DecoderCommand: convert to strictly-typed enum

33 files changed, 219 insertions, 223 deletions

diff --git a/src/DecoderAPI.cxx b/src/DecoderAPI.cxx
index 71c3d0497..06313c909 100644
--- a/src/DecoderAPI.cxx
+++ b/src/DecoderAPI.cxx
@@ -106,7 +106,7 @@ decoder_prepare_initial_seek(struct decoder *decoder)
 			return false;
 		}
 
-		if (dc->command == DECODE_COMMAND_NONE) {
+		if (dc->command == DecoderCommand::NONE) {
 			/* begin initial seek */
 
 			decoder->initial_seek_pending = false;
@@ -129,19 +129,19 @@ decoder_prepare_initial_seek(struct decoder *decoder)
  * track.
  */
 gcc_pure
-static enum decoder_command
+static DecoderCommand
 decoder_get_virtual_command(struct decoder *decoder)
 {
 	const struct decoder_control *dc = decoder->dc;
 	assert(dc->pipe != NULL);
 
 	if (decoder_prepare_initial_seek(decoder))
-		return DECODE_COMMAND_SEEK;
+		return DecoderCommand::SEEK;
 
 	return dc->command;
 }
 
-enum decoder_command
+DecoderCommand
 decoder_get_command(struct decoder *decoder)
 {
 	return decoder_get_virtual_command(decoder);
@@ -154,9 +154,9 @@ decoder_command_finished(struct decoder *decoder)
 
 	dc->Lock();
 
-	assert(dc->command != DECODE_COMMAND_NONE ||
+	assert(dc->command != DecoderCommand::NONE ||
 	       decoder->initial_seek_running);
-	assert(dc->command != DECODE_COMMAND_SEEK ||
+	assert(dc->command != DecoderCommand::SEEK ||
 	       decoder->initial_seek_running ||
 	       dc->seek_error || decoder->seeking);
 	assert(dc->pipe != NULL);
@@ -187,7 +187,7 @@ decoder_command_finished(struct decoder *decoder)
 		decoder->timestamp = dc->seek_where;
 	}
 
-	dc->command = DECODE_COMMAND_NONE;
+	dc->command = DecoderCommand::NONE;
 	dc->client_cond.signal();
 	dc->Unlock();
 }
@@ -201,7 +201,7 @@ double decoder_seek_where(gcc_unused struct decoder * decoder)
 	if (decoder->initial_seek_running)
 		return dc->start_ms / 1000.;
 
-	assert(dc->command == DECODE_COMMAND_SEEK);
+	assert(dc->command == DecoderCommand::SEEK);
 
 	decoder->seeking = true;
 
@@ -221,7 +221,7 @@ void decoder_seek_error(struct decoder * decoder)
 		return;
 	}
 
-	assert(dc->command == DECODE_COMMAND_SEEK);
+	assert(dc->command == DecoderCommand::SEEK);
 
 	dc->seek_error = true;
 	decoder->seeking = false;
@@ -241,12 +241,12 @@ decoder_check_cancel_read(const struct decoder *decoder)
 		return false;
 
 	const struct decoder_control *dc = decoder->dc;
-	if (dc->command == DECODE_COMMAND_NONE)
+	if (dc->command == DecoderCommand::NONE)
 		return false;
 
 	/* ignore the SEEK command during initialization, the plugin
 	   should handle that after it has initialized successfully */
-	if (dc->command == DECODE_COMMAND_SEEK &&
+	if (dc->command == DecoderCommand::SEEK &&
 	    (dc->state == DECODE_STATE_START || decoder->seeking))
 		return false;
 
@@ -308,7 +308,7 @@ decoder_timestamp(struct decoder *decoder, double t)
  * Sends a #tag as-is to the music pipe.  Flushes the current chunk
  * (decoder.chunk) if there is one.
  */
-static enum decoder_command
+static DecoderCommand
 do_send_tag(struct decoder *decoder, const Tag &tag)
 {
 	struct music_chunk *chunk;
@@ -324,12 +324,12 @@ do_send_tag(struct decoder *decoder, const Tag &tag)
 
 	chunk = decoder_get_chunk(decoder);
 	if (chunk == NULL) {
-		assert(decoder->dc->command != DECODE_COMMAND_NONE);
+		assert(decoder->dc->command != DecoderCommand::NONE);
 		return decoder->dc->command;
 	}
 
 	chunk->tag = new Tag(tag);
-	return DECODE_COMMAND_NONE;
+	return DecoderCommand::NONE;
 }
 
 static bool
@@ -355,14 +355,14 @@ update_stream_tag(struct decoder *decoder, struct input_stream *is)
 	return true;
 }
 
-enum decoder_command
+DecoderCommand
 decoder_data(struct decoder *decoder,
 	     struct input_stream *is,
 	     const void *data, size_t length,
 	     uint16_t kbit_rate)
 {
 	struct decoder_control *dc = decoder->dc;
-	enum decoder_command cmd;
+	DecoderCommand cmd;
 
 	assert(dc->state == DECODE_STATE_DECODE);
 	assert(dc->pipe != NULL);
@@ -372,7 +372,7 @@ decoder_data(struct decoder *decoder,
 	cmd = decoder_get_virtual_command(decoder);
 	dc->Unlock();
 
-	if (cmd == DECODE_COMMAND_STOP || cmd == DECODE_COMMAND_SEEK ||
+	if (cmd == DecoderCommand::STOP || cmd == DecoderCommand::SEEK ||
 	    length == 0)
 		return cmd;
 
@@ -389,7 +389,7 @@ decoder_data(struct decoder *decoder,
 			/* send only the stream tag */
 			cmd = do_send_tag(decoder, *decoder->stream_tag);
 
-		if (cmd != DECODE_COMMAND_NONE)
+		if (cmd != DecoderCommand::NONE)
 			return cmd;
 	}
 
@@ -405,7 +405,7 @@ decoder_data(struct decoder *decoder,
 			   playback, since we have no better way to
 			   bail out */
 			g_warning("%s", error.GetMessage());
-			return DECODE_COMMAND_STOP;
+			return DecoderCommand::STOP;
 		}
 	}
 
@@ -416,7 +416,7 @@ decoder_data(struct decoder *decoder,
 
 		chunk = decoder_get_chunk(decoder);
 		if (chunk == NULL) {
-			assert(dc->command != DECODE_COMMAND_NONE);
+			assert(dc->command != DecoderCommand::NONE);
 			return dc->command;
 		}
 
