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buffer: update docs

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This commit is contained in:
Wim Taymans 2011-11-08 13:13:55 +01:00
parent 47eb1fe52b
commit 79aeef49b8
1 changed files with 12 additions and 21 deletions
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33
gst/gstbuffer.c
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@ -23,7 +23,7 @@
/**
* SECTION:gstbuffer
* @short_description: Data-passing buffer type, supporting sub-buffers.
* @see_also: #GstPad, #GstMiniObject
* @see_also: #GstPad, #GstMiniObject, #GstBufferPool
*
* Buffers are the basic unit of data transfer in GStreamer. The #GstBuffer
* type provides all the state necessary to define the regions of memory as
@ -32,39 +32,30 @@
* ensure that neither memory space goes away prematurely.
*
* Buffers are usually created with gst_buffer_new(). After a buffer has been
* created one will typically allocate memory for it and set the size of the
* buffer data. The following example creates a buffer that can hold a given
* video frame with a given width, height and bits per plane.
* 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>
* <title>Creating a buffer for a video frame</title>
* <programlisting>
* GstBuffer *buffer;
* GstMemory *memory;
* gint size, width, height, bpp;
* ...
* size = width * height * bpp;
* buffer = gst_buffer_new ();
* GST_BUFFER_SIZE (buffer) = size;
* GST_BUFFER_MALLOCDATA (buffer) = g_malloc (size);
* GST_BUFFER_DATA (buffer) = GST_BUFFER_MALLOCDATA (buffer);
* memory = gst_allocator_alloc (NULL, size, 0);
* gst_buffer_take_memory (buffer, -1, memory);
* ...
* </programlisting>
* </example>
*
* Alternatively, use gst_buffer_new_and_alloc()
* Alternatively, use gst_buffer_new_allocate()
* to create a buffer with preallocated data of a given size.
*
* The data pointed to by the buffer can be retrieved with the GST_BUFFER_DATA()
* macro. The size of the data can be found with GST_BUFFER_SIZE(). For buffers
* of size 0, the data pointer is undefined (usually NULL) and should never be used.
*
* If an element knows what pad you will push the buffer out on, it should use
* gst_pad_alloc_buffer() instead to create a buffer. This allows downstream
* elements to provide special buffers to write in, like hardware buffers.
*
* A buffer has a pointer to a #GstCaps describing the media type of the data
* in the buffer. Attach caps to the buffer with gst_buffer_set_caps(); this
* is typically done before pushing out a buffer using gst_pad_push() so that
* the downstream element knows the type of the buffer.
* 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
@ -107,7 +98,7 @@
* the refcount drops to 0, any data pointed to by the buffer is unreffed as
* well.
*
* Last reviewed on March 30, 2011 (0.11.0)
* Last reviewed on November 8, 2011 (0.11.2)
*/
#include "gst_private.h"