BufferPool

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

A gstreamer.BufferPool is created with Buffer.poolNew.

Once a pool is created, it needs to be configured. A call to Buffer.poolGetConfig returns the current configuration structure from the pool. With Buffer.poolConfigSetParams and Buffer.poolConfigSetAllocator 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 Buffer.poolConfigAddOption. The available options can be retrieved with Buffer.poolGetOptions. Some options allow for additional configuration properties to be set.

After the configuration structure has been configured, Buffer.poolSetConfig 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 Buffer.poolSetActive. This will preallocate the configured resources in the pool.

When the pool is active, Buffer.poolAcquireBuffer can be used to retrieve a buffer from the pool.

Buffers allocated from a bufferpool will automatically be returned to the pool with Buffer.poolReleaseBuffer when their refcount drops to 0.

The bufferpool can be deactivated again with Buffer.poolSetActive. All further Buffer.poolAcquireBuffer 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 gstreamer.BufferPool 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 Buffer.poolSetConfig 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 Buffer.poolConfigAddOption.
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 Buffer.poolSetActive call.
releaseBuffer void releaseBuffer(Buffer buffer): Release buffer to pool. buffer should have previously been allocated from pool with Buffer.poolAcquireBuffer.
setActive bool setActive(bool active): Control the active state of pool. When the pool is inactive, new calls to Buffer.poolAcquireBuffer 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 Buffer.poolSetConfig 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 gstreamer.ControlBinding to the object. If there already was a gstreamer.ControlBinding for this property it will be replaced.
defaultError void defaultError(ErrorG error, string debug_): A default error function that uses g_printerr() to display the error message and the optional debug string..
getControlBinding ControlBinding getControlBinding(string propertyName): Gets the corresponding gstreamer.ControlBinding for the property. This should be unreferenced again after use.
getControlRate GstClockTime getControlRate(): Obtain the control-rate for this object. Audio processing gstreamer.Element objects will use this rate to sub-divide their processing loop and call gst_object_sync_values() in between. 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 gobject.Values for the given controlled property starting at the requested time. The array values need to hold enough space for n_values of gobject.Value
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 gstreamer.Element is inside a gstreamer.Pipeline
hasAsAncestor bool hasAsAncestor(ObjectGst ancestor): Check if object has an ancestor ancestor somewhere up in the hierarchy. One can e.g. check if a gstreamer.Element is inside a gstreamer.Pipeline
hasAsParent bool hasAsParent(ObjectGst parent): Check if parent is the parent of object. E.g. a gstreamer.Element can check if it owns a given gstreamer.Pad
ref_ ObjectGst ref_(): 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 gstreamer.ControlBinding 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 gstreamer.Element objects will use this rate to sub-divide their processing loop and call gst_object_sync_values() in between. 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 gstreamer.ControlSources 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.

gstreamer BufferPool classes

BufferPool