BufferPool

A #GstBufferPool is an object that can be used to pre-allocate and recycle buffers of the same size and with the same properties.

A #GstBufferPool is created with gst_buffer_pool_new().

Once a pool is created, it needs to be configured. A call to gst_buffer_pool_get_config() returns the current configuration structure from the pool. With gst_buffer_pool_config_set_params() and gst_buffer_pool_config_set_allocator() the bufferpool parameters and allocator can be configured. Other properties can be configured in the pool depending on the pool implementation.

A bufferpool can have extra options that can be enabled with gst_buffer_pool_config_add_option(). The available options can be retrieved with gst_buffer_pool_get_options(). Some options allow for additional configuration properties to be set.

After the configuration structure has been configured, gst_buffer_pool_set_config() updates the configuration in the pool. This can fail when the configuration structure is not accepted.

After the a pool has been configured, it can be activated with gst_buffer_pool_set_active(). This will preallocate the configured resources in the pool.

When the pool is active, gst_buffer_pool_acquire_buffer() can be used to retrieve a buffer from the pool.

Buffers allocated from a bufferpool will automatically be returned to the pool with gst_buffer_pool_release_buffer() when their refcount drops to 0.

The bufferpool can be deactivated again with gst_buffer_pool_set_active(). All further gst_buffer_pool_acquire_buffer() calls will return an error. When all buffers are returned to the pool they will be freed.

Use gst_object_unref() to release the reference to a bufferpool. If the refcount of the pool reaches 0, the pool will be freed.

class BufferPool : ObjectGst {

protected

GstBufferPool* gstBufferPool;

GstBufferPool* getBufferPoolStruct(bool transferOwnership);

void* getStruct();

this(GstBufferPool* gstBufferPool, bool ownedRef);

static GType getType();

this();

static void configAddOption(Structure config, string option);

static bool configGetAllocator(Structure config, Allocator allocator, AllocationParams params);

static string configGetOption(Structure config, uint index);

static bool configGetParams(Structure config, Caps caps, uint size, uint minBuffers, uint maxBuffers);

static bool configHasOption(Structure config, string option);

static uint configNOptions(Structure config);

static void configSetAllocator(Structure config, Allocator allocator, AllocationParams params);

static void configSetParams(Structure config, Caps caps, uint size, uint minBuffers, uint maxBuffers);

static bool configValidateParams(Structure config, Caps caps, uint size, uint minBuffers, uint maxBuffers);

GstFlowReturn acquireBuffer(Buffer buffer, GstBufferPoolAcquireParams* params);

Structure getConfig();

string[] getOptions();

bool hasOption(string option);

bool isActive();

void releaseBuffer(Buffer buffer);

bool setActive(bool active);

bool setConfig(Structure config);

void setFlushing(bool flushing);

}

Constructors

this this(GstBufferPool* gstBufferPool, bool ownedRef): Sets our main struct and passes it to the parent class.
this this(): Creates a new #GstBufferPool instance.

Members

Functions

acquireBuffer GstFlowReturn acquireBuffer(Buffer buffer, GstBufferPoolAcquireParams* params): Acquire a buffer from @pool. @buffer should point to a memory location that can hold a pointer to the new buffer.
getBufferPoolStruct GstBufferPool* getBufferPoolStruct(bool transferOwnership): Get the main Gtk struct
getConfig Structure getConfig(): Get a copy of the current configuration of the pool. This configuration can either be modified and used for the gst_buffer_pool_set_config() call or it must be freed after usage.
getOptions string[] getOptions(): Get a %NULL terminated array of string with supported bufferpool options for @pool. An option would typically be enabled with gst_buffer_pool_config_add_option().
getStruct void* getStruct(): the main Gtk struct as a void*
hasOption bool hasOption(string option): Check if the bufferpool supports @option.
isActive bool isActive(): Check if @pool is active. A pool can be activated with the gst_buffer_pool_set_active() call.
releaseBuffer void releaseBuffer(Buffer buffer): Release @buffer to @pool. @buffer should have previously been allocated from @pool with gst_buffer_pool_acquire_buffer().
setActive bool setActive(bool active): Control the active state of @pool. When the pool is inactive, new calls to gst_buffer_pool_acquire_buffer() will return with %GST_FLOW_FLUSHING.
setConfig bool setConfig(Structure config): Set the configuration of the pool. If the pool is already configured, and the configuration haven't change, this function will return %TRUE. If the pool is active, this method will return %FALSE and active configuration will remain. Buffers allocated form this pool must be returned or else this function will do nothing and return %FALSE.
setFlushing void setFlushing(bool flushing): Enable or disable the flushing state of a @pool without freeing or allocating buffers.