@@ -459,18 +459,18 @@ decoder_data(struct decoder *decoder,
 		    decoder->timestamp >= dc->end_ms / 1000.0)
 			/* the end of this range has been reached:
 			   stop decoding */
-			return DECODE_COMMAND_STOP;
+			return DecoderCommand::STOP;
 	}
 
-	return DECODE_COMMAND_NONE;
+	return DecoderCommand::NONE;
 }
 
-enum decoder_command
+DecoderCommand
 decoder_tag(gcc_unused struct decoder *decoder, struct input_stream *is,
 	    Tag &&tag)
 {
 	gcc_unused const struct decoder_control *dc = decoder->dc;
-	enum decoder_command cmd;
+	DecoderCommand cmd;
 
 	assert(dc->state == DECODE_STATE_DECODE);
 	assert(dc->pipe != NULL);
@@ -490,7 +490,7 @@ decoder_tag(gcc_unused struct decoder *decoder, struct input_stream *is,
 		/* during initial seek, no music chunk must be created
 		   until seeking is finished; skip the rest of the
 		   function here */
-		return DECODE_COMMAND_SEEK;
+		return DecoderCommand::SEEK;
 
 	/* send tag to music pipe */
 
diff --git a/src/DecoderAPI.hxx b/src/DecoderAPI.hxx
index ff7cdc27b..f96aa596a 100644
--- a/src/DecoderAPI.hxx
+++ b/src/DecoderAPI.hxx
@@ -54,10 +54,10 @@ decoder_initialized(struct decoder *decoder,
  * Determines the pending decoder command.
  *
  * @param decoder the decoder object
- * @return the current command, or DECODE_COMMAND_NONE if there is no
+ * @return the current command, or DecoderCommand::NONE if there is no
  * command pending
  */
-enum decoder_command
+DecoderCommand
 decoder_get_command(struct decoder *decoder);
 
 /**
@@ -71,7 +71,7 @@ void
 decoder_command_finished(struct decoder *decoder);
 
 /**
- * Call this when you have received the DECODE_COMMAND_SEEK command.
+ * Call this when you have received the DecoderCommand::SEEK command.
  *
  * @param decoder the decoder object
  * @return the destination position for the week
@@ -120,10 +120,10 @@ decoder_timestamp(struct decoder *decoder, double t);
  * for the player
  * @param data the source buffer
  * @param length the number of bytes in the buffer
- * @return the current command, or DECODE_COMMAND_NONE if there is no
+ * @return the current command, or DecoderCommand::NONE if there is no
  * command pending
  */
-enum decoder_command
+DecoderCommand
 decoder_data(struct decoder *decoder, struct input_stream *is,
 	     const void *data, size_t length,
 	     uint16_t kbit_rate);
@@ -136,10 +136,10 @@ decoder_data(struct decoder *decoder, struct input_stream *is,
  * @param is an input stream which is buffering while we are waiting
  * for the player
  * @param tag the tag to send
- * @return the current command, or DECODE_COMMAND_NONE if there is no
+ * @return the current command, or DecoderCommand::NONE if there is no
  * command pending
  */
-enum decoder_command
+DecoderCommand
 decoder_tag(struct decoder *decoder, struct input_stream *is, Tag &&tag);
 
 /**
diff --git a/src/DecoderCommand.hxx b/src/DecoderCommand.hxx
index e6dc26982..394f270c2 100644
--- a/src/DecoderCommand.hxx
+++ b/src/DecoderCommand.hxx
@@ -20,11 +20,13 @@
 #ifndef MPD_DECODER_COMMAND_HXX
 #define MPD_DECODER_COMMAND_HXX
 
-enum decoder_command {
-	DECODE_COMMAND_NONE = 0,
-	DECODE_COMMAND_START,
-	DECODE_COMMAND_STOP,
-	DECODE_COMMAND_SEEK
+#include <stdint.h>
+
+enum class DecoderCommand : uint8_t {
+	NONE = 0,
+	START,
+	STOP,
+	SEEK
 };
 
 #endif
diff --git a/src/DecoderControl.cxx b/src/DecoderControl.cxx
index 063a78644..53957195e 100644
--- a/src/DecoderControl.cxx
+++ b/src/DecoderControl.cxx
@@ -30,7 +30,7 @@
 decoder_control::decoder_control()
 	:thread(nullptr),
 	 state(DECODE_STATE_STOP),
-	 command(DECODE_COMMAND_NONE),
+	 command(DecoderCommand::NONE),
 	 song(nullptr),
 	 replay_gain_db(0), replay_gain_prev_db(0),
 	 mixramp_start(nullptr), mixramp_end(nullptr),
@@ -84,7 +84,7 @@ decoder_control::Start(Song *_song,
 	buffer = &_buffer;
 	pipe = &_pipe;
 
-	LockSynchronousCommand(DECODE_COMMAND_START);
+	LockSynchronousCommand(DecoderCommand::START);
 }
 
 void
@@ -92,15 +92,15 @@ decoder_control::Stop()
 {
 	Lock();
 
-	if (command != DECODE_COMMAND_NONE)
+	if (command != DecoderCommand::NONE)
 		/* Attempt to cancel the current command.  If it's too
 		   late and the decoder thread is already executing
 		   the old command, we'll call STOP again in this
 		   function (see below). */
-		SynchronousCommandLocked(DECODE_COMMAND_STOP);
+		SynchronousCommandLocked(DecoderCommand::STOP);
 
 	if (state != DECODE_STATE_STOP && state != DECODE_STATE_ERROR)
-		SynchronousCommandLocked(DECODE_COMMAND_STOP);
+		SynchronousCommandLocked(DecoderCommand::STOP);
 
 	Unlock();
 }
@@ -117,7 +117,7 @@ decoder_control::Seek(double where)
 
 	seek_where = where;
 	seek_error = false;
-	SynchronousCommandLocked(DECODE_COMMAND_SEEK);
+	SynchronousCommandLocked(DecoderCommand::SEEK);
 
 	return !seek_error;
 }
@@ -128,7 +128,7 @@ decoder_control::Quit()
 	assert(thread != nullptr);
 
 	quit = true;
-	LockAsynchronousCommand(DECODE_COMMAND_STOP);
+	LockAsynchronousCommand(DecoderCommand::STOP);
 
 	g_thread_join(thread);
 	thread = nullptr;
diff --git a/src/DecoderControl.hxx b/src/DecoderControl.hxx
index b9c58dcf2..8afe103c2 100644
--- a/src/DecoderControl.hxx
+++ b/src/DecoderControl.hxx
@@ -72,7 +72,7 @@ struct decoder_control {
 	Cond client_cond;
 
 	enum decoder_state state;
-	enum decoder_command command;
+	DecoderCommand command;
 
