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Original commit message from CVS:
doc updates
This commit is contained in:
Thomas Vander Stichele 2002-08-30 14:54:58 +00:00
parent f2a11148a8
commit 56c8649f39
2 changed files with 159 additions and 127 deletions
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147
docs/gst/tmpl/gstbuffer.sgml
View file

@ -15,10 +15,13 @@ neither memory space goes away.
<para>
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.
buffer data. The following example creates a buffer that can hold a given
video frame with a given width, height and bits per plane.
<programlisting>
GstBuffer *buffer;
gint size, widht, height, bpp;
gint size, width, height, bpp;
...
size = width * height * bpp;
@ -29,7 +32,8 @@ buffer data.
</programlisting>
</para>
<para>
Alternatively, use gst_buffer_new_and_alloc() to create a buffer with preallocated
Alternatively, use gst_buffer_new_and_alloc()
to create a buffer with preallocated
data of a given size.
</para>
<para>
@ -47,18 +51,30 @@ To efficiently create a smaller buffer out of an existing one, you can
use gst_buffer_create_sub().
</para>
<para>
If the plug-in wants to modify the buffer in-place, it should first obtain
a buffer that is safe to modify by using gst_buffer_copy_on_write(). This
function is optimized so that a copy will only be made when it is necessary.
</para>
<para>
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 it
a certain flag is set.
a certain #GstBufferFlag is set.
</para>
<para>
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.
</para>
<para>
An element should either unref the buffer or push it out on a src pad
using gst_pad_push() (see #GstPad).
Buffers usually are freed by unreffing them with gst_buffer_unref().
gst_buffer_free() can also be used to effectively free the buffer
regardless of the refcount (dangerous).
Do not use gst_buffer_free() : this function effectively frees the buffer
regardless of the refcount, which is dangerous.
</para>
<para>
Last reviewed on August 30th, 2002 (0.4.0.1)
</para>
<!-- ##### SECTION See_Also ##### -->
@ -71,31 +87,32 @@ regardless of the refcount (dangerous).
Casts an object to a GstBuffer.
</para>
@buf: object to cast
@buf: an object to cast.
@Returns: the #GstBuffer to which the given object points.
<!-- ##### MACRO GST_IS_BUFFER ##### -->
<para>
Checks if the pointer is a GstBuffer
Checks if the pointer is a GstBuffer.
</para>
@buf: The buffer to query
@buf: a pointer to query.
<!-- ##### MACRO GST_BUFFER_REFCOUNT ##### -->
<para>
Get a handle to the refcount structure of the buffer
Gets a handle to the refcount structure of the buffer.
</para>
@buf: The buffer to query
@buf: a #GstBuffer to get the refcount structure of.
<!-- ##### MACRO GST_BUFFER_REFCOUNT_VALUE ##### -->
<para>
Get the current refcount value of the buffer
Gets the current refcount value of the buffer.
</para>
@buf: The buffer to query
@buf: a #GstBuffer to get the refcount value of.
<!-- ##### MACRO GST_BUFFER_COPY_FUNC ##### -->
@ -103,7 +120,7 @@ Get the current refcount value of the buffer
Calls the buffer-specific copy function on the given buffer.
</para>
@buf: a #GstBuffer to copy
@buf: a #GstBuffer to copy.
<!-- ##### MACRO GST_BUFFER_FREE_FUNC ##### -->
@ -111,7 +128,7 @@ Calls the buffer-specific copy function on the given buffer.
Calls the buffer-specific free function on the given buffer.
</para>
@buf: a #GstBuffer to free
@buf: a #GstBuffer to free.
<!-- ##### MACRO GST_BUFFER_FLAGS ##### -->
@ -119,16 +136,16 @@ Calls the buffer-specific free function on the given buffer.
Gets the flags from this buffer.
</para>
@buf: a #GstBuffer to retrieve the flags from
@buf: a #GstBuffer to retrieve the flags from.
<!-- ##### MACRO GST_BUFFER_FLAG_IS_SET ##### -->
<para>
Gives the status of a given #GstBufferFlag.
Gives the status of a given flag of a buffer.
