gstreamer/ges/ges-timeline.c
2010-11-27 17:23:23 +01:00

819 lines
23 KiB
C

/* GStreamer Editing Services
* Copyright (C) 2009 Edward Hervey <edward.hervey@collabora.co.uk>
* 2009 Nokia Corporation
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
/**
* SECTION:ges-timeline
* @short_description: Multimedia timeline
*
* #GESTimeline is the central object for any multimedia timeline.
*
* Contains a list of #GESTimelineLayer which users should use to arrange the
* various timeline objects through time.
*
* The output type is determined by the #GESTrack that are set on
* the #GESTimeline.
*/
#include "gesmarshal.h"
#include "ges-internal.h"
#include "ges-timeline.h"
#include "ges-track.h"
#include "ges-timeline-layer.h"
#include "ges.h"
G_DEFINE_TYPE (GESTimeline, ges_timeline, GST_TYPE_BIN);
/* private structure to contain our track-related information */
typedef struct
{
GESTimeline *timeline;
GESTrack *track;
GstPad *pad; /* Pad from the track */
GstPad *ghostpad;
} TrackPrivate;
enum
{
TRACK_ADDED,
TRACK_REMOVED,
LAYER_ADDED,
LAYER_REMOVED,
LAST_SIGNAL
};
static GstBinClass *parent_class;
static guint ges_timeline_signals[LAST_SIGNAL] = { 0 };
gint custom_find_track (TrackPrivate * priv, GESTrack * track);
static GstStateChangeReturn
ges_timeline_change_state (GstElement * element, GstStateChange transition);
static void
discoverer_finished_cb (GstDiscoverer * discoverer, GESTimeline * timeline);
static void
discoverer_discovered_cb (GstDiscoverer * discoverer,
GstDiscovererInfo * info, GError * err, GESTimeline * timeline);
static void
ges_timeline_get_property (GObject * object, guint property_id,
GValue * value, GParamSpec * pspec)
{
switch (property_id) {
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
}
}
static void
ges_timeline_set_property (GObject * object, guint property_id,
const GValue * value, GParamSpec * pspec)
{
switch (property_id) {
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
}
}
static void
ges_timeline_dispose (GObject * object)
{
GESTimeline *timeline = GES_TIMELINE (object);
if (timeline->discoverer) {
gst_discoverer_stop (timeline->discoverer);
g_object_unref (timeline->discoverer);
timeline->discoverer = NULL;
}
while (timeline->layers) {
GESTimelineLayer *layer = (GESTimelineLayer *) timeline->layers->data;
ges_timeline_remove_layer (timeline, layer);
}
/* FIXME: it should be possible to remove tracks before removing
* layers, but at the moment this creates a problem because the track
* objects aren't notified that their gnlobjects have been destroyed.
*/
while (timeline->tracks) {
TrackPrivate *priv = (TrackPrivate *) timeline->tracks->data;
ges_timeline_remove_track (timeline, priv->track);
}
G_OBJECT_CLASS (ges_timeline_parent_class)->dispose (object);
}
static void
ges_timeline_finalize (GObject * object)
{
G_OBJECT_CLASS (ges_timeline_parent_class)->finalize (object);
}
static void
ges_timeline_class_init (GESTimelineClass * klass)
{
GObjectClass *object_class = G_OBJECT_CLASS (klass);
GstElementClass *element_class = GST_ELEMENT_CLASS (klass);
parent_class = g_type_class_peek_parent (klass);
element_class->change_state = ges_timeline_change_state;
object_class->get_property = ges_timeline_get_property;
object_class->set_property = ges_timeline_set_property;
object_class->dispose = ges_timeline_dispose;
object_class->finalize = ges_timeline_finalize;
/**
* GESTimeline::track-added
* @timeline: the #GESTimeline
* @track: the #GESTrack that was added to the timeline
*
* Will be emitted after the track was added to the timeline.
*/
ges_timeline_signals[TRACK_ADDED] =
g_signal_new ("track-added", G_TYPE_FROM_CLASS (klass),
G_SIGNAL_RUN_FIRST, G_STRUCT_OFFSET (GESTimelineClass, track_added), NULL,
NULL, ges_marshal_VOID__OBJECT, G_TYPE_NONE, 1, GES_TYPE_TRACK);
/**
* GESTimeline::track-removed
* @timeline: the #GESTimeline
* @track: the #GESTrack that was removed from the timeline
*
* Will be emitted after the track was removed from the timeline.
