GstBus

Gst.Bus

GObject.Object
    ╰──GObject.InitiallyUnowned
        ╰──Gst.Object
            ╰──Gst.Bus

Gst.Bus.prototype.new

function Gst.Bus.prototype.new(): {
    // javascript wrapper for 'gst_bus_new'
}

Creates a new Gst.Bus instance.

Gst.Bus.prototype.add_signal_watch

function Gst.Bus.prototype.add_signal_watch(): {
    // javascript wrapper for 'gst_bus_add_signal_watch'
}

Adds a bus signal watch to the default main context with the default priority ( GLib.PRIORITY_DEFAULT ). It is also possible to use a non-default main context set up using GLib.MainContext.prototype.push_thread_default (before one had to create a bus watch source and attach it to the desired main context 'manually').

After calling this statement, the bus will emit the "message" signal for each message posted on the bus.

This function may be called multiple times. To clean up, the caller is responsible for calling Gst.Bus.prototype.remove_signal_watch as many times as this function is called.

Gst.Bus.prototype.add_signal_watch_full

function Gst.Bus.prototype.add_signal_watch_full(priority: Number): {
    // javascript wrapper for 'gst_bus_add_signal_watch_full'
}

Adds a bus signal watch to the default main context with the given priority (e.g. GLib.PRIORITY_DEFAULT). It is also possible to use a non-default main context set up using GLib.MainContext.prototype.push_thread_default (before one had to create a bus watch source and attach it to the desired main context 'manually').

After calling this statement, the bus will emit the "message" signal for each message posted on the bus when the GMainLoop (not introspectable) is running.

This function may be called multiple times. To clean up, the caller is responsible for calling Gst.Bus.prototype.remove_signal_watch as many times as this function is called.

There can only be a single bus watch per bus, you must remove any signal watch before you can set another type of watch.

Gst.Bus.prototype.add_watch_full

function Gst.Bus.prototype.add_watch_full(priority: Number, func: Gst.BusFunc, user_data: Object): {
    // javascript wrapper for 'gst_bus_add_watch_full'
}

Adds a bus watch to the default main context with the given priority (e.g. GLib.PRIORITY_DEFAULT). It is also possible to use a non-default main context set up using GLib.MainContext.prototype.push_thread_default (before one had to create a bus watch source and attach it to the desired main context 'manually').

This function is used to receive asynchronous messages in the main loop. There can only be a single bus watch per bus, you must remove it before you can set a new one.

The bus watch will only work if a GMainLoop (not introspectable) is being run.

When func is called, the message belongs to the caller; if you want to keep a copy of it, call gst_message_ref (not introspectable) before leaving func.

The watch can be removed using Gst.Bus.prototype.remove_watch or by returning false from func. If the watch was added to the default main context it is also possible to remove the watch using GLib.prototype.source_remove.

The bus watch will take its own reference to the bus, so it is safe to unref bus using Gst.Object.prototype.unref after setting the bus watch.

Gst.Bus.prototype.async_signal_func

function Gst.Bus.prototype.async_signal_func(message: Gst.Message, data: Object): {
    // javascript wrapper for 'gst_bus_async_signal_func'
}

A helper Gst.BusFunc that can be used to convert all asynchronous messages into signals.

Gst.Bus.prototype.create_watch

function Gst.Bus.prototype.create_watch(): {
    // javascript wrapper for 'gst_bus_create_watch'
}

Create watch for this bus. The GSource (not introspectable) will be dispatched whenever a message is on the bus. After the GSource is dispatched, the message is popped off the bus and unreffed.

As with other watches, there can only be one watch on the bus, including any signal watch added with Gst.Bus.prototype.add_signal_watch.

Gst.Bus.prototype.disable_sync_message_emission

function Gst.Bus.prototype.disable_sync_message_emission(): {
    // javascript wrapper for 'gst_bus_disable_sync_message_emission'
}

Instructs GStreamer to stop emitting the "sync-message" signal for this bus. See Gst.Bus.prototype.enable_sync_message_emission for more information.

In the event that multiple pieces of code have called Gst.Bus.prototype.enable_sync_message_emission, the sync-message emissions will only be stopped after all calls to Gst.Bus.prototype.enable_sync_message_emission were "cancelled" by calling this function. In this way the semantics are exactly the same as Gst.Object.prototype.ref that which calls enable should also call disable.

Gst.Bus.prototype.enable_sync_message_emission

function Gst.Bus.prototype.enable_sync_message_emission(): {
    // javascript wrapper for 'gst_bus_enable_sync_message_emission'
}

Instructs GStreamer to emit the "sync-message" signal after running the bus's sync handler. This function is here so that code can ensure that they can synchronously receive messages without having to affect what the bin's sync handler is.

