GStreamer 1.0 Core Reference Manual: GstBuffer

## GstBuffer GstBuffer — Data-passing buffer type |

## Functions

#define | GST_BUFFER_FLAGS()
#define | GST_BUFFER_FLAG_IS_SET()
#define | GST_BUFFER_FLAG_SET()
#define | GST_BUFFER_FLAG_UNSET()
#define | GST_BUFFER_PTS()
#define | GST_BUFFER_DTS()
#define | GST_BUFFER_DURATION()
#define | GST_BUFFER_OFFSET()
#define | GST_BUFFER_OFFSET_END()
#define | GST_BUFFER_OFFSET_NONE
#define | GST_BUFFER_DURATION_IS_VALID()
#define | GST_BUFFER_PTS_IS_VALID()
#define | GST_BUFFER_DTS_IS_VALID()
#define | GST_BUFFER_OFFSET_IS_VALID()
#define | GST_BUFFER_OFFSET_END_IS_VALID()
#define | GST_BUFFER_IS_DISCONT()
GstBuffer * | gst_buffer_new ()
GstBuffer * | gst_buffer_new_allocate ()
GstBuffer * | gst_buffer_new_wrapped ()
GstBuffer * | gst_buffer_new_wrapped_full ()
GstBuffer * | gst_buffer_ref ()
void | gst_buffer_unref ()
gsize | gst_buffer_get_sizes ()
gsize | gst_buffer_get_size ()
gsize | gst_buffer_get_sizes_range ()
gboolean | gst_buffer_resize_range ()
void | gst_buffer_resize ()
void | gst_buffer_set_size ()
GstMemory * | gst_buffer_peek_memory ()
guint | gst_buffer_n_memory ()
void | gst_buffer_insert_memory ()
void | gst_buffer_replace_memory_range ()
GstMemory * | gst_buffer_get_memory_range ()
void | gst_buffer_remove_memory_range ()
gboolean | gst_buffer_find_memory ()
void | gst_buffer_prepend_memory ()
void | gst_buffer_append_memory ()
void | gst_buffer_replace_memory ()
void | gst_buffer_replace_all_memory ()
GstMemory * | gst_buffer_get_memory ()
GstMemory * | gst_buffer_get_all_memory ()
void | gst_buffer_remove_memory ()
void | gst_buffer_remove_all_memory ()
gboolean | gst_buffer_map ()
gboolean | gst_buffer_map_range ()
void | gst_buffer_unmap ()
gint | gst_buffer_memcmp ()
gsize | gst_buffer_extract ()
void | gst_buffer_extract_dup ()
gsize | gst_buffer_fill ()
gsize | gst_buffer_memset ()
#define | GST_BUFFER_COPY_METADATA
#define | GST_BUFFER_COPY_ALL
GstBuffer * | gst_buffer_copy ()
gboolean | gst_buffer_copy_into ()
GstBuffer * | gst_buffer_copy_region ()
#define | gst_buffer_is_writable()
#define | gst_buffer_make_writable()
gboolean | gst_buffer_replace ()
GstBuffer * | gst_buffer_append ()
GstBuffer * | gst_buffer_append_region ()
GstMeta * | gst_buffer_get_meta ()
GstMeta * | gst_buffer_add_meta ()
gboolean | gst_buffer_remove_meta ()
GstMeta * | gst_buffer_iterate_meta ()
gboolean | (*GstBufferForeachMetaFunc) ()
gboolean | gst_buffer_foreach_meta ()

## Types and Values

struct | GstBuffer
enum | GstBufferFlags
enum | GstBufferCopyFlags

## Object Hierarchy

## Includes

    #include <gst/gst.h>

## Description

Buffers are the basic unit of data transfer in GStreamer. They contain the timing and offset along with other arbitrary metadata that is associated with the GstMemory blocks that the buffer contains.

Buffers are usually created with `gst_buffer_new()`. After a buffer has been created one will typically allocate memory for it and add it to the buffer. The following example creates a buffer that can hold a given video frame with a given width, height and bits per plane.

Example 3. Creating a buffer for a video frame

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    GstBuffer *buffer;
    GstMemory *memory;
    gint size, width, height, bpp;
    ...
    size = width * height * bpp;
    buffer = gst_buffer_new ();
    memory = gst_allocator_alloc (NULL, size, NULL);
    gst_buffer_insert_memory (buffer, -1, memory);
    ...

Alternatively, use `gst_buffer_new_allocate()` to create a buffer with preallocated data of a given size.

Buffers can contain a list of GstMemory objects. You can retrieve how many memory objects with `gst_buffer_n_memory()` and you can get a pointer to memory with `gst_buffer_peek_memory()`

A buffer will usually have timestamps, 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 timestamps and duration are measured in nanoseconds (they are GstClockTime values).

The buffer DTS refers to the timestamp when the buffer should be decoded and is usually monotonically increasing. The buffer PTS refers to the timestamp when the buffer content should be presented to the user and is not always monotonically increasing.

