output/Internal: rename CloseFilter() to CloseSoftwareMixer()

src/output/Internal.cxx

@@ -99,7 +99,7 @@ AudioOutput::CloseOutput(bool drain) noexcept
 }
 
 void
-AudioOutput::CloseFilter() noexcept
+AudioOutput::CloseSoftwareMixer() noexcept
 {
 	if (mixer != nullptr && mixer->IsPlugin(software_mixer_plugin))
 		software_mixer_set_filter(*mixer, nullptr);
@@ -109,7 +109,7 @@ void
 AudioOutput::Close(bool drain) noexcept
 {
 	CloseOutput(drain);
-	CloseFilter();
+	CloseSoftwareMixer();
 
 	FormatDebug(output_domain, "closed plugin=%s name=\"%s\"",
 		    plugin.name, name);

src/output/Internal.hxx

@@ -163,7 +163,7 @@ public:
 	/**
 	 * Mutex must not be locked.
 	 */
-	void CloseFilter() noexcept;
+	void CloseSoftwareMixer() noexcept;
 
 	void BeginPause() noexcept;
 	bool IteratePause() noexcept;

src/output/Thread.cxx

@@ -73,7 +73,7 @@ AudioOutputControl::InternalOpen2(const AudioFormat in_audio_format)
 			output->OpenOutputAndConvert(output->filter_audio_format);
 		} catch (...) {
 			const ScopeUnlock unlock(mutex);
-			output->CloseFilter();
+			output->CloseSoftwareMixer();
 			throw;
 		}