adaptivedemux2: Add start/stop vfuncs

Remove the can_start() vfunc, in favour of vfuncs when the stream starts/stops,
allowing the sub-class to do custom logic before (or preventing) the stream from
starting and stopping.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3883>

subprojects/gst-plugins-good/ext/adaptivedemux2/gstadaptivedemux-stream.c

@@ -53,6 +53,10 @@ static void gst_adaptive_demux2_stream_update_track_ids (GstAdaptiveDemux2Stream
 static GstFlowReturn
 gst_adaptive_demux2_stream_submit_request_default (GstAdaptiveDemux2Stream *
     stream, DownloadRequest * download_req);
+static void
+gst_adaptive_demux2_stream_start_default (GstAdaptiveDemux2Stream * stream);
+static void
+gst_adaptive_demux2_stream_stop_default (GstAdaptiveDemux2Stream * stream);
 
 #define gst_adaptive_demux2_stream_parent_class parent_class
 G_DEFINE_ABSTRACT_TYPE (GstAdaptiveDemux2Stream, gst_adaptive_demux2_stream,
@@ -65,6 +69,8 @@ gst_adaptive_demux2_stream_class_init (GstAdaptiveDemux2StreamClass * klass)
 
   gobject_class->finalize = gst_adaptive_demux2_stream_finalize;
 
+  klass->start = gst_adaptive_demux2_stream_start_default;
+  klass->stop = gst_adaptive_demux2_stream_stop_default;
   klass->data_received = gst_adaptive_demux2_stream_data_received_default;
   klass->finish_fragment = gst_adaptive_demux2_stream_finish_fragment_default;
   klass->submit_request = gst_adaptive_demux2_stream_submit_request_default;
@@ -2066,45 +2072,35 @@ gst_adaptive_demux2_stream_next_download (GstAdaptiveDemux2Stream * stream)
   return gst_adaptive_demux2_stream_load_a_fragment (stream);
 }
 
-static gboolean
-gst_adaptive_demux2_stream_can_start (GstAdaptiveDemux2Stream * stream)
-{
-  GstAdaptiveDemux2StreamClass *klass =
-      GST_ADAPTIVE_DEMUX2_STREAM_GET_CLASS (stream);
-
-  if (!klass->can_start)
-    return TRUE;
-  return klass->can_start (stream);
-}
-
 /**
  * gst_adaptive_demux2_stream_start:
  * @stream: a #GstAdaptiveDemux2Stream
  *
- * Start the given @stream. Should be called by subclasses that previously
- * returned %FALSE in `GstAdaptiveDemux::stream_can_start()`
+ * Start the given @stream. Can be called by subclasses that previously
+ * returned %FALSE in `GstAdaptiveDemux2Stream::start()`, or from
+ * the demuxer when a stream should start downloading.
  */
 void
 gst_adaptive_demux2_stream_start (GstAdaptiveDemux2Stream * stream)
 {
-  GstAdaptiveDemux *demux;
-
   g_return_if_fail (stream && stream->demux);
 
-  demux = stream->demux;
-
   if (stream->pending_cb_id != 0 || stream->download_active) {
     /* There is already something active / pending on this stream */
     GST_LOG_OBJECT (stream, "Stream already running");
     return;
   }
 
-  /* Some streams require a delayed start, i.e. they need more information
-   * before they can actually be started */
-  if (!gst_adaptive_demux2_stream_can_start (stream)) {
-    GST_LOG_OBJECT (stream, "Stream will be started asynchronously");
-    return;
-  }
+  GstAdaptiveDemux2StreamClass *klass =
+      GST_ADAPTIVE_DEMUX2_STREAM_GET_CLASS (stream);
+
+  klass->start (stream);
+}
+
+static void
+gst_adaptive_demux2_stream_start_default (GstAdaptiveDemux2Stream * stream)
+{
+  GstAdaptiveDemux *demux = stream->demux;
 
   if (stream->state == GST_ADAPTIVE_DEMUX2_STREAM_STATE_EOS) {
     GST_LOG_OBJECT (stream, "Stream is EOS already");
@@ -2130,6 +2126,15 @@ gst_adaptive_demux2_stream_start (GstAdaptiveDemux2Stream * stream)
 
