Do not show channel count on debug overlay when using passthrough

This usually showed "stereo" output when passthrough was enabled, and
without any context that it was using passthrough. Pretty misleading.

src/player/PlayerComponent.cpp

@@ -816,8 +816,18 @@ QString PlayerComponent::videoInformation() const
   info << "Codec: " << MPV_PROPERTY("audio-codec") << endl;
   info << "Bitrate: " << MPV_PROPERTY("audio-bitrate") << endl;
   info << "Channels (input): " << MPV_PROPERTY("audio-params/channels") << endl;
-  info << "Channels (output): " << MPV_PROPERTY("audio-out-params/hr-channels")
-                                << " (" << MPV_PROPERTY("audio-out-params/channels") << ")" << endl;
+  // Guess if it's a passthrough format. Don't show the channel layout in this
+  // case, because it's confusing.
+  QString audio_format = MPV_PROPERTY("audio-out-params/format");
+  if (audio_format.startsWith("spdif-"))
+  {
+    info << "Channels (output): passthrough (" << audio_format << ")";
+  }
+  else
+  {
+    info << "Channels (output): " << MPV_PROPERTY("audio-out-params/hr-channels")
+                                  << " (" << MPV_PROPERTY("audio-out-params/channels") << ")" << endl;
+  }
   info << endl;
   info << "Performance: " << endl;
   info << "A/V: " << MPV_PROPERTY("avsync") << endl;