org.gstreamer.Pad Maven / Gradle / Ivy
Show all versions of gstreamer-java Show documentation
/*
* Copyright (C) 2009 Tamas Korodi
* Copyright (C) 2007 Wayne Meissner
* Copyright (C) 1999,2000 Erik Walthinsen
* 2000 Wim Taymans
*
* This file is part of gstreamer-java.
*
* This code is free software: you can redistribute it and/or modify it under
* the terms of the GNU Lesser General Public License version 3 only, as
* published by the Free Software Foundation.
*
* This code 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 Lesser General Public License
* version 3 for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* version 3 along with this work. If not, see
* A {@link Element} is linked to other elements via "pads", which are extremely
* light-weight generic link points.
* After two pads are retrieved from an element with {@link Element#getPad},
* the pads can be link with {@link #link}. (For quick links,
* you can also use {@link Element#link}, which will make the obvious
* link for you if it's straightforward.)
*
* Pads are typically created from a {@link PadTemplate} with {@link #Pad(PadTemplate, String)}.
*
* Pads have {@link Caps} attached to it to describe the media type they are
* capable of dealing with. {@link #getCaps} and {@link #setCaps} are
* used to manipulate the caps of the pads.
* Pads created from a pad template cannot set capabilities that are
* incompatible with the pad template capabilities.
*
* Pads without pad templates can be created with gst_pad_new(),
* which takes a direction and a name as an argument. If the name is NULL,
* then a guaranteed unique name will be assigned to it.
*
* {@link #getParentElement} will retrieve the Element that owns the pad.
*
* An Element creating a pad will typically use the various
* gst_pad_set_*_function() calls to register callbacks for various events
* on the pads.
*
* GstElements will use gst_pad_push() and gst_pad_pull_range() to push out
* or pull in a buffer.
*
* To send an Event on a pad, use {@link #sendEvent} and {@link #pushEvent}.
*
* @see PadTemplate
* @see Element
* @see Event
*/
public class Pad extends GstObject {
private static interface API extends GstPadAPI {
@CallerOwnsReturn Pointer ptr_gst_pad_new(String name, PadDirection direction);
@CallerOwnsReturn Pointer ptr_gst_pad_new_from_template(PadTemplate templ, String name);
}
private static final API gst = GstNative.load(API.class);
/**
* Creates a new instance of Pad
*/
public Pad(Initializer init) {
super(init);
}
/**
* Creates a new pad with the given name in the given direction.
* If name is null, a guaranteed unique name (across all pads)
* will be assigned.
*
* @param name The name of the new pad.
* @param direction The direction of the new pad.
*/
public Pad(String name, PadDirection direction) {
this(initializer(gst.ptr_gst_pad_new(name, direction)));
}
/**
* Creates a new pad with the given name from the given template.
*
* If name is null, a guaranteed unique name (across all pads)
* will be assigned.
*
* @param template The pad template to use.
* @param name The name of the new pad.
*/
public Pad(PadTemplate template, String name) {
this(initializer(gst.ptr_gst_pad_new_from_template(template, name)));
}
/**
* Get the capabilities this pad can produce or consume.
*
* This method returns all possible caps a pad can operate with, using
* the pad's get_caps function; not just the Caps as set by {@link #setCaps}.
*
* This returns the pad template caps if not explicitly set.
*
* MT safe.
* @return a newly allocated copy of the {@link Caps} of this pad.
*/
public Caps getCaps() {
return gst.gst_pad_get_caps(this);
}
/**
* Sets the capabilities of this pad.
*
* The caps must be fixed. Any previous caps on the pad will be destroyed.
*
* It is possible to set null caps, which will make the pad unnegotiated
* again.
*
* MT safe.
* @param caps The {@link Caps} to set.
* @return true if the caps could be set. false if the caps were not fixed
* or bad parameters were provided to this function.
*/
public boolean setCaps(Caps caps) {
return gst.gst_pad_set_caps(this, caps);
}
/**
* Gets the capabilities of the allowed media types that can flow through this pad and its peer.
*
* The allowed capabilities is calculated as the intersection of the results of
* calling {@link #getCaps} on this pad and its peer.
*
* MT safe.
* @return The allowed {@link Caps} of the pad link, or null if this pad has no peer.
*/
public Caps getAllowedCaps() {
return gst.gst_pad_get_allowed_caps(this);
}
/**
* Get the capabilities of the media type that currently flows through this pad
* and its peer.
