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/*
* Copyright (c) 2007 Wayne Meissner
*
* 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 shutdownTasks = Collections.synchronizedList(new ArrayList());
private static final GstAPI gst = GstNative.load(GstAPI.class);
/** Creates a new instance of Gst */
private Gst() {
}
/**
* Gets the version of gstreamer currently in use.
*
* @return the version of gstreamer
*/
public static Version getVersion() {
long[] major = { 0 }, minor = { 0 }, micro = { 0 }, nano = { 0 };
gst.gst_version(major, minor, micro, nano);
return new Version(major[0], minor[0], micro[0], nano[0]);
}
/**
* Gets the the version of gstreamer currently in use, as a String.
*
* @return a string representation of the version.
*/
public static String getVersionString() {
return gst.gst_version_string();
}
/**
* Gets the common {@code Executor} used to execute background tasks.
*
* @return an executor that can be used for background tasks.
*/
public static Executor getExecutor() {
return getScheduledExecutorService();
}
/**
* Gets the common {@code ExecutorService} used to execute background tasks.
*
* @return an executor that can be used for background tasks.
*/
public static ExecutorService getExecutorService() {
return getScheduledExecutorService();
}
/**
* Gets the common {@code ScheduledExecutorService} used to execute
* background tasks and schedule timeouts.
*
* @return an executor that can be used for background tasks.
*/
public static ScheduledExecutorService getScheduledExecutorService() {
return executorService;
}
/**
* Signals the thread that called {@link #run} to return.
*/
public static void quit() {
quit.countDown();
}
/**
* Waits for the gstreamer system to shutdown via a call to {@link #quit}.
* For most gui programs, this is of little use. However, it can be
* a convenient way of keeping the main thread alive whilst gstreamer
* processing on other threads continues.
*/
public static void main() {
try {
CountDownLatch latch = quit;
if (latch != null) {
latch.await();
}
} catch (InterruptedException ex) {
} finally {
quit = new CountDownLatch(1);
}
}
/**
* Schedules a task for execution on the gstreamer background
* {@link java.util.concurrent.Executor}.
*
* @param task the task to execute.
*/
public static void invokeLater(final Runnable task) {
getExecutor().execute(task);
}
/**
* Executes a task on the gstreamer background
* {@link java.util.concurrent.Executor}, waiting until the task completes
* before returning.
*
* @param task the task to execute.
*/
public static void invokeAndWait(Runnable task) {
try {
getExecutorService().submit(task).get();
} catch (Exception ex) {
throw new RuntimeException(ex.getCause());
}
}
/**
* Gets the current main context used (if any).
*
* @return a main context.
*/
public static GMainContext getMainContext() {
return mainContext;
}
/**
* Initializes the GStreamer library.
*
This is a shortcut if no arguments are to be passed to gstreamer.
*
* @throws org.gstreamer.GstException
*/
public static final void init() throws GstException {
init("unknown", new String[] {});
}
/**
* Initializes the GStreamer library.
*
This sets up internal path lists, registers built-in elements, and
* loads standard plugins.
*
*
* This method should be called before calling any other GLib functions. If
* this is not an option, your program must initialise the GLib thread system
* using g_thread_init() before any other GLib functions are called.
*
*
* Note:
* This method will throw a GstException if it fails.
*
* @param progname the java program name.
* @param args the java argument list.
* @return the list of arguments with any gstreamer specific options stripped
* out.
* @throws org.gstreamer.GstException
*/
public static synchronized final String[] init(String progname, String[] args) throws GstException {
//
// Only do real init the first time through
//
if (initCount.getAndIncrement() > 0) {
return args;
}
NativeArgs argv = new NativeArgs(progname, args);
Logger.getLogger("org.gstreamer").setLevel(Level.WARNING);
Pointer[] error = { null };
if (!gst.gst_init_check(argv.argcRef, argv.argvRef, error)) {
initCount.decrementAndGet();
throw new GstException(new GError(new GErrorStruct(error[0])));
}
logger.fine("after gst_init, argc=" + argv.argcRef.getValue());
if (useDefaultContext) {
mainContext = GMainContext.getDefaultContext();
executorService = new MainContextExecutorService(mainContext);
} else {
mainContext = new GMainContext();
executorService = Executors.newSingleThreadScheduledExecutor(threadFactory);
}
quit = new CountDownLatch(1);
return argv.toStringArray();
}
/**
* Undoes all the initialization done in {@link #init}.
