Setting sample length for songs with preview file to 0 uses length of preview file

src/NotesLoaderBMS.cpp

@@ -1588,6 +1588,7 @@ void BMSSongLoader::AddToSong()
 
 		out->m_sMusicFile = main.info.musicFile;
 		out->m_PreviewFile= main.info.previewFile;
+		out->m_fMusicSampleLengthSeconds = 0.00f; // to ensure whole preview file is heard
 		out->m_SongTiming = main.steps->m_Timing;
 	}
 

src/Song.cpp

@@ -748,6 +748,34 @@ void Song::TidyUpData( bool from_cache, bool /* duringCache */ )
 				m_fMusicLengthSeconds);
 			m_fMusicLengthSeconds = 0;
 		}
+		if(!m_PreviewFile.empty() && m_fMusicSampleLengthSeconds <= 0.00f) { // if there's a preview file and sample length isn't specified, set sample length to length of preview file
+			RString error;
+			RageSoundReader *Sample = RageSoundReader_FileReader::OpenFile(GetPreviewMusicPath(), error);
+			if(Sample == NULL && m_sMusicFile != "")
+			{
+				LOG->UserLog("Sound file", GetPreviewMusicPath(), "couldn't be opened: %s", error.c_str());
+
+				// Don't use this file.
+				m_PreviewFile = "";
+				m_fMusicSampleLengthSeconds = DEFAULT_MUSIC_SAMPLE_LENGTH;
+			}
+			else if(Sample != NULL)
+			{
+				m_fMusicSampleLengthSeconds = Sample->GetLength() / 1000.0f;
+				delete Sample;
+
+				if(m_fMusicSampleLengthSeconds < 0)
+				{
+					// It failed; bad file or something. It's already logged a warning.
+					m_fMusicSampleLengthSeconds = DEFAULT_MUSIC_SAMPLE_LENGTH;
+				}
+				else if(m_fMusicSampleLengthSeconds == 0)
+				{
+					LOG->UserLog("Sound file", GetPreviewMusicPath(), "is empty.");
+				}
+			}
+		} else { // no preview file, calculate sample from music as normal
+
 			if(m_fMusicSampleStartSeconds == -1 ||
 				m_fMusicSampleLengthSeconds == 0 ||
 				m_fMusicSampleStartSeconds+m_fMusicSampleLengthSeconds > this->m_fMusicLengthSeconds)
@@ -769,6 +797,8 @@ void Song::TidyUpData( bool from_cache, bool /* duringCache */ )
 			if(m_fMusicSampleLengthSeconds <= 0.00f)
 			{ m_fMusicSampleLengthSeconds = DEFAULT_MUSIC_SAMPLE_LENGTH; }
 
+		}
+
 		// Here's the problem:  We have a directory full of images. We want to
 		// determine which image is the banner, which is the background, and
 		// which is the CDTitle.