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 preceeding CAPS event). 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. The buffer refcount determines the writability of the buffer, a buffer is only writable when the refcount is exactly 1, i.e. when the caller has the only reference to the buffer.

To efficiently create a smaller buffer out of an existing one, you can use `gst_buffer_copy_region()`. This method tries to share the memory objects between the two buffers.

If a plug-in wants to modify the buffer data or metadata 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.

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_append()`. Copying of memory will only be done when absolutely needed.

Arbitrary extra metadata can be set on a buffer with `gst_buffer_add_meta()`. Metadata can be retrieved with `gst_buffer_get_meta()`. See also GstMeta

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 memory and metadata pointed to by the buffer is unreffed as well. Buffers allocated from a GstBufferPool will be returned to the pool when the refcount drops to 0.

Last reviewed on 2012-03-28 (0.11.3)

## Functions

### GST_BUFFER_FLAGS()

    #define GST_BUFFER_FLAGS(buf)                   GST_MINI_OBJECT_FLAGS(buf)

A flags word containing GstBufferFlag flags set on this buffer.

#### Parameters

buf | a GstBuffer. |

### GST_BUFFER_FLAG_IS_SET()

    #define GST_BUFFER_FLAG_IS_SET(buf,flag)        GST_MINI_OBJECT_FLAG_IS_SET (buf, flag)

Gives the status of a specific flag on a buffer.

#### Parameters

buf | a GstBuffer. |
flag | the GstBufferFlag to check. |

### GST_BUFFER_FLAG_SET()

    #define GST_BUFFER_FLAG_SET(buf,flag)           GST_MINI_OBJECT_FLAG_SET (buf, flag)

Sets a buffer flag on a buffer.

#### Parameters

buf | a GstBuffer. |
flag | the GstBufferFlag to set. |

### GST_BUFFER_FLAG_UNSET()

    #define GST_BUFFER_FLAG_UNSET(buf,flag)         GST_MINI_OBJECT_FLAG_UNSET (buf, flag)

Clears a buffer flag.

#### Parameters

buf | a GstBuffer. |
flag | the GstBufferFlag to clear. |

### GST_BUFFER_PTS()

    #define GST_BUFFER_PTS(buf)                     (GST_BUFFER_CAST(buf)->pts)

The presentation timestamp (pts) in nanoseconds (as a GstClockTime) of the data in the buffer. This is the timestamp when the media should be presented to the user. Value will be `GST_CLOCK_TIME_NONE` if the pts is unknown.

#### Parameters

buf | a GstBuffer.: |

### GST_BUFFER_DTS()

    #define GST_BUFFER_DTS(buf)                     (GST_BUFFER_CAST(buf)->dts)

The decoding timestamp (dts) in nanoseconds (as a GstClockTime) of the data in the buffer. This is the timestamp when the media should be decoded or processed otherwise. Value will be `GST_CLOCK_TIME_NONE` if the dts is unknown.

#### Parameters

buf | a GstBuffer.: |

### GST_BUFFER_DURATION()

    #define GST_BUFFER_DURATION(buf)                (GST_BUFFER_CAST(buf)->duration)

The duration in nanoseconds (as a GstClockTime) of the data in the buffer. Value will be `GST_CLOCK_TIME_NONE` if the duration is unknown.

#### Parameters

buf | a GstBuffer. |

### GST_BUFFER_OFFSET()

    #define GST_BUFFER_OFFSET(buf)                  (GST_BUFFER_CAST(buf)->offset)

The offset in the source file of the beginning of this buffer.

#### Parameters

buf | a GstBuffer. |

### GST_BUFFER_OFFSET_END()

    #define GST_BUFFER_OFFSET_END(buf)              (GST_BUFFER_CAST(buf)->offset_end)

The offset in the source file of the end of this buffer.

#### Parameters

buf | a GstBuffer. |

### GST_BUFFER_OFFSET_NONE

    #define GST_BUFFER_OFFSET_NONE  ((guint64)-1)

Constant for no-offset return results.

### GST_BUFFER_DURATION_IS_VALID()

    #define GST_BUFFER_DURATION_IS_VALID(buffer)    (GST_CLOCK_TIME_IS_VALID (GST_BUFFER_DURATION (buffer)))

Tests if the duration is known.

#### Parameters

buffer | a GstBuffer |

### GST_BUFFER_PTS_IS_VALID()

    #define GST_BUFFER_PTS_IS_VALID(buffer)   (GST_CLOCK_TIME_IS_VALID (GST_BUFFER_PTS (buffer)))

Tests if the pts is known.

#### Parameters

buffer | a GstBuffer |

### GST_BUFFER_DTS_IS_VALID()

    #define GST_BUFFER_DTS_IS_VALID(buffer)   (GST_CLOCK_TIME_IS_VALID (GST_BUFFER_DTS (buffer)))

Tests if the dts is known.

#### Parameters

buffer | a GstBuffer |

### GST_BUFFER_OFFSET_IS_VALID()

    #define GST_BUFFER_OFFSET_IS_VALID(buffer)      (GST_BUFFER_OFFSET (buffer) != GST_BUFFER_OFFSET_NONE)

Tests if the start offset is known.