This function may be called multiple times. To clean up, the caller is responsible for calling Gst.Bus.prototype.disable_sync_message_emission as many times as this function is called.

While this function looks similar to Gst.Bus.prototype.add_signal_watch, it is not exactly the same -- this function enables *synchronous* emission of signals when messages arrive; Gst.Bus.prototype.add_signal_watch adds an idle callback to pop messages off the bus asynchronously. The sync-message signal comes from the thread of whatever object posted the message; the "message" signal is marshalled to the main thread via the GMainLoop (not introspectable).

Gst.Bus.prototype.get_pollfd

function Gst.Bus.prototype.get_pollfd(): {
    // javascript wrapper for 'gst_bus_get_pollfd'
}

Gets the file descriptor from the bus which can be used to get notified about messages being available with functions like GLib.prototype.poll, and allows integration into other event loops based on file descriptors. Whenever a message is available, the POLLIN / GObject.IOCondition.IN event is set.

Warning: NEVER read or write anything to the returned fd but only use it for getting notifications via GLib.prototype.poll or similar and then use the normal GstBus API, e.g. Gst.Bus.prototype.pop.

Since : 1.14

Gst.Bus.prototype.have_pending

function Gst.Bus.prototype.have_pending(): {
    // javascript wrapper for 'gst_bus_have_pending'
}

Checks if there are pending messages on the bus that should be handled.

Gst.Bus.prototype.peek

function Gst.Bus.prototype.peek(): {
    // javascript wrapper for 'gst_bus_peek'
}

Peeks the message on the top of the bus' queue. The message will remain on the bus' message queue.

Gst.Bus.prototype.poll

function Gst.Bus.prototype.poll(events: Gst.MessageType, timeout: Number): {
    // javascript wrapper for 'gst_bus_poll'
}

Polls the bus for messages. Will block while waiting for messages to come. You can specify a maximum time to poll with the timeout parameter. If timeout is negative, this function will block indefinitely.

All messages not in events will be popped off the bus and will be ignored. It is not possible to use message enums beyond Gst.MessageType.EXTENDED in the events mask

Because poll is implemented using the "message" signal enabled by Gst.Bus.prototype.add_signal_watch, calling Gst.Bus.prototype.poll will cause the "message" signal to be emitted for every message that poll sees. Thus a "message" signal handler will see the same messages that this function sees -- neither will steal messages from the other.

This function will run a GMainLoop (not introspectable) from the default main context when polling.

You should never use this function, since it is pure evil. This is especially true for GUI applications based on Gtk+ or Qt, but also for any other non-trivial application that uses the GLib main loop. As this function runs a GLib main loop, any callback attached to the default GLib main context may be invoked. This could be timeouts, GUI events, I/O events etc.; even if Gst.Bus.prototype.poll is called with a 0 timeout. Any of these callbacks may do things you do not expect, e.g. destroy the main application window or some other resource; change other application state; display a dialog and run another main loop until the user clicks it away. In short, using this function may add a lot of complexity to your code through unexpected re-entrancy and unexpected changes to your application's state.

For 0 timeouts use Gst.Bus.prototype.pop_filtered instead of this function; for other short timeouts use Gst.Bus.prototype.timed_pop_filtered; everything else is better handled by setting up an asynchronous bus watch and doing things from there.

Gst.Bus.prototype.pop

function Gst.Bus.prototype.pop(): {
    // javascript wrapper for 'gst_bus_pop'
}

Gets a message from the bus.

Gst.Bus.prototype.pop_filtered

function Gst.Bus.prototype.pop_filtered(types: Gst.MessageType): {
    // javascript wrapper for 'gst_bus_pop_filtered'
}

Gets a message matching type from the bus. Will discard all messages on the bus that do not match type and that have been posted before the first message that does match type. If there is no message matching type on the bus, all messages will be discarded. It is not possible to use message enums beyond Gst.MessageType.EXTENDED in the events mask.

Gst.Bus.prototype.post

function Gst.Bus.prototype.post(message: Gst.Message): {
    // javascript wrapper for 'gst_bus_post'
}

Posts a message on the given bus. Ownership of the message is taken by the bus.

Gst.Bus.prototype.remove_signal_watch

function Gst.Bus.prototype.remove_signal_watch(): {
    // javascript wrapper for 'gst_bus_remove_signal_watch'
}

Removes a signal watch previously added with Gst.Bus.prototype.add_signal_watch.

Gst.Bus.prototype.remove_watch

function Gst.Bus.prototype.remove_watch(): {
    // javascript wrapper for 'gst_bus_remove_watch'
}

Removes an installed bus watch from bus.