*
* This function can be used on both src and sink pads. Note that srcpads are
* always negotiated before sinkpads so it is possible that the negotiated caps
* on the srcpad do not match the negotiated caps of the peer.
*
* MT safe.
* @return the negotiated #GstCaps of the pad link, or null if this pad has
* no peer, or is not negotiated yet
*
*/
public Caps getNegotiatedCaps() {
return gst.gst_pad_get_negotiated_caps(this);
}
/**
* Get the peer of this pad.
*
* MT safe.
* @return The peer Pad of this Pad.
*/
public Pad getPeer() {
return gst.gst_pad_get_peer(this);
}
/**
* Get the capabilities of the peer connected to this pad.
*
* @return the {@link Caps} of the peer pad, or null if there is no peer pad.
*/
public Caps getPeerCaps() {
return gst.gst_pad_peer_get_caps(this);
}
/**
* Check if the pad accepts the given caps.
*
* @param caps a {@link Caps} to check on the pad.
* @return true if the pad can accept the caps.
*/
public boolean acceptCaps(Caps caps) {
return gst.gst_pad_accept_caps(this, caps);
}
/**
* Check if the peer of this pad accepts the caps.
* If this pad has no peer, this method returns true.
*
* @param caps {@link Caps} to check on the pad
* @return true if the peer pad can accept the caps or this pad no peer.
*/
public boolean peerAcceptCaps(Caps caps) {
return gst.gst_pad_peer_accept_caps(this, caps);
}
/**
* Links this pad and a sink pad.
*
* MT Safe.
* @param pad the sink Pad to link.
* @return A result code indicating if the connection worked or what went wrong.
*/
public PadLinkReturn link(Pad pad) {
return gst.gst_pad_link(this, pad);
}
/**
*
* Unlinks the source pad from the sink pad.
* Will emit the "unlinked" signal on both pads.
*
* MT safe.
*
* @param pad the sink Pad to unlink.
* @return true if the pads were unlinked. This function returns false if
* the pads were not linked together.
*/
public boolean unlink(Pad pad) {
return gst.gst_pad_unlink(this, pad);
}
/**
* Check if this pad is linked to another pad or not.
*
* @return true if the pad is linked, else false.
*/
public boolean isLinked() {
return gst.gst_pad_is_linked(this);
}
/**
* Get the direction of the pad.
* The direction of the pad is decided at construction time so this function
* does not take the LOCK.
*
* @return The {@link PadDirection} of the pad.
*/
public PadDirection getDirection() {
return gst.gst_pad_get_direction(this);
}
/**
* Get the parent of this pad, cast to a {@link Element}.
* If this pad has no parent or its parent is not an element, returns null.
*
* @return The parent of the pad.
*/
public Element getParentElement() {
return gst.gst_pad_get_parent_element(this);
}
/**
* Activates or deactivates the given pad.
* Normally called from within core state change functions.
*
* If active is true, makes sure the pad is active. If it is already active, either in
* push or pull mode, just return. Otherwise dispatches to the pad's activate
* function to perform the actual activation.
*
* If not @active, checks the pad's current mode and calls
* gst_pad_activate_push() or gst_pad_activate_pull(), as appropriate, with a
* FALSE argument.
*
* @param active whether or not the pad should be active.
* @return true if the operation was successful.
*/
public boolean setActive(boolean active) {
return gst.gst_pad_set_active(this, active);
}
/**
*
* Blocks or unblocks the dataflow on a pad.
*
* MT safe.
* @param blocked boolean indicating we should block or unblock
* @return true if the pad could be blocked. This function can fail if the
* wrong parameters were passed or the pad was already in the requested state.
*/
public boolean setBlocked(boolean blocked) {
return gst.gst_pad_set_blocked(this, blocked);
}
/**
* Checks if the pad is blocked or not.
* This function returns the last requested state of the pad. It is not
* certain that the pad is actually blocking at this point (see {@link #isBlocking}).
*
* @return true if the pad is blocked.
*/
public boolean isBlocked() {
return gst.gst_pad_is_blocked(this);
}
public boolean setBlockedAsync(boolean blocked, PadBlockCallback callback) {
return gst.gst_pad_set_blocked_async(this, blocked, callback, null);
}
/**
* Checks if the pad is blocking or not. This is a guaranteed state
* of whether the pad is actually blocking on a {@link Buffer} or a {@link Event}.
*
* @return true if the pad is blocking.