Static functions

configAddOption void configAddOption(Structure config, string option): Enabled the option in @config. This will instruct the @bufferpool to enable the specified option on the buffers that it allocates.
configGetAllocator bool configGetAllocator(Structure config, Allocator allocator, AllocationParams params): Get the @allocator and @params from @config.
configGetOption string configGetOption(Structure config, uint index): Parse an available @config and get the option at @index of the options API array.
configGetParams bool configGetParams(Structure config, Caps caps, uint size, uint minBuffers, uint maxBuffers): Get the configuration values from @config.
configHasOption bool configHasOption(Structure config, string option): Check if @config contains @option.
configNOptions uint configNOptions(Structure config): Retrieve the number of values currently stored in the options array of the @config structure.
configSetAllocator void configSetAllocator(Structure config, Allocator allocator, AllocationParams params): Set the @allocator and @params on @config.
configSetParams void configSetParams(Structure config, Caps caps, uint size, uint minBuffers, uint maxBuffers): Configure @config with the given parameters.
configValidateParams bool configValidateParams(Structure config, Caps caps, uint size, uint minBuffers, uint maxBuffers): Validate that changes made to @config are still valid in the context of the expected parameters. This function is a helper that can be used to validate changes made by a pool to a config when gst_buffer_pool_set_config() returns %FALSE. This expects that @caps haven't changed and that @min_buffers aren't lower then what we initially expected. This does not check if options or allocator parameters are still valid, won't check if size have changed, since changing the size is valid to adapt padding.
getType GType getType()