*
This will run any cleanup tasks, terminate any timers and other
* asynchronous tasks, and de-initialize the gstreamer library.
*/
public static synchronized final void deinit() {
//
// Only perform real shutdown if called as many times as Gst.init() is
//
if (initCount.decrementAndGet() > 0) {
return;
}
// Perform any cleanup tasks
for (Object task : shutdownTasks.toArray()) {
((Runnable) task).run();
}
// Stop any more tasks/timers from being scheduled
executorService.shutdown();
// Wake up the run thread.
quit();
// Wait for tasks to complete.
try {
if (!executorService.awaitTermination(100, TimeUnit.MILLISECONDS)) {
// Force-kill everything
executorService.shutdownNow();
}
} catch (InterruptedException ex) { }
mainContext = null;
System.gc(); // Make sure any dangling objects are unreffed before calling deinit().
gst.gst_deinit();
}
/**
* Adds a task to be called when {@link Gst#deinit} is called.
*
This is used internally, and is not recommended for other uses.
*
* @param task the task to execute.
*/
public static void addStaticShutdownTask(Runnable task) {
shutdownTasks.add(task);
}
/**
* Instructs gstreamer-java to use the default main context.
*
* This may be useful if integration with the GTK main loop is desirable,
* as all {@link Bus} signals and timers will be executed in the context
* of the GTK main loop.
*
* For the majority of programs though, it is better to wrap the individual
* listeners in a proxy which executes the listener in the appropriate
* context.
*
* @param useDefault if true, use the default glib main context.
*/
public static void setUseDefaultContext(boolean useDefault) {
useDefaultContext = useDefault;
}
// Make the gstreamer executor threads daemon, so they don't stop the main
// program from exiting
private static final ThreadFactory threadFactory = new ThreadFactory() {
private final AtomicInteger counter = new AtomicInteger(0);
/**
* Determines if Gst has been started from an applet and returns
* it's parent group.
*
* This is to avoid a problem where the service thread is killed when
* an applet is destroyed. If multiple applets are active simultaneously,
* this could be a problem.
*
* @return Applet's parent ("main") thread group or null, if not
* running inside an applet
*/
private ThreadGroup getThreadGroup() {
ThreadGroup tg = Thread.currentThread().getThreadGroup();
try {
Class atgClass = Class.forName("sun.applet.AppletThreadGroup");
return atgClass.isInstance(tg) ? tg.getParent() : null;
} catch (ClassNotFoundException ex) {
return null;
}
}
public Thread newThread(Runnable task) {
final String name = "gstreamer service thread " + counter.incrementAndGet();
Thread t = new Thread(getThreadGroup(), task, name);
t.setDaemon(true);
t.setPriority(Thread.NORM_PRIORITY);
return t;
}
};
}
class NativeArgs {
IntByReference argcRef;
PointerByReference argvRef;
Memory[] argsCopy;
Memory argvMemory;
public NativeArgs(String progname, String[] args) {
//
// Allocate some native memory to pass the args down to the native layer
//
argsCopy = new Memory[args.length + 2];
argvMemory = new Memory(argsCopy.length * Pointer.SIZE);
//
// Insert the program name as argv[0]
//
Memory arg = new Memory(progname.length() + 4);
arg.setString(0, progname, false);
argsCopy[0] = arg;
for (int i = 0; i < args.length; i++) {
arg = new Memory(args[i].length() + 1);
arg.setString(0, args[i], false);
argsCopy[i + 1] = arg;
}
argvMemory.write(0, argsCopy, 0, argsCopy.length);
argvRef = new PointerByReference(argvMemory);
argcRef = new IntByReference(args.length + 1);
}
String[] toStringArray() {
//
// Unpack the native arguments back into a String array
//
List args = new ArrayList();
Pointer argv = argvRef.getValue();
for (int i = 1; i < argcRef.getValue(); i++) {
Pointer arg = argv.getPointer(i * Pointer.SIZE);
if (arg != null) {
args.add(arg.getString(0, false));
}
}
return args.toArray(new String[args.size()]);
}
}