</para>
@buf: a #GstBuffer to query
@flag: the #GstBufferFlag to check
@buf: a #GstBuffer to query flags of.
@flag: the #GstBufferFlag to check.
<!-- ##### MACRO GST_BUFFER_FLAG_SET ##### -->
@ -136,8 +153,8 @@ Gives the status of a given #GstBufferFlag.
Sets a buffer flag.
</para>
@buf: a #GstBuffer to modify
@flag: the #GstBufferFlag to set
@buf: a #GstBuffer to modify flags of.
@flag: the #GstBufferFlag to set.
<!-- ##### MACRO GST_BUFFER_FLAG_UNSET ##### -->
@ -145,8 +162,8 @@ Sets a buffer flag.
Clears a buffer flag.
</para>
@buf: a #GstBuffer to modify
@flag: the #GstBufferFlag to clear
@buf: a #GstBuffer to modify flags of.
@flag: the #GstBufferFlag to clear.
<!-- ##### MACRO GST_BUFFER_DATA ##### -->
@ -154,7 +171,8 @@ Clears a buffer flag.
Retrieves a pointer to the data element of this buffer.
</para>
@buf: a #GstBuffer to get data pointer of
@buf: a #GstBuffer to get data pointer of.
@Returns: the pointer to the actual data contents of the buffer.
<!-- ##### MACRO GST_BUFFER_SIZE ##### -->
@ -162,7 +180,7 @@ Retrieves a pointer to the data element of this buffer.
Gets the size of the data in this buffer.
</para>
@buf: a #GstBuffer to get data size of
@buf: a #GstBuffer to get data size of.
<!-- ##### MACRO GST_BUFFER_MAXSIZE ##### -->
@ -170,7 +188,7 @@ Gets the size of the data in this buffer.
Gets the maximum size of this buffer.
</para>
@buf: a #GstBuffer to get maximum size of
@buf: a #GstBuffer to get maximum size of.
<!-- ##### MACRO GST_BUFFER_TIMESTAMP ##### -->
@ -178,7 +196,7 @@ Gets the maximum size of this buffer.
Gets the timestamp for this buffer.
</para>
@buf: a #GstBuffer to get timestamp of
@buf: a #GstBuffer to get timestamp of.
<!-- ##### MACRO GST_BUFFER_OFFSET ##### -->
@ -186,7 +204,7 @@ Gets the timestamp for this buffer.
Gets the offset in the source file of this buffer.
</para>
@buf: a #GstBuffer to get offset of
@buf: a #GstBuffer to get offset of.
<!-- ##### MACRO GST_BUFFER_BUFFERPOOL ##### -->
@ -194,7 +212,8 @@ Gets the offset in the source file of this buffer.
Gets the bufferpool for this buffer.
</para>
@buf: a #GstBuffer to get bufferpool of
@buf: a #GstBuffer to get the bufferpool of.
@Returns: the #GstBufferPool of this buffer.
<!-- ##### MACRO GST_BUFFER_POOL_PRIVATE ##### -->
@ -202,34 +221,31 @@ Gets the bufferpool for this buffer.
Gets the bufferpool private data.
</para>
@buf: a #GstBuffer to get bufferpool's private data of
<<<<<<< gstbuffer.sgml
@buf: a #GstBuffer to get bufferpool's private data of.
<!-- ##### ENUM GstBufferFlag ##### -->
<para>
This enumeration type describes the flags that can be used for a buffer.
A set of buffer flags used to describe properties of a #GstBuffer.
</para>
@GST_BUFFER_READONLY: buffer is read-only
@GST_BUFFER_SUBBUFFER: This buffer is a subbuffer, the parent buffer can be found with the
GST_BUFFER_POOL_PRIVATE() macro.
@GST_BUFFER_ORIGINAL: buffer is not a copy of another buffer
@GST_BUFFER_DONTFREE: do not try to free the data when this buffer is unreferenced
@GST_BUFFER_DISCONTINOUS: This buffer is the first one after a discontinuity in the stream
@GST_BUFFER_KEY_UNIT: This buffer holds a key unit, a unit that can be decoded independently
of other buffers
@GST_BUFFER_PREROLL: This buffer should be decoded but not rendered, it is mainly used
to resynchronise the stream
@GST_BUFFER_FLAG_LAST: Additional flags can be added starting from this flag.
