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GStreamer 1.0 Core Reference Manual | |
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| Top | Description | ||||
#include <gst/gst.h> struct GstBuffer; enum GstBufferFlags; #define GST_BUFFER_FLAGS (buf) #define GST_BUFFER_FLAG_IS_SET (buf, flag) #define GST_BUFFER_FLAG_SET (buf, flag) #define GST_BUFFER_FLAG_UNSET (buf, flag) #define GST_BUFFER_PTS (buf) #define GST_BUFFER_DTS (buf) #define GST_BUFFER_DURATION (buf) #define GST_BUFFER_OFFSET (buf) #define GST_BUFFER_OFFSET_END (buf) #define GST_BUFFER_OFFSET_NONE #define GST_BUFFER_DURATION_IS_VALID (buffer) #define GST_BUFFER_PTS_IS_VALID (buffer) #define GST_BUFFER_DTS_IS_VALID (buffer) #define GST_BUFFER_OFFSET_IS_VALID (buffer) #define GST_BUFFER_OFFSET_END_IS_VALID (buffer) #define GST_BUFFER_IS_DISCONT (buffer) GstBuffer * gst_buffer_new (void); GstBuffer * gst_buffer_new_allocate (GstAllocator *allocator,gsize size,GstAllocationParams *params); GstBuffer * gst_buffer_new_wrapped (gpointer data,gsize size); GstBuffer * gst_buffer_new_wrapped_full (GstMemoryFlags flags,gpointer data,gsize maxsize,gsize offset,gsize size,gpointer user_data,GDestroyNotify notify); GstBuffer * gst_buffer_ref (GstBuffer *buf); void gst_buffer_unref (GstBuffer *buf); gsize gst_buffer_get_sizes (GstBuffer *buffer,gsize *offset,gsize *maxsize); gsize gst_buffer_get_size (GstBuffer *buffer); gsize gst_buffer_get_sizes_range (GstBuffer *buffer,guint idx,gint length,gsize *offset,gsize *maxsize); gboolean gst_buffer_resize_range (GstBuffer *buffer,guint idx,gint length,gssize offset,gssize size); void gst_buffer_resize (GstBuffer *buffer,gssize offset,gssize size); void gst_buffer_set_size (GstBuffer *buffer,gssize size); GstMemory * gst_buffer_peek_memory (GstBuffer *buffer,guint idx); guint gst_buffer_n_memory (GstBuffer *buffer); void gst_buffer_insert_memory (GstBuffer *buffer,gint idx,GstMemory *mem); void gst_buffer_replace_memory_range (GstBuffer *buffer,guint idx,gint length,GstMemory *mem); GstMemory * gst_buffer_get_memory_range (GstBuffer *buffer,guint idx,gint length); void gst_buffer_remove_memory_range (GstBuffer *buffer,guint idx,gint length); gboolean gst_buffer_find_memory (GstBuffer *buffer,gsize offset,gsize size,guint *idx,guint *length,gsize *skip); void gst_buffer_prepend_memory (GstBuffer *buffer,GstMemory *mem); void gst_buffer_append_memory (GstBuffer *buffer,GstMemory *mem); void gst_buffer_replace_memory (GstBuffer *buffer,guint idx,GstMemory *mem); void gst_buffer_replace_all_memory (GstBuffer *buffer,GstMemory *mem); GstMemory * gst_buffer_get_memory (GstBuffer *buffer,guint idx); GstMemory * gst_buffer_get_all_memory (GstBuffer *buffer); void gst_buffer_remove_memory (GstBuffer *buffer,guint idx); void gst_buffer_remove_all_memory (GstBuffer *buffer); gboolean gst_buffer_map (GstBuffer *buffer,GstMapInfo *info,GstMapFlags flags); gboolean gst_buffer_map_range (GstBuffer *buffer,guint idx,gint length,GstMapInfo *info,GstMapFlags flags); void gst_buffer_unmap (GstBuffer *buffer,GstMapInfo *info); gint gst_buffer_memcmp (GstBuffer *buffer,gsize offset,gconstpointer mem,gsize size); gsize gst_buffer_extract (GstBuffer *buffer,gsize offset,gpointer dest,gsize size); void gst_buffer_extract_dup (GstBuffer *buffer,gsize offset,gsize size,gpointer *dest,gsize *dest_size); gsize gst_buffer_fill (GstBuffer *buffer,gsize offset,gconstpointer src,gsize size); gsize gst_buffer_memset (GstBuffer *buffer,gsize offset,guint8 val,gsize size); enum GstBufferCopyFlags; #define GST_BUFFER_COPY_METADATA #define GST_BUFFER_COPY_ALL GstBuffer * gst_buffer_copy (const GstBuffer *buf); gboolean gst_buffer_copy_into (GstBuffer *dest,GstBuffer *src,GstBufferCopyFlags flags,gsize offset,gsize size); GstBuffer * gst_buffer_copy_region (GstBuffer *parent,GstBufferCopyFlags flags,gsize offset,gsize size); #define gst_buffer_is_writable (buf) #define gst_buffer_make_writable (buf) gboolean gst_buffer_replace (GstBuffer **obuf,GstBuffer *nbuf); GstBuffer * gst_buffer_append (GstBuffer *buf1,GstBuffer *buf2); GstBuffer * gst_buffer_append_region (GstBuffer *buf1,GstBuffer *buf2,gssize offset,gssize size); GstMeta * gst_buffer_get_meta (GstBuffer *buffer,GType api); GstMeta * gst_buffer_add_meta (GstBuffer *buffer,const GstMetaInfo *info,gpointer params); gboolean gst_buffer_remove_meta (GstBuffer *buffer,GstMeta *meta); GstMeta * gst_buffer_iterate_meta (GstBuffer *buffer,gpointer *state); gboolean (*GstBufferForeachMetaFunc) (GstBuffer *buffer,GstMeta **meta,gpointer user_data); gboolean gst_buffer_foreach_meta (GstBuffer *buffer,GstBufferForeachMetaFunc func,gpointer user_data);
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
1 2 3 4 5 6 7 8 9 |
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)
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.