*/
ges_timeline_signals[TRACK_REMOVED] =
g_signal_new ("track-removed", G_TYPE_FROM_CLASS (klass),
G_SIGNAL_RUN_FIRST, G_STRUCT_OFFSET (GESTimelineClass, track_removed),
NULL, NULL, ges_marshal_VOID__OBJECT, G_TYPE_NONE, 1, GES_TYPE_TRACK);
/**
* GESTimeline::layer-added
* @timeline: the #GESTimeline
* @layer: the #GESTimelineLayer that was added to the timeline
*
* Will be emitted after the layer was added to the timeline.
*/
ges_timeline_signals[LAYER_ADDED] =
g_signal_new ("layer-added", G_TYPE_FROM_CLASS (klass),
G_SIGNAL_RUN_FIRST, G_STRUCT_OFFSET (GESTimelineClass, layer_added), NULL,
NULL, ges_marshal_VOID__OBJECT, G_TYPE_NONE, 1, GES_TYPE_TIMELINE_LAYER);
/**
* GESTimeline::layer-removed
* @timeline: the #GESTimeline
* @layer: the #GESTimelineLayer that was removed from the timeline
*
* Will be emitted after the layer was removed from the timeline.
*/
ges_timeline_signals[LAYER_REMOVED] =
g_signal_new ("layer-removed", G_TYPE_FROM_CLASS (klass),
G_SIGNAL_RUN_FIRST, G_STRUCT_OFFSET (GESTimelineClass, layer_removed),
NULL, NULL, ges_marshal_VOID__OBJECT, G_TYPE_NONE, 1,
GES_TYPE_TIMELINE_LAYER);
}
static void
ges_timeline_init (GESTimeline * self)
{
self->layers = NULL;
self->tracks = NULL;
/* New discoverer with a 15s timeout */
self->discoverer = gst_discoverer_new (15 * GST_SECOND, NULL);
g_signal_connect (self->discoverer, "finished",
G_CALLBACK (discoverer_finished_cb), self);
g_signal_connect (self->discoverer, "discovered",
G_CALLBACK (discoverer_discovered_cb), self);
gst_discoverer_start (self->discoverer);
}
/**
* ges_timeline_new:
*
* Creates a new empty #GESTimeline.
*
* Returns: The new timeline.
*/
GESTimeline *
ges_timeline_new (void)
{
return g_object_new (GES_TYPE_TIMELINE, NULL);
}
/**
* ges_timeline_load_from_uri:
* @uri: The URI to load from
*
* Creates a timeline from the contents of given uri.
*
* NOT_IMPLEMENTED !
*
* Returns: A new #GESTimeline if loading was successful, else NULL.
*/
GESTimeline *
ges_timeline_load_from_uri (gchar * uri)
{
/* FIXME : IMPLEMENT */
return NULL;
}
/**
* ges_timeline_save:
* @timeline: a #GESTimeline
* @uri: The location to save to
*
* Saves the timeline to the given location
*
* NOT_IMPLEMENTED !
*
* Returns: TRUE if the timeline was successfully saved to the given location,
* else FALSE.
