diff -r 000000000000 -r 0e761a78d257 gstreamer_core/gst/gstbuffer.c --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/gstreamer_core/gst/gstbuffer.c Thu Dec 17 08:53:32 2009 +0200 @@ -0,0 +1,791 @@ +/* GStreamer + * Copyright (C) 1999,2000 Erik Walthinsen + * 2000 Wim Taymans + * + * gstbuffer.c: Buffer operations + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Library General Public + * License as published by the Free Software Foundation; either + * version 2 of the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Library General Public License for more details. + * + * You should have received a copy of the GNU Library General Public + * License along with this library; if not, write to the + * Free Software Foundation, Inc., 59 Temple Place - Suite 330, + * Boston, MA 02111-1307, USA. + */ + +/** + * SECTION:gstbuffer + * @short_description: Data-passing buffer type, supporting sub-buffers. + * @see_also: #GstPad, #GstMiniObject + * + * Buffers are the basic unit of data transfer in GStreamer. The #GstBuffer + * type provides all the state necessary to define a region of memory as part + * of a stream. Sub-buffers are also supported, allowing a smaller region of a + * buffer to become its own buffer, with mechanisms in place to ensure that + * neither memory space goes away prematurely. + * + * Buffers are usually created with gst_buffer_new(). After a buffer has been + * created one will typically allocate memory for it and set the size of the + * buffer data. The following example creates a buffer that can hold a given + * video frame with a given width, height and bits per plane. + * + * Creating a buffer for a video frame + * + * GstBuffer *buffer; + * gint size, width, height, bpp; + * ... + * size = width * height * bpp; + * buffer = gst_buffer_new (); + * GST_BUFFER_SIZE (buffer) = size; + * GST_BUFFER_MALLOCDATA (buffer) = g_malloc (size); + * GST_BUFFER_DATA (buffer) = GST_BUFFER_MALLOCDATA (buffer); + * ... + * + * + * + * Alternatively, use gst_buffer_new_and_alloc() + * to create a buffer with preallocated data of a given size. + * + * The data pointed to by the buffer can be retrieved with the GST_BUFFER_DATA() + * macro. The size of the data can be found with GST_BUFFER_SIZE(). For buffers + * of size 0, the data pointer is undefined (usually NULL) and should never be used. + * + * If an element knows what pad you will push the buffer out on, it should use + * gst_pad_alloc_buffer() instead to create a buffer. This allows downstream + * elements to provide special buffers to write in, like hardware buffers. + * + * A buffer has a pointer to a #GstCaps describing the media type of the data + * in the buffer. Attach caps to the buffer with gst_buffer_set_caps(); this + * is typically done before pushing out a buffer using gst_pad_push() so that + * the downstream element knows the type of the buffer. + * + * A buffer will usually have a timestamp, and a duration, but neither of these + * are guaranteed (they may be set to #GST_CLOCK_TIME_NONE). Whenever a + * meaningful value can be given for these, they should be set. The timestamp + * and duration are measured in nanoseconds (they are #GstClockTime values). + * + * A buffer can also have one or both of a start and an end offset. These are + * media-type specific. For video buffers, the start offset will generally be + * the frame number. For audio buffers, it will be the