GI.GstBase.Objects.CollectPads

Manages a set of pads that operate in collect mode. This means that control is given to the manager of this object when all pads have data.

• Collectpads are created with collectPadsNew. A callback should then be installed with gst_collect_pads_set_function ().
• Pads are added to the collection with collectPadsAddPad/ collectPadsRemovePad. The pad has to be a sinkpad. When added, the chain, event and query functions of the pad are overridden. The element_private of the pad is used to store private information for the collectpads.
• For each pad, data is queued in the _chain function or by performing a pull_range.
• When data is queued on all pads in waiting mode, the callback function is called.
• Data can be dequeued from the pad with the collectPadsPop method. One can peek at the data with the collectPadsPeek function. These functions will return Nothing if the pad received an EOS event. When all pads return Nothing from a collectPadsPeek, the element can emit an EOS event itself.
• Data can also be dequeued in byte units using the collectPadsAvailable, collectPadsReadBuffer and collectPadsFlush calls.
• Elements should call collectPadsStart and collectPadsStop in their state change functions to start and stop the processing of the collectpads. The collectPadsStop call should be called before calling the parent element state change function in the PAUSED_TO_READY state change to ensure no pad is blocked and the element can finish streaming.
• collectPadsSetWaiting sets a pad to waiting or non-waiting mode. CollectPads element is not waiting for data to be collected on non-waiting pads. Thus these pads may but need not have data when the callback is called. All pads are in waiting mode by default.

Exported types

newtype CollectPads

Memory-managed wrapper type.

Constructors

CollectPads (ManagedPtr CollectPads)

Instances

GObject CollectPads

Defined in GI.GstBase.Objects.CollectPads

Methods

gobjectType :: IO GType

HasParentTypes CollectPads

Defined in GI.GstBase.Objects.CollectPads

type ParentTypes CollectPads

Defined in GI.GstBase.Objects.CollectPads

type ParentTypes CollectPads = Object ': (Object ': ([] :: [Type]))

class (GObject o, IsDescendantOf CollectPads o) => IsCollectPads o

Type class for types which can be safely cast to CollectPads, for instance with toCollectPads.

Instances

(GObject o, IsDescendantOf CollectPads o) => IsCollectPads o

Defined in GI.GstBase.Objects.CollectPads

toCollectPads :: (MonadIO m, IsCollectPads o) => o -> m CollectPads

Cast to CollectPads, for types for which this is known to be safe. For general casts, use castTo.

noCollectPads :: Maybe CollectPads

A convenience alias for Nothing :: Maybe CollectPads.

Methods

addPad

collectPadsAddPad

Arguments

:: (HasCallStack, MonadIO m, IsCollectPads a, IsPad b)

=> a

pads: the collectpads to use

-> b

pad: the pad to add

-> Word32

size: the size of the returned CollectData structure

-> CollectDataDestroyNotify

destroyNotify: function to be called before the returned CollectData structure is freed

-> Bool

lock: whether to lock this pad in usual waiting state

-> m (Maybe CollectData)

Returns: a new CollectData to identify the new pad. Or Nothing if wrong parameters are supplied.

Add a pad to the collection of collect pads. The pad has to be a sinkpad. The refcount of the pad is incremented. Use collectPadsRemovePad to remove the pad from the collection again.

You specify a size for the returned CollectData structure so that you can use it to store additional information.

You can also specify a CollectDataDestroyNotify that will be called just before the CollectData structure is freed. It is passed the pointer to the structure and should free any custom memory and resources allocated for it.

Keeping a pad locked in waiting state is only relevant when using the default collection algorithm (providing the oldest buffer). It ensures a buffer must be available on this pad for a collection to take place. This is of typical use to a muxer element where non-subtitle streams should always be in waiting state, e.g. to assure that caps information is available on all these streams when initial headers have to be written.

The pad will be automatically activated in push mode when pads is started.

MT safe.

available

collectPadsAvailable

Arguments

:: (HasCallStack, MonadIO m, IsCollectPads a)

=> a

pads: the collectpads to query

-> m Word32

Returns: The maximum number of bytes queued on all pads. This function returns 0 if a pad has no queued buffer.

Query how much bytes can be read from each queued buffer. This means that the result of this call is the maximum number of bytes that can be read from each of the pads.

This function should be called with pads STREAM_LOCK held, such as in the callback.

MT safe.

clipRunningTime

collectPadsClipRunningTime

Arguments

:: (HasCallStack, MonadIO m, IsCollectPads a)

=> a

pads: the collectpads to use

-> CollectData

cdata: collect data of corresponding pad

-> Buffer

buf: buffer being clipped

-> Ptr ()

userData: user data (unused)

-> m (FlowReturn, Maybe Buffer)

Convenience clipping function that converts incoming buffer's timestamp to running time, or clips the buffer if outside configured segment.