#### Parameters

buffer | a GstBuffer |

### GST_BUFFER_OFFSET_END_IS_VALID()

    #define GST_BUFFER_OFFSET_END_IS_VALID(buffer)  (GST_BUFFER_OFFSET_END (buffer) != GST_BUFFER_OFFSET_NONE)

Tests if the end offset is known.

#### Parameters

buffer | a GstBuffer |

### GST_BUFFER_IS_DISCONT()

    #define GST_BUFFER_IS_DISCONT(buffer)   (GST_BUFFER_FLAG_IS_SET (buffer, GST_BUFFER_FLAG_DISCONT))

Tests if the buffer marks a discontinuity in the stream.

#### Parameters

buffer | a GstBuffer |

### gst_buffer_new ()

    GstBuffer *
    gst_buffer_new (void);

Creates a newly allocated buffer without any data.

MT safe.

#### Returns

the new GstBuffer.

[transfer full]

### gst_buffer_new_allocate ()

    GstBuffer *
    gst_buffer_new_allocate (GstAllocator *allocator,
                             gsize size,
                             GstAllocationParams *params);

Tries to create a newly allocated buffer with data of the given size and extra parameters from `allocator` . If the requested amount of memory can't be allocated, NULL will be returned. The allocated buffer memory is not cleared.

When `allocator` is NULL, the default memory allocator will be used.

Note that when `size` == 0, the buffer will not have memory associated with it.

MT safe.

#### Parameters

allocator | the GstAllocator to use, or NULL to use the default allocator. | [transfer none][allow-none]
size | the size in bytes of the new buffer's data. |
params | optional parameters. | [transfer none][allow-none]

#### Returns

a new GstBuffer, or NULL if the memory couldn't be allocated.

[transfer full]

### gst_buffer_new_wrapped ()

    GstBuffer *
    gst_buffer_new_wrapped (gpointer data,
                            gsize size);

Creates a new buffer that wraps the given `data` . The memory will be freed with g_free and will be marked writable.

MT safe.

#### Parameters

data | data to wrap. | [array length=size][element-type guint8][transfer full]
size | allocated size of `data` |

#### Returns

a new GstBuffer.

[transfer full]

### gst_buffer_new_wrapped_full ()

    GstBuffer *
    gst_buffer_new_wrapped_full (GstMemoryFlags flags,
                                 gpointer data,
                                 gsize maxsize,
                                 gsize offset,
                                 gsize size,
                                 gpointer user_data,
                                 GDestroyNotify notify);

Allocate a new buffer that wraps the given memory. `data` must point to `maxsize` of memory, the wrapped buffer will have the region from `offset` and `size` visible.

When the buffer is destroyed, `notify` will be called with `user_data` .

The prefix/padding must be filled with 0 if `flags` contains GST_MEMORY_FLAG_ZERO_PREFIXED and GST_MEMORY_FLAG_ZERO_PADDED respectively.

#### Parameters

flags | GstMemoryFlags |
data | data to wrap. | [array length=size][element-type guint8][transfer none]
maxsize | allocated size of `data` |
offset | offset in `data` |
size | size of valid data |
user_data | user_data. | [allow-none]
notify | called with `user_data` when the memory is freed. | [allow-none][scope async][closure user_data]

#### Returns

a new GstBuffer.

[transfer full]

### gst_buffer_ref ()

    GstBuffer *
    gst_buffer_ref (GstBuffer *buf);

Increases the refcount of the given buffer by one.

Note that the refcount affects the writeability of `buf` and its metadata, see `gst_buffer_is_writable()`. It is important to note that keeping additional references to GstBuffer instances can potentially increase the number of memcpy operations in a pipeline.

#### Parameters

buf | a GstBuffer. |

#### Returns

`buf` .

[transfer full]

### gst_buffer_unref ()

    void
    gst_buffer_unref (GstBuffer *buf);

Decreases the refcount of the buffer. If the refcount reaches 0, the buffer with the associated metadata and memory will be freed.

#### Parameters

buf | a GstBuffer. | [transfer full]

### gst_buffer_get_sizes ()

    gsize
    gst_buffer_get_sizes (GstBuffer *buffer,
                          gsize *offset,
                          gsize *maxsize);

Get the total size of the memory blocks in `b` .

When not `NULL`, `offset` will contain the offset of the data in the first memory block in `buffer` and `maxsize` will contain the sum of the size and `offset` and the amount of extra padding on the last memory block. `offset` and `maxsize` can be used to resize the buffer memory blocks with `gst_buffer_resize()`.

#### Parameters

buffer | a GstBuffer. |
offset | a pointer to the offset. | [out]
maxsize | a pointer to the maxsize. | [out]

#### Returns

total size of the memory blocks in `buffer` .

### gst_buffer_get_size ()

    gsize
    gst_buffer_get_size (GstBuffer *buffer);

Get the total size of the memory blocks in `buffer` .

