gme: add configurable fade-out time

Also include fade-out time in song length.

doc/plugins.rst

@@ -391,6 +391,8 @@ Video game music file emulator based on `game-music-emu <https://bitbucket.org/m
      - Description
    * - **accuracy yes|no**
      - Enable more accurate sound emulation.
+   * - **default_fade**
+     - The default fade-out time, in seconds. Used by songs that don't specify their own fade-out time.
 
 hybrid_dsd
 ----------

src/decoder/plugins/GmeDecoderPlugin.cxx

@@ -60,6 +60,7 @@ struct GmeContainerPath {
 #if GME_VERSION >= 0x000600
 static int gme_accuracy;
 #endif
+static unsigned gme_default_fade;
 
 static bool
 gme_plugin_init([[maybe_unused]] const ConfigBlock &block)
@@ -70,6 +71,10 @@ gme_plugin_init([[maybe_unused]] const ConfigBlock &block)
 		? (int)accuracy->GetBoolValue()
 		: -1;
 #endif
+	auto fade = block.GetBlockParam("default_fade");
+	gme_default_fade = fade != nullptr
+		? fade->GetUnsignedValue() * 1000
+		: 8000;
 
 	return true;
 }
@@ -171,7 +176,7 @@ gme_file_decode(DecoderClient &client, Path path_fs)
 	gme_free_info(ti);
 
 	const SignedSongTime song_len = length > 0
-		? SignedSongTime::FromMS(length)
+		? SignedSongTime::FromMS(length + gme_default_fade)
 		: SignedSongTime::Negative();
 
 	/* initialize the MPD decoder */
@@ -189,7 +194,7 @@ gme_file_decode(DecoderClient &client, Path path_fs)
 	if (length > 0)
 		gme_set_fade(emu, length
 #if GME_VERSION >= 0x000700
-			     , 8000
+			     , gme_default_fade
 #endif
 			     );
 
@@ -224,7 +229,7 @@ ScanGmeInfo(const gme_info_t &info, unsigned song_num, int track_count,
 	    TagHandler &handler) noexcept
 {
 	if (info.play_length > 0)
-		handler.OnDuration(SongTime::FromMS(info.play_length));
+		handler.OnDuration(SongTime::FromMS(info.play_length + gme_default_fade));
 
 	if (track_count > 1)
 		handler.OnTag(TAG_TRACK, StringFormat<16>("%u", song_num + 1).c_str());