GstMiniObject |
the parent structure |
GstBufferPool * |
pointer to the pool owner of the buffer |
GstClockTime |
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 |
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 in time of the buffer data, can be GST_CLOCK_TIME_NONE when the duration is not known or relevant. |
| 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. | |
the last offset contained in this buffer. It has the same
format as offset. |
typedef enum {
GST_BUFFER_FLAG_LIVE = (GST_MINI_OBJECT_FLAG_LAST << 0),
GST_BUFFER_FLAG_DECODE_ONLY = (GST_MINI_OBJECT_FLAG_LAST << 1),
GST_BUFFER_FLAG_DISCONT = (GST_MINI_OBJECT_FLAG_LAST << 2),
GST_BUFFER_FLAG_RESYNC = (GST_MINI_OBJECT_FLAG_LAST << 3),
GST_BUFFER_FLAG_CORRUPTED = (GST_MINI_OBJECT_FLAG_LAST << 4),
GST_BUFFER_FLAG_MARKER = (GST_MINI_OBJECT_FLAG_LAST << 5),
GST_BUFFER_FLAG_HEADER = (GST_MINI_OBJECT_FLAG_LAST << 6),
GST_BUFFER_FLAG_GAP = (GST_MINI_OBJECT_FLAG_LAST << 7),
GST_BUFFER_FLAG_DROPPABLE = (GST_MINI_OBJECT_FLAG_LAST << 8),
GST_BUFFER_FLAG_DELTA_UNIT = (GST_MINI_OBJECT_FLAG_LAST << 9),
GST_BUFFER_FLAG_LAST = (GST_MINI_OBJECT_FLAG_LAST << 16)
} GstBufferFlags;
A set of buffer flags used to describe properties of a GstBuffer.
| the buffer is live data and should be discarded in the PAUSED state. | |
| 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. | |
| 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. | |
| the buffer timestamps might have a discontinuity and this buffer is a good point to resynchronize. | |
| the buffer data is corrupted. | |
| 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. | |
| the buffer contains header information that is needed to decode the following data. | |
| 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). | |
| the buffer can be dropped without breaking the stream, for example to reduce bandwidth. | |
| this unit cannot be decoded independently. | |
| additional media specific flags can be added starting from this flag. |
#define GST_BUFFER_FLAGS(buf) GST_MINI_OBJECT_FLAGS(buf)
A flags word containing GstBufferFlag flags set on this buffer.
|
a GstBuffer. |
#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.
|
a GstBuffer. |
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the GstBufferFlag to check. |
#define GST_BUFFER_FLAG_SET(buf,flag) GST_MINI_OBJECT_FLAG_SET (buf, flag)
Sets a buffer flag on a buffer.
|
a GstBuffer. |
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the GstBufferFlag to set. |
#define GST_BUFFER_FLAG_UNSET(buf,flag) GST_MINI_OBJECT_FLAG_UNSET (buf, flag)
Clears a buffer flag.
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a GstBuffer. |
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the GstBufferFlag to clear. |
#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.
|
a GstBuffer.: |
#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.
|
a GstBuffer.: |
#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.
|
a GstBuffer. |
#define GST_BUFFER_OFFSET(buf) (GST_BUFFER_CAST(buf)->offset)
The offset in the source file of the beginning of this buffer.
|
a GstBuffer. |
#define GST_BUFFER_OFFSET_END(buf) (GST_BUFFER_CAST(buf)->offset_end)
The offset in the source file of the end of this buffer.
|
a GstBuffer. |
#define GST_BUFFER_OFFSET_NONE ((guint64)-1)
Constant for no-offset return results.