=======
@GST_BUFFER_READONLY: the buffer is read-only.
@GST_BUFFER_SUBBUFFER: the buffer is a subbuffer, the parent buffer can be
found with the GST_BUFFER_POOL_PRIVATE() macro.
@GST_BUFFER_ORIGINAL: buffer is not a copy of another buffer.
@GST_BUFFER_DONTFREE: do not try to free the data when this buffer is
unreferenced.
@GST_BUFFER_DISCONTINUOUS: the buffer is the first one after a discontinuity
in the stream.
@GST_BUFFER_KEY_UNIT: the buffer holds a key unit, a unit that can be
decoded independently of other buffers.
@GST_BUFFER_PREROLL: the buffer should be decoded but not rendered, it is
mainly used to resynchronise the stream.
@GST_BUFFER_FLAG_LAST: additional flags can be added starting from this flag.
<!-- ##### STRUCT GstBuffer ##### -->
<para>
The basic structure of a buffer
The basic structure of a buffer.
</para>
@data_type:
@ -288,55 +304,58 @@ The basic structure of a buffer
<!-- ##### MACRO gst_buffer_ref ##### -->
<para>
Increase the refcount of the given buffer
Increases the refcount of the given buffer by one.
</para>
@buf: The buffer to refcount
@buf: a #GstBuffer to increase the refcount of.
<!-- ##### MACRO gst_buffer_ref_by_count ##### -->
<para>
Increase the refcount of the buffer with the given value.
Increases the refcount of the buffer by the given value.
</para>
@buf: The buffer to refcount
@c: The value to add to the refcount.
@buf: a #GstBuffer to increase the refcount of.
@c: the value to add to the refcount.
<!-- ##### MACRO gst_buffer_unref ##### -->
<para>
Decrease the refcount of the buffer. If the refcount reaches 0, the buffer
Decreases the refcount of the buffer. If the refcount reaches 0, the buffer
will be freed.
</para>
@buf: The buffer to unref
@buf: a #GstBuffer to unref.
<!-- ##### MACRO gst_buffer_copy ##### -->
<para>
Copy the given buffer using the copy function of the parent GstData structure.
Copies the given buffer using the copy function of the parent GstData structure.
</para>
@buffer: The buffer to copy
@Returns: A new copy of the buffer
@buf: a #GstBuffer to copy.
@Returns: a new #GstBuffer copy of the buffer.
<!-- ##### MACRO gst_buffer_copy_on_write ##### -->
<para>
Copy the buffer if the refcount > 1 so that the newly created buffer can be safely
written to. If the refcount is 1, this function just returns the original buffer.
This function returns a buffer that is safe to write to.
Copy the buffer if the refcount > 1 so that the newly
created buffer can be safely written to.
If the refcount is 1, this function just returns the original buffer.
</para>
@buffer: The buffer to copy.
@buffer: a #GstBuffer to copy.
@Returns: the #GstBuffer that can safely be written to.
<!-- ##### MACRO gst_buffer_free ##### -->
<para>
Free the given buffer. It is dangerous to use this function, use gst_buffer_unref()
instead.
Frees the given buffer, regardless of the refcount.
It is dangerous to use this function, you should use gst_buffer_unref() instead.
</para>
@buffer: The buffer to free.
@buffer: a #GstBuffer to free.