Since : 1.6

Gst.Bus.prototype.set_flushing

function Gst.Bus.prototype.set_flushing(flushing: Number): {
    // javascript wrapper for 'gst_bus_set_flushing'
}

If flushing, flushes out and unrefs any messages queued in the bus. Releases references to the message origin objects. Will flush future messages until Gst.Bus.prototype.set_flushing sets flushing to false.

Gst.Bus.prototype.set_sync_handler

function Gst.Bus.prototype.set_sync_handler(func: Gst.BusSyncHandler, user_data: Object): {
    // javascript wrapper for 'gst_bus_set_sync_handler'
}

Sets the synchronous handler on the bus. The function will be called every time a new message is posted on the bus. Note that the function will be called in the same thread context as the posting object. This function is usually only called by the creator of the bus. Applications should handle messages asynchronously using the gst_bus watch and poll functions.

Before 1.16.3 it was not possible to replace an existing handler and clearing an existing handler with null was not thread-safe.

Gst.Bus.prototype.sync_signal_handler

function Gst.Bus.prototype.sync_signal_handler(message: Gst.Message, data: Object): {
    // javascript wrapper for 'gst_bus_sync_signal_handler'
}

A helper Gst.BusSyncHandler that can be used to convert all synchronous messages into signals.

Gst.Bus.prototype.timed_pop

function Gst.Bus.prototype.timed_pop(timeout: Number): {
    // javascript wrapper for 'gst_bus_timed_pop'
}

Gets a message from the bus, waiting up to the specified timeout.

If timeout is 0, this function behaves like Gst.Bus.prototype.pop. If timeout is Gst.CLOCK_TIME_NONE, this function will block forever until a message was posted on the bus.

Gst.Bus.prototype.timed_pop_filtered

function Gst.Bus.prototype.timed_pop_filtered(timeout: Number, types: Gst.MessageType): {
    // javascript wrapper for 'gst_bus_timed_pop_filtered'
}

Gets a message from the bus whose type matches the message type mask types, waiting up to the specified timeout (and discarding any messages that do not match the mask provided).

If timeout is 0, this function behaves like Gst.Bus.prototype.pop_filtered. If timeout is Gst.CLOCK_TIME_NONE, this function will block forever until a matching message was posted on the bus.

message

function message_callback(self: Gst.Bus, message: Gst.Message, user_data: Object): {
    // javascript callback for the 'message' signal
}

A message has been posted on the bus. This signal is emitted from a GSource (not introspectable) added to the mainloop. this signal will only be emitted when there is a GMainLoop (not introspectable) running.

Flags: Run Last

sync-message

function sync_message_callback(self: Gst.Bus, message: Gst.Message, user_data: Object): {
    // javascript callback for the 'sync-message' signal
}

A message has been posted on the bus. This signal is emitted from the thread that posted the message so one has to be careful with locking.

This signal will not be emitted by default, you have to call Gst.Bus.prototype.enable_sync_message_emission before.

Flags: Run Last

enable-async

“enable-async” Number

Enables async message delivery support for bus watches, Gst.Bus.prototype.pop and similar API. Without this only the synchronous message handlers are called.

This property is used to create the child element buses in Gst.Bin.

Flags : Read / Write / Construct Only

vfunc_message

function vfunc_message(bus: Gst.Bus, message: Gst.Message): {
    // javascript implementation of the 'message' virtual method
}

A message has been posted on the bus.

vfunc_sync_message

function vfunc_sync_message(bus: Gst.Bus, message: Gst.Message): {
    // javascript implementation of the 'sync_message' virtual method
}

A message has been posted on the bus.

Gst.BusFlags

The standard flags that a bus may have.

Gst.BusSyncReply

The result values for a GstBusSyncHandler.

Gst.BusFunc

function Gst.BusFunc(bus: Gst.Bus, message: Gst.Message, user_data: Object): {
    // javascript wrapper for 'GstBusFunc'
}

Specifies the type of function passed to gst_bus_add_watch (not introspectable) or Gst.Bus.prototype.add_watch_full, which is called from the mainloop when a message is available on the bus.

The message passed to the function will be unreffed after execution of this function so it should not be freed in the function.

Note that this function is used as a GLib.SourceFunc which means that returning false will remove the GSource (not introspectable) from the mainloop.

Gst.BusSyncHandler

function Gst.BusSyncHandler(bus: Gst.Bus, message: Gst.Message, user_data: Object): {
    // javascript wrapper for 'GstBusSyncHandler'
}

Handler will be invoked synchronously, when a new message has been injected into the bus. This function is mostly used internally. Only one sync handler can be attached to a given bus.

If the handler returns Gst.BusSyncReply.DROP, it should unref the message, else the message should not be unreffed by the sync handler.