gstreamer/subprojects/gst-plugins-base/gst-libs/gst/gl/gstglbasememory.c
Sebastian Dröge a10b35c011 gl: Mark GL memory GType functions as deprecated
They can't be used in any useful way. The type of every GstMemory is
always GST_TYPE_MEMORY and the subtyping relationship has to be
implemented on top of that via the associated allocator and mem_type
string.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/1764>
2022-02-21 21:26:43 +00:00

772 lines
21 KiB
C

/*
* GStreamer
* Copyright (C) 2015 Matthew Waters <matthew@centricular.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <string.h>
#include "gstglbasememory.h"
#include "gstglcontext.h"
#include "gstglcontext_private.h"
#include "gstglquery.h"
/**
* SECTION:gstglbasememory
* @title: GstGLBaseMemory
* @short_description: memory subclass for GL buffers
* @see_also: #GstMemory, #GstAllocator
*
* GstGLBaseMemory is a #GstMemory subclass providing the basis of support
* for the mapping of GL buffers.
*
* Data is uploaded or downloaded from the GPU as is necessary.
*/
#define USING_OPENGL(context) (gst_gl_context_check_gl_version (context, GST_GL_API_OPENGL, 1, 0))
#define USING_OPENGL3(context) (gst_gl_context_check_gl_version (context, GST_GL_API_OPENGL3, 3, 1))
#define USING_GLES(context) (gst_gl_context_check_gl_version (context, GST_GL_API_GLES, 1, 0))
#define USING_GLES2(context) (gst_gl_context_check_gl_version (context, GST_GL_API_GLES2, 2, 0))
#define USING_GLES3(context) (gst_gl_context_check_gl_version (context, GST_GL_API_GLES2, 3, 0))
GST_DEBUG_CATEGORY_STATIC (GST_CAT_GL_BASE_MEMORY);
#define GST_CAT_DEFUALT GST_CAT_GL_BASE_MEMORY
#ifndef GST_REMOVE_DEPRECATED
GST_DEFINE_MINI_OBJECT_TYPE (GstGLBaseMemory, gst_gl_base_memory);
#endif
/**
* gst_gl_base_memory_error_quark:
*
* Returns: the quark used for #GstGLBaseMemory in #GError's
*/
GQuark
gst_gl_base_memory_error_quark (void)
{
return g_quark_from_static_string ("gst-gl-base-memory-error-quark");
}
static gboolean
_default_create (GstGLBaseMemory * mem, GError ** error)
{
g_set_error (error, GST_GL_BASE_MEMORY_ERROR, GST_GL_BASE_MEMORY_ERROR_FAILED,
"subclass should define create() vfunc");
g_critical ("subclass should override "
"GstGLBaseMemoryAllocatorClass::create() function");
return FALSE;
}
struct create_data
{
GstGLBaseMemory *mem;
gboolean result;
};
static void
_mem_create_gl (GstGLContext * context, struct create_data *transfer)
{
GstGLBaseMemoryAllocatorClass *alloc_class;
GError *error = NULL;
GST_CAT_TRACE (GST_CAT_GL_BASE_MEMORY, "Create memory %p", transfer->mem);
alloc_class =
GST_GL_BASE_MEMORY_ALLOCATOR_GET_CLASS (transfer->mem->mem.allocator);
g_return_if_fail (alloc_class->create != NULL);
/* Don't do expensive queries when debugging is disabled */
transfer->mem->query = NULL;
if (_gst_gl_context_debug_is_enabled (context))
transfer->mem->query =
gst_gl_query_new (context, GST_GL_QUERY_TIME_ELAPSED);
if ((transfer->result = alloc_class->create (transfer->mem, &error)))
return;
g_assert (error != NULL);
GST_CAT_ERROR (GST_CAT_GL_BASE_MEMORY, "Failed to create GL buffer: %s",
error->message);
g_clear_error (&error);
}
/**
* gst_gl_base_memory_init:
* @mem: the #GstGLBaseMemory to initialize
* @allocator: the #GstAllocator to initialize with
* @parent: (allow-none): the parent #GstMemory to initialize with
* @context: the #GstGLContext to initialize with
* @params: (allow-none): the @GstAllocationParams to initialize with
* @size: the number of bytes to be allocated
* @user_data: (allow-none): user data to call @notify with
* @notify: (allow-none): a #GDestroyNotify
*
* Initializes @mem with the required parameters
*
* Since: 1.8
*/
void
gst_gl_base_memory_init (GstGLBaseMemory * mem, GstAllocator * allocator,
GstMemory * parent, GstGLContext * context,
const GstAllocationParams * params, gsize size, gpointer user_data,
GDestroyNotify notify)
{
gsize align = gst_memory_alignment, offset = 0, maxsize;
GstMemoryFlags flags = 0;
struct create_data data;
/* A note on sizes.