 	/**
 	 * The error that occurred in the decoder thread.  This
@@ -95,7 +95,7 @@ struct decoder_control {
 
 	/**
 	 * The song currently being decoded.  This attribute is set by
-	 * the player thread, when it sends the #DECODE_COMMAND_START
+	 * the player thread, when it sends the #DecoderCommand::START
 	 * command.
 	 *
 	 * This is a duplicate, and must be freed when this attribute
@@ -207,7 +207,7 @@ struct decoder_control {
 	}
 
 	bool HasFailed() const {
-		assert(command == DECODE_COMMAND_NONE);
+		assert(command == DecoderCommand::NONE);
 
 		return state == DECODE_STATE_ERROR;
 	}
@@ -228,7 +228,7 @@ struct decoder_control {
 	 */
 	gcc_pure
 	Error GetError() const {
-		assert(command == DECODE_COMMAND_NONE);
+		assert(command == DecoderCommand::NONE);
 		assert(state != DECODE_STATE_ERROR || error.IsDefined());
 
 		Error result;
@@ -286,7 +286,7 @@ private:
 	 * object.
 	 */
 	void WaitCommandLocked() {
-		while (command != DECODE_COMMAND_NONE)
+		while (command != DecoderCommand::NONE)
 			WaitForDecoder();
 	}
 
@@ -297,7 +297,7 @@ private:
 	 * To be called from the client thread.  Caller must lock the
 	 * object.
 	 */
-	void SynchronousCommandLocked(decoder_command cmd) {
+	void SynchronousCommandLocked(DecoderCommand cmd) {
 		command = cmd;
 		Signal();
 		WaitCommandLocked();
@@ -310,14 +310,14 @@ private:
 	 * To be called from the client thread.  This method locks the
 	 * object.
 	 */
-	void LockSynchronousCommand(decoder_command cmd) {
+	void LockSynchronousCommand(DecoderCommand cmd) {
 		Lock();
 		ClearError();
 		SynchronousCommandLocked(cmd);
 		Unlock();
 	}
 
-	void LockAsynchronousCommand(decoder_command cmd) {
+	void LockAsynchronousCommand(DecoderCommand cmd) {
 		Lock();
 		command = cmd;
 		Signal();
diff --git a/src/DecoderInternal.cxx b/src/DecoderInternal.cxx
index 0c9a10436..307a3550b 100644
--- a/src/DecoderInternal.cxx
+++ b/src/DecoderInternal.cxx
@@ -41,11 +41,11 @@ decoder::~decoder()
  * All chunks are full of decoded data; wait for the player to free
  * one.
  */
-static enum decoder_command
+static DecoderCommand
 need_chunks(struct decoder_control *dc, bool do_wait)
 {
-	if (dc->command == DECODE_COMMAND_STOP ||
-	    dc->command == DECODE_COMMAND_SEEK)
+	if (dc->command == DecoderCommand::STOP ||
+	    dc->command == DecoderCommand::SEEK)
 		return dc->command;
 
 	if (do_wait) {
@@ -55,14 +55,14 @@ need_chunks(struct decoder_control *dc, bool do_wait)
 		return dc->command;
 	}
 
-	return DECODE_COMMAND_NONE;
+	return DecoderCommand::NONE;
 }
 
 struct music_chunk *
 decoder_get_chunk(struct decoder *decoder)
 {
 	struct decoder_control *dc = decoder->dc;
-	enum decoder_command cmd;
+	DecoderCommand cmd;
 
 	assert(decoder != NULL);
 
@@ -84,7 +84,7 @@ decoder_get_chunk(struct decoder *decoder)
 		dc->Lock();
 		cmd = need_chunks(dc, true);
 		dc->Unlock();
-	} while (cmd == DECODE_COMMAND_NONE);
+	} while (cmd == DecoderCommand::NONE);
 
 	return NULL;
 }
diff --git a/src/DecoderThread.cxx b/src/DecoderThread.cxx
index a789cc30f..235865fd3 100644
--- a/src/DecoderThread.cxx
+++ b/src/DecoderThread.cxx
@@ -52,9 +52,9 @@
 static void
 decoder_command_finished_locked(struct decoder_control *dc)
 {
-	assert(dc->command != DECODE_COMMAND_NONE);
+	assert(dc->command != DecoderCommand::NONE);
 
-	dc->command = DECODE_COMMAND_NONE;
+	dc->command = DecoderCommand::NONE;
 
 	dc->client_cond.signal();
 }
@@ -67,7 +67,7 @@ decoder_command_finished_locked(struct decoder_control *dc)
  *
  * Unlock the decoder before calling this function.
  *
- * @return an input_stream on success or if #DECODE_COMMAND_STOP is
+ * @return an input_stream on success or if #DecoderCommand::STOP is
  * received, NULL on error
  */
 static struct input_stream *
@@ -90,7 +90,7 @@ decoder_input_stream_open(struct decoder_control *dc, const char *uri)
 
 	is->Update();
 	while (!is->ready &&
-	       dc->command != DECODE_COMMAND_STOP) {
+	       dc->command != DecoderCommand::STOP) {
 		dc->Wait();
 
 		is->Update();
@@ -124,7 +124,7 @@ decoder_stream_decode(const struct decoder_plugin *plugin,
 
 	g_debug("probing plugin %s", plugin->name);
 
-	if (decoder->dc->command == DECODE_COMMAND_STOP)
+	if (decoder->dc->command == DecoderCommand::STOP)
 		return true;
 
 	/* rewind the stream, so each plugin gets a fresh start */
@@ -157,7 +157,7 @@ decoder_file_decode(const struct decoder_plugin *plugin,
 
 	g_debug("probing plugin %s", plugin->name);
 
-	if (decoder->dc->command == DECODE_COMMAND_STOP)
+	if (decoder->dc->command == DecoderCommand::STOP)
 		return true;
 
 	decoder->dc->Unlock();
@@ -286,7 +286,7 @@ decoder_run_stream(struct decoder *decoder, const char *uri)
 
 	GSList *tried = NULL;
 