*/
gboolean
ges_timeline_save (GESTimeline * timeline, gchar * uri)
{
/* FIXME : IMPLEMENT */
return FALSE;
}
static void
add_object_to_track (GESTimelineObject * object, GESTrack * track)
{
if (!ges_timeline_object_create_track_objects (object, track)) {
GST_WARNING ("error creating track objects");
}
}
static void
add_object_to_tracks (GESTimeline * timeline, GESTimelineObject * object)
{
GList *tmp;
for (tmp = timeline->tracks; tmp; tmp = g_list_next (tmp)) {
TrackPrivate *priv = (TrackPrivate *) tmp->data;
GESTrack *track = priv->track;
GST_LOG ("Trying with track %p", track);
add_object_to_track (object, track);
}
}
static void
do_async_start (GESTimeline * timeline)
{
GstMessage *message;
GList *tmp;
timeline->async_pending = TRUE;
/* Freeze state of tracks */
for (tmp = timeline->tracks; tmp; tmp = tmp->next) {
TrackPrivate *priv = (TrackPrivate *) tmp->data;
gst_element_set_locked_state ((GstElement *) priv->track, TRUE);
}
message = gst_message_new_async_start (GST_OBJECT_CAST (timeline), FALSE);
parent_class->handle_message (GST_BIN_CAST (timeline), message);
}
static void
do_async_done (GESTimeline * timeline)
{
GstMessage *message;
if (timeline->async_pending) {
GList *tmp;
/* Unfreeze state of tracks */
for (tmp = timeline->tracks; tmp; tmp = tmp->next) {
TrackPrivate *priv = (TrackPrivate *) tmp->data;
gst_element_set_locked_state ((GstElement *) priv->track, FALSE);
gst_element_sync_state_with_parent ((GstElement *) priv->track);
}
GST_DEBUG_OBJECT (timeline, "Emitting async-done");
message = gst_message_new_async_done (GST_OBJECT_CAST (timeline));
parent_class->handle_message (GST_BIN_CAST (timeline), message);
timeline->async_pending = FALSE;
}
}
static void
discoverer_finished_cb (GstDiscoverer * discoverer, GESTimeline * timeline)
{
do_async_done (timeline);
}
static void
discoverer_discovered_cb (GstDiscoverer * discoverer,
GstDiscovererInfo * info, GError * err, GESTimeline * timeline)
{
GList *tmp;
gboolean found = FALSE;
gboolean is_image = FALSE;
GESTimelineFileSource *tfs = NULL;
const gchar *uri = gst_discoverer_info_get_uri (info);
GST_DEBUG ("Discovered uri %s", uri);
/* Find corresponding TimelineFileSource in the sources */
for (tmp = timeline->pendingobjects; tmp; tmp = tmp->next) {
tfs = (GESTimelineFileSource *) tmp->data;
if (!g_strcmp0 (tfs->uri, uri)) {
found = TRUE;
break;
}
}
if (found) {
GList *stream_list;
/* Remove object from list */
timeline->pendingobjects =
g_list_delete_link (timeline->pendingobjects, tmp);
/* FIXME : Handle errors in discovery */
stream_list = gst_discoverer_info_get_stream_list (info);
/* Update timelinefilesource properties based on info */
for (tmp = stream_list; tmp; tmp = tmp->next) {
GstDiscovererStreamInfo *sinf = (GstDiscovererStreamInfo *) tmp->data;
if (GST_IS_DISCOVERER_AUDIO_INFO (sinf))
tfs->supportedformats |= GES_TRACK_TYPE_AUDIO;
else if (GST_IS_DISCOVERER_VIDEO_INFO (sinf)) {
tfs->supportedformats |= GES_TRACK_TYPE_VIDEO;
if (gst_discoverer_video_info_is_image ((GstDiscovererVideoInfo *)
sinf)) {
tfs->supportedformats |= GES_TRACK_TYPE_AUDIO;
is_image = TRUE;
}
}
}
if (stream_list)
gst_discoverer_stream_info_list_free (stream_list);
if (is_image) {
/* don't set max-duration on still images */
g_object_set (tfs, "is_image", (gboolean) TRUE, NULL);
}
else {
g_object_set (tfs, "max-duration",
gst_discoverer_info_get_duration (info), NULL);
}
/* Continue the processing on tfs */
add_object_to_tracks (timeline, GES_TIMELINE_OBJECT (tfs));
}
}
static GstStateChangeReturn
ges_timeline_change_state (GstElement * element, GstStateChange transition)
{
GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
GESTimeline *timeline = GES_TIMELINE (element);
switch (transition) {
case GST_STATE_CHANGE_READY_TO_PAUSED:
if (timeline->pendingobjects) {
do_async_start (timeline);
ret = GST_STATE_CHANGE_ASYNC;
}
break;
default:
break;
}
{
GstStateChangeReturn bret;
bret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
if (G_UNLIKELY (bret == GST_STATE_CHANGE_NO_PREROLL)) {