* gl_mem->alloc_size: the size to allocate when we control the allocation.
* Size of the unaligned allocation.
* mem->maxsize: the size that is used by GstMemory for mapping, to map the
* entire memory. The size of the aligned allocation
* mem->size: represents the size of the valid data. Can be reduced with
* gst_memory_resize()
*
* It holds that:
* mem->size + mem->offset <= mem->maxsize
* and
* mem->maxsize + alignment offset <= gl_mem->alloc_size
*
* We need to add the alignment mask to the allocated size in order to have
* the freedom to align the gl_mem->data pointer correctly which may be offset
* by at most align bytes in the alloc_data pointer.
*
* maxsize is not suitable for this as it is used by GstMemory as the size
* to map with.
*/
mem->alloc_size = maxsize = size;
if (params) {
flags = params->flags;
align |= params->align;
offset = params->prefix;
maxsize += params->prefix + params->padding;
/* deals with any alignment */
mem->alloc_size = maxsize + align;
}
gst_memory_init (GST_MEMORY_CAST (mem), flags, allocator, parent, maxsize,
align, offset, size);
mem->context = gst_object_ref (context);
mem->notify = notify;
mem->user_data = user_data;
g_mutex_init (&mem->lock);
data.mem = mem;
gst_gl_context_thread_add (context,
(GstGLContextThreadFunc) _mem_create_gl, &data);
if (!data.result) {
GST_CAT_ERROR (GST_CAT_GL_BASE_MEMORY,
"Could not create GL buffer with context:%p", context);
}
GST_CAT_DEBUG (GST_CAT_GL_BASE_MEMORY, "new GL buffer memory:%p size:%"
G_GSIZE_FORMAT, mem, maxsize);
}
static gpointer
_align_data (gpointer data, gsize align)
{
guint8 *ret = data;
gsize aoffset;
/* do alignment, data must have enough padding at the end to move at most
* align bytes */
if ((aoffset = ((guintptr) ret & align))) {
aoffset = (align + 1) - aoffset;
ret += aoffset;
}
return ret;
}
/* subclass usage only */
/**
* gst_gl_base_memory_alloc_data:
* @gl_mem: a #GstGLBaseMemory
*
* Note: only intended for subclass usage to allocate the system memory buffer
* on demand. If there is already a non-NULL data pointer in @gl_mem->data,
* then this function imply returns TRUE.
*
* Returns: whether the system memory could be allocated
*/
gboolean
gst_gl_base_memory_alloc_data (GstGLBaseMemory * gl_mem)
{
GstMemory *mem = (GstMemory *) gl_mem;
if (gl_mem->data)
return TRUE;
GST_CAT_LOG (GST_CAT_GL_BASE_MEMORY, "%p attempting allocation of data "
"pointer of size %" G_GSIZE_FORMAT, gl_mem, gl_mem->alloc_size);
gl_mem->alloc_data = g_try_malloc (gl_mem->alloc_size);
if (gl_mem->alloc_data == NULL)
return FALSE;
gl_mem->data = _align_data (gl_mem->alloc_data, mem->align);
GST_CAT_DEBUG (GST_CAT_GL_BASE_MEMORY, "%p allocated data pointer alloc %p, "
"data %p", gl_mem, gl_mem->alloc_data, gl_mem->data);
return TRUE;
}
struct map_data
{
GstGLBaseMemory *mem;
GstMapInfo *info;
gsize size;
gpointer data;
};
static void