<!-- ##### FUNCTION gst_buffer_create_sub ##### -->

127
gst/gstbuffer.c
View file

@ -52,7 +52,8 @@ _gst_buffer_initialize (void)
_gst_buffer_live = 0;
_gst_buffer_pool_live = 0;
chunk = gst_mem_chunk_new ("GstBufferChunk", sizeof (GstBuffer), sizeof (GstBuffer) * 200, 0);
chunk = gst_mem_chunk_new ("GstBufferChunk", sizeof (GstBuffer),
sizeof (GstBuffer) * 200, 0);
GST_INFO (GST_CAT_BUFFER, "Buffers are initialized now");
}
@ -65,10 +66,10 @@ _gst_buffer_initialize (void)
void
gst_buffer_print_stats (void)
{
g_log (g_log_domain_gstreamer, G_LOG_LEVEL_INFO,
"%d live buffer(s)", _gst_buffer_live);
g_log (g_log_domain_gstreamer, G_LOG_LEVEL_INFO,
"%d live bufferpool(s)", _gst_buffer_pool_live);
g_log (g_log_domain_gstreamer, G_LOG_LEVEL_INFO, "%d live buffer(s)",
_gst_buffer_live);
g_log (g_log_domain_gstreamer, G_LOG_LEVEL_INFO, "%d live bufferpool(s)",
_gst_buffer_pool_live);
}
static void
@ -97,9 +98,9 @@ _gst_buffer_sub_free (GstBuffer *buffer)
/**
* gst_buffer_default_free:
* @buffer: a #GstBuffer to free
* @buffer: a #GstBuffer to free.
*
* Free the memory associated with the buffer including the buffer data,
* Frees the memory associated with the buffer including the buffer data,
* unless the GST_BUFFER_DONTFREE flags was set or the buffer data is NULL.
* This function is used by buffer pools.
*/
@ -128,12 +129,12 @@ _gst_buffer_copy_from_pool (GstBuffer *buffer)
/**
* gst_buffer_default_copy:
* @buffer: a #GstBuffer to make a copy of
* @buffer: a #GstBuffer to make a copy of.
*
* Make a full newly allocated copy of the given buffer, data and all.
* This function is used by buffer pools.
*
* Returns: new #GstBuffer
* Returns: the new #GstBuffer.
*/
GstBuffer*
gst_buffer_default_copy (GstBuffer *buffer)
@ -144,7 +145,8 @@ gst_buffer_default_copy (GstBuffer *buffer)
copy = gst_buffer_new ();
/* we simply copy everything from our parent */
GST_BUFFER_DATA (copy) = g_memdup (GST_BUFFER_DATA (buffer), GST_BUFFER_SIZE (buffer));
GST_BUFFER_DATA (copy) = g_memdup (GST_BUFFER_DATA (buffer),
GST_BUFFER_SIZE (buffer));
GST_BUFFER_SIZE (copy) = GST_BUFFER_SIZE (buffer);
GST_BUFFER_MAXSIZE (copy) = GST_BUFFER_MAXSIZE (buffer);
GST_BUFFER_TIMESTAMP (copy) = GST_BUFFER_TIMESTAMP (buffer);
@ -158,7 +160,7 @@ gst_buffer_default_copy (GstBuffer *buffer)
*
* Creates a newly allocated buffer without any data.
*
* Returns: new #GstBuffer
* Returns: the new #GstBuffer.
*/
GstBuffer*
gst_buffer_new (void)
@ -182,11 +184,11 @@ gst_buffer_new (void)
/**
* gst_buffer_new_and_alloc:
* @size: the size of the buffer and the memory to allocate
* @size: the size of the new buffer's data.
*
* Creates a newly allocated buffer with data of the given size.
*
* Returns: new #GstBuffer
* Returns: the new #GstBuffer.
*/
GstBuffer*
gst_buffer_new_and_alloc (guint size)
@ -203,13 +205,14 @@ gst_buffer_new_and_alloc (guint size)
/**
* gst_buffer_new_from_pool:
* @pool: the buffer pool to use
* @offset: the offset of the new buffer
* @size: the size of the new buffer
* @pool: a #GstBufferPool to use.
* @offset: the offset of the new buffer.
* @size: the size of the new buffer.
*
* Creates a newly allocated buffer using the specified bufferpool, offset and size.
* Creates a newly allocated buffer using the specified buffer pool,
* offset and size.
*
* Returns: new #GstBuffer
* Returns: the new #GstBuffer, or NULL if there was an error.