number of samples + * produced so far. For compressed data, it could be the byte offset in a + * source or destination file. Likewise, the end offset will be the offset of + * the end of the buffer. These can only be meaningfully interpreted if you + * know the media type of the buffer (the #GstCaps set on it). Either or both + * can be set to #GST_BUFFER_OFFSET_NONE. + * + * gst_buffer_ref() is used to increase the refcount of a buffer. This must be + * done when you want to keep a handle to the buffer after pushing it to the + * next element. + * + * To efficiently create a smaller buffer out of an existing one, you can + * use gst_buffer_create_sub(). + * + * If a plug-in wants to modify the buffer data in-place, it should first obtain + * a buffer that is safe to modify by using gst_buffer_make_writable(). This + * function is optimized so that a copy will only be made when it is necessary. + * + * A plugin that only wishes to modify the metadata of a buffer, such as the + * offset, timestamp or caps, should use gst_buffer_make_metadata_writable(), + * which will create a subbuffer of the original buffer to ensure the caller + * has sole ownership, and not copy the buffer data. + * + * Several flags of the buffer can be set and unset with the + * GST_BUFFER_FLAG_SET() and GST_BUFFER_FLAG_UNSET() macros. Use + * GST_BUFFER_FLAG_IS_SET() to test if a certain #GstBufferFlag is set. + * + * Buffers can be efficiently merged into a larger buffer with + * gst_buffer_merge() and gst_buffer_span() if the gst_buffer_is_span_fast() + * function returns TRUE. + * + * An element should either unref the buffer or push it out on a src pad + * using gst_pad_push() (see #GstPad). + * + * Buffers are usually freed by unreffing them with gst_buffer_unref(). When + * the refcount drops to 0, any data pointed to by GST_BUFFER_MALLOCDATA() will + * also be freed. + * + * Last reviewed on August 11th, 2006 (0.10.10) + */ +#include "gst_private.h" + +#include "gstbuffer.h" +#include "gstinfo.h" +#include "gstutils.h" +#include "gstminiobject.h" + +static void gst_buffer_init (GTypeInstance * instance, gpointer g_class); +static void gst_buffer_class_init (gpointer g_class, gpointer class_data); +static void gst_buffer_finalize (GstBuffer * buffer); +static GstBuffer *_gst_buffer_copy (GstBuffer * buffer); +static GType gst_subbuffer_get_type (void); + +static GType _gst_subbuffer_type = 0; +static GType _gst_buffer_type = 0; + +static GstMiniObjectClass *parent_class = NULL; +#ifdef __SYMBIAN32__ +EXPORT_C +#endif + + +void +_gst_buffer_initialize (void) +{ + /* the GstMiniObject types need to be class_ref'd once before it can be + * done from multiple threads; + * see http://bugzilla.gnome.org/show_bug.cgi?id=304551 */ + g_type_class_ref (gst_buffer_get_type ()); + g_type_class_ref (gst_subbuffer_get_type ()); +} +#ifdef __SYMBIAN32__ +EXPORT_C +#endif + + +GType +gst_buffer_get_type (void) +{ + if (G_UNLIKELY (_gst_buffer_type == 0)) { + static const GTypeInfo buffer_info = { + sizeof (GstBufferClass), + NULL, + NULL, + gst_buffer_class_init, + NULL, + NULL, + sizeof (GstBuffer), + 0, + gst_buffer_init, + NULL + }; + + _gst_buffer_type = g_type_register_static (GST_TYPE_MINI_OBJECT, + "GstBuffer", &buffer_info, 0); + } + return _gst_buffer_type; +} + +static void +gst_buffer_class_init (gpointer g_class, gpointer class_data) +{ + GstBufferClass *buffer_class = GST_BUFFER_CLASS (g_class); + + parent_class = g_type_class_peek_parent (g_class); + + buffer_class->mini_object_class.copy = + (GstMiniObjectCopyFunction) _gst_buffer_copy; + buffer_class->mini_object_class.finalize = + (GstMiniObjectFinalizeFunction) gst_buffer_finalize; + +} + +static void +gst_buffer_finalize (GstBuffer * buffer) +{ + g_return_if_fail (buffer != NULL); + + GST_CAT_LOG (GST_CAT_BUFFER, "finalize %p", buffer); + + /* free our data */ + g_free (buffer->malloc_data); + + gst_caps_replace (&GST_BUFFER_CAPS (buffer), NULL); + + GST_MINI_OBJECT_CLASS (parent_class)->finalize (GST_MINI_OBJECT (buffer)); +} + +/** + * gst_buffer_copy_metadata: + * @dest: a destination #GstBuffer + * @src: a source #GstBuffer + * @flags: flags indicating what metadata fields should be copied. + * + * Copies the metadata from @src into @dest. The data, size and mallocdata + * fields are not copied. + * + * @flags indicate which fields will be copied. Use #GST_BUFFER_COPY_ALL to copy + * all the metadata fields. + * + * This function is typically called from a custom buffer copy function after + * creating @dest and setting the data, size, mallocdata. + * + * Since: 0.10.13 + */ +#ifdef __SYMBIAN32__ +EXPORT_C +#endif + +void +gst_buffer_copy_metadata (GstBuffer * dest, const GstBuffer * src, + GstBufferCopyFlags flags) +{ + g_return_if_fail (dest != NULL); + g_return_if_fail (src != NULL); + + GST_CAT_LOG (GST_CAT_BUFFER, "copy %p to %p", src, dest); + + if (flags & GST_BUFFER_COPY_FLAGS) { + guint mask; + + /* copy relevant flags */ + mask = GST_BUFFER_FLAG_PREROLL | GST_BUFFER_FLAG_IN_CAPS | + GST_BUFFER_FLAG_DELTA_UNIT | GST_BUFFER_FLAG_DISCONT | + GST_BUFFER_FLAG_GAP; + GST_MINI_OBJECT_FLAGS (dest) |= GST_MINI_OBJECT_FLAGS (src) & mask; + } + + if (flags & GST_BUFFER_COPY_TIMESTAMPS) { + GST_BUFFER_TIMESTAMP (dest) = GST_BUFFER_TIMESTAMP (src); + GST_BUFFER_DURATION (dest) = GST_BUFFER_DURATION (src); + GST_BUFFER_OFFSET (dest) = GST_BUFFER_OFFSET (src); + GST_BUFFER_OFFSET_END (dest) = GST_BUFFER_OFFSET_END (src); + } + + if (flags & GST_BUFFER_COPY_CAPS) { + if (GST_BUFFER_CAPS (src)) + GST_BUFFER_CAPS (dest) = gst_caps_ref (GST_BUFFER_CAPS (src)); + else + GST_BUFFER_CAPS (dest) = NULL; + } +} + +static GstBuffer * +_gst_buffer_copy (GstBuffer * buffer) +{ + GstBuffer *copy; + + g_return_val_if_fail (buffer != NULL, NULL); + + /* create a fresh new buffer */ + copy = gst_buffer_new (); + + /* we simply copy everything from our parent */ + copy->data = g_memdup (buffer->data, buffer->size); + /* make sure it gets freed (even if the parent is subclassed, we return a + normal buffer) */ + copy->malloc_data = copy->data; + copy->size = buffer->size; + + gst_buffer_copy_metadata (copy, buffer, GST_BUFFER_COPY_ALL); + + return copy; +} + +static void +gst_buffer_init (GTypeInstance * instance, gpointer g_class) +{ + GstBuffer *buffer; + + buffer = (GstBuffer *) instance; + + GST_CAT_LOG (GST_CAT_BUFFER, "init %p", buffer); + + GST_BUFFER_TIMESTAMP (buffer) = GST_CLOCK_TIME_NONE; + GST_BUFFER_DURATION (buffer) = GST_CLOCK_TIME_NONE; + GST_BUFFER_OFFSET (buffer) = GST_BUFFER_OFFSET_NONE; + GST_BUFFER_OFFSET_END (buffer) = GST_BUFFER_OFFSET_NONE; +} + +/** + * gst_buffer_new: + * + * Creates a newly allocated buffer without any data. + * + * MT safe. + * Returns: the new #GstBuffer. + */ +#ifdef __SYMBIAN32__ +EXPORT_C +#endif + +GstBuffer * +gst_buffer_new (void) +{ + GstBuffer *newbuf; + + newbuf = (GstBuffer *) gst_mini_object_new (_gst_buffer_type); + + GST_CAT_LOG (GST_CAT_BUFFER, "new %p", newbuf); + + return newbuf; +} + +/** + * gst_buffer_new_and_alloc: + * @size: the size of the new buffer's data. + * + * Creates a newly allocated buffer with data of the given size. + * The buffer memory is not cleared. If the requested amount of + * memory can't be allocated, the program will abort. Use + * gst_buffer_try_new_and_alloc() if you want to handle this case + * gracefully or have gotten the size to allocate from an untrusted + * source such as a media stream. + * + * + * Note that when @size == 0, the buffer data pointer will be NULL. + * + * MT safe. + * Returns: the new #GstBuffer. + */ +#ifdef __SYMBIAN32__ +EXPORT_C +#endif + +GstBuffer * +gst_buffer_new_and_alloc (guint size) +{ + GstBuffer *newbuf; + + newbuf = gst_buffer_new (); + + newbuf->malloc_data = g_malloc (size); + GST_BUFFER_DATA (newbuf) = newbuf->malloc_data; + GST_BUFFER_SIZE (newbuf) = size; + + GST_CAT_LOG (GST_CAT_BUFFER, "new %p of size %d", newbuf, size); + + return newbuf; +} + +/** + * gst_buffer_try_new_and_alloc: + * @size: the size of the new buffer's data. + * + * Tries to create a newly allocated buffer with data of the given size. If + * the requested amount of memory can't be allocated, NULL will be returned. + * The buffer memory is not cleared. + * + * Note that when @size == 0, the buffer data pointer will be NULL. + * + * MT safe. + * + * Returns: a new #GstBuffer, or NULL if the memory couldn't be allocated. + * + * Since: 0.10.13 + */ +#ifdef __SYMBIAN32__ +EXPORT_C +#endif + +GstBuffer * +gst_buffer_try_new_and_alloc (guint size) +{ + GstBuffer *newbuf; + guint8 *malloc_data; + + malloc_data = g_try_malloc (size); + + if (G_UNLIKELY (malloc_data == NULL && size != 0)) { + GST_CAT_WARNING (GST_CAT_BUFFER, "failed to allocate %d bytes", size); + return NULL; + } + + /* FIXME: there's no g_type_try_create_instance() in GObject yet, so this + * will still abort if a new GstBuffer structure can't be allocated */ + newbuf = gst_buffer_new (); + + GST_BUFFER_MALLOCDATA (newbuf) = malloc_data; + GST_BUFFER_DATA (newbuf) = malloc_data; + GST_BUFFER_SIZE (newbuf) = size; + + GST_CAT_LOG (GST_CAT_BUFFER, "new %p of size %d", newbuf, size); + + return newbuf; +} + +/** + * gst_buffer_get_caps: + * @buffer: a #GstBuffer. + * + * Gets the media type of the buffer. This can be NULL if there + * is no media type attached to this buffer. + * + * Returns: a reference to the #GstCaps. unref after usage. + * Returns NULL if there were no caps on this buffer. + */ +/* this is not made atomic because if the buffer were reffed from multiple + * threads, it would have a refcount > 2 and thus be immutable. + */ +#ifdef __SYMBIAN32__ +EXPORT_C +#endif + +GstCaps * +gst_buffer_get_caps (GstBuffer * buffer) +{ + GstCaps *ret; + + g_return_val_if_fail (buffer != NULL, NULL); + + ret = GST_BUFFER_CAPS (buffer); + + if (ret) + gst_caps_ref (ret); + + return ret; +} + +/** + * gst_buffer_set_caps: + * @buffer: a #GstBuffer. + * @caps: a #GstCaps. + * + * Sets the media type on the buffer. The refcount of the caps will + * be increased and any previous caps on the buffer will be + * unreffed. + */ +/* this is not made atomic because if the buffer were reffed from multiple + * threads, it would have a refcount > 2 and thus be immutable. + */ +#ifdef __SYMBIAN32__ +EXPORT_C +#endif + +void +gst_buffer_set_caps (GstBuffer * buffer, GstCaps * caps) +{ + g_return_if_fail (buffer != NULL); + + 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. + */ +#ifdef __SYMBIAN32__ +EXPORT_C +#endif + +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. + */ +#ifdef __SYMBIAN32__ +EXPORT_C +#endif + +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; +} + +typedef struct _GstSubBuffer GstSubBuffer; +typedef struct _GstSubBufferClass GstSubBufferClass; + +#define GST_IS_SUBBUFFER(obj) (G_TYPE_CHECK_INSTANCE_TYPE ((obj), _gst_subbuffer_type)) +#define GST_SUBBUFFER_CAST(obj) ((GstSubBuffer *)(obj)) + +struct _GstSubBuffer +{ + GstBuffer buffer; + + GstBuffer *parent; +}; + +struct _GstSubBufferClass +{ + GstBufferClass buffer_class; +}; + +static GstBufferClass *sub_parent_class; + +static void gst_subbuffer_init (GTypeInstance * instance, gpointer g_class); +static void gst_subbuffer_class_init (gpointer g_class, gpointer class_data); +static void gst_subbuffer_finalize (GstSubBuffer * buffer); + +static GType +gst_subbuffer_get_type (void) +{ + if (G_UNLIKELY (_gst_subbuffer_type == 0)) { + static const GTypeInfo subbuffer_info = { + sizeof (GstSubBufferClass), + NULL, + NULL, + gst_subbuffer_class_init, + NULL, + NULL, + sizeof (GstSubBuffer), + 0, + gst_subbuffer_init, + NULL + }; + + _gst_subbuffer_type = g_type_register_static (GST_TYPE_BUFFER, + "GstSubBuffer", &subbuffer_info, 0); + } + return _gst_subbuffer_type; +} + +static void +gst_subbuffer_class_init (gpointer g_class, gpointer class_data) +{ + GstBufferClass *buffer_class = GST_BUFFER_CLASS (g_class); + + sub_parent_class = g_type_class_peek_parent (g_class); + + buffer_class->mini_object_class.finalize = + (GstMiniObjectFinalizeFunction) gst_subbuffer_finalize; +} + +static void +gst_subbuffer_finalize (GstSubBuffer * buffer) +{ + gst_buffer_unref (buffer->parent); + + GST_MINI_OBJECT_CLASS (sub_parent_class)-> + finalize (GST_MINI_OBJECT_CAST (buffer)); +} + +static void +gst_subbuffer_init (GTypeInstance * instance, gpointer g_class) +{ + GST_BUFFER_FLAG_SET (GST_BUFFER_CAST (instance), GST_BUFFER_FLAG_READONLY); +} + +/** + * 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. + */ +#ifdef __SYMBIAN32__ +EXPORT_C +#endif + +GstBuffer * +gst_buffer_create_sub (GstBuffer * buffer, guint offset, guint size) +{ + GstSubBuffer *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 = GST_SUBBUFFER_CAST (buffer)->parent; + } else { + parent = buffer; + } + gst_buffer_ref (parent); + + /* create the new buffer */ + subbuffer = (GstSubBuffer *) gst_mini_object_new (_gst_subbuffer_type); + subbuffer->parent = parent; + + GST_CAT_LOG (GST_CAT_BUFFER, "new subbuffer %p (parent %p)", subbuffer, + parent); + + /* set the right values in the child */ + GST_BUFFER_DATA (GST_BUFFER_CAST (subbuffer)) = buffer->data + offset; + GST_BUFFER_SIZE (GST_BUFFER_CAST (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 GST_BUFFER_CAST (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. + */ +#ifdef __SYMBIAN32__ +EXPORT_C +#endif + +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) && + (GST_SUBBUFFER_CAST (buf1)->parent == GST_SUBBUFFER_CAST (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. + */ +#ifdef __SYMBIAN32__ +EXPORT_C +#endif + +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 = GST_SUBBUFFER_CAST (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; +}