gstreamer/tutorials/android-tutorial-2/jni/tutorial-2.c
2016-10-09 15:24:09 +02:00

275 lines
10 KiB
C

#include <string.h>
#include <jni.h>
#include <android/log.h>
#include <gst/gst.h>
#include <pthread.h>
GST_DEBUG_CATEGORY_STATIC (debug_category);
#define GST_CAT_DEFAULT debug_category
/*
* These macros provide a way to store the native pointer to CustomData, which might be 32 or 64 bits, into
* a jlong, which is always 64 bits, without warnings.
*/
#if GLIB_SIZEOF_VOID_P == 8
# define GET_CUSTOM_DATA(env, thiz, fieldID) (CustomData *)(*env)->GetLongField (env, thiz, fieldID)
# define SET_CUSTOM_DATA(env, thiz, fieldID, data) (*env)->SetLongField (env, thiz, fieldID, (jlong)data)
#else
# define GET_CUSTOM_DATA(env, thiz, fieldID) (CustomData *)(jint)(*env)->GetLongField (env, thiz, fieldID)
# define SET_CUSTOM_DATA(env, thiz, fieldID, data) (*env)->SetLongField (env, thiz, fieldID, (jlong)(jint)data)
#endif
/* Structure to contain all our information, so we can pass it to callbacks */
typedef struct _CustomData {
jobject app; /* Application instance, used to call its methods. A global reference is kept. */
GstElement *pipeline; /* The running pipeline */
GMainContext *context; /* GLib context used to run the main loop */
GMainLoop *main_loop; /* GLib main loop */
gboolean initialized; /* To avoid informing the UI multiple times about the initialization */
} CustomData;
/* These global variables cache values which are not changing during execution */
static pthread_t gst_app_thread;
static pthread_key_t current_jni_env;
static JavaVM *java_vm;
static jfieldID custom_data_field_id;
static jmethodID set_message_method_id;
static jmethodID on_gstreamer_initialized_method_id;
/*
* Private methods
*/
/* Register this thread with the VM */
static JNIEnv *attach_current_thread (void) {
JNIEnv *env;
JavaVMAttachArgs args;
GST_DEBUG ("Attaching thread %p", g_thread_self ());
args.version = JNI_VERSION_1_4;
args.name = NULL;
args.group = NULL;
if ((*java_vm)->AttachCurrentThread (java_vm, &env, &args) < 0) {
GST_ERROR ("Failed to attach current thread");
return NULL;
}
return env;
}
/* Unregister this thread from the VM */
static void detach_current_thread (void *env) {
GST_DEBUG ("Detaching thread %p", g_thread_self ());
(*java_vm)->DetachCurrentThread (java_vm);
}
/* Retrieve the JNI environment for this thread */
static JNIEnv *get_jni_env (void) {
JNIEnv *env;
if ((env = pthread_getspecific (current_jni_env)) == NULL) {
env = attach_current_thread ();
pthread_setspecific (current_jni_env, env);
}
return env;
}
/* Change the content of the UI's TextView */
static void set_ui_message (const gchar *message, CustomData *data) {
JNIEnv *env = get_jni_env ();
GST_DEBUG ("Setting message to: %s", message);
jstring jmessage = (*env)->NewStringUTF(env, message);
(*env)->CallVoidMethod (env, data->app, set_message_method_id, jmessage);
if ((*env)->ExceptionCheck (env)) {
GST_ERROR ("Failed to call Java method");
(*env)->ExceptionClear (env);
}
(*env)->DeleteLocalRef (env, jmessage);
}
/* Retrieve errors from the bus and show them on the UI */
static void error_cb (GstBus *bus, GstMessage *msg, CustomData *data) {
GError *err;
gchar *debug_info;
gchar *message_string;
gst_message_parse_error (msg, &err, &debug_info);
message_string = g_strdup_printf ("Error received from element %s: %s", GST_OBJECT_NAME (msg->src), err->message);
g_clear_error (&err);
g_free (debug_info);
set_ui_message (message_string, data);
g_free (message_string);
gst_element_set_state (data->pipeline, GST_STATE_NULL);
}
/* Notify UI about pipeline state changes */
static void state_changed_cb (GstBus *bus, GstMessage *msg, CustomData *data) {
GstState old_state, new_state, pending_state;
gst_message_parse_state_changed (msg, &old_state, &new_state, &pending_state);
/* Only pay attention to messages coming from the pipeline, not its children */
if (GST_MESSAGE_SRC (msg) == GST_OBJECT (data->pipeline)) {
gchar *message = g_strdup_printf("State changed to %s", gst_element_state_get_name(new_state));
set_ui_message(message, data);
g_free (message);
}
}
/* Check if all conditions are met to report GStreamer as initialized.