*/
GstBuffer*
gst_buffer_new_from_pool (GstBufferPool *pool, guint64 offset, guint size)
@ -236,14 +239,14 @@ gst_buffer_new_from_pool (GstBufferPool *pool, guint64 offset, guint size)
/**
* gst_buffer_create_sub:
* @parent: parent #GstBuffer
* @offset: offset into parent #GstBuffer
* @size: size of new sub-buffer
* @parent: a parent #GstBuffer to create a subbuffer from.
* @offset: the offset into parent #GstBuffer.
* @size: the size of the new #GstBuffer sub-buffer (with size > 0).
*
* Creates a sub-buffer from the parent at a given offset.
* This sub-buffer uses the actual memory space of the parent buffer.
*
* Returns: a new #GstBuffer
* Returns: the new #GstBuffer, or NULL if there was an error.
*/
GstBuffer*
gst_buffer_create_sub (GstBuffer *parent, guint offset, guint size)
@ -274,7 +277,8 @@ gst_buffer_create_sub (GstBuffer *parent, guint offset, guint size)
buffer = gst_mem_chunk_alloc0 (chunk);
_gst_buffer_live++;
/* make sure nobody overwrites data in the new buffer by setting the READONLY flag */
/* make sure nobody overwrites data in the new buffer
* by setting the READONLY flag */
_GST_DATA_INIT (GST_DATA (buffer),
_gst_buffer_type,
GST_DATA_FLAG_SHIFT (GST_BUFFER_SUBBUFFER) |
@ -297,8 +301,8 @@ gst_buffer_create_sub (GstBuffer *parent, guint offset, guint size)
/**
* gst_buffer_merge:
* @buf1: first source #GstBuffer to merge
* @buf2: second source #GstBuffer to merge
* @buf1: a first source #GstBuffer to merge.
* @buf2: the second source #GstBuffer to merge.
*
* Create a new buffer that is the concatenation of the two source
* buffers. The original source buffers will not be modified or
@ -307,7 +311,7 @@ gst_buffer_create_sub (GstBuffer *parent, guint offset, guint size)
* Internally is nothing more than a specialized gst_buffer_span(),
* so the same optimizations can occur.
*
* Returns: a new #GstBuffer that's the concatenation of the source buffers
* Returns: the new #GstBuffer that's the concatenation of the source buffers.
*/
GstBuffer*
gst_buffer_merge (GstBuffer *buf1, GstBuffer *buf2)
@ -321,13 +325,14 @@ gst_buffer_merge (GstBuffer *buf1, GstBuffer *buf2)
/**
* gst_buffer_is_span_fast:
* @buf1: first source buffer
* @buf2: second source buffer
* @buf1: a first source #GstBuffer.
* @buf2: the second source #GstBuffer.
*
* Determines whether a gst_buffer_span() is free (as in free beer),
* or requires a memcpy.
*
* Returns: TRUE if the buffers are contiguous, FALSE if a copy would be required.
* Returns: TRUE if the buffers are contiguous,
* FALSE if a copy would be required.
*/
gboolean
gst_buffer_is_span_fast (GstBuffer *buf1, GstBuffer *buf2)
@ -344,10 +349,11 @@ gst_buffer_is_span_fast (GstBuffer *buf1, GstBuffer *buf2)
/**
* gst_buffer_span:
* @buf1: first source #GstBuffer to merge
* @offset: offset in first buffer to start new buffer
* @buf2: second source #GstBuffer to merge
* @len: length of new buffer
* @buf1: a 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
@ -359,7 +365,7 @@ gst_buffer_is_span_fast (GstBuffer *buf1, GstBuffer *buf2)
* parent, and thus no copying is necessary. you can use
* gst_buffer_is_span_fast() to determine if a memcpy will be needed.
*
* Returns: a new #GstBuffer that spans the two source buffers
* Returns: the new #GstBuffer that spans the two source buffers.
