| /* GStreamer |
| * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu> |
| * 2000 Wim Taymans <wtay@chello.be> |
| * |
| * 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. |
| * <example> |
| * <title>Creating a buffer for a video frame</title> |
| * <programlisting> |
| * 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); |
| * ... |
| * </programlisting> |
| * </example> |
| * |
| * 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; |
| |
| 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 ()); |
| } |
| |
| 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); |
| |
| 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_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 |
| */ |
| 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. |
| */ |
| 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. |
| */ |
| 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 |
| */ |
| 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. |
| */ |
| /* FIXME can we make this threadsafe without a lock on the buffer? |
| * We can use compare and swap and atomic reads. */ |
| 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. |
| */ |
| /* FIXME can we make this threadsafe without a lock on the buffer? |
| * We can use compare and swap and atomic reads. Another idea is to |
| * not attach the caps to the buffer but use an event to signal a caps |
| * change. */ |
| 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. |
| */ |
| 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)); |
| |
| /* copy all the flags except IN_CAPS */ |
| GST_BUFFER_FLAGS (ret) = GST_BUFFER_FLAGS (buf); |
| GST_BUFFER_FLAG_UNSET (ret, GST_BUFFER_FLAG_IN_CAPS); |
| /* data should always be set to READONLY */ |
| GST_BUFFER_FLAG_SET (ret, GST_BUFFER_FLAG_READONLY); |
| |
| 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. |
| */ |
| 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; |
| |
| /* 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. |
| */ |
| 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. |
| */ |
| 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; |
| } |