#### Parameters

buffer | a GstBuffer. |

#### Returns

total size of the memory blocks in `buffer` .

### gst_buffer_get_sizes_range ()

    gsize
    gst_buffer_get_sizes_range (GstBuffer *buffer,
                                guint idx,
                                gint length,
                                gsize *offset,
                                gsize *maxsize);

Get the total size of `length` memory blocks stating from `idx` in `buffer` .

When not `NULL`, `offset` will contain the offset of the data in the memory block in `buffer` at `idx` and `maxsize` will contain the sum of the size and `offset` and the amount of extra padding on the memory block at `idx` + `length` -1. `offset` and `maxsize` can be used to resize the buffer memory blocks with `gst_buffer_resize_range()`.

#### Parameters

buffer | a GstBuffer. |
idx | an index |
length | a length |
offset | a pointer to the offset. | [out]
maxsize | a pointer to the maxsize. | [out]

#### Returns

total size of `length` memory blocks starting at `idx` in `buffer` .

### gst_buffer_resize_range ()

    gboolean
    gst_buffer_resize_range (GstBuffer *buffer,
                             guint idx,
                             gint length,
                             gssize offset,
                             gssize size);

Set the total size of the `length` memory blocks starting at `idx` in `buffer`

#### Parameters

buffer | a GstBuffer. |
idx | an index |
length | a length |
offset | the offset adjustement |
size | the new size or -1 to just adjust the offset |

#### Returns

`TRUE` if resizing succeeded, `FALSE` otherwise.

### gst_buffer_resize ()

    void
    gst_buffer_resize (GstBuffer *buffer,
                       gssize offset,
                       gssize size);

Set the offset and total size of the memory blocks in `buffer` .

#### Parameters

buffer | a GstBuffer. |
offset | the offset adjustement |
size | the new size or -1 to just adjust the offset |

### gst_buffer_set_size ()

    void
    gst_buffer_set_size (GstBuffer *buffer,
                         gssize size);

Set the total size of the memory blocks in `buffer` .

#### Parameters

buffer | a GstBuffer. |
size | the new size |

### gst_buffer_peek_memory ()

    GstMemory *
    gst_buffer_peek_memory (GstBuffer *buffer,
                            guint idx);

Get the memory block at `idx` in `buffer` . The memory block stays valid until the memory block in `buffer` is removed, replaced or merged, typically with any call that modifies the memory in `buffer` .

#### Parameters

buffer | a GstBuffer. |
idx | an index |

#### Returns

the GstMemory at `idx` .

[transfer none]

### gst_buffer_n_memory ()

    guint
    gst_buffer_n_memory (GstBuffer *buffer);

Get the amount of memory blocks that this buffer has. This amount is never larger than what `gst_buffer_get_max_memory()` returns.

#### Parameters

buffer | a GstBuffer. |

#### Returns

the amount of memory block in this buffer.

[transfer full]

### gst_buffer_insert_memory ()

    void
    gst_buffer_insert_memory (GstBuffer *buffer,
                              gint idx,
                              GstMemory *mem);

Insert the memory block `mem` to `buffer` at `idx` . This function takes ownership of `mem` and thus doesn't increase its refcount.

Only `gst_buffer_get_max_memory()` can be added to a buffer. If more memory is added, existing memory blocks will automatically be merged to make room for the new memory.

#### Parameters

buffer | a GstBuffer. |
idx | the index to add the memory at, or -1 to append it to the end |
mem | a GstMemory. | [transfer full]

### gst_buffer_replace_memory_range ()

    void
    gst_buffer_replace_memory_range (GstBuffer *buffer,
                                     guint idx,
                                     gint length,
                                     GstMemory *mem);

Replaces `length` memory blocks in `buffer` starting at `idx` with `mem` .

If `length` is -1, all memory starting from `idx` will be removed and replaced with `mem` .

`buffer` should be writable.

#### Parameters

buffer | a GstBuffer. |
idx | an index |
length | a length should not be 0 |
mem | a GstMemory. | [transfer full]

### gst_buffer_get_memory_range ()

    GstMemory *
    gst_buffer_get_memory_range (GstBuffer *buffer,
                                 guint idx,
                                 gint length);

Get `length` memory blocks in `buffer` starting at `idx` . The memory blocks will be merged into one large GstMemory.

If `length` is -1, all memory starting from `idx` is merged.

#### Parameters

buffer | a GstBuffer. |
idx | an index |
length | a length |

#### Returns

a GstMemory that contains the merged data of `length` blocks starting at `idx` . Use `gst_memory_unref()` after usage.

[transfer full]

### gst_buffer_remove_memory_range ()

    void
    gst_buffer_remove_memory_range (GstBuffer *buffer,
                                    guint idx,
                                    gint length);

Remove `length` memory blocks in `buffer` starting from `idx` .

`length` can be -1, in which case all memory starting from `idx` is removed.