_map_data_gl (GstGLContext * context, struct map_data *transfer)
{
GstGLBaseMemoryAllocatorClass *alloc_class;
GstGLBaseMemory *mem = transfer->mem;
GstMapInfo *info = transfer->info;
guint prev_map_flags;
guint prev_gl_map_count;
alloc_class =
GST_GL_BASE_MEMORY_ALLOCATOR_GET_CLASS (transfer->mem->mem.allocator);
g_return_if_fail (alloc_class->map != NULL);
g_mutex_lock (&mem->lock);
prev_map_flags = mem->map_flags;
prev_gl_map_count = mem->gl_map_count;
GST_CAT_LOG (GST_CAT_GL_BASE_MEMORY, "mapping mem %p flags %04x", mem,
info->flags);
/* FIXME: validate map flags based on the memory domain */
if (mem->map_count++ == 0)
mem->map_flags = info->flags;
else {
/* assert that the flags are a subset of the first map flags */
g_assert ((((GST_MAP_GL - 1) & info->flags) & mem->map_flags) != 0);
GST_CAT_LOG (GST_CAT_GL_BASE_MEMORY, "multiple map no %d flags %04x "
"all flags %04x", mem->map_count, info->flags, mem->map_flags);
}
if ((info->flags & GST_MAP_GL) != (mem->map_flags & GST_MAP_GL))
mem->map_flags |= GST_MAP_GL;
if (info->flags & GST_MAP_GL)
mem->gl_map_count++;
transfer->data = alloc_class->map (transfer->mem, transfer->info,
transfer->size);
if (transfer->data) {
if (info->flags & GST_MAP_GL) {
if (info->flags & GST_MAP_WRITE)
GST_MINI_OBJECT_FLAG_SET (mem,
GST_GL_BASE_MEMORY_TRANSFER_NEED_DOWNLOAD);
GST_MEMORY_FLAG_UNSET (mem, GST_GL_BASE_MEMORY_TRANSFER_NEED_UPLOAD);
} else {
if (info->flags & GST_MAP_WRITE)
GST_MINI_OBJECT_FLAG_SET (mem, GST_GL_BASE_MEMORY_TRANSFER_NEED_UPLOAD);
GST_MEMORY_FLAG_UNSET (mem, GST_GL_BASE_MEMORY_TRANSFER_NEED_DOWNLOAD);
}
} else {
/* undo state tracking on error */
mem->map_flags = prev_map_flags;
mem->gl_map_count = prev_gl_map_count;
mem->map_count--;
}
g_mutex_unlock (&mem->lock);
}
static gpointer
_mem_map_full (GstGLBaseMemory * mem, GstMapInfo * info, gsize size)
{
struct map_data transfer;
transfer.mem = mem;
transfer.info = info;
transfer.size = size;
transfer.data = NULL;
gst_gl_context_thread_add (mem->context,
(GstGLContextThreadFunc) _map_data_gl, &transfer);
return transfer.data;
}
struct unmap_data
{
GstGLBaseMemory *mem;
GstMapInfo *info;
};
static void
_unmap_data_gl (GstGLContext * context, struct unmap_data *transfer)
{
GstGLBaseMemoryAllocatorClass *alloc_class;
GstGLBaseMemory *mem = transfer->mem;
GstMapInfo *info = transfer->info;
alloc_class =
GST_GL_BASE_MEMORY_ALLOCATOR_GET_CLASS (transfer->mem->mem.allocator);
g_return_if_fail (alloc_class->unmap != NULL);
g_mutex_lock (&mem->lock);
GST_CAT_LOG (GST_CAT_GL_BASE_MEMORY, "unmapping mem %p flags %04x", mem,
info->flags);
alloc_class->unmap (transfer->mem, transfer->info);
if (info->flags & GST_MAP_GL && --mem->gl_map_count)
/* unset the gl flag */
mem->map_flags &= ~GST_MAP_GL;
if (--mem->map_count <= 0) {
mem->map_flags = 0;
}
if (info->flags & GST_MAP_GL) {
if (info->flags & GST_MAP_WRITE)