Variables

gstBufferPool GstBufferPool* gstBufferPool;: the main Gtk struct

Inherited Members

From ObjectGst

gstObject GstObject* gstObject;: the main Gtk struct
getObjectGstStruct GstObject* getObjectGstStruct(bool transferOwnership): Get the main Gtk struct
getStruct void* getStruct(): the main Gtk struct as a void*
getType GType getType()
checkUniqueness bool checkUniqueness(ListG list, string name): Checks to see if there is any object named @name in @list. This function does not do any locking of any kind. You might want to protect the provided list with the lock of the owner of the list. This function will lock each #GstObject in the list to compare the name, so be careful when passing a list with a locked object.
defaultDeepNotify void defaultDeepNotify(ObjectG object, ObjectGst orig, ParamSpec pspec, string[] excludedProps): A default deep_notify signal callback for an object. The user data should contain a pointer to an array of strings that should be excluded from the notify. The default handler will print the new value of the property using g_print.
refSink void* refSink(void* object): Increase the reference count of @object, and possibly remove the floating reference, if @object has a floating reference.
replace bool replace(ObjectGst oldobj, ObjectGst newobj): Atomically modifies a pointer to point to a new object. The reference count of @oldobj is decreased and the reference count of @newobj is increased.
addControlBinding bool addControlBinding(ControlBinding binding): Attach the #GstControlBinding to the object. If there already was a #GstControlBinding for this property it will be replaced.
defaultError void defaultError(ErrorG error, string dbg): A default error function that uses g_printerr() to display the error message and the optional debug sting..
getControlBinding ControlBinding getControlBinding(string propertyName): Gets the corresponding #GstControlBinding for the property. This should be unreferenced again after use.
getControlRate GstClockTime getControlRate(): Obtain the control-rate for this @object. Audio processing #GstElement objects will use this rate to sub-divide their processing loop and call gst_object_sync_values() inbetween. The length of the processing segment should be up to @control-rate nanoseconds.
getGValueArray bool getGValueArray(string propertyName, GstClockTime timestamp, GstClockTime interval, Value[] values): Gets a number of #GValues for the given controlled property starting at the requested time. The array @values need to hold enough space for @n_values of #GValue.
getName string getName(): Returns a copy of the name of @object. Caller should g_free() the return value after usage. For a nameless object, this returns %NULL, which you can safely g_free() as well.
getParent ObjectGst getParent(): Returns the parent of @object. This function increases the refcount of the parent object so you should gst_object_unref() it after usage.
getPathString string getPathString(): Generates a string describing the path of @object in the object hierarchy. Only useful (or used) for debugging.
getValue Value getValue(string propertyName, GstClockTime timestamp): Gets the value for the given controlled property at the requested time.
getValueArray bool getValueArray(string propertyName, GstClockTime timestamp, GstClockTime interval, uint nValues, void* values): Gets a number of values for the given controlled property starting at the requested time. The array @values need to hold enough space for @n_values of the same type as the objects property's type.
hasActiveControlBindings bool hasActiveControlBindings(): Check if the @object has active controlled properties.
hasAncestor bool hasAncestor(ObjectGst ancestor): Check if @object has an ancestor @ancestor somewhere up in the hierarchy. One can e.g. check if a #GstElement is inside a #GstPipeline.
hasAsAncestor bool hasAsAncestor(ObjectGst ancestor): Check if @object has an ancestor @ancestor somewhere up in the hierarchy. One can e.g. check if a #GstElement is inside a #GstPipeline.
hasAsParent bool hasAsParent(ObjectGst parent): Check if @parent is the parent of @object. E.g. a #GstElement can check if it owns a given #GstPad.
doref ObjectGst doref(): Increments the reference count on @object. This function does not take the lock on @object because it relies on atomic refcounting.
removeControlBinding bool removeControlBinding(ControlBinding binding): Removes the corresponding #GstControlBinding. If it was the last ref of the binding, it will be disposed.
setControlBindingDisabled void setControlBindingDisabled(string propertyName, bool disabled): This function is used to disable the control bindings on a property for some time, i.e. gst_object_sync_values() will do nothing for the property.
setControlBindingsDisabled void setControlBindingsDisabled(bool disabled): This function is used to disable all controlled properties of the @object for some time, i.e. gst_object_sync_values() will do nothing.
setControlRate void setControlRate(GstClockTime controlRate): Change the control-rate for this @object. Audio processing #GstElement objects will use this rate to sub-divide their processing loop and call gst_object_sync_values() inbetween. The length of the processing segment should be up to @control-rate nanoseconds.
setName bool setName(string name): Sets the name of @object, or gives @object a guaranteed unique name (if @name is %NULL). This function makes a copy of the provided name, so the caller retains ownership of the name it sent.
setParent bool setParent(ObjectGst parent): Sets the parent of @object to @parent. The object's reference count will be incremented, and any floating reference will be removed (see gst_object_ref_sink()).
suggestNextSync GstClockTime suggestNextSync(): Returns a suggestion for timestamps where buffers should be split to get best controller results.
syncValues bool syncValues(GstClockTime timestamp): Sets the properties of the object, according to the #GstControlSources that (maybe) handle them and for the given timestamp.
unparent void unparent(): Clear the parent of @object, removing the associated reference. This function decreases the refcount of @object.
unref void unref(): Decrements the reference count on @object. If reference count hits zero, destroy @object. This function does not take the lock on @object as it relies on atomic refcounting.
addOnDeepNotify gulong addOnDeepNotify(void delegate(ObjectGst, ParamSpec, ObjectGst) dlg, ConnectFlags connectFlags): The deep notify signal is used to be notified of property changes. It is typically attached to the toplevel bin to receive notifications from all the elements contained in that bin.