*/
public boolean isBlocking() {
return gst.gst_pad_is_blocking(this);
}
/**
* Signal emitted when new data is available on the {@link Pad}
*
* @see #connect(HAVE_DATA)
* @see #disconnect(HAVE_DATA)
*/
public static interface HAVE_DATA {
/**
* Called when a {@link Pad} has data available.
*
* @param pad the pad which emitted the signal.
* @param data the new data.
*/
public void haveData(Pad pad, MiniObject data);
}
/**
* Signal emitted when new this {@link Pad} is linked to another {@link Pad}
*
* @see #connect(LINKED)
* @see #disconnect(LINKED)
*/
public static interface LINKED {
/**
* Called when a {@link Pad} is linked to another Pad.
*
* @param pad the pad that emitted the signal.
* @param peer the peer pad that has been connected.
*/
public void linked(Pad pad, Pad peer);
}
/**
* Signal emitted when new this {@link Pad} is disconnected from a peer {@link Pad}
*
* @see #connect(UNLINKED)
* @see #disconnect(UNLINKED)
*/
public static interface UNLINKED {
/**
* Called when a {@link Pad} is unlinked from another Pad.
*
* @param pad the pad that emitted the signal.
* @param peer the peer pad that has been connected.
*/
public void unlinked(Pad pad, Pad peer);
}
/**
* Signal emitted when a connection to a peer {@link Pad} is requested.
*
* @see #connect(REQUEST_LINK)
* @see #disconnect(REQUEST_LINK)
*/
public static interface REQUEST_LINK {
/**
* Called when a pad connection has been requested.
* @param pad the pad that emitted the signal.
* @param peer the peer pad for which a connection is requested.
*/
public void requestLink(Pad pad, Pad peer);
}
/**
* Signal emitted when an event passes through this Pad.
*
* @see #addEventProbe(EVENT_PROBE)
* @see #removeEventProbe(EVENT_PROBE)
*/
public static interface EVENT_PROBE {
public boolean eventReceived(Pad pad, Event event);
}
/**
* Add a listener for the have-data signal on this {@link Pad}
*
* @param listener The listener to be called when data is available.
*/
public void connect(final HAVE_DATA listener) {
connect(HAVE_DATA.class, listener, new GstCallback() {
@SuppressWarnings("unused")
public boolean callback(Pad pad, Buffer buffer) {
listener.haveData(pad, buffer);
return true;
}
});
}
/**
* Remove a listener for the have-data signal on this {@link Pad}
*
* @param listener The listener previously added for this signal.
*/
public void disconnect(HAVE_DATA listener) {
disconnect(HAVE_DATA.class, listener);
}
/**
* Add a listener for the linked signal on this {@link Pad}
*
* @param listener The listener to be called when a peer {@link Pad} is linked.
*/
public void connect(final LINKED listener) {
connect(LINKED.class, listener, new GstCallback() {
@SuppressWarnings("unused")
public boolean callback(Pad pad, Pad peer, Pointer user_data) {
listener.linked(pad, peer);
return true;
}
});
}
/**
* Remove a listener for the linked signal on this {@link Pad}
*
* @param listener The listener previously added for this signal.
*/
public void disconnect(LINKED listener) {
disconnect(LINKED.class, listener);
}
/**
* Add a listener for the unlinked signal on this {@link Pad}
*
* @param listener The listener to be called when when a peer {@link Pad} is unlinked.
*/
public void connect(final UNLINKED listener) {
connect(UNLINKED.class, listener, new GstCallback() {
@SuppressWarnings("unused")
public boolean callback(Pad pad, Pad peer, Pointer user_data) {
listener.unlinked(pad, peer);
return true;
}
});
}
/**
* Remove a listener for the unlinked signal on this {@link Pad}
*
* @param listener The listener previously added for this signal.
*/
public void disconnect(UNLINKED listener) {
disconnect(UNLINKED.class, listener);
}
/**
* Add a listener for the request-link signal on this {@link Pad}
*
* @param listener The listener to be called when a peer {@link Pad} requests
* to be linked to this one.
*/
public void connect(final REQUEST_LINK listener) {
connect(REQUEST_LINK.class, listener, new GstCallback() {
@SuppressWarnings("unused")
public boolean callback(Pad pad, Pad peer, Pointer user_daa) {
listener.requestLink(pad, peer);
return true;
}
});
}
/**
* Remove a listener for the request-link signal on this {@link Pad}
*
* @param listener The listener previously added for this signal.
