gstreamer/subprojects/gst-docs/examples/tutorials/playback-tutorial-1.c
Piotr Brzeziński 3bb8700577 macos: Add wrapper API to run a NSApplication in the main thread
On macOS, a Cocoa event loop is needed in the main thread to ensure
things like opening a GL window work correctly. In the past, this was
patched into glib via Cerbero, but that prevented us from updating it.
This workaround simply runs an NSApplication and then calls the
main function on a secondary thread, allowing GStreamer to correctly
display windows and/or system permission prompts, for example.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3532>
2022-12-13 17:50:32 +00:00

256 lines
7.8 KiB
C

#include <stdio.h>
#include <gst/gst.h>
#ifdef __APPLE__
#include <TargetConditionals.h>
#endif
/* Structure to contain all our information, so we can pass it around */
typedef struct _CustomData
{
GstElement *playbin; /* Our one and only element */
gint n_video; /* Number of embedded video streams */
gint n_audio; /* Number of embedded audio streams */
gint n_text; /* Number of embedded subtitle streams */
gint current_video; /* Currently playing video stream */
gint current_audio; /* Currently playing audio stream */
gint current_text; /* Currently playing subtitle stream */
GMainLoop *main_loop; /* GLib's Main Loop */
} CustomData;
/* playbin flags */
typedef enum
{
GST_PLAY_FLAG_VIDEO = (1 << 0), /* We want video output */
GST_PLAY_FLAG_AUDIO = (1 << 1), /* We want audio output */
GST_PLAY_FLAG_TEXT = (1 << 2) /* We want subtitle output */
} GstPlayFlags;
/* Forward definition for the message and keyboard processing functions */
static gboolean handle_message (GstBus * bus, GstMessage * msg,
CustomData * data);
static gboolean handle_keyboard (GIOChannel * source, GIOCondition cond,
CustomData * data);
int
tutorial_main (int argc, char *argv[])
{
CustomData data;
GstBus *bus;
GstStateChangeReturn ret;
gint flags;
GIOChannel *io_stdin;
/* Initialize GStreamer */
gst_init (&argc, &argv);
/* Create the elements */
data.playbin = gst_element_factory_make ("playbin", "playbin");
if (!data.playbin) {
g_printerr ("Not all elements could be created.\n");
return -1;
}
/* Set the URI to play */
g_object_set (data.playbin, "uri",
"https://www.freedesktop.org/software/gstreamer-sdk/data/media/sintel_cropped_multilingual.webm",
NULL);
/* Set flags to show Audio and Video but ignore Subtitles */
g_object_get (data.playbin, "flags", &flags, NULL);
flags |= GST_PLAY_FLAG_VIDEO | GST_PLAY_FLAG_AUDIO;
flags &= ~GST_PLAY_FLAG_TEXT;
g_object_set (data.playbin, "flags", flags, NULL);
/* Set connection speed. This will affect some internal decisions of playbin */
g_object_set (data.playbin, "connection-speed", 56, NULL);
/* Add a bus watch, so we get notified when a message arrives */
bus = gst_element_get_bus (data.playbin);
gst_bus_add_watch (bus, (GstBusFunc) handle_message, &data);
/* Add a keyboard watch so we get notified of keystrokes */
#ifdef G_OS_WIN32
io_stdin = g_io_channel_win32_new_fd (fileno (stdin));
#else
io_stdin = g_io_channel_unix_new (fileno (stdin));
#endif
g_io_add_watch (io_stdin, G_IO_IN, (GIOFunc) handle_keyboard, &data);
/* Start playing */
ret = gst_element_set_state (data.playbin, GST_STATE_PLAYING);
if (ret == GST_STATE_CHANGE_FAILURE) {
g_printerr ("Unable to set the pipeline to the playing state.\n");
gst_object_unref (data.playbin);
return -1;
}
/* Create a GLib Main Loop and set it to run */
data.main_loop = g_main_loop_new (NULL, FALSE);
g_main_loop_run (data.main_loop);
/* Free resources */
g_main_loop_unref (data.main_loop);
g_io_channel_unref (io_stdin);
gst_object_unref (bus);
gst_element_set_state (data.playbin, GST_STATE_NULL);
gst_object_unref (data.playbin);
return 0;
}
/* Extract some metadata from the streams and print it on the screen */
static void
analyze_streams (CustomData * data)
{
gint i;
GstTagList *tags;
gchar *str;
guint rate;
/* Read some properties */