 void
 gst_adaptive_demux2_stream_stop (GstAdaptiveDemux2Stream * stream)
+{
+  GstAdaptiveDemux2StreamClass *klass =
+      GST_ADAPTIVE_DEMUX2_STREAM_GET_CLASS (stream);
+
+  klass->stop (stream);
+}
+
+static void
+gst_adaptive_demux2_stream_stop_default (GstAdaptiveDemux2Stream * stream)
 {
   GstAdaptiveDemux *demux = stream->demux;
 

subprojects/gst-plugins-good/ext/adaptivedemux2/gstadaptivedemux-stream.h

@@ -154,14 +154,26 @@ struct _GstAdaptiveDemux2StreamClass
 				    GstClockTimeDiff       * final_ts);
 
   /**
-   * can_start:
+   * start:
    * @stream: a #GstAdaptiveDemux2Stream
    *
-   * Called before starting a @stream. sub-classes can return %FALSE if more
-   * information is required before it can be started. Sub-classes will have to
-   * call gst_adaptive_demux2_stream_start() when the stream should be started.
+   * Called to start downloading a @stream, sub-classes should chain up to the default
+   * implementation. Sub-classes can return %FALSE if more
+   * information is required before the stream can be started. In that case, sub-classes
+   * will have to call gst_adaptive_demux2_stream_start() again when the stream should
+   * be started.
    */
-  gboolean      (*can_start) (GstAdaptiveDemux2Stream *stream);
+  void       (*start) (GstAdaptiveDemux2Stream *stream);
+
+  /**
+   * stop:
+   * @stream: a #GstAdaptiveDemux2Stream
+   *
+   * Called to stop downloading a @stream, sub-classes should chain up to the default
+   * implementation.
+   */
+  void       (*stop) (GstAdaptiveDemux2Stream *stream);
+
 
   /**
    * create_tracks:

subprojects/gst-plugins-good/ext/adaptivedemux2/hls/gsthlsdemux-stream.c

@@ -72,8 +72,8 @@ gst_hls_demux_stream_update_fragment_info (GstAdaptiveDemux2Stream * stream);
 static GstFlowReturn
 gst_hls_demux_stream_submit_request (GstAdaptiveDemux2Stream * stream,
     DownloadRequest * download_req);
-static gboolean gst_hls_demux_stream_can_start (GstAdaptiveDemux2Stream *
-    stream);
+static void gst_hls_demux_stream_start (GstAdaptiveDemux2Stream * stream);
+static void gst_hls_demux_stream_stop (GstAdaptiveDemux2Stream * stream);
 static void gst_hls_demux_stream_create_tracks (GstAdaptiveDemux2Stream *
     stream);
 static gboolean gst_hls_demux_stream_select_bitrate (GstAdaptiveDemux2Stream *
@@ -107,7 +107,8 @@ gst_hls_demux_stream_class_init (GstHLSDemuxStreamClass * klass)
       gst_hls_demux_stream_advance_fragment;
   adaptivedemux2stream_class->select_bitrate =
       gst_hls_demux_stream_select_bitrate;
-  adaptivedemux2stream_class->can_start = gst_hls_demux_stream_can_start;
+  adaptivedemux2stream_class->start = gst_hls_demux_stream_start;
+  adaptivedemux2stream_class->stop = gst_hls_demux_stream_stop;
   adaptivedemux2stream_class->create_tracks =
       gst_hls_demux_stream_create_tracks;
 
@@ -2007,6 +2008,23 @@ gst_hls_demux_stream_can_start (GstAdaptiveDemux2Stream * stream)
   return FALSE;
 }
 
+static void
+gst_hls_demux_stream_start (GstAdaptiveDemux2Stream * stream)
+{
+  if (!gst_hls_demux_stream_can_start (stream))
+    return;
+
+  /* Chain up, to start the downloading */
+  GST_ADAPTIVE_DEMUX2_STREAM_CLASS (stream_parent_class)->start (stream);
+}
+
+static void
+gst_hls_demux_stream_stop (GstAdaptiveDemux2Stream * stream)
+{
+  /* Chain up, to stop the downloading */
+  GST_ADAPTIVE_DEMUX2_STREAM_CLASS (stream_parent_class)->stop (stream);
+}
+
 /* Returns TRUE if the rendition stream switched group-id */
 static gboolean
 gst_hls_demux_update_rendition_stream (GstHLSDemux * hlsdemux,