#### Parameters

buffer | a GstBuffer. |
idx | an index |
length | a length |

### gst_buffer_find_memory ()

    gboolean
    gst_buffer_find_memory (GstBuffer *buffer,
                            gsize offset,
                            gsize size,
                            guint *idx,
                            guint *length,
                            gsize *skip);

Find the memory blocks that span `size` bytes starting from `offset` in `buffer` .

When this function returns `TRUE`, `idx` will contain the index of the first memory bock where the byte for `offset` can be found and `length` contains the number of memory blocks containing the `size` remaining bytes. `skip` contains the number of bytes to skip in the memory bock at `idx` to get to the byte for `offset` .

`size` can be -1 to get all the memory blocks after `idx` .

#### Parameters

buffer | a GstBuffer. |
offset | an offset |
size | a size |
idx | pointer to index. | [out]
length | pointer to length. | [out]
skip | pointer to skip. | [out]

#### Returns

`TRUE` when `size` bytes starting from `offset` could be found in `buffer` and `idx` , `length` and `skip` will be filled.

### gst_buffer_prepend_memory ()

    void
    gst_buffer_prepend_memory (GstBuffer *buffer,
                               GstMemory *mem);

Prepend the memory block `mem` to `buffer` . This function takes ownership of `mem` and thus doesn't increase its refcount.

This function is identical to `gst_buffer_insert_memory()` with an index of 0. See `gst_buffer_insert_memory()` for more details.

#### Parameters

buffer | a GstBuffer. |
mem | a GstMemory. | [transfer full]

### gst_buffer_append_memory ()

    void
    gst_buffer_append_memory (GstBuffer *buffer,
                              GstMemory *mem);

Append the memory block `mem` to `buffer` . This function takes ownership of `mem` and thus doesn't increase its refcount.

This function is identical to `gst_buffer_insert_memory()` with an index of -1. See `gst_buffer_insert_memory()` for more details.

#### Parameters

buffer | a GstBuffer. |
mem | a GstMemory. | [transfer full]

### gst_buffer_replace_memory ()

    void
    gst_buffer_replace_memory (GstBuffer *buffer,
                               guint idx,
                               GstMemory *mem);

Replaces the memory block at index `idx` in `buffer` with `mem` .

#### Parameters

buffer | a GstBuffer. |
idx | an index |
mem | a GstMemory. | [transfer full]

### gst_buffer_replace_all_memory ()

    void
    gst_buffer_replace_all_memory (GstBuffer *buffer,
                                   GstMemory *mem);

Replaces all memory in `buffer` with `mem` .

#### Parameters

buffer | a GstBuffer. |
mem | a GstMemory. | [transfer full]

### gst_buffer_get_memory ()

    GstMemory *
    gst_buffer_get_memory (GstBuffer *buffer,
                           guint idx);

Get the memory block at index `idx` in `buffer` .

#### Parameters

buffer | a GstBuffer. |
idx | an index |

#### Returns

a GstMemory that contains the data of the memory block at `idx` . Use `gst_memory_unref()` after usage.

[transfer full]

### gst_buffer_get_all_memory ()

    GstMemory *
    gst_buffer_get_all_memory (GstBuffer *buffer);

Get all the memory block in `buffer` . The memory blocks will be merged into one large GstMemory.

#### Parameters

buffer | a GstBuffer. |

#### Returns

a GstMemory that contains the merged memory. Use `gst_memory_unref()` after usage.

[transfer full]

### gst_buffer_remove_memory ()

    void
    gst_buffer_remove_memory (GstBuffer *buffer,
                              guint idx);

Remove the memory block in `b` at index `i` .

#### Parameters

buffer | a GstBuffer. |
idx | an index |

### gst_buffer_remove_all_memory ()

    void
    gst_buffer_remove_all_memory (GstBuffer *buffer);

Remove all the memory blocks in `buffer` .

#### Parameters

buffer | a GstBuffer. |

### gst_buffer_map ()

    gboolean
    gst_buffer_map (GstBuffer *buffer,
                    GstMapInfo *info,
                    GstMapFlags flags);

This function fills `info` with the GstMapInfo of all merged memory blocks in `buffer` .

`flags` describe the desired access of the memory. When `flags` is GST_MAP_WRITE, `buffer` should be writable (as returned from `gst_buffer_is_writable()`).

When `buffer` is writable but the memory isn't, a writable copy will automatically be created and returned. The readonly copy of the buffer memory will then also be replaced with this writable copy.

The memory in `info` should be unmapped with `gst_buffer_unmap()` after usage.

#### Parameters

buffer | a GstBuffer. |
info | info about the mapping. | [out]
flags | flags for the mapping |

#### Returns

`TRUE` if the map succeeded and `info` contains valid data.

### gst_buffer_map_range ()

    gboolean
    gst_buffer_map_range (GstBuffer *buffer,
                          guint idx,
                          gint length,
                          GstMapInfo *info,
                          GstMapFlags flags);

This function fills `info` with the GstMapInfo of `length` merged memory blocks starting at `idx` in `buffer` . When `length` is -1, all memory blocks starting from `idx` are merged and mapped.