#define GST_BUFFER_DURATION_IS_VALID(buffer) (GST_CLOCK_TIME_IS_VALID (GST_BUFFER_DURATION (buffer)))
Tests if the duration is known.
|
a GstBuffer |
#define GST_BUFFER_PTS_IS_VALID(buffer) (GST_CLOCK_TIME_IS_VALID (GST_BUFFER_PTS (buffer)))
Tests if the pts is known.
|
a GstBuffer |
#define GST_BUFFER_DTS_IS_VALID(buffer) (GST_CLOCK_TIME_IS_VALID (GST_BUFFER_DTS (buffer)))
Tests if the dts is known.
|
a GstBuffer |
#define GST_BUFFER_OFFSET_IS_VALID(buffer) (GST_BUFFER_OFFSET (buffer) != GST_BUFFER_OFFSET_NONE)
Tests if the start offset is known.
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a GstBuffer |
#define GST_BUFFER_OFFSET_END_IS_VALID(buffer) (GST_BUFFER_OFFSET_END (buffer) != GST_BUFFER_OFFSET_NONE)
Tests if the end offset is known.
|
a GstBuffer |
#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.
|
a GstBuffer |
GstBuffer * gst_buffer_new (void);
Creates a newly allocated buffer without any data.
MT safe.
Returns : |
the new GstBuffer. [transfer full] |
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.
|
the GstAllocator to use, or NULL to use the default allocator. [transfer none][allow-none] |
|
the size in bytes of the new buffer's data. |
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optional parameters. [transfer none][allow-none] |
Returns : |
a new GstBuffer, or NULL if the memory couldn't be allocated. [transfer full] |
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.
|
data to wrap. [array length=size][element-type guint8][transfer full] |
|
allocated size of data
|
Returns : |
a new GstBuffer. [transfer 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.
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GstMemoryFlags |
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data to wrap. [array length=size][element-type guint8][transfer none] |
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allocated size of data
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offset in data
|
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size of valid data |
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user_data. [allow-none] |
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called with user_data when the memory is freed. [allow-none][scope async][closure user_data]
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Returns : |
a new GstBuffer. [transfer full] |
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.
|
a GstBuffer. |
Returns : |
buf. [transfer full]
|
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.
|
a GstBuffer. [transfer full] |
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().
|
a GstBuffer. |
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a pointer to the offset. [out] |
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a pointer to the maxsize. [out] |
Returns : |
total size of the memory blocks in buffer. |
gsize gst_buffer_get_size (GstBuffer *buffer);
Get the total size of the memory blocks in buffer.
|
a GstBuffer. |
Returns : |
total size of the memory blocks in buffer. |
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().
|
a GstBuffer. |
|
an index |
|
a length |
|
a pointer to the offset. [out] |
|
a pointer to the maxsize. [out] |
Returns : |
total size of length memory blocks starting at idx in buffer. |
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
void gst_buffer_resize (GstBuffer *buffer,gssize offset,gssize size);
Set the offset and total size of the memory blocks in buffer.
|
a GstBuffer. |
|
the offset adjustement |
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the new size or -1 to just adjust the offset |
void gst_buffer_set_size (GstBuffer *buffer,gssize size);
Set the total size of the memory blocks in buffer.
|
a GstBuffer. |
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the new size |
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.
Since this call does not influence the refcount of the memory,
gst_memory_is_writable() can be used to check if buffer is the sole owner
of the returned 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.
|
a GstBuffer. |
Returns : |
the amount of memory block in this buffer. [transfer full] |
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.
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.
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.
|
a GstBuffer. |
|
an index |
|
a length |
Returns : |
a GstMemory that contains the merged data of length
blocks starting at idx. Use gst_memory_unref() after usage. [transfer full]
|
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.
|
a GstBuffer. |
|
an index |
|
a length |
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.
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.
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.
void gst_buffer_replace_memory (GstBuffer *buffer,guint idx,GstMemory *mem);
Replaces the memory block at index idx in buffer with mem.
void gst_buffer_replace_all_memory (GstBuffer *buffer,GstMemory *mem);
Replaces all memory in buffer with mem.
GstMemory * gst_buffer_get_memory (GstBuffer *buffer,guint idx);
Get the memory block at index idx in buffer.
|
a GstBuffer. |
|
an index |
Returns : |
a GstMemory that contains the data of the
memory block at idx. Use gst_memory_unref() after usage. [transfer full]
|
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.
|
a GstBuffer. |
Returns : |
a GstMemory that contains the merged memory.