do_async_done (timeline);
ret = bret;
}
}
switch (transition) {
case GST_STATE_CHANGE_PAUSED_TO_READY:
do_async_done (timeline);
break;
default:
break;
}
return ret;
}
static void
layer_object_added_cb (GESTimelineLayer * layer, GESTimelineObject * object,
GESTimeline * timeline)
{
GST_DEBUG ("New TimelineObject %p added to layer %p", object, layer);
if (GES_IS_TIMELINE_FILE_SOURCE (object)) {
GESTimelineFileSource *tfs = GES_TIMELINE_FILE_SOURCE (object);
/* Send the filesource to the discoverer if:
* * it doesn't have specified supported formats
* * OR it doesn't have a specified max-duration
* * OR it doesn't have a valid duration */
if (tfs->supportedformats == GES_TRACK_TYPE_UNKNOWN ||
tfs->maxduration == GST_CLOCK_TIME_NONE || object->duration == 0) {
GST_LOG ("Incomplete TimelineFileSource, discovering it");
timeline->pendingobjects =
g_list_append (timeline->pendingobjects, object);
gst_discoverer_discover_uri_async (timeline->discoverer,
GES_TIMELINE_FILE_SOURCE (object)->uri);
} else
add_object_to_tracks (timeline, object);
} else {
add_object_to_tracks (timeline, object);
}
GST_DEBUG ("done");
}
static void
layer_object_removed_cb (GESTimelineLayer * layer, GESTimelineObject * object,
GESTimeline * timeline)
{
GList *tmp, *next;
GST_DEBUG ("TimelineObject %p removed from layer %p", object, layer);
/* Go over the object's track objects and figure out which one belongs to
* the list of tracks we control */
for (tmp = object->trackobjects; tmp; tmp = next) {
GESTrackObject *trobj = (GESTrackObject *) tmp->data;
next = g_list_next (tmp);
GST_DEBUG ("Trying to remove TrackObject %p", trobj);
if (G_LIKELY (g_list_find_custom (timeline->tracks,
(gconstpointer) trobj->track,
(GCompareFunc) custom_find_track))) {
GST_DEBUG ("Belongs to one of the tracks we control");
ges_track_remove_object (trobj->track, trobj);
ges_timeline_object_release_track_object (object, trobj);
}
}
GST_DEBUG ("Done");
}
/**
* ges_timeline_add_layer:
* @timeline: a #GESTimeline
* @layer: the #GESTimelineLayer to add
*
* Add the layer to the timeline. The reference to the @layer will be stolen
* by the @timeline.
*
* Returns: TRUE if the layer was properly added, else FALSE.
*/
gboolean
ges_timeline_add_layer (GESTimeline * timeline, GESTimelineLayer * layer)
{
GList *objects, *tmp;
GST_DEBUG ("timeline:%p, layer:%p", timeline, layer);
/* We can only add a layer that doesn't already belong to another timeline */
if (G_UNLIKELY (layer->timeline)) {
GST_WARNING ("Layer belongs to another timeline, can't add it");
return FALSE;
}
/* Add to the list of layers, make sure we don't already control it */
if (G_UNLIKELY (g_list_find (timeline->layers, (gconstpointer) layer))) {
GST_WARNING ("Layer is already controlled by this timeline");
return FALSE;
}
/* Reference is stolen */
timeline->layers = g_list_append (timeline->layers, layer);
/* Inform the layer that it belongs to a new timeline */
ges_timeline_layer_set_timeline (layer, timeline);
/* Connect to 'object-added'/'object-removed' signal from the new layer */
g_signal_connect (layer, "object-added", G_CALLBACK (layer_object_added_cb),
timeline);
g_signal_connect (layer, "object-removed",
G_CALLBACK (layer_object_removed_cb), timeline);
GST_DEBUG ("Done adding layer, emitting 'layer-added' signal");
g_signal_emit (timeline, ges_timeline_signals[LAYER_ADDED], 0, layer);
/* add any existing timeline objects to the timeline */
objects = ges_timeline_layer_get_objects (layer);
for (tmp = objects; tmp; tmp = tmp->next) {
layer_object_added_cb (layer, tmp->data, timeline);
g_object_unref (tmp->data);
tmp->data = NULL;
}
g_list_free (objects);
return TRUE;
}
/**
* ges_timeline_remove_layer:
* @timeline: a #GESTimeline
* @layer: the #GESTimelineLayer to remove
*
* Removes the layer from the timeline. The reference that the @timeline holds on
* the layer will be dropped. If you wish to use the @layer after calling this
* method, you need to take a reference before calling.