GST_MINI_OBJECT_FLAG_SET (mem, GST_GL_BASE_MEMORY_TRANSFER_NEED_DOWNLOAD);
} else {
if (info->flags & GST_MAP_WRITE)
GST_MINI_OBJECT_FLAG_SET (mem, GST_GL_BASE_MEMORY_TRANSFER_NEED_UPLOAD);
}
g_mutex_unlock (&mem->lock);
}
static void
_mem_unmap_full (GstGLBaseMemory * mem, GstMapInfo * info)
{
struct unmap_data transfer;
transfer.mem = mem;
transfer.info = info;
gst_gl_context_thread_add (mem->context,
(GstGLContextThreadFunc) _unmap_data_gl, &transfer);
}
static GstGLBaseMemory *
_default_copy (GstGLBaseMemory * src, gssize offset, gssize size)
{
return NULL;
}
struct copy_params
{
GstGLBaseMemory *src;
GstGLBaseMemory *dest;
gssize offset;
gssize size;
gboolean result;
};
static void
_mem_copy_gl (GstGLContext * context, struct copy_params *transfer)
{
GstGLBaseMemoryAllocatorClass *alloc_class;
alloc_class =
GST_GL_BASE_MEMORY_ALLOCATOR_GET_CLASS (transfer->src->mem.allocator);
g_return_if_fail (alloc_class->copy != NULL);
transfer->dest =
alloc_class->copy (transfer->src, transfer->offset, transfer->size);
}
static GstMemory *
_mem_copy (GstGLBaseMemory * src, gssize offset, gssize size)
{
struct copy_params transfer;
transfer.dest = NULL;
transfer.src = src;
transfer.offset = offset;
transfer.size = size;
if (size == -1 || size > 0)
gst_gl_context_thread_add (src->context,
(GstGLContextThreadFunc) _mem_copy_gl, &transfer);
return (GstMemory *) transfer.dest;
}
static GstMemory *
_mem_share (GstGLBaseMemory * mem, gssize offset, gssize size)
{
return NULL;
}
static gboolean
_mem_is_span (GstGLBaseMemory * mem1, GstGLBaseMemory * mem2, gsize * offset)
{
return FALSE;
}
static GstMemory *
_mem_alloc (GstAllocator * allocator, gsize size, GstAllocationParams * params)
{
g_critical ("Subclass should override GstAllocatorClass::alloc() function");
return NULL;
}
static void
_default_destroy (GstGLBaseMemory * mem)
{
}
static void
_destroy_gl_objects (GstGLContext * context, GstGLBaseMemory * mem)
{
GstGLBaseMemoryAllocatorClass *alloc_class;
alloc_class = GST_GL_BASE_MEMORY_ALLOCATOR_GET_CLASS (mem->mem.allocator);
g_return_if_fail (alloc_class->destroy != NULL);
alloc_class->destroy (mem);
if (mem->query)
gst_gl_query_free (mem->query);
}
static void
_mem_free (GstAllocator * allocator, GstMemory * memory)
{
GstGLBaseMemory *mem = (GstGLBaseMemory *) memory;
GST_CAT_TRACE (GST_CAT_GL_BASE_MEMORY, "freeing buffer memory:%p", mem);
gst_gl_context_thread_add (mem->context,
(GstGLContextThreadFunc) _destroy_gl_objects, mem);
g_mutex_clear (&mem->lock);
if (mem->alloc_data) {
g_free (mem->alloc_data);
mem->alloc_data = NULL;
}
mem->data = NULL;
if (mem->notify)
mem->notify (mem->user_data);
gst_object_unref (mem->context);
g_free (memory);
}
/**
* gst_gl_base_memory_init_once:
*
* Initializes the GL Base Memory allocator. It is safe to call this function
* multiple times. This must be called before any other GstGLBaseMemory operation.