-	success = dc->command == DECODE_COMMAND_STOP ||
+	success = dc->command == DecoderCommand::STOP ||
 		/* first we try mime types: */
 		decoder_run_stream_mime_type(decoder, input_stream, &tried) ||
 		/* if that fails, try suffix matching the URL: */
@@ -455,7 +455,7 @@ decoder_task(gpointer arg)
 		       dc->state == DECODE_STATE_ERROR);
 
 		switch (dc->command) {
-		case DECODE_COMMAND_START:
+		case DecoderCommand::START:
 			dc->MixRampStart(nullptr);
 			dc->MixRampPrevEnd(dc->mixramp_end);
 			dc->mixramp_end = NULL; /* Don't free, it's copied above. */
@@ -464,19 +464,19 @@ decoder_task(gpointer arg)
 
                         /* fall through */
 
-		case DECODE_COMMAND_SEEK:
+		case DecoderCommand::SEEK:
 			decoder_run(dc);
 			break;
 
-		case DECODE_COMMAND_STOP:
+		case DecoderCommand::STOP:
 			decoder_command_finished_locked(dc);
 			break;
 
-		case DECODE_COMMAND_NONE:
+		case DecoderCommand::NONE:
 			dc->Wait();
 			break;
 		}
-	} while (dc->command != DECODE_COMMAND_NONE || !dc->quit);
+	} while (dc->command != DecoderCommand::NONE || !dc->quit);
 
 	dc->Unlock();
 
diff --git a/src/decoder/AdPlugDecoderPlugin.cxx b/src/decoder/AdPlugDecoderPlugin.cxx
index 51a3f7ea7..5c04e116d 100644
--- a/src/decoder/AdPlugDecoderPlugin.cxx
+++ b/src/decoder/AdPlugDecoderPlugin.cxx
@@ -68,7 +68,7 @@ adplug_file_decode(struct decoder *decoder, const char *path_fs)
 
 	int16_t buffer[2048];
 	const unsigned frames_per_buffer = G_N_ELEMENTS(buffer) / 2;
-	enum decoder_command cmd;
+	DecoderCommand cmd;
 
 	do {
 		if (!player->update())
@@ -78,7 +78,7 @@ adplug_file_decode(struct decoder *decoder, const char *path_fs)
 		cmd = decoder_data(decoder, NULL,
 				   buffer, sizeof(buffer),
 				   0);
-	} while (cmd == DECODE_COMMAND_NONE);
+	} while (cmd == DecoderCommand::NONE);
 
 	delete player;
 }
diff --git a/src/decoder/AudiofileDecoderPlugin.cxx b/src/decoder/AudiofileDecoderPlugin.cxx
index 6b638bb3f..1ee57de4a 100644
--- a/src/decoder/AudiofileDecoderPlugin.cxx
+++ b/src/decoder/AudiofileDecoderPlugin.cxx
@@ -166,7 +166,6 @@ audiofile_stream_decode(struct decoder *decoder, struct input_stream *is)
 	uint16_t bit_rate;
 	int ret;
 	char chunk[CHUNK_SIZE];
-	enum decoder_command cmd;
 
 	if (!is->IsSeekable()) {
 		g_warning("not seekable");
@@ -202,6 +201,7 @@ audiofile_stream_decode(struct decoder *decoder, struct input_stream *is)
 
 	decoder_initialized(decoder, audio_format, true, total_time);
 
+	DecoderCommand cmd;
 	do {
 		ret = afReadFrames(af_fp, AF_DEFAULT_TRACK, chunk,
 				   CHUNK_SIZE / fs);
@@ -212,15 +212,15 @@ audiofile_stream_decode(struct decoder *decoder, struct input_stream *is)
 				   chunk, ret * fs,
 				   bit_rate);
 
-		if (cmd == DECODE_COMMAND_SEEK) {
+		if (cmd == DecoderCommand::SEEK) {
 			AFframecount frame = decoder_seek_where(decoder) *
 				audio_format.sample_rate;
 			afSeekFrame(af_fp, AF_DEFAULT_TRACK, frame);
 
 			decoder_command_finished(decoder);
-			cmd = DECODE_COMMAND_NONE;
+			cmd = DecoderCommand::NONE;
 		}
-	} while (cmd == DECODE_COMMAND_NONE);
+	} while (cmd == DecoderCommand::NONE);
 
 	afCloseFile(af_fp);
 }
diff --git a/src/decoder/DsdiffDecoderPlugin.cxx b/src/decoder/DsdiffDecoderPlugin.cxx
index 49b0c601d..80b88a2c2 100644
--- a/src/decoder/DsdiffDecoderPlugin.cxx
+++ b/src/decoder/DsdiffDecoderPlugin.cxx
@@ -403,17 +403,16 @@ dsdiff_decode_chunk(struct decoder *decoder, struct input_stream *is,
 		if (lsbitfirst)
 			bit_reverse_buffer(buffer, buffer + nbytes);
 
-		enum decoder_command cmd =
-			decoder_data(decoder, is, buffer, nbytes, 0);
+		const auto cmd = decoder_data(decoder, is, buffer, nbytes, 0);
 		switch (cmd) {
-		case DECODE_COMMAND_NONE:
+		case DecoderCommand::NONE:
 			break;
 
-		case DECODE_COMMAND_START:
-		case DECODE_COMMAND_STOP:
+		case DecoderCommand::START:
+		case DecoderCommand::STOP:
 			return false;
 
-		case DECODE_COMMAND_SEEK:
+		case DecoderCommand::SEEK:
 
 			/* Not implemented yet */
 			decoder_seek_error(decoder);
diff --git a/src/decoder/DsfDecoderPlugin.cxx b/src/decoder/DsfDecoderPlugin.cxx
index 275f34929..b327fc9dc 100644
--- a/src/decoder/DsfDecoderPlugin.cxx
+++ b/src/decoder/DsfDecoderPlugin.cxx
@@ -258,17 +258,16 @@ dsf_decode_chunk(struct decoder *decoder, struct input_stream *is,
 
 		dsf_to_pcm_order(buffer, dsf_scratch_buffer, nbytes);
 
-		enum decoder_command cmd =
-			decoder_data(decoder, is, buffer, nbytes, 0);
+		const auto cmd = decoder_data(decoder, is, buffer, nbytes, 0);
 		switch (cmd) {
-		case DECODE_COMMAND_NONE:
+		case DecoderCommand::NONE:
 			break;
 
-		case DECODE_COMMAND_START:
-		case DECODE_COMMAND_STOP:
+		case DecoderCommand::START:
+		case DecoderCommand::STOP:
 			return false;
 
-		case DECODE_COMMAND_SEEK:
+		case DecoderCommand::SEEK:
 