*
* Returns: TRUE if the layer was properly removed, else FALSE.
*/
gboolean
ges_timeline_remove_layer (GESTimeline * timeline, GESTimelineLayer * layer)
{
GST_DEBUG ("timeline:%p, layer:%p", timeline, layer);
if (G_UNLIKELY (!g_list_find (timeline->layers, layer))) {
GST_WARNING ("Layer doesn't belong to this timeline");
return FALSE;
}
/* Disconnect signals */
GST_DEBUG ("Disconnecting signal callbacks");
g_signal_handlers_disconnect_by_func (layer, layer_object_added_cb, timeline);
g_signal_handlers_disconnect_by_func (layer, layer_object_removed_cb,
timeline);
timeline->layers = g_list_remove (timeline->layers, layer);
ges_timeline_layer_set_timeline (layer, NULL);
g_signal_emit (timeline, ges_timeline_signals[LAYER_REMOVED], 0, layer);
g_object_unref (layer);
return TRUE;
}
static void
pad_added_cb (GESTrack * track, GstPad * pad, TrackPrivate * priv)
{
gchar *padname;
GST_DEBUG ("track:%p, pad:%s:%s", track, GST_DEBUG_PAD_NAME (pad));
if (G_UNLIKELY (priv->pad)) {
GST_WARNING ("We are already controlling a pad for this track");
return;
}
/* Remember the pad */
priv->pad = pad;
/* ghost it ! */
GST_DEBUG ("Ghosting pad and adding it to ourself");
padname = g_strdup_printf ("track_%p_src", track);
priv->ghostpad = gst_ghost_pad_new (padname, pad);
g_free (padname);
gst_pad_set_active (priv->ghostpad, TRUE);
gst_element_add_pad (GST_ELEMENT (priv->timeline), priv->ghostpad);
}
static void
pad_removed_cb (GESTrack * track, GstPad * pad, TrackPrivate * priv)
{
GST_DEBUG ("track:%p, pad:%s:%s", track, GST_DEBUG_PAD_NAME (pad));
if (G_UNLIKELY (priv->pad != pad)) {
GST_WARNING ("Not the pad we're controlling");
return;
}
if (G_UNLIKELY (priv->ghostpad == NULL)) {
GST_WARNING ("We don't have a ghostpad for this pad !");
return;
}
GST_DEBUG ("Removing ghostpad");
gst_pad_set_active (priv->ghostpad, FALSE);
gst_element_remove_pad (GST_ELEMENT (priv->timeline), priv->ghostpad);
priv->ghostpad = NULL;
priv->pad = NULL;
}
gint
custom_find_track (TrackPrivate * priv, GESTrack * track)
{
if (priv->track == track)
return 0;
return -1;
}
/**
* ges_timeline_add_track:
* @timeline: a #GESTimeline
* @track: the #GESTrack to add
*
* Add a track to the timeline. The reference to the track will be stolen by the
* pipeline.
*
* Returns: TRUE if the track was properly added, else FALSE.