*
* Since: 1.8
*/
void
gst_gl_base_memory_init_once (void)
{
static gsize _init = 0;
if (g_once_init_enter (&_init)) {
GST_DEBUG_CATEGORY_INIT (GST_CAT_GL_BASE_MEMORY, "glbasememory", 0,
"OpenGL BaseMemory");
g_once_init_leave (&_init, 1);
}
}
G_DEFINE_ABSTRACT_TYPE (GstGLBaseMemoryAllocator, gst_gl_base_memory_allocator,
GST_TYPE_ALLOCATOR);
static void
gst_gl_base_memory_allocator_class_init (GstGLBaseMemoryAllocatorClass * klass)
{
GstAllocatorClass *allocator_class = (GstAllocatorClass *) klass;
allocator_class->alloc = _mem_alloc;
allocator_class->free = _mem_free;
klass->create = _default_create;
klass->copy = _default_copy;
klass->destroy = _default_destroy;
}
static void
gst_gl_base_memory_allocator_init (GstGLBaseMemoryAllocator * allocator)
{
GstAllocator *alloc = GST_ALLOCATOR_CAST (allocator);
/* Keep the fallback copy function around, we will need it when copying with
* at an offset or smaller size */
allocator->fallback_mem_copy = alloc->mem_copy;
alloc->mem_map_full = (GstMemoryMapFullFunction) _mem_map_full;
alloc->mem_unmap_full = (GstMemoryUnmapFullFunction) _mem_unmap_full;
alloc->mem_copy = (GstMemoryCopyFunction) _mem_copy;
alloc->mem_share = (GstMemoryShareFunction) _mem_share;
alloc->mem_is_span = (GstMemoryIsSpanFunction) _mem_is_span;
}
/**
* gst_is_gl_base_memory:
* @mem:a #GstMemory
*
* Returns: whether the memory at @mem is a #GstGLBaseMemory
*
* Since: 1.8
*/
gboolean
gst_is_gl_base_memory (GstMemory * mem)
{
return mem != NULL && mem->allocator != NULL &&
g_type_is_a (G_OBJECT_TYPE (mem->allocator),
GST_TYPE_GL_BASE_MEMORY_ALLOCATOR);
}
/**
* gst_gl_base_memory_memcpy:
* @src: the source #GstGLBaseMemory
* @dest: the destination #GstGLBaseMemory
* @offset: the offset to start at
* @size: the number of bytes to copy
*
* Returns: whether the copy succeeded.
*
* Since: 1.8
*/
gboolean
gst_gl_base_memory_memcpy (GstGLBaseMemory * src, GstGLBaseMemory * dest,
gssize offset, gssize size)
{
GstMapInfo sinfo, dinfo;
if (!gst_gl_base_memory_alloc_data (GST_GL_BASE_MEMORY_CAST (dest)))
return FALSE;
if (!gst_memory_map ((GstMemory *) src, &sinfo, GST_MAP_READ)) {
GST_CAT_WARNING (GST_CAT_GL_BASE_MEMORY,
"could not read map source memory %p", src);
return FALSE;
}
if (!gst_memory_map ((GstMemory *) dest, &dinfo, GST_MAP_WRITE)) {
GST_CAT_WARNING (GST_CAT_GL_BASE_MEMORY,
"could not write map dest memory %p", dest);
gst_memory_unmap ((GstMemory *) src, &sinfo);
return FALSE;
}
if (size == -1)
size = sinfo.size > offset ? sinfo.size - offset : 0;
GST_CAT_DEBUG (GST_CAT_GL_BASE_MEMORY,
"memcpy %" G_GSSIZE_FORMAT " memory %p -> %p", size, src, dest);
memcpy (dinfo.data, sinfo.data + offset, size);
gst_memory_unmap ((GstMemory *) dest, &dinfo);
gst_memory_unmap ((GstMemory *) src, &sinfo);
return TRUE;
}
/**
* gst_gl_allocation_params_init: (skip)
* @params: the #GstGLAllocationParams to initialize
* @struct_size: the struct size of the implementation
* @alloc_flags: some alloc flags
* @copy: a copy function
* @free: a free function
* @context: (transfer none): a #GstGLContext
* @alloc_size: the number of bytes to allocate.
* @alloc_params: (transfer none) (allow-none): a #GstAllocationParams to apply
* @wrapped_data: (transfer none) (allow-none): a sysmem data pointer to initialize the allocation with
* @gl_handle: (transfer none): a GL handle to initialize the allocation with
* @user_data: (transfer none) (allow-none): user data to call @notify with
* @notify: (allow-none): a #GDestroyNotify
*
* @notify will be called once for each allocated memory using these @params
* when freeing the memory.
