From 65941a3c5168a1a5ea8fb5f961353ceea1a4228f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fernando=20Jim=C3=A9nez=20Moreno?= <ferjmoreno@gmail.com>
Date: Thu, 29 Nov 2018 12:01:42 +0100
Subject: [PATCH] Check that we have the required elements to instantiate a
 gst-player

---
 backends/gstreamer/src/lib.rs    | 1 +
 backends/gstreamer/src/player.rs | 8 ++++++++
 2 files changed, 9 insertions(+)

diff --git a/backends/gstreamer/src/lib.rs b/backends/gstreamer/src/lib.rs
index c70a2aa9..9b9219fd 100644
--- a/backends/gstreamer/src/lib.rs
+++ b/backends/gstreamer/src/lib.rs
@@ -29,6 +29,7 @@ pub enum BackendError {
     Gstreamer(gst::Error),
     InvalidMediaFormat,
     InvalidSample,
+    MissingElement(&'static str),
     PadLinkFailed,
     PipelineBusError(String),
     PipelineFailed(&'static str),
diff --git a/backends/gstreamer/src/player.rs b/backends/gstreamer/src/player.rs
index 340de170..44d6493f 100644
--- a/backends/gstreamer/src/player.rs
+++ b/backends/gstreamer/src/player.rs
@@ -234,6 +234,14 @@ impl GStreamerPlayer {
             return Ok(());
         }
 
+        // Check that we actually have the elements that we
+        // need to make this work.
+        for element in vec!["playbin", "queue"].iter() {
+            if gst::ElementFactory::find(element).is_none() {
+                return Err(BackendError::MissingElement(element));
+            }
+        }
+
         let player = gst_player::Player::new(
             /* video renderer */ None, /* signal dispatcher */ None,
         );