g_object_get (data->playbin, "n-video", &data->n_video, NULL);
g_object_get (data->playbin, "n-audio", &data->n_audio, NULL);
g_object_get (data->playbin, "n-text", &data->n_text, NULL);
g_print ("%d video stream(s), %d audio stream(s), %d text stream(s)\n",
data->n_video, data->n_audio, data->n_text);
g_print ("\n");
for (i = 0; i < data->n_video; i++) {
tags = NULL;
/* Retrieve the stream's video tags */
g_signal_emit_by_name (data->playbin, "get-video-tags", i, &tags);
if (tags) {
g_print ("video stream %d:\n", i);
gst_tag_list_get_string (tags, GST_TAG_VIDEO_CODEC, &str);
g_print (" codec: %s\n", str ? str : "unknown");
g_free (str);
gst_tag_list_unref (tags);
}
}
g_print ("\n");
for (i = 0; i < data->n_audio; i++) {
tags = NULL;
/* Retrieve the stream's audio tags */
g_signal_emit_by_name (data->playbin, "get-audio-tags", i, &tags);
if (tags) {
g_print ("audio stream %d:\n", i);
if (gst_tag_list_get_string (tags, GST_TAG_AUDIO_CODEC, &str)) {
g_print (" codec: %s\n", str);
g_free (str);
}
if (gst_tag_list_get_string (tags, GST_TAG_LANGUAGE_CODE, &str)) {
g_print (" language: %s\n", str);
g_free (str);
}
if (gst_tag_list_get_uint (tags, GST_TAG_BITRATE, &rate)) {
g_print (" bitrate: %d\n", rate);
}
gst_tag_list_unref (tags);
}
}
g_print ("\n");
for (i = 0; i < data->n_text; i++) {
tags = NULL;
/* Retrieve the stream's subtitle tags */
g_signal_emit_by_name (data->playbin, "get-text-tags", i, &tags);
if (tags) {
g_print ("subtitle stream %d:\n", i);
if (gst_tag_list_get_string (tags, GST_TAG_LANGUAGE_CODE, &str)) {
g_print (" language: %s\n", str);
g_free (str);
}
gst_tag_list_unref (tags);
}
}
g_object_get (data->playbin, "current-video", &data->current_video, NULL);
g_object_get (data->playbin, "current-audio", &data->current_audio, NULL);
g_object_get (data->playbin, "current-text", &data->current_text, NULL);
g_print ("\n");
g_print
("Currently playing video stream %d, audio stream %d and text stream %d\n",
data->current_video, data->current_audio, data->current_text);
g_print
("Type any number and hit ENTER to select a different audio stream\n");
}
/* Process messages from GStreamer */
static gboolean
handle_message (GstBus * bus, GstMessage * msg, CustomData * data)
{
GError *err;
gchar *debug_info;
switch (GST_MESSAGE_TYPE (msg)) {
case GST_MESSAGE_ERROR:
gst_message_parse_error (msg, &err, &debug_info);
g_printerr ("Error received from element %s: %s\n",
GST_OBJECT_NAME (msg->src), err->message);
g_printerr ("Debugging information: %s\n",
debug_info ? debug_info : "none");
g_clear_error (&err);
g_free (debug_info);
g_main_loop_quit (data->main_loop);
break;
case GST_MESSAGE_EOS:
g_print ("End-Of-Stream reached.\n");
g_main_loop_quit (data->main_loop);
break;
case GST_MESSAGE_STATE_CHANGED:{
GstState old_state, new_state, pending_state;
gst_message_parse_state_changed (msg, &old_state, &new_state,
&pending_state);
if (GST_MESSAGE_SRC (msg) == GST_OBJECT (data->playbin)) {
if (new_state == GST_STATE_PLAYING) {
/* Once we are in the playing state, analyze the streams */
analyze_streams (data);
}
}
}
break;
default:
break;
}
/* We want to keep receiving messages */
return TRUE;
}
/* Process keyboard input */
static gboolean
handle_keyboard (GIOChannel * source, GIOCondition cond, CustomData * data)
{
gchar *str = NULL;
if (g_io_channel_read_line (source, &str, NULL, NULL,
NULL) == G_IO_STATUS_NORMAL) {
int index = g_ascii_strtoull (str, NULL, 0);
if (index < 0 || index >= data->n_audio) {
g_printerr ("Index out of bounds\n");
} else {
/* If the input was a valid audio stream index, set the current audio stream */
g_print ("Setting current audio stream to %d\n", index);
g_object_set (data->playbin, "current-audio", index, NULL);
}
}
g_free (str);
return TRUE;
}
int
main (int argc, char *argv[])
{
#if defined(__APPLE__) && TARGET_OS_MAC && !TARGET_OS_IPHONE
return gst_macos_main (tutorial_main, argc, argv, NULL);
#else
return tutorial_main (argc, argv);
#endif
}