`flags` describe the desired access of the memory. When `flags` is GST_MAP_WRITE, `buffer` should be writable (as returned from `gst_buffer_is_writable()`).

When `buffer` is writable but the memory isn't, a writable copy will automatically be created and returned. The readonly copy of the buffer memory will then also be replaced with this writable copy.

The memory in `info` should be unmapped with `gst_buffer_unmap()` after usage.

#### Parameters

buffer | a GstBuffer. |
idx | an index |
length | a length |
info | info about the mapping. | [out]
flags | flags for the mapping |

#### Returns

`TRUE` if the map succeeded and `info` contains valid data.

### gst_buffer_unmap ()

    void
    gst_buffer_unmap (GstBuffer *buffer,
                      GstMapInfo *info);

Release the memory previously mapped with `gst_buffer_map()`.

#### Parameters

buffer | a GstBuffer. |
info | a GstMapInfo |

### gst_buffer_memcmp ()

    gint
    gst_buffer_memcmp (GstBuffer *buffer,
                       gsize offset,
                       gconstpointer mem,
                       gsize size);

Compare `size` bytes starting from `offset` in `buffer` with the memory in `mem` .

#### Parameters

buffer | a GstBuffer. |
offset | the offset in `buffer` |
mem | the memory to compare. | [array length=size][element-type guint8]
size | the size to compare |

#### Returns

0 if the memory is equal.

### gst_buffer_extract ()

    gsize
    gst_buffer_extract (GstBuffer *buffer,
                        gsize offset,
                        gpointer dest,
                        gsize size);

Copy `size` bytes starting from `offset` in `buffer` to `dest` .

#### Parameters

buffer | a GstBuffer. |
offset | the offset to extract |
dest | the destination address |
size | the size to extract |

#### Returns

The amount of bytes extracted. This value can be lower than `size` when `buffer` did not contain enough data.

### gst_buffer_extract_dup ()

    void
    gst_buffer_extract_dup (GstBuffer *buffer,
                            gsize offset,
                            gsize size,
                            gpointer *dest,
                            gsize *dest_size);

Extracts a copy of at most `size` bytes the data at `offset` into a GBytes. `dest` must be freed using `g_free()` when done.

#### Parameters

buffer | a GstBuffer |
offset | the offset to extract |
size | the size to extract |
dest | A pointer where the destination array will be written. | [array length=dest_size][element-type guint8][out]
dest_size | A location where the size of `dest` can be written. | [out]

Since 1.0.10

### gst_buffer_fill ()

    gsize
    gst_buffer_fill (GstBuffer *buffer,
                     gsize offset,
                     gconstpointer src,
                     gsize size);

Copy `size` bytes from `src` to `buffer` at `offset` .

#### Parameters

buffer | a GstBuffer. |
offset | the offset to fill |
src | the source address. | [array length=size][element-type guint8]
size | the size to fill |

#### Returns

The amount of bytes copied. This value can be lower than `size` when `buffer` did not contain enough data.

### gst_buffer_memset ()

    gsize
    gst_buffer_memset (GstBuffer *buffer,
                       gsize offset,
                       guint8 val,
                       gsize size);

Fill `buf` with `size` bytes with `val` starting from `offset` .

#### Parameters

buffer | a GstBuffer. |
offset | the offset in `buffer` |
val | the value to set |
size | the size to set |

#### Returns

The amount of bytes filled. This value can be lower than `size` when `buffer` did not contain enough data.

### GST_BUFFER_COPY_METADATA

    #define             GST_BUFFER_COPY_METADATA

Combination of all possible metadata fields that can be copied with `gst_buffer_copy_into()`.

### GST_BUFFER_COPY_ALL

    #define GST_BUFFER_COPY_ALL  ((GstBufferCopyFlags)(GST_BUFFER_COPY_METADATA | GST_BUFFER_COPY_MEMORY))

Combination of all possible fields that can be copied with `gst_buffer_copy_into()`.

### gst_buffer_copy ()

    GstBuffer *
    gst_buffer_copy (const GstBuffer *buf);

Create a copy of the given buffer. This will also make a newly allocated copy of the data the source buffer contains.

#### Parameters

buf | a GstBuffer. |

#### Returns

a new copy of `buf` .

[transfer full]

### gst_buffer_copy_into ()

    gboolean
    gst_buffer_copy_into (GstBuffer *dest,
                          GstBuffer *src,
                          GstBufferCopyFlags flags,
                          gsize offset,
                          gsize size);

Copies the information from `src` into `dest` .

If `dest` already contains memory and `flags` contains GST_BUFFER_COPY_MEMORY, the memory from `src` will be appended to `dest` .

`flags` indicate which fields will be copied.

#### Parameters

dest | a destination GstBuffer |
src | a source GstBuffer |
flags | flags indicating what metadata fields should be copied. |
offset | offset to copy from |
size | total size to copy. If -1, all data is copied. |

#### Returns

`TRUE` if the copying succeeded, `FALSE` otherwise.

### gst_buffer_copy_region ()

    GstBuffer *
    gst_buffer_copy_region (GstBuffer *parent,
                            GstBufferCopyFlags flags,
                            gsize offset,
                            gsize size);

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.

