent = buf1->parent;
|
|
|
|
/* we simply create a subbuffer of the common parent */
|
|
newbuf = gst_buffer_create_sub (parent,
|
|
buf1->data - parent->data + offset, len);
|
|
} else {
|
|
GST_CAT_DEBUG (GST_CAT_BUFFER,
|
|
"slow path taken while spanning buffers %p and %p", buf1, buf2);
|
|
/* otherwise we simply have to brute-force copy the buffers */
|
|
newbuf = gst_buffer_new_and_alloc (len);
|
|
|
|
/* copy the first buffer's data across */
|
|
memcpy (newbuf->data, buf1->data + offset, buf1->size - offset);
|
|
/* copy the second buffer's data across */
|
|
memcpy (newbuf->data + (buf1->size - offset), buf2->data,
|
|
len - (buf1->size - offset));
|
|
}
|
|
/* if the offset is 0, the new buffer has the same timestamp as buf1 */
|
|
if (offset == 0) {
|
|
GST_BUFFER_OFFSET (newbuf) = GST_BUFFER_OFFSET (buf1);
|
|
GST_BUFFER_TIMESTAMP (newbuf) = GST_BUFFER_TIMESTAMP (buf1);
|
|
|
|
/* if we completely merged the two buffers (appended), we can
|
|
* calculate the duration too. Also make sure we's not messing with
|
|
* invalid DURATIONS */
|
|
if (buf1->size + buf2->size == len) {
|
|
if (GST_BUFFER_DURATION_IS_VALID (buf1) &&
|
|
GST_BUFFER_DURATION_IS_VALID (buf2)) {
|
|
/* add duration */
|
|
GST_BUFFER_DURATION (newbuf) = GST_BUFFER_DURATION (buf1) +
|
|
GST_BUFFER_DURATION (buf2);
|
|
}
|
|
if (GST_BUFFER_OFFSET_END_IS_VALID (buf2)) {
|
|
/* add offset_end */
|
|
GST_BUFFER_OFFSET_END (newbuf) = GST_BUFFER_OFFSET_END (buf2);
|
|
}
|
|
}
|
|
}
|
|
|
|
return newbuf;
|
|
}
|