Since 1.6, this clipping function also sets the DTS parameter of the GstCollectData structure. This version of the running time DTS can be negative. G_MININT64 is used to indicate invalid value.

eventDefault

collectPadsEventDefault

Arguments

:: (HasCallStack, MonadIO m, IsCollectPads a)

=> a

pads: the collectpads to use

-> CollectData

data: collect data of corresponding pad

-> Event

event: event being processed

-> Bool

discard: process but do not send event downstream

-> m Bool

Default CollectPads event handling that elements should always chain up to to ensure proper operation. Element might however indicate event should not be forwarded downstream.

flush

collectPadsFlush

Arguments

:: (HasCallStack, MonadIO m, IsCollectPads a)

=> a

pads: the collectpads to query

-> CollectData

data: the data to use

-> Word32

size: the number of bytes to flush

-> m Word32

Returns: The number of bytes flushed This can be less than size and is 0 if the pad was end-of-stream.

Flush size bytes from the pad data.

This function should be called with pads STREAM_LOCK held, such as in the callback.

MT safe.

new

collectPadsNew

Arguments

:: (HasCallStack, MonadIO m)

=> m CollectPads

Returns: a new CollectPads, or Nothing in case of an error.

Create a new instance of CollectPads.

MT safe.

peek

collectPadsPeek

Arguments

:: (HasCallStack, MonadIO m, IsCollectPads a)

=> a

pads: the collectpads to peek

-> CollectData

data: the data to use

-> m (Maybe Buffer)

Returns: The buffer in data or Nothing if no buffer is queued. should unref the buffer after usage.

Peek at the buffer currently queued in data. This function should be called with the pads STREAM_LOCK held, such as in the callback handler.

MT safe.

pop

collectPadsPop

Arguments

:: (HasCallStack, MonadIO m, IsCollectPads a)

=> a

pads: the collectpads to pop

-> CollectData

data: the data to use

-> m (Maybe Buffer)

Returns: The buffer in data or Nothing if no buffer was queued. You should unref the buffer after usage.

Pop the buffer currently queued in data. This function should be called with the pads STREAM_LOCK held, such as in the callback handler.

MT safe.

queryDefault

collectPadsQueryDefault

Arguments

:: (HasCallStack, MonadIO m, IsCollectPads a)

=> a

pads: the collectpads to use

-> CollectData

data: collect data of corresponding pad

-> Query

query: query being processed

-> Bool

discard: process but do not send event downstream

-> m Bool

Default CollectPads query handling that elements should always chain up to to ensure proper operation. Element might however indicate query should not be forwarded downstream.

readBuffer

collectPadsReadBuffer

Arguments

:: (HasCallStack, MonadIO m, IsCollectPads a)

=> a

pads: the collectpads to query

-> CollectData

data: the data to use

-> Word32

size: the number of bytes to read

-> m (Maybe Buffer)

Returns: A sub buffer. The size of the buffer can be less that requested. A return of Nothing signals that the pad is end-of-stream. Unref the buffer after use.

Get a subbuffer of size bytes from the given pad data.

This function should be called with pads STREAM_LOCK held, such as in the callback.

MT safe.

removePad

collectPadsRemovePad

Arguments

:: (HasCallStack, MonadIO m, IsCollectPads a, IsPad b)

=> a

pads: the collectpads to use

-> b

pad: the pad to remove

-> m Bool

Returns: True if the pad could be removed.

Remove a pad from the collection of collect pads. This function will also free the CollectData and all the resources that were allocated with collectPadsAddPad.

The pad will be deactivated automatically when pads is stopped.

MT safe.

setBufferFunction

collectPadsSetBufferFunction

Arguments

:: (HasCallStack, MonadIO m, IsCollectPads a)

=> a

pads: the collectpads to use

-> CollectPadsBufferFunction

func: the function to set

-> m ()

Set the callback function and user data that will be called with the oldest buffer when all pads have been collected, or Nothing on EOS. If a buffer is passed, the callback owns a reference and must unref it.

MT safe.

setClipFunction

collectPadsSetClipFunction

Arguments

:: (HasCallStack, MonadIO m, IsCollectPads a)

=> a

pads: the collectpads to use

-> CollectPadsClipFunction

clipfunc: clip function to install

-> m ()

Install a clipping function that is called right after a buffer is received on a pad managed by pads. See CollectPadsClipFunction for more info.

setCompareFunction

collectPadsSetCompareFunction

Arguments

:: (HasCallStack, MonadIO m, IsCollectPads a)

=> a

pads: the pads to use

-> CollectPadsCompareFunction

func: the function to set

-> m ()

Set the timestamp comparison function.