#### Parameters

parent | a GstBuffer. |
flags | the GstBufferCopyFlags |
offset | the offset into parent GstBuffer at which the new sub-buffer begins. |
size | the size of the new GstBuffer sub-buffer, in bytes. |

#### Returns

the new GstBuffer or NULL if the arguments were invalid.

[transfer full]

### gst_buffer_is_writable()

    #define         gst_buffer_is_writable(buf)     gst_mini_object_is_writable (GST_MINI_OBJECT_CAST (buf))

Tests if you can safely write to a buffer's metadata or its memory array. It is only safe to change buffer metadata when the current reference is writable, i.e. nobody can see the modifications you will make.

#### Parameters

buf | a GstBuffer |

### gst_buffer_make_writable()

    #define         gst_buffer_make_writable(buf)   GST_BUFFER_CAST (gst_mini_object_make_writable (GST_MINI_OBJECT_CAST (buf)))

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

#### Parameters

buf | a GstBuffer. | [transfer full]

#### Returns

a writable buffer which may or may not be the same as `buf` .

[transfer full]

### gst_buffer_replace ()

    gboolean
    gst_buffer_replace (GstBuffer **obuf,
                        GstBuffer *nbuf);

Modifies a pointer to a GstBuffer to point to a different GstBuffer. The modification is done atomically (so this is useful for ensuring thread safety in some cases), and the reference counts are updated appropriately (the old buffer is unreffed, the new is reffed).

Either `nbuf` or the GstBuffer pointed to by `obuf` may be NULL.

#### Parameters

obuf | pointer to a pointer to a GstBuffer to be replaced. | [inout][transfer full]
nbuf | pointer to a GstBuffer that will replace the buffer pointed to by `obuf` . | [transfer none][allow-none]

#### Returns

TRUE when `obuf` was different from `nbuf` .

### gst_buffer_append ()

    GstBuffer *
    gst_buffer_append (GstBuffer *buf1,
                       GstBuffer *buf2);

Append all the memory from `buf2` to `buf1` . The result buffer will contain a concatenation of the memory of `buf1` and `buf2` .

#### Parameters

buf1 | the first source GstBuffer to append. | [transfer full]
buf2 | the second source GstBuffer to append. | [transfer full]

#### Returns

the new GstBuffer that contains the memory of the two source buffers.

[transfer full]

### gst_buffer_append_region ()

    GstBuffer *
    gst_buffer_append_region (GstBuffer *buf1,
                              GstBuffer *buf2,
                              gssize offset,
                              gssize size);

Append `size` bytes at `offset` from `buf2` to `buf1` . The result buffer will contain a concatenation of the memory of `buf1` and the requested region of `buf2` .

#### Parameters

buf1 | the first source GstBuffer to append. | [transfer full]
buf2 | the second source GstBuffer to append. | [transfer full]
offset | the offset in `buf2` |
size | the size or -1 of `buf2` |

#### Returns

the new GstBuffer that contains the memory of the two source buffers.

[transfer full]

### gst_buffer_get_meta ()

    GstMeta *
    gst_buffer_get_meta (GstBuffer *buffer,
                         GType api);

Get the metadata for `api` on buffer. When there is no such metadata, NULL is returned.

#### Parameters

buffer | a GstBuffer |
api | the GType of an API |

#### Returns

the metadata for `api` on `buffer` .

[transfer none]

### gst_buffer_add_meta ()

    GstMeta *
    gst_buffer_add_meta (GstBuffer *buffer,
                         const GstMetaInfo *info,
                         gpointer params);

Add metadata for `info` to `buffer` using the parameters in `params` .

#### Parameters

buffer | a GstBuffer |
info | a GstMetaInfo |
params | params for `info` |

#### Returns

the metadata for the api in `info` on `buffer` .

[transfer none]

### gst_buffer_remove_meta ()

    gboolean
    gst_buffer_remove_meta (GstBuffer *buffer,
                            GstMeta *meta);

Remove the metadata for `meta` on `buffer` .

#### Parameters

buffer | a GstBuffer |
meta | a GstMeta |

#### Returns

`TRUE` if the metadata existed and was removed, `FALSE` if no such metadata was on `buffer` .

### gst_buffer_iterate_meta ()

    GstMeta *
    gst_buffer_iterate_meta (GstBuffer *buffer,
                             gpointer *state);

Retrieve the next GstMeta after `current` . If `state` points to `NULL`, the first metadata is returned.

`state` will be updated with an opage state pointer

#### Parameters

buffer | a GstBuffer |
state | an opaque state pointer |

#### Returns

The next GstMeta or `NULL` when there are no more items.

[transfer none]

### GstBufferForeachMetaFunc ()

    gboolean
    (*GstBufferForeachMetaFunc) (GstBuffer *buffer,
                                 GstMeta **meta,
                                 gpointer user_data);

A function that will be called from `gst_buffer_foreach_meta()`. The `meta` field will point to a the reference of the meta.

