GstBufferList

GstBufferList — Lists of buffers for data-passing

Synopsis

#include <gst/gst.h>

                    GstBufferList;
GstBufferList *     gst_buffer_list_new                 (void);
GstBufferList *     gst_buffer_list_new_sized           (guint size);
guint               gst_buffer_list_length              (GstBufferList *list);
#define             gst_buffer_list_add                 (l,
                                                         b)
void                gst_buffer_list_insert              (GstBufferList *list,
                                                         gint idx,
                                                         GstBuffer *buffer);
void                gst_buffer_list_remove              (GstBufferList *list,
                                                         guint idx,
                                                         guint length);
GstBufferList *     gst_buffer_list_ref                 (GstBufferList *list);
void                gst_buffer_list_unref               (GstBufferList *list);
GstBufferList *     gst_buffer_list_copy                (const GstBufferList *list);
#define             gst_buffer_list_is_writable         (list)
#define             gst_buffer_list_make_writable       (list)
gboolean            (*GstBufferListFunc)                (GstBuffer **buffer,
                                                         guint idx,
                                                         gpointer user_data);
gboolean            gst_buffer_list_foreach             (GstBufferList *list,
                                                         GstBufferListFunc func,
                                                         gpointer user_data);
GstBuffer *         gst_buffer_list_get                 (GstBufferList *list,
                                                         guint idx);

Description

Buffer lists are an object containing a list of buffers.

Buffer lists are created with gst_buffer_list_new() and filled with data using a gst_buffer_list_insert().

Buffer lists can be pushed on a srcpad with gst_pad_push_list(). This is interesting when multiple buffers need to be pushed in one go because it can reduce the amount of overhead for pushing each buffer individually.

Last reviewed on 2012-03-28 (0.11.3)

Details

GstBufferList

typedef struct _GstBufferList GstBufferList;

Opaque list of grouped buffers.


gst_buffer_list_new ()

GstBufferList *     gst_buffer_list_new                 (void);

Creates a new, empty GstBufferList. The caller is responsible for unreffing the returned GstBufferList.

Free-function: gst_buffer_list_unref

Returns :

the new GstBufferList. gst_buffer_list_unref() after usage. [transfer full]

gst_buffer_list_new_sized ()

GstBufferList *     gst_buffer_list_new_sized           (guint size);

Creates a new, empty GstBufferList. The caller is responsible for unreffing the returned GstBufferList. The list will have size space preallocated so that memory reallocations can be avoided.

Free-function: gst_buffer_list_unref

size :

an initial reserved size

Returns :

the new GstBufferList. gst_buffer_list_unref() after usage. [transfer full]

gst_buffer_list_length ()

guint               gst_buffer_list_length              (GstBufferList *list);

Returns the number of buffers in list.

list :

a GstBufferList

Returns :

the number of buffers in the buffer list

gst_buffer_list_add()

#define gst_buffer_list_add(l,b) gst_buffer_list_insert((l),-1,(b));

Append b at the end of l.

l :

a GstBufferList

b :

a GstBuffer

gst_buffer_list_insert ()

void                gst_buffer_list_insert              (GstBufferList *list,
                                                         gint idx,
                                                         GstBuffer *buffer);

Insert buffer at idx in list. Other buffers are moved to make room for this new buffer.

A -1 value for idx will append the buffer at the end.

list :

a GstBufferList

idx :

the index

buffer :

a GstBuffer. [transfer full]

gst_buffer_list_remove ()

void                gst_buffer_list_remove              (GstBufferList *list,
                                                         guint idx,
                                                         guint length);

Remove length buffers starting from idx in list. The following buffers are moved to close the gap.

list :

a GstBufferList

idx :

the index

length :

the amount to remove

gst_buffer_list_ref ()

GstBufferList *     gst_buffer_list_ref                 (GstBufferList *list);

Increases the refcount of the given buffer list by one.

Note that the refcount affects the writeability of list and its data, see gst_buffer_list_make_writable(). It is important to note that keeping additional references to GstBufferList instances can potentially increase the number of memcpy operations in a pipeline.

list :

a GstBufferList

Returns :

list. [transfer full]

gst_buffer_list_unref ()

void                gst_buffer_list_unref               (GstBufferList *list);

Decreases the refcount of the buffer list. If the refcount reaches 0, the buffer list will be freed.

list :

a GstBufferList. [transfer full]

gst_buffer_list_copy ()

GstBufferList *     gst_buffer_list_copy                (const GstBufferList *list);

Create a shallow copy of the given buffer list. This will make a newly allocated copy of the source list with copies of buffer pointers. The refcount of buffers pointed to will be increased by one.

list :

a GstBufferList

Returns :

a new copy of list. [transfer full]

gst_buffer_list_is_writable()

#define gst_buffer_list_is_writable(list) gst_mini_object_is_writable (GST_MINI_OBJECT_CAST (list))

Tests if you can safely add buffers and groups into a buffer list.

list :

a GstBufferList

gst_buffer_list_make_writable()

#define gst_buffer_list_make_writable(list) GST_BUFFER_LIST_CAST (gst_mini_object_make_writable (GST_MINI_OBJECT_CAST (list)))

Makes a writable buffer list from the given buffer list. If the source buffer list is already writable, this will simply return the same buffer list. A copy will otherwise be made using gst_buffer_list_copy().

list :

a GstBufferList. [transfer full]

Returns :

a writable list, which may or may not be the same as list. [transfer full]

GstBufferListFunc ()

gboolean            (*GstBufferListFunc)                (GstBuffer **buffer,
                                                         guint idx,
                                                         gpointer user_data);

A function that will be called from gst_buffer_list_foreach(). The buffer field will point to a the reference of the buffer at idx.

When this function returns TRUE, the next buffer will be returned. When FALSE is returned, gst_buffer_list_foreach() will return.

When buffer is set to NULL, the item will be removed from the bufferlist. When buffer has been made writable, the new buffer reference can be assigned to buffer. This function is responsible for unreffing the old buffer when removing or modifying.

buffer :

pointer the buffer

idx :

the index of buffer

user_data :

user data passed to gst_buffer_list_foreach()

Returns :

FALSE when gst_buffer_list_foreach() should stop

gst_buffer_list_foreach ()

gboolean            gst_buffer_list_foreach             (GstBufferList *list,
                                                         GstBufferListFunc func,
                                                         gpointer user_data);

Call func with data for each buffer in list.

func can modify the passed buffer pointer or its contents. The return value of func define if this function returns or if the remaining buffers in the list should be skipped.

list :

a GstBufferList

func :

a GstBufferListFunc to call. [scope call]

user_data :

user data passed to func. [closure]

Returns :

TRUE when func returned TRUE for each buffer in list or when list is empty.

gst_buffer_list_get ()

GstBuffer *         gst_buffer_list_get                 (GstBufferList *list,
                                                         guint idx);

Get the buffer at idx.

list :

a GstBufferList

idx :

the index

Returns :

the buffer at idx in group or NULL when there is no buffer. The buffer remains valid as long as list is valid. [transfer none]

See Also

GstPad, GstMiniObject