 			/* not implemented yet */
 			decoder_seek_error(decoder);
diff --git a/src/decoder/FaadDecoderPlugin.cxx b/src/decoder/FaadDecoderPlugin.cxx
index c8acfb521..f026a6216 100644
--- a/src/decoder/FaadDecoderPlugin.cxx
+++ b/src/decoder/FaadDecoderPlugin.cxx
@@ -368,7 +368,6 @@ faad_stream_decode(struct decoder *mpd_decoder, struct input_stream *is)
 	bool ret;
 	uint16_t bit_rate = 0;
 	DecoderBuffer *buffer;
-	enum decoder_command cmd;
 
 	buffer = decoder_buffer_new(mpd_decoder, is,
 				    FAAD_MIN_STREAMSIZE * AAC_MAX_CHANNELS);
@@ -386,7 +385,7 @@ faad_stream_decode(struct decoder *mpd_decoder, struct input_stream *is)
 	NeAACDecSetConfiguration(decoder, config);
 
 	while (!decoder_buffer_is_full(buffer) && !is->LockIsEOF() &&
-	       decoder_get_command(mpd_decoder) == DECODE_COMMAND_NONE) {
+	       decoder_get_command(mpd_decoder) == DecoderCommand::NONE) {
 		adts_find_frame(buffer);
 		decoder_buffer_fill(buffer);
 	}
@@ -407,6 +406,7 @@ faad_stream_decode(struct decoder *mpd_decoder, struct input_stream *is)
 
 	/* the decoder loop */
 
+	DecoderCommand cmd;
 	do {
 		size_t frame_size;
 		const void *decoded;
@@ -457,7 +457,7 @@ faad_stream_decode(struct decoder *mpd_decoder, struct input_stream *is)
 		cmd = decoder_data(mpd_decoder, is, decoded,
 				   (size_t)frame_info.samples * 2,
 				   bit_rate);
-	} while (cmd != DECODE_COMMAND_STOP);
+	} while (cmd != DecoderCommand::STOP);
 
 	/* cleanup */
 
diff --git a/src/decoder/FfmpegDecoderPlugin.cxx b/src/decoder/FfmpegDecoderPlugin.cxx
index a0ac5b8fb..a725e1f7d 100644
--- a/src/decoder/FfmpegDecoderPlugin.cxx
+++ b/src/decoder/FfmpegDecoderPlugin.cxx
@@ -253,7 +253,7 @@ copy_interleave_frame(const AVCodecContext *codec_context,
 	return data_size;
 }
 
-static enum decoder_command
+static DecoderCommand
 ffmpeg_send_packet(struct decoder *decoder, struct input_stream *is,
 		   const AVPacket *packet,
 		   AVCodecContext *codec_context,
@@ -269,9 +269,8 @@ ffmpeg_send_packet(struct decoder *decoder, struct input_stream *is,
 
 	uint8_t *output_buffer;
 
-	enum decoder_command cmd = DECODE_COMMAND_NONE;
-	while (packet2.size > 0 &&
-	       cmd == DECODE_COMMAND_NONE) {
+	DecoderCommand cmd = DecoderCommand::NONE;
+	while (packet2.size > 0 && cmd == DecoderCommand::NONE) {
 		int audio_size = 0;
 		int got_frame = 0;
 		int len = avcodec_decode_audio4(codec_context,
@@ -470,7 +469,7 @@ ffmpeg_decode(struct decoder *decoder, struct input_stream *input)
 	uint8_t *interleaved_buffer = NULL;
 	int interleaved_buffer_size = 0;
 
-	enum decoder_command cmd;
+	DecoderCommand cmd;
 	do {
 		AVPacket packet;
 		if (av_read_frame(format_context, &packet) < 0)
@@ -488,7 +487,7 @@ ffmpeg_decode(struct decoder *decoder, struct input_stream *input)
 
 		av_free_packet(&packet);
 
-		if (cmd == DECODE_COMMAND_SEEK) {
+		if (cmd == DecoderCommand::SEEK) {
 			int64_t where =
 				time_to_ffmpeg(decoder_seek_where(decoder),
 					       av_stream->time_base);
@@ -501,7 +500,7 @@ ffmpeg_decode(struct decoder *decoder, struct input_stream *input)
 				decoder_command_finished(decoder);
 			}
 		}
-	} while (cmd != DECODE_COMMAND_STOP);
+	} while (cmd != DecoderCommand::STOP);
 
 #if LIBAVCODEC_VERSION_INT >= AV_VERSION_INT(54, 28, 0)
 	avcodec_free_frame(&frame);
diff --git a/src/decoder/FlacCommon.cxx b/src/decoder/FlacCommon.cxx
index 62409d3cc..9f5d81f85 100644
--- a/src/decoder/FlacCommon.cxx
+++ b/src/decoder/FlacCommon.cxx
@@ -158,7 +158,6 @@ flac_common_write(struct flac_data *data, const FLAC__Frame * frame,
 		  const FLAC__int32 *const buf[],
 		  FLAC__uint64 nbytes)
 {
-	enum decoder_command cmd;
 	void *buffer;
 	unsigned bit_rate;
 
@@ -178,19 +177,19 @@ flac_common_write(struct flac_data *data, const FLAC__Frame * frame,
 	else
 		bit_rate = 0;
 
-	cmd = decoder_data(data->decoder, data->input_stream,
-			   buffer, buffer_size,
-			   bit_rate);
+	auto cmd = decoder_data(data->decoder, data->input_stream,
+				buffer, buffer_size,
+				bit_rate);
 	data->next_frame += frame->header.blocksize;
 	switch (cmd) {
-	case DECODE_COMMAND_NONE:
-	case DECODE_COMMAND_START:
+	case DecoderCommand::NONE:
+	case DecoderCommand::START:
 		break;
 
-	case DECODE_COMMAND_STOP:
+	case DecoderCommand::STOP:
 		return FLAC__STREAM_DECODER_WRITE_STATUS_ABORT;
 
