Better errors if butler doesn't give video during export.

diff --git a/src/lib/ffmpeg_encoder.cc b/src/lib/ffmpeg_encoder.cc
index 4614903dbec11996f437bd315b2e755a9fcc8cc3..0233632d71e04f08deb0de325435555689e5e21d 100644 (file)
--- a/src/lib/ffmpeg_encoder.cc
+++ b/src/lib/ffmpeg_encoder.cc
@@ -141,7 +141,11 @@ FFmpegEncoder::go ()
                }
 
                for (int j = 0; j < gets_per_frame; ++j) {
-                       pair<shared_ptr<PlayerVideo>, DCPTime> v = _butler->get_video ();
+                       Butler::Error e;
+                       pair<shared_ptr<PlayerVideo>, DCPTime> v = _butler->get_video (&e);
+                       if (!v.first) {
+                               throw ProgrammingError(__FILE__, __LINE__, String::compose("butler returned no video; error was %1", static_cast<int>(e)));
+                       }
                        shared_ptr<FFmpegFileEncoder> fe = encoder->get (v.first->eyes());
                        if (fe) {
                                fe->video(v.first, v.second);