* These conditions will change depending on the application */
static void check_initialization_complete (CustomData *data) {
JNIEnv *env = get_jni_env ();
if (!data->initialized && data->main_loop) {
GST_DEBUG ("Initialization complete, notifying application. main_loop:%p", data->main_loop);
(*env)->CallVoidMethod (env, data->app, on_gstreamer_initialized_method_id);
if ((*env)->ExceptionCheck (env)) {
GST_ERROR ("Failed to call Java method");
(*env)->ExceptionClear (env);
}
data->initialized = TRUE;
}
}
/* Main method for the native code. This is executed on its own thread. */
static void *app_function (void *userdata) {
JavaVMAttachArgs args;
GstBus *bus;
CustomData *data = (CustomData *)userdata;
GSource *bus_source;
GError *error = NULL;
GST_DEBUG ("Creating pipeline in CustomData at %p", data);
/* Create our own GLib Main Context and make it the default one */
data->context = g_main_context_new ();
g_main_context_push_thread_default(data->context);
/* Build pipeline */
data->pipeline = gst_parse_launch("audiotestsrc ! audioconvert ! audioresample ! autoaudiosink", &error);
if (error) {
gchar *message = g_strdup_printf("Unable to build pipeline: %s", error->message);
g_clear_error (&error);
set_ui_message(message, data);
g_free (message);
return NULL;
}
/* Instruct the bus to emit signals for each received message, and connect to the interesting signals */
bus = gst_element_get_bus (data->pipeline);
bus_source = gst_bus_create_watch (bus);
g_source_set_callback (bus_source, (GSourceFunc) gst_bus_async_signal_func, NULL, NULL);
g_source_attach (bus_source, data->context);
g_source_unref (bus_source);
g_signal_connect (G_OBJECT (bus), "message::error", (GCallback)error_cb, data);
g_signal_connect (G_OBJECT (bus), "message::state-changed", (GCallback)state_changed_cb, data);
gst_object_unref (bus);
/* Create a GLib Main Loop and set it to run */
GST_DEBUG ("Entering main loop... (CustomData:%p)", data);
data->main_loop = g_main_loop_new (data->context, FALSE);
check_initialization_complete (data);
g_main_loop_run (data->main_loop);
GST_DEBUG ("Exited main loop");
g_main_loop_unref (data->main_loop);
data->main_loop = NULL;
/* Free resources */
g_main_context_pop_thread_default(data->context);
g_main_context_unref (data->context);
gst_element_set_state (data->pipeline, GST_STATE_NULL);
gst_object_unref (data->pipeline);
return NULL;
}
/*
* Java Bindings
*/
/* Instruct the native code to create its internal data structure, pipeline and thread */
static void gst_native_init (JNIEnv* env, jobject thiz) {
CustomData *data = g_new0 (CustomData, 1);
SET_CUSTOM_DATA (env, thiz, custom_data_field_id, data);
GST_DEBUG_CATEGORY_INIT (debug_category, "tutorial-2", 0, "Android tutorial 2");
gst_debug_set_threshold_for_name("tutorial-2", GST_LEVEL_DEBUG);
GST_DEBUG ("Created CustomData at %p", data);
data->app = (*env)->NewGlobalRef (env, thiz);
GST_DEBUG ("Created GlobalRef for app object at %p", data->app);