-	case DECODE_COMMAND_SEEK:
+	case DecoderCommand::SEEK:
 		return FLAC__STREAM_DECODER_WRITE_STATUS_CONTINUE;
 	}
 
diff --git a/src/decoder/FlacDecoderPlugin.cxx b/src/decoder/FlacDecoderPlugin.cxx
index c5dd03665..a6b10fbe2 100644
--- a/src/decoder/FlacDecoderPlugin.cxx
+++ b/src/decoder/FlacDecoderPlugin.cxx
@@ -168,11 +168,11 @@ flac_decoder_loop(struct flac_data *data, FLAC__StreamDecoder *flac_dec,
 		  FLAC__uint64 t_start, FLAC__uint64 t_end)
 {
 	struct decoder *decoder = data->decoder;
-	enum decoder_command cmd;
 
 	data->first_frame = t_start;
 
 	while (true) {
+		DecoderCommand cmd;
 		if (!data->tag.IsEmpty()) {
 			cmd = decoder_tag(data->decoder, data->input_stream,
 					  std::move(data->tag));
@@ -180,7 +180,7 @@ flac_decoder_loop(struct flac_data *data, FLAC__StreamDecoder *flac_dec,
 		} else
 			cmd = decoder_get_command(decoder);
 
-		if (cmd == DECODE_COMMAND_SEEK) {
+		if (cmd == DecoderCommand::SEEK) {
 			FLAC__uint64 seek_sample = t_start +
 				decoder_seek_where(decoder) *
 				data->audio_format.sample_rate;
@@ -192,7 +192,7 @@ flac_decoder_loop(struct flac_data *data, FLAC__StreamDecoder *flac_dec,
 				decoder_command_finished(decoder);
 			} else
 				decoder_seek_error(decoder);
-		} else if (cmd == DECODE_COMMAND_STOP ||
+		} else if (cmd == DecoderCommand::STOP ||
 			   FLAC__stream_decoder_get_state(flac_dec) == FLAC__STREAM_DECODER_END_OF_STREAM)
 			break;
 
@@ -201,7 +201,7 @@ flac_decoder_loop(struct flac_data *data, FLAC__StreamDecoder *flac_dec,
 			break;
 
 		if (!FLAC__stream_decoder_process_single(flac_dec) &&
-		    decoder_get_command(decoder) == DECODE_COMMAND_NONE) {
+		    decoder_get_command(decoder) == DecoderCommand::NONE) {
 			/* a failure that was not triggered by a
 			   decoder command */
 			flacPrintErroredState(FLAC__stream_decoder_get_state(flac_dec));
diff --git a/src/decoder/FlacInput.cxx b/src/decoder/FlacInput.cxx
index 947177cde..19abfca81 100644
--- a/src/decoder/FlacInput.cxx
+++ b/src/decoder/FlacInput.cxx
@@ -33,7 +33,7 @@ FlacInput::Read(FLAC__byte buffer[], size_t *bytes)
 	if (r == 0) {
 		if (input_stream->LockIsEOF() ||
 		    (decoder != nullptr &&
-		     decoder_get_command(decoder) != DECODE_COMMAND_NONE))
+		     decoder_get_command(decoder) != DecoderCommand::NONE))
 			return FLAC__STREAM_DECODER_READ_STATUS_END_OF_STREAM;
 		else
 			return FLAC__STREAM_DECODER_READ_STATUS_ABORT;
@@ -79,8 +79,8 @@ FLAC__bool
 FlacInput::Eof()
 {
 	return (decoder != nullptr &&
-		decoder_get_command(decoder) != DECODE_COMMAND_NONE &&
-		decoder_get_command(decoder) != DECODE_COMMAND_SEEK) ||
+		decoder_get_command(decoder) != DecoderCommand::NONE &&
+		decoder_get_command(decoder) != DecoderCommand::SEEK) ||
 		input_stream->LockIsEOF();
 }
 
@@ -88,7 +88,7 @@ void
 FlacInput::Error(FLAC__StreamDecoderErrorStatus status)
 {
 	if (decoder == nullptr ||
-	    decoder_get_command(decoder) != DECODE_COMMAND_STOP)
+	    decoder_get_command(decoder) != DecoderCommand::STOP)
 		g_warning("%s", FLAC__StreamDecoderErrorStatusString[status]);
 }
 
diff --git a/src/decoder/FluidsynthDecoderPlugin.cxx b/src/decoder/FluidsynthDecoderPlugin.cxx
index 533f02ef1..4db4f1618 100644
--- a/src/decoder/FluidsynthDecoderPlugin.cxx
+++ b/src/decoder/FluidsynthDecoderPlugin.cxx
@@ -102,7 +102,6 @@ fluidsynth_file_decode(struct decoder *decoder, const char *path_fs)
 	fluid_synth_t *synth;
 	fluid_player_t *player;
 	int ret;
-	enum decoder_command cmd;
 
 	/* set up fluid settings */
 
@@ -167,6 +166,7 @@ fluidsynth_file_decode(struct decoder *decoder, const char *path_fs)
 	const AudioFormat audio_format(sample_rate, SampleFormat::S16, 2);
 	decoder_initialized(decoder, audio_format, false, -1);
 
+	DecoderCommand cmd;
 	while (fluid_player_get_status(player) == FLUID_PLAYER_PLAYING) {
 		int16_t buffer[2048];
 		const unsigned max_frames = G_N_ELEMENTS(buffer) / 2;
@@ -182,7 +182,7 @@ fluidsynth_file_decode(struct decoder *decoder, const char *path_fs)
 
 		cmd = decoder_data(decoder, nullptr, buffer, sizeof(buffer),
 				   0);
-		if (cmd != DECODE_COMMAND_NONE)
+		if (cmd != DecoderCommand::NONE)
 			break;
 	}
 
diff --git a/src/decoder/GmeDecoderPlugin.cxx b/src/decoder/GmeDecoderPlugin.cxx
index cc31c6bab..dbe1d000f 100644
--- a/src/decoder/GmeDecoderPlugin.cxx
+++ b/src/decoder/GmeDecoderPlugin.cxx
@@ -174,7 +174,7 @@ gme_file_decode(struct decoder *decoder, const char *path_fs)
 		gme_set_fade(emu, ti->length);
 