*/
GstBuffer*
gst_buffer_span (GstBuffer *buf1, guint32 offset, GstBuffer *buf2, guint32 len)
@ -374,10 +380,13 @@ gst_buffer_span (GstBuffer *buf1, guint32 offset, GstBuffer *buf2, guint32 len)
if (gst_buffer_is_span_fast (buf1, buf2)) {
GstBuffer *parent = GST_BUFFER (buf1->pool_private);
/* we simply create a subbuffer of the common parent */
newbuf = gst_buffer_create_sub (parent, buf1->data - parent->data + offset, len);
newbuf = gst_buffer_create_sub (parent,
buf1->data - parent->data + offset, len);
}
else {
GST_DEBUG (GST_CAT_BUFFER,"slow path taken while spanning buffers %p and %p", buffer, append);
GST_DEBUG (GST_CAT_BUFFER,
"slow path taken while spanning buffers %p and %p",
buffer, append);
/* otherwise we simply have to brute-force copy the buffers */
newbuf = gst_buffer_new_and_alloc (len);
@ -387,7 +396,8 @@ gst_buffer_span (GstBuffer *buf1, guint32 offset, GstBuffer *buf2, guint32 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));
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)
@ -406,16 +416,19 @@ gst_buffer_pool_default_free (GstBufferPool *pool)
/**
* gst_buffer_pool_new:
* @free: The function to free the bufferpool
* @copy: The function to copy the bufferpool
* @buffer_new: the function to create a new buffer from this pool
* @buffer_copy: the function to copy a buffer from this pool
* @buffer_free: the function to free a buffer in this pool
* @user_data: user data passed to buffer_* functions
* @free: the #GstDataFreeFunction to free the buffer pool.
* @copy: the #GstDataCopyFunction to copy the buffer pool.
* @buffer_new: the #GstBufferPoolBufferNewFunction to create a new buffer
* from this pool
* @buffer_copy: the #GstBufferPoolBufferCopyFunction to copy a buffer
* from this pool
* @buffer_free: the #GstBufferPoolBufferFreeFunction to free a buffer
* in this pool
* @user_data: the user data gpointer passed to buffer_* functions.
*
* Create a new bufferpool with the given functions.
* Creates a new buffer pool with the given functions.
*
* Returns: a new GstBufferPool or NULL on error.
* Returns: a new #GstBufferPool, or NULL on error.
*/
GstBufferPool*
gst_buffer_pool_new (GstDataFreeFunction free,
@ -453,9 +466,9 @@ gst_buffer_pool_new (GstDataFreeFunction free,
/**
* gst_buffer_pool_is_active:
* @pool: the pool to query
* @pool: the #GstBufferPool to query.
*
* Query if the geven bufferpool is active.
* Queries if the given buffer pool is active.
*
* Returns: TRUE if the pool is active.
*/
@ -467,11 +480,11 @@ gst_buffer_pool_is_active (GstBufferPool *pool)
/**
* gst_buffer_pool_set_active:
* @pool: the pool to activate
* @active: new status of the pool
* @pool: a #GstBufferPool to set the activity status on.
* @active: the new status of the pool.
*
* Set the given pool to the active or inactive state depending on the
* activate parameter
* Sets the given pool to the active or inactive state depending on the
* active parameter.
*/
void
gst_buffer_pool_set_active (GstBufferPool *pool, gboolean active)
@ -481,10 +494,10 @@ gst_buffer_pool_set_active (GstBufferPool *pool, gboolean active)
/**
* gst_buffer_pool_set_user_data:
* @pool: the pool set the user data for
* @user_data: the user_data to set
* @pool: the #GstBufferPool to set the user data for.
* @user_data: the user_data to set on the buffer pool.
*
* Set the given user data to the bufferpool
* Sets the given user data on the buffer pool.
*/
void
gst_buffer_pool_set_user_data (GstBufferPool *pool, gpointer user_data)
@ -494,11 +507,11 @@ gst_buffer_pool_set_user_data (GstBufferPool *pool, gpointer user_data)
/**
* gst_buffer_pool_get_user_data:
* @pool: the pool get the user data for
* @pool: the #GstBufferPool to get the user data for.
*
* Get the user data of the bufferpool
* Gets the user data of the buffer pool.
*
* Returns: the user data associated with this bufferpool
* Returns: the user data associated with this buffer pool.
*/
gpointer
gst_buffer_pool_get_user_data (GstBufferPool *pool)