`buffer` should not be modified from this callback.

When this function returns `TRUE`, the next meta will be returned. When `FALSE` is returned, `gst_buffer_foreach_meta()` will return.

When `meta` is set to NULL, the item will be removed from the buffer.

#### Parameters

buffer | a GstBuffer |
meta | a pointer to a GstMeta |
user_data | user data passed to `gst_buffer_foreach_meta()` |

#### Returns

`FALSE` when `gst_buffer_foreach_meta()` should stop

### gst_buffer_foreach_meta ()

    gboolean
    gst_buffer_foreach_meta (GstBuffer *buffer,
                             GstBufferForeachMetaFunc func,
                             gpointer user_data);

Call `func` with `user_data` for each meta in `buffer` .

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

#### Parameters

buffer | a GstBuffer |
func | a GstBufferForeachMetaFunc to call. | [scope call]
user_data | user data passed to `func` . | [closure]

#### Returns

`FALSE` when `func` returned `FALSE` for one of the metadata.

## Types and Values

### struct GstBuffer

    struct GstBuffer {
      GstMiniObject          mini_object;

      GstBufferPool         *pool;

      /* timestamp */
      GstClockTime           pts;
      GstClockTime           dts;
      GstClockTime           duration;

      /* media specific offset */
      guint64                offset;
      guint64                offset_end;
    };

The structure of a GstBuffer. Use the associated macros to access the public variables.

#### Members

GstMiniObject `mini_object`; | the parent structure |
GstBufferPool *`pool`; | pointer to the pool owner of the buffer |
GstClockTime `pts`; | presentation timestamp of the buffer, can be GST_CLOCK_TIME_NONE when the pts is not known or relevant. The pts contains the timestamp when the media should be presented to the user. |
GstClockTime `dts`; | decoding timestamp of the buffer, can be GST_CLOCK_TIME_NONE when the dts is not known or relevant. The dts contains the timestamp when the media should be processed. |
GstClockTime `duration`; | duration in time of the buffer data, can be GST_CLOCK_TIME_NONE when the duration is not known or relevant. |
guint64 `offset`; | a media specific offset for the buffer data. For video frames, this is the frame number of this buffer. For audio samples, this is the offset of the first sample in this buffer. For file data or compressed data this is the byte offset of the first byte in this buffer. |
guint64 `offset_end`; | the last offset contained in this buffer. It has the same format as `offset` . |

### enum GstBufferFlags

A set of buffer flags used to describe properties of a GstBuffer.

#### Members

GST_BUFFER_FLAG_LIVE | the buffer is live data and should be discarded in the PAUSED state. |
GST_BUFFER_FLAG_DECODE_ONLY | the buffer contains data that should be dropped because it will be clipped against the segment boundaries or because it does not contain data that should be shown to the user. |
GST_BUFFER_FLAG_DISCONT | the buffer marks a data discontinuity in the stream. This typically occurs after a seek or a dropped buffer from a live or network source. |
GST_BUFFER_FLAG_RESYNC | the buffer timestamps might have a discontinuity and this buffer is a good point to resynchronize. |
GST_BUFFER_FLAG_CORRUPTED | the buffer data is corrupted. |
GST_BUFFER_FLAG_MARKER | the buffer contains a media specific marker. for video this is typically the end of a frame boundary, for audio this is usually the start of a talkspurt. |
GST_BUFFER_FLAG_HEADER | the buffer contains header information that is needed to decode the following data. |
GST_BUFFER_FLAG_GAP | the buffer has been created to fill a gap in the stream and contains media neutral data (elements can switch to optimized code path that ignores the buffer content). |
GST_BUFFER_FLAG_DROPPABLE | the buffer can be dropped without breaking the stream, for example to reduce bandwidth. |
GST_BUFFER_FLAG_DELTA_UNIT | this unit cannot be decoded independently. |
GST_BUFFER_FLAG_LAST | additional media specific flags can be added starting from this flag. |

### enum GstBufferCopyFlags

A set of flags that can be provided to the `gst_buffer_copy_into()` function to specify which items should be copied.

#### Members

GST_BUFFER_COPY_NONE | copy nothing |
GST_BUFFER_COPY_FLAGS | flag indicating that buffer flags should be copied |
GST_BUFFER_COPY_TIMESTAMPS | flag indicating that buffer pts, dts, duration, offset and offset_end should be copied |
GST_BUFFER_COPY_META | flag indicating that buffer meta should be copied |
GST_BUFFER_COPY_MEMORY | flag indicating that buffer memory should be reffed and appended to already existing memory. Unless the memory is marked as NO_SHARE, no actual copy of the memory is made but it is simply reffed. Add `GST_BUFFER_COPY_DEEP` to force a real copy. |
GST_BUFFER_COPY_MERGE | flag indicating that buffer memory should be merged |
GST_BUFFER_COPY_DEEP | flag indicating that memory should always be copied instead of reffed (Since 1.2) |

## See Also

GstPad, GstMiniObject, GstMemory, GstMeta, GstBufferPool