 	/* play */
-	enum decoder_command cmd;
+	DecoderCommand cmd;
 	do {
 		short buf[GME_BUFFER_SAMPLES];
 		gme_err = gme_play(emu, GME_BUFFER_SAMPLES, buf);
@@ -184,7 +184,7 @@ gme_file_decode(struct decoder *decoder, const char *path_fs)
 		}
 
 		cmd = decoder_data(decoder, nullptr, buf, sizeof(buf), 0);
-		if (cmd == DECODE_COMMAND_SEEK) {
+		if (cmd == DecoderCommand::SEEK) {
 			float where = decoder_seek_where(decoder);
 			gme_err = gme_seek(emu, int(where * 1000));
 			if (gme_err != nullptr)
@@ -194,7 +194,7 @@ gme_file_decode(struct decoder *decoder, const char *path_fs)
 
 		if (gme_track_ended(emu))
 			break;
-	} while (cmd != DECODE_COMMAND_STOP);
+	} while (cmd != DecoderCommand::STOP);
 
 	gme_free_info(ti);
 	gme_delete(emu);
diff --git a/src/decoder/MadDecoderPlugin.cxx b/src/decoder/MadDecoderPlugin.cxx
index dc2d0b806..b7d90892b 100644
--- a/src/decoder/MadDecoderPlugin.cxx
+++ b/src/decoder/MadDecoderPlugin.cxx
@@ -171,13 +171,13 @@ struct MadDecoder {
 	/**
 	 * Sends the synthesized current frame via decoder_data().
 	 */
-	enum decoder_command SendPCM(unsigned i, unsigned pcm_length);
+	DecoderCommand SendPCM(unsigned i, unsigned pcm_length);
 
 	/**
 	 * Synthesize the current frame and send it via
 	 * decoder_data().
 	 */
-	enum decoder_command SyncAndSend();
+	DecoderCommand SyncAndSend();
 
 	bool Read();
 };
@@ -953,7 +953,7 @@ MadDecoder::UpdateTimerNextFrame()
 	elapsed_time = mad_timer_count(timer, MAD_UNITS_MILLISECONDS) / 1000.0;
 }
 
-enum decoder_command
+DecoderCommand
 MadDecoder::SendPCM(unsigned i, unsigned pcm_length)
 {
 	unsigned max_samples;
@@ -963,7 +963,6 @@ MadDecoder::SendPCM(unsigned i, unsigned pcm_length)
 		MAD_NCHANNELS(&frame.header);
 
 	while (i < pcm_length) {
-		enum decoder_command cmd;
 		unsigned int num_samples = pcm_length - i;
 		if (num_samples > max_samples)
 			num_samples = max_samples;
@@ -975,17 +974,17 @@ MadDecoder::SendPCM(unsigned i, unsigned pcm_length)
 				       MAD_NCHANNELS(&frame.header));
 		num_samples *= MAD_NCHANNELS(&frame.header);
 
-		cmd = decoder_data(decoder, input_stream, output_buffer,
-				   sizeof(output_buffer[0]) * num_samples,
-				   bit_rate / 1000);
-		if (cmd != DECODE_COMMAND_NONE)
+		auto cmd = decoder_data(decoder, input_stream, output_buffer,
+					sizeof(output_buffer[0]) * num_samples,
+					bit_rate / 1000);
+		if (cmd != DecoderCommand::NONE)
 			return cmd;
 	}
 
-	return DECODE_COMMAND_NONE;
+	return DecoderCommand::NONE;
 }
 
-inline enum decoder_command
+inline DecoderCommand
 MadDecoder::SyncAndSend()
 {
 	mad_synth_frame(&synth, &frame);
@@ -1001,12 +1000,12 @@ MadDecoder::SyncAndSend()
 
 	if (drop_start_frames > 0) {
 		drop_start_frames--;
-		return DECODE_COMMAND_NONE;
+		return DecoderCommand::NONE;
 	} else if ((drop_end_frames > 0) &&
 		   (current_frame == (max_frames + 1 - drop_end_frames))) {
 		/* stop decoding, effectively dropping all remaining
 		   frames */
-		return DECODE_COMMAND_STOP;
+		return DecoderCommand::STOP;
 	}
 
 	unsigned i = 0;
@@ -1024,28 +1023,29 @@ MadDecoder::SyncAndSend()
 			pcm_length -= drop_end_samples;
 	}
 
-	enum decoder_command cmd = SendPCM(i, pcm_length);
-	if (cmd != DECODE_COMMAND_NONE)
+	auto cmd = SendPCM(i, pcm_length);
+	if (cmd != DecoderCommand::NONE)
 		return cmd;
 
 	if (drop_end_samples &&
 	    (current_frame == max_frames - drop_end_frames))
 		/* stop decoding, effectively dropping
 		 * all remaining samples */
-		return DECODE_COMMAND_STOP;
+		return DecoderCommand::STOP;
 
-	return DECODE_COMMAND_NONE;
+	return DecoderCommand::NONE;
 }
 
 inline bool
 MadDecoder::Read()
 {
 	enum mp3_action ret;
-	enum decoder_command cmd;
 
 	UpdateTimerNextFrame();
 
 	switch (mute_frame) {
+		DecoderCommand cmd;
+
 	case MUTEFRAME_SKIP:
 		mute_frame = MUTEFRAME_NONE;
 		break;
@@ -1055,7 +1055,7 @@ MadDecoder::Read()
 		break;
 	case MUTEFRAME_NONE:
 		cmd = SyncAndSend();
-		if (cmd == DECODE_COMMAND_SEEK) {
+		if (cmd == DecoderCommand::SEEK) {
 			unsigned long j;
 
 			assert(input_stream->IsSeekable());
@@ -1072,7 +1072,7 @@ MadDecoder::Read()
 				mute_frame = MUTEFRAME_SEEK;
 				decoder_command_finished(decoder);
 			}
-		} else if (cmd != DECODE_COMMAND_NONE)
+		} else if (cmd != DecoderCommand::NONE)
 			return false;
 	}
 
@@ -1119,7 +1119,7 @@ mp3_decode(struct decoder *decoder, struct input_stream *input_stream)
 	if (!data.DecodeFirstFrame(&tag)) {
 		delete tag;
 
-		if (decoder_get_command(decoder) == DECODE_COMMAND_NONE)
+		if (decoder_get_command(decoder) == DecoderCommand::NONE)
 			g_warning
 			    ("Input does not appear to be a mp3 bit stream.\n");
 		return;
diff --git a/src/decoder/MikmodDecoderPlugin.cxx b/src/decoder/MikmodDecoderPlugin.cxx
index f98b22a6d..78a26891a 100644
--- a/src/decoder/MikmodDecoderPlugin.cxx
+++ b/src/decoder/MikmodDecoderPlugin.cxx
@@ -148,7 +148,6 @@ mikmod_decoder_file_decode(struct decoder *decoder, const char *path_fs)
 	MODULE *handle;
 	int ret;
 	SBYTE buffer[MIKMOD_FRAME_SIZE];
-	enum decoder_command cmd = DECODE_COMMAND_NONE;
 
 	path2 = g_strdup(path_fs);
 	handle = Player_Load(path2, 128, 0);
@@ -168,7 +167,9 @@ mikmod_decoder_file_decode(struct decoder *decoder, const char *path_fs)
 	decoder_initialized(decoder, audio_format, false, 0);
 