*
* Returns: whether the parameters could be initialized
*
* Since: 1.8
*/
gboolean
gst_gl_allocation_params_init (GstGLAllocationParams * params,
gsize struct_size, guint alloc_flags, GstGLAllocationParamsCopyFunc copy,
GstGLAllocationParamsFreeFunc free, GstGLContext * context,
gsize alloc_size, const GstAllocationParams * alloc_params,
gpointer wrapped_data, gpointer gl_handle, gpointer user_data,
GDestroyNotify notify)
{
memset (params, 0, sizeof (*params));
g_return_val_if_fail (struct_size > 0, FALSE);
g_return_val_if_fail (copy != NULL, FALSE);
g_return_val_if_fail (free != NULL, FALSE);
g_return_val_if_fail (GST_IS_GL_CONTEXT (context), FALSE);
params->struct_size = struct_size;
params->alloc_size = alloc_size;
params->copy = copy;
params->free = free;
params->alloc_flags = alloc_flags;
params->context = gst_object_ref (context);
if (alloc_params)
params->alloc_params = gst_allocation_params_copy (alloc_params);
params->notify = notify;
params->user_data = user_data;
params->wrapped_data = wrapped_data;
params->gl_handle = gl_handle;
return TRUE;
}
/**
* gst_gl_allocation_params_copy:
* @src: the #GstGLAllocationParams to initialize
*
* Returns: (transfer full): a copy of the #GstGLAllocationParams specified by
* @src or %NULL on failure
*
* Since: 1.8
*/
GstGLAllocationParams *
gst_gl_allocation_params_copy (GstGLAllocationParams * src)
{
GstGLAllocationParams *dest;
g_return_val_if_fail (src != NULL, NULL);
dest = g_malloc0 (src->struct_size);
if (src->copy)
src->copy (src, dest);
return dest;
}
/**
* gst_gl_allocation_params_free:
* @params: the #GstGLAllocationParams to initialize
*
* Frees the #GstGLAllocationParams and all associated data.
*
* Since: 1.8
*/
void
gst_gl_allocation_params_free (GstGLAllocationParams * params)
{
if (params->free)
params->free (params);
g_free (params);
}
/**
* gst_gl_allocation_params_free_data:
* @params: the source #GstGLAllocationParams
*
* Frees the dynamically allocated data in @params. Direct subclasses
* should call this function in their own overridden free function.
*
* Since: 1.8
*/
void
gst_gl_allocation_params_free_data (GstGLAllocationParams * params)
{
if (params->context)
gst_object_unref (params->context);
if (params->alloc_params)
gst_allocation_params_free (params->alloc_params);
}
/**
* gst_gl_allocation_params_copy_data:
* @src: the source #GstGLAllocationParams
* @dest: the destination #GstGLAllocationParams
*
* Copies the dynamically allocated data from @src to @dest. Direct subclasses
* should call this function in their own overridden copy function.
*
* Since: 1.8
*/
void
gst_gl_allocation_params_copy_data (GstGLAllocationParams * src,
GstGLAllocationParams * dest)
{
gst_gl_allocation_params_init (dest, src->struct_size, src->alloc_flags,
src->copy, src->free, src->context, src->alloc_size, NULL,
src->wrapped_data, src->gl_handle, src->user_data, src->notify);
if (src->alloc_params)
dest->alloc_params = gst_allocation_params_copy (src->alloc_params);
}
G_DEFINE_BOXED_TYPE (GstGLAllocationParams, gst_gl_allocation_params,
(GBoxedCopyFunc) gst_gl_allocation_params_copy,
(GBoxedFreeFunc) gst_gl_allocation_params_free);
/**
* gst_gl_base_memory_alloc:
* @allocator: a #GstGLBaseMemoryAllocator
* @params: the #GstGLAllocationParams to allocate the memory with
*
* Returns: a new #GstGLBaseMemory from @allocator with the requested @params.
*
* Since: 1.8
*/
GstGLBaseMemory *
gst_gl_base_memory_alloc (GstGLBaseMemoryAllocator * allocator,
GstGLAllocationParams * params)
{
GstGLBaseMemoryAllocatorClass *alloc_class;
g_return_val_if_fail (GST_IS_GL_BASE_MEMORY_ALLOCATOR (allocator), NULL);
alloc_class = GST_GL_BASE_MEMORY_ALLOCATOR_GET_CLASS (allocator);
g_return_val_if_fail (alloc_class != NULL, NULL);
g_return_val_if_fail (alloc_class->alloc != NULL, NULL);
return alloc_class->alloc (allocator, params);
}