MT safe.

setEventFunction

collectPadsSetEventFunction

Arguments

:: (HasCallStack, MonadIO m, IsCollectPads a)

=> a

pads: the collectpads to use

-> CollectPadsEventFunction

func: the function to set

-> m ()

Set the event callback function and user data that will be called when collectpads has received an event originating from one of the collected pads. If the event being processed is a serialized one, this callback is called with pads STREAM_LOCK held, otherwise not. As this lock should be held when calling a number of CollectPads functions, it should be acquired if so (unusually) needed.

MT safe.

setFlushFunction

collectPadsSetFlushFunction

Arguments

:: (HasCallStack, MonadIO m, IsCollectPads a)

=> a

pads: the collectpads to use

-> CollectPadsFlushFunction

func: flush function to install

-> m ()

Install a flush function that is called when the internal state of all pads should be flushed as part of flushing seek handling. See CollectPadsFlushFunction for more info.

Since: 1.4

setFlushing

collectPadsSetFlushing

Arguments

:: (HasCallStack, MonadIO m, IsCollectPads a)

=> a

pads: the collectpads to use

-> Bool

flushing: desired state of the pads

-> m ()

Change the flushing state of all the pads in the collection. No pad is able to accept anymore data when flushing is True. Calling this function with flushing False makes pads accept data again. Caller must ensure that downstream streaming (thread) is not blocked, e.g. by sending a FLUSH_START downstream.

MT safe.

setFunction

collectPadsSetFunction

Arguments

:: (HasCallStack, MonadIO m, IsCollectPads a)

=> a

pads: the collectpads to use

-> CollectPadsFunction

func: the function to set

-> m ()

CollectPads provides a default collection algorithm that will determine the oldest buffer available on all of its pads, and then delegate to a configured callback. However, if circumstances are more complicated and/or more control is desired, this sets a callback that will be invoked instead when all the pads added to the collection have buffers queued. Evidently, this callback is not compatible with collectPadsSetBufferFunction callback. If this callback is set, the former will be unset.

MT safe.

setQueryFunction

collectPadsSetQueryFunction

Arguments

:: (HasCallStack, MonadIO m, IsCollectPads a)

=> a

pads: the collectpads to use

-> CollectPadsQueryFunction

func: the function to set

-> m ()

Set the query callback function and user data that will be called after collectpads has received a query originating from one of the collected pads. If the query being processed is a serialized one, this callback is called with pads STREAM_LOCK held, otherwise not. As this lock should be held when calling a number of CollectPads functions, it should be acquired if so (unusually) needed.

MT safe.

setWaiting

collectPadsSetWaiting

Arguments

:: (HasCallStack, MonadIO m, IsCollectPads a)

=> a

pads: the collectpads

-> CollectData

data: the data to use

-> Bool

waiting: boolean indicating whether this pad should operate in waiting or non-waiting mode

-> m ()

Sets a pad to waiting or non-waiting mode, if at least this pad has not been created with locked waiting state, in which case nothing happens.

This function should be called with pads STREAM_LOCK held, such as in the callback.

MT safe.

srcEventDefault

collectPadsSrcEventDefault

Arguments

:: (HasCallStack, MonadIO m, IsCollectPads a, IsPad b)

=> a

pads: the CollectPads to use

-> b

pad: src Pad that received the event

-> Event

event: event being processed

-> m Bool

Default CollectPads event handling for the src pad of elements. Elements can chain up to this to let flushing seek event handling be done by CollectPads.

Since: 1.4

start

collectPadsStart

Arguments

:: (HasCallStack, MonadIO m, IsCollectPads a)

=> a

pads: the collectpads to use

-> m ()

Starts the processing of data in the collect_pads.

MT safe.

stop

collectPadsStop

Arguments

:: (HasCallStack, MonadIO m, IsCollectPads a)

=> a

pads: the collectpads to use

-> m ()

Stops the processing of data in the collect_pads. this function will also unblock any blocking operations.

MT safe.

takeBuffer

collectPadsTakeBuffer

Arguments

:: (HasCallStack, MonadIO m, IsCollectPads a)

=> a

pads: the collectpads to query

-> CollectData

data: the data to use

-> Word32

size: the number of bytes to read

-> m (Maybe Buffer)

Returns: A sub buffer. The size of the buffer can be less that requested. A return of Nothing signals that the pad is end-of-stream. Unref the buffer after use.

Get a subbuffer of size bytes from the given pad data. Flushes the amount of read bytes.

This function should be called with pads STREAM_LOCK held, such as in the callback.

MT safe.