*/
gboolean
ges_timeline_add_track (GESTimeline * timeline, GESTrack * track)
{
TrackPrivate *priv;
GList *tmp;
GST_DEBUG ("timeline:%p, track:%p", timeline, track);
/* make sure we don't already control it */
if (G_UNLIKELY (g_list_find_custom (timeline->tracks, (gconstpointer) track,
(GCompareFunc) custom_find_track))) {
GST_WARNING ("Track is already controlled by this timeline");
return FALSE;
}
/* Add the track to ourself (as a GstBin)
* Reference is stolen ! */
if (G_UNLIKELY (!gst_bin_add (GST_BIN (timeline), GST_ELEMENT (track)))) {
GST_WARNING ("Couldn't add track to ourself (GST)");
return FALSE;
}
priv = g_new0 (TrackPrivate, 1);
priv->timeline = timeline;
priv->track = track;
/* Add the track to the list of tracks we track */
timeline->tracks = g_list_append (timeline->tracks, priv);
/* Listen to pad-added/-removed */
g_signal_connect (track, "pad-added", (GCallback) pad_added_cb, priv);
g_signal_connect (track, "pad-removed", (GCallback) pad_removed_cb, priv);
/* Inform the track that it's currently being used by ourself */
ges_track_set_timeline (track, timeline);
GST_DEBUG ("Done adding track, emitting 'track-added' signal");
/* emit 'track-added' */
g_signal_emit (timeline, ges_timeline_signals[TRACK_ADDED], 0, track);
/* ensure that each existing timeline object has the opportunity to create a
* track object for this track*/
for (tmp = timeline->layers; tmp; tmp = tmp->next) {
GList *objects, *obj;
objects = ges_timeline_layer_get_objects (tmp->data);
for (obj = objects; obj; obj = obj->next) {
add_object_to_track (obj->data, track);
g_object_unref (obj->data);
obj->data = NULL;
}
g_list_free (objects);
}
return TRUE;
}
/**
* ges_timeline_remove_track:
* @timeline: a #GESTimeline
* @track: the #GESTrack to remove
*
* Remove the @track from the @timeline. The reference stolen when adding the
* @track will be removed. If you wish to use the @track after calling this
* function you must ensure that you have a reference to it.
*
* Returns: TRUE if the @track was properly removed, else FALSE.
*/
gboolean
ges_timeline_remove_track (GESTimeline * timeline, GESTrack * track)
{
GList *tmp;
TrackPrivate *priv;
GST_DEBUG ("timeline:%p, track:%p", timeline, track);
if (G_UNLIKELY (!(tmp =
g_list_find_custom (timeline->tracks, (gconstpointer) track,
(GCompareFunc) custom_find_track)))) {
GST_WARNING ("Track doesn't belong to this timeline");
return FALSE;
}
priv = tmp->data;
timeline->tracks = g_list_remove (timeline->tracks, priv);
ges_track_set_timeline (track, NULL);
/* Remove ghost pad */
if (priv->ghostpad) {
GST_DEBUG ("Removing ghostpad");
gst_pad_set_active (priv->ghostpad, FALSE);
gst_ghost_pad_set_target ((GstGhostPad *) priv->ghostpad, NULL);
gst_element_remove_pad (GST_ELEMENT (timeline), priv->ghostpad);
}
/* Remove pad-added/-removed handlers */
g_signal_handlers_disconnect_by_func (track, pad_added_cb, priv);
g_signal_handlers_disconnect_by_func (track, pad_removed_cb, priv);
/* Signal track removal to all layers/objects */
g_signal_emit (timeline, ges_timeline_signals[TRACK_REMOVED], 0, track);
/* remove track from our bin */
if (G_UNLIKELY (!gst_bin_remove (GST_BIN (timeline), GST_ELEMENT (track)))) {
GST_WARNING ("Couldn't remove track to ourself (GST)");
return FALSE;
}
g_free (priv);
return TRUE;
}
/**
* ges_timeline_get_track_for_pad:
* @timeline: The #GESTimeline
* @pad: The #GstPad
*
* Search the #GESTrack corresponding to the given @timeline's @pad.
*
* Returns: The corresponding #GESTrack if it is found, or #NULL if there is
* an error.
*/
GESTrack *
ges_timeline_get_track_for_pad (GESTimeline * timeline, GstPad * pad)
{
GList *tmp;
for (tmp = timeline->tracks; tmp; tmp = g_list_next (tmp)) {
TrackPrivate *priv = (TrackPrivate *) tmp->data;
if (pad == priv->ghostpad)
return priv->track;
}
return NULL;
}
/**
* ges_timeline_get_tracks:
* @timeline: a #GESTimeline
*
* Returns the list of #GESTrack used by the Timeline.
*
* Returns: A list of #GESTrack. The caller should unref each track
* once he is done with them. */
GList *
ges_timeline_get_tracks (GESTimeline * timeline)
{
GList *tmp, *res = NULL;
for (tmp = timeline->tracks; tmp; tmp = g_list_next (tmp)) {
TrackPrivate *priv = (TrackPrivate *) tmp->data;
res = g_list_append (res, g_object_ref (priv->track));
}
return res;
}