Use gst_memory_unref() after usage. [transfer full]
|
void gst_buffer_remove_memory (GstBuffer *buffer,guint idx);
Remove the memory block in b at index i.
|
a GstBuffer. |
|
an index |
void gst_buffer_remove_all_memory (GstBuffer *buffer);
Remove all the memory blocks in buffer.
|
a GstBuffer. |
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.
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.
void gst_buffer_unmap (GstBuffer *buffer,GstMapInfo *info);
Release the memory previously mapped with gst_buffer_map().
|
a GstBuffer. |
|
a GstMapInfo |
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.
|
a GstBuffer. |
|
the offset in buffer
|
|
the memory to compare. [array length=size][element-type guint8] |
|
the size to compare |
Returns : |
0 if the memory is equal. |
gsize gst_buffer_extract (GstBuffer *buffer,gsize offset,gpointer dest,gsize size);
Copy size bytes starting from offset in buffer to dest.
|
a GstBuffer. |
|
the offset to extract |
|
the destination address |
|
the size to extract |
Returns : |
The amount of bytes extracted. This value can be lower than size
when buffer did not contain enough data. |
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.
|
a GstBuffer |
|
the offset to extract |
|
the size to extract |
|
A pointer where the destination array will be written. [array length=dest_size][element-type guint8][out] |
|
A location where the size of dest can be written. [out]
|
Since 1.2
gsize gst_buffer_fill (GstBuffer *buffer,gsize offset,gconstpointer src,gsize size);
Copy size bytes from src to buffer at offset.
|
a GstBuffer. |
|
the offset to fill |
|
the source address. [array length=size][element-type guint8] |
|
the size to fill |
Returns : |
The amount of bytes copied. This value can be lower than size
when buffer did not contain enough data. |
gsize gst_buffer_memset (GstBuffer *buffer,gsize offset,guint8 val,gsize size);
Fill buf with size bytes with val starting from offset.
|
a GstBuffer. |
|
the offset in buffer
|
|
the value to set |
|
the size to set |
Returns : |
The amount of bytes filled. This value can be lower than size
when buffer did not contain enough data. |
typedef enum {
GST_BUFFER_COPY_NONE = 0,
GST_BUFFER_COPY_FLAGS = (1 << 0),
GST_BUFFER_COPY_TIMESTAMPS = (1 << 1),
GST_BUFFER_COPY_META = (1 << 2),
GST_BUFFER_COPY_MEMORY = (1 << 3),
GST_BUFFER_COPY_MERGE = (1 << 4),
GST_BUFFER_COPY_DEEP = (1 << 5)
} GstBufferCopyFlags;
A set of flags that can be provided to the gst_buffer_copy_into()
function to specify which items should be copied.
| copy nothing | |
| flag indicating that buffer flags should be copied | |
| flag indicating that buffer pts, dts, duration, offset and offset_end should be copied | |
| flag indicating that buffer meta should be copied | |
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.
|
|
| flag indicating that buffer memory should be merged | |
| flag indicating that memory should always be copied instead of reffed (Since 1.2) |
#define GST_BUFFER_COPY_METADATA
Combination of all possible metadata fields that can be copied with
gst_buffer_copy_into().
#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().
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.
|
a GstBuffer. |
Returns : |
a new copy of buf. [transfer full]
|
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.
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.
|
a GstBuffer. |
|
the GstBufferCopyFlags |
|
the offset into parent GstBuffer at which the new sub-buffer begins. |
|
the size of the new GstBuffer sub-buffer, in bytes. |
Returns : |
the new GstBuffer or NULL if the arguments were invalid. [transfer full] |
#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.
|
a GstBuffer |
#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().
|
a GstBuffer. [transfer full] |
Returns : |
a writable buffer which may or may not be the
same as buf. [transfer full]
|
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.
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.
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.
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.
GstMeta * gst_buffer_add_meta (GstBuffer *buffer,const GstMetaInfo *info,gpointer params);
Add metadata for info to buffer using the parameters in params.
|
a GstBuffer |
|
a GstMetaInfo |
|
params for info
|
Returns : |
the metadata for the api in info on buffer. [transfer none]
|
gboolean gst_buffer_remove_meta (GstBuffer *buffer,GstMeta *meta);
Remove the metadata for meta on buffer.
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
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.
|
a GstBuffer |
|
a pointer to a GstMeta |
|
user data passed to gst_buffer_foreach_meta()
|
Returns : |
FALSE when gst_buffer_foreach_meta() should stop |
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.
|
a GstBuffer |
|
a GstBufferForeachMetaFunc to call. [scope call] |
|
user data passed to func. [closure]
|
Returns : |
FALSE when func returned FALSE for one of the metadata. |