*/
public void disconnect(REQUEST_LINK listener) {
disconnect(REQUEST_LINK.class, listener);
}
public void addEventProbe(final EVENT_PROBE listener) {
final GstPadAPI.PadEventProbe probe = new GstPadAPI.PadEventProbe() {
public boolean callback(Pad pad, Event ev, Pointer unused) {
//We have to negate the return value to keep consistency with gstreamer's API
return !listener.eventReceived(pad, ev);
}
};
GCallback cb = new GCallback(gst.gst_pad_add_event_probe(this, probe, null), probe) {
@Override
protected void disconnect() {
gst.gst_pad_remove_event_probe(Pad.this, id);
}
};
addCallback(EVENT_PROBE.class, listener, cb);
}
public void removeEventProbe(EVENT_PROBE listener) {
removeCallback(EVENT_PROBE.class, listener);
}
/**
* Sends the event to this pad.
*
This function can be used by applications to send events in the pipeline.
*
*
If this pad is a source pad, event should be an upstream event.
* If this pad is a sink pad, event should be a downstream event.
*
For example, you would not send a {@link EventType#EOS} on a src pad;
* EOS events only propagate downstream.
*
*
Furthermore, some downstream events have to be serialized with data flow,
* like EOS, while some can travel out-of-band, like {@link EventType#FLUSH_START}. If
* the event needs to be serialized with data flow, this function will take the
* pad's stream lock while calling its event function.
*
* @param event the event to send.
* @return true if the event was handled.
*/
public boolean sendEvent(Event event) {
return gst.gst_pad_send_event(this, event);
}
/**
* Sends the event to the peer of this pad.
*
*
This function is mainly used by elements to send events to their peer elements.
*
* @param event the event to send
* @return true if the event was handled
*/
public boolean pushEvent(Event event) {
return gst.gst_pad_push_event(this, event);
}
/**
* Chain a buffer to pad.
*
* The function returns {@link org.gstreamer.FlowReturn#WRONG_STATE} if the pad was flushing.
*
* If the caps on buffer are different from the current caps on pad, this function will call any
* function installed on pad (see gst_pad_set_setcaps_function()).
* If the new caps are not acceptable for pad, this function returns
* {@link org.gstreamer.FlowReturn#NOT_NEGOTIATED}.
*
* The function proceeds calling the chain function installed on pad and the return value of that function is
* returned to the caller. {@link org.gstreamer.FlowReturn#NOT_SUPPORTED} is returned if pad has no chain function.
*
* In all cases, success or failure, the caller loses its reference to buffer after calling this function.
*
* @param buffer the Buffer, returns {@link org.gstreamer.FlowReturn#ERROR} if NULL.
* @return a org.gstreamer.FlowReturn
*/
public FlowReturn chain(Buffer buffer) {
return gst.gst_pad_chain(this, buffer);
}
/**
* When pad is flushing this function returns {@link org.gstreamer.FlowReturn#WRONG_STATE} immediatly.
*
* Calls the getRange function of pad, see GstPadGetRangeFunction for a description of a getRange function.
* If pad has no getRange function installed (see gst_pad_set_getrange_function()) this function returns
* {@link FlowReturn#NOT_SUPPORTED}.
*
* This is a lowlevel function. Usualy {@link Pad#pullRange} is used.
*
* @param offset The start offset of the buffer
* @param size The length of the buffer
* @param buffer the Buffer, returns {@link FlowReturn#ERROR} if NULL.
* @return a FlowReturn from the peer pad. When this function returns OK, buffer will contain a valid Buffer.
*/
public FlowReturn getRange(long offset, int size, Buffer[] buffer) {
return gst.gst_pad_get_range(this, offset, size, buffer);
}
/**
* Pulls a buffer from the peer pad.
*
* This function will first trigger the pad block signal if it was installed.
*
* When pad is not linked {@link FlowReturn#NOT_LINKED} is returned else this function returns
* the result of {@link Pad#getRange} on the peer pad. See {@link Pad#getRange} for a list of return values and for
* the semantics of the arguments of this function.
*
* buffer's caps must either be unset or the same as what is already configured on pad.
* Renegotiation within a running pull-mode pipeline is not supported.
* @param offset The start offset of the buffer
* @param size The length of the buffer
* @param buffer the Buffer, returns {@link FlowReturn#ERROR} if NULL.
* @return a FlowReturn from the peer pad. When this function returns OK, buffer will contain a valid Buffer.
* MT safe.
*/
public FlowReturn pullRange(long offset, int size, Buffer[] buffer) {
return gst.gst_pad_pull_range(this, offset, size, buffer);
}
}