pthread_create (&gst_app_thread, NULL, &app_function, data);
}
/* Quit the main loop, remove the native thread and free resources */
static void gst_native_finalize (JNIEnv* env, jobject thiz) {
CustomData *data = GET_CUSTOM_DATA (env, thiz, custom_data_field_id);
if (!data) return;
GST_DEBUG ("Quitting main loop...");
g_main_loop_quit (data->main_loop);
GST_DEBUG ("Waiting for thread to finish...");
pthread_join (gst_app_thread, NULL);
GST_DEBUG ("Deleting GlobalRef for app object at %p", data->app);
(*env)->DeleteGlobalRef (env, data->app);
GST_DEBUG ("Freeing CustomData at %p", data);
g_free (data);
SET_CUSTOM_DATA (env, thiz, custom_data_field_id, NULL);
GST_DEBUG ("Done finalizing");
}
/* Set pipeline to PLAYING state */
static void gst_native_play (JNIEnv* env, jobject thiz) {
CustomData *data = GET_CUSTOM_DATA (env, thiz, custom_data_field_id);
if (!data) return;
GST_DEBUG ("Setting state to PLAYING");
gst_element_set_state (data->pipeline, GST_STATE_PLAYING);
}
/* Set pipeline to PAUSED state */
static void gst_native_pause (JNIEnv* env, jobject thiz) {
CustomData *data = GET_CUSTOM_DATA (env, thiz, custom_data_field_id);
if (!data) return;
GST_DEBUG ("Setting state to PAUSED");
gst_element_set_state (data->pipeline, GST_STATE_PAUSED);
}
/* Static class initializer: retrieve method and field IDs */
static jboolean gst_native_class_init (JNIEnv* env, jclass klass) {
custom_data_field_id = (*env)->GetFieldID (env, klass, "native_custom_data", "J");
set_message_method_id = (*env)->GetMethodID (env, klass, "setMessage", "(Ljava/lang/String;)V");
on_gstreamer_initialized_method_id = (*env)->GetMethodID (env, klass, "onGStreamerInitialized", "()V");
if (!custom_data_field_id || !set_message_method_id || !on_gstreamer_initialized_method_id) {
/* We emit this message through the Android log instead of the GStreamer log because the later
* has not been initialized yet.
*/
__android_log_print (ANDROID_LOG_ERROR, "tutorial-2", "The calling class does not implement all necessary interface methods");
return JNI_FALSE;
}
return JNI_TRUE;
}
/* List of implemented native methods */
static JNINativeMethod native_methods[] = {
{ "nativeInit", "()V", (void *) gst_native_init},
{ "nativeFinalize", "()V", (void *) gst_native_finalize},
{ "nativePlay", "()V", (void *) gst_native_play},
{ "nativePause", "()V", (void *) gst_native_pause},
{ "nativeClassInit", "()Z", (void *) gst_native_class_init}
};
/* Library initializer */
jint JNI_OnLoad(JavaVM *vm, void *reserved) {
JNIEnv *env = NULL;
java_vm = vm;
if ((*vm)->GetEnv(vm, (void**) &env, JNI_VERSION_1_4) != JNI_OK) {
__android_log_print (ANDROID_LOG_ERROR, "tutorial-2", "Could not retrieve JNIEnv");
return 0;
}
jclass klass = (*env)->FindClass (env, "org/freedesktop/gstreamer/tutorials/tutorial_2/Tutorial2");
(*env)->RegisterNatives (env, klass, native_methods, G_N_ELEMENTS(native_methods));
pthread_key_create (&current_jni_env, detach_current_thread);
return JNI_VERSION_1_4;
}