 	Player_Start(handle);
-	while (cmd == DECODE_COMMAND_NONE && Player_Active()) {
+
+	DecoderCommand cmd = DecoderCommand::NONE;
+	while (cmd == DecoderCommand::NONE && Player_Active()) {
 		ret = VC_WriteBytes(buffer, sizeof(buffer));
 		cmd = decoder_data(decoder, nullptr, buffer, ret, 0);
 	}
diff --git a/src/decoder/ModplugDecoderPlugin.cxx b/src/decoder/ModplugDecoderPlugin.cxx
index d6840300c..9cbf44b15 100644
--- a/src/decoder/ModplugDecoderPlugin.cxx
+++ b/src/decoder/ModplugDecoderPlugin.cxx
@@ -99,7 +99,6 @@ mod_decode(struct decoder *decoder, struct input_stream *is)
 	GByteArray *bdatas;
 	int ret;
 	char audio_buffer[MODPLUG_FRAME_SIZE];
-	enum decoder_command cmd = DECODE_COMMAND_NONE;
 
 	bdatas = mod_loadfile(decoder, is);
 
@@ -131,6 +130,7 @@ mod_decode(struct decoder *decoder, struct input_stream *is)
 			    is->IsSeekable(),
 			    ModPlug_GetLength(f) / 1000.0);
 
+	DecoderCommand cmd;
 	do {
 		ret = ModPlug_Read(f, audio_buffer, MODPLUG_FRAME_SIZE);
 		if (ret <= 0)
@@ -140,7 +140,7 @@ mod_decode(struct decoder *decoder, struct input_stream *is)
 				   audio_buffer, ret,
 				   0);
 
-		if (cmd == DECODE_COMMAND_SEEK) {
+		if (cmd == DecoderCommand::SEEK) {
 			float where = decoder_seek_where(decoder);
 
 			ModPlug_Seek(f, (int)(where * 1000.0));
@@ -148,7 +148,7 @@ mod_decode(struct decoder *decoder, struct input_stream *is)
 			decoder_command_finished(decoder);
 		}
 
-	} while (cmd != DECODE_COMMAND_STOP);
+	} while (cmd != DecoderCommand::STOP);
 
 	ModPlug_Unload(f);
 }
diff --git a/src/decoder/MpcdecDecoderPlugin.cxx b/src/decoder/MpcdecDecoderPlugin.cxx
index d9c7a17d1..252fe92e6 100644
--- a/src/decoder/MpcdecDecoderPlugin.cxx
+++ b/src/decoder/MpcdecDecoderPlugin.cxx
@@ -147,7 +147,7 @@ mpcdec_decode(struct decoder *mpd_decoder, struct input_stream *is)
 
 	mpc_demux *demux = mpc_demux_init(&reader);
 	if (demux == nullptr) {
-		if (decoder_get_command(mpd_decoder) != DECODE_COMMAND_STOP)
+		if (decoder_get_command(mpd_decoder) != DecoderCommand::STOP)
 			g_warning("Not a valid musepack stream");
 		return;
 	}
@@ -178,9 +178,9 @@ mpcdec_decode(struct decoder *mpd_decoder, struct input_stream *is)
 			    is->IsSeekable(),
 			    mpc_streaminfo_get_length(&info));
 
-	enum decoder_command cmd = DECODE_COMMAND_NONE;
+	DecoderCommand cmd = DecoderCommand::NONE;
 	do {
-		if (cmd == DECODE_COMMAND_SEEK) {
+		if (cmd == DecoderCommand::SEEK) {
 			mpc_int64_t where = decoder_seek_where(mpd_decoder) *
 				audio_format.sample_rate;
 			bool success;
@@ -218,7 +218,7 @@ mpcdec_decode(struct decoder *mpd_decoder, struct input_stream *is)
 		cmd = decoder_data(mpd_decoder, is,
 				   chunk, ret * sizeof(chunk[0]),
 				   bit_rate);
-	} while (cmd != DECODE_COMMAND_STOP);
+	} while (cmd != DecoderCommand::STOP);
 
 	mpc_demux_exit(demux);
 }
diff --git a/src/decoder/Mpg123DecoderPlugin.cxx b/src/decoder/Mpg123DecoderPlugin.cxx
index a44fc1241..3100a0f1c 100644
--- a/src/decoder/Mpg123DecoderPlugin.cxx
+++ b/src/decoder/Mpg123DecoderPlugin.cxx
@@ -106,7 +106,6 @@ mpd_mpg123_file_decode(struct decoder *decoder, const char *path_fs)
 	mpg123_handle *handle;
 	int error;
 	off_t num_samples;
-	enum decoder_command cmd;
 	struct mpg123_frameinfo info;
 
 	/* open the file */
@@ -149,6 +148,7 @@ mpd_mpg123_file_decode(struct decoder *decoder, const char *path_fs)
 
 	/* the decoder main loop */
 
+	DecoderCommand cmd;
 	do {
 		unsigned char buffer[8192];
 		size_t nbytes;
@@ -175,7 +175,7 @@ mpd_mpg123_file_decode(struct decoder *decoder, const char *path_fs)
 
 		cmd = decoder_data(decoder, nullptr, buffer, nbytes, info.bitrate);
 
-		if (cmd == DECODE_COMMAND_SEEK) {
+		if (cmd == DecoderCommand::SEEK) {
 			off_t c = decoder_seek_where(decoder)*audio_format.sample_rate;
 			c = mpg123_seek(handle, c, SEEK_SET);
 			if (c < 0)
@@ -185,9 +185,9 @@ mpd_mpg123_file_decode(struct decoder *decoder, const char *path_fs)
 				decoder_timestamp(decoder, c/(double)audio_format.sample_rate);
 			}
 
-			cmd = DECODE_COMMAND_NONE;
+			cmd = DecoderCommand::NONE;
 		}
-	} while (cmd == DECODE_COMMAND_NONE);
+	} while (cmd == DecoderCommand::NONE);
 
 	/* cleanup */
 
diff --git a/src/decoder/OpusDecoderPlugin.cxx b/src/decoder/OpusDecoderPlugin.cxx
index c757d66ef..ea1d6660c 100644
--- a/src/decoder/OpusDecoderPlugin.cxx
+++ b/src/decoder/OpusDecoderPlugin.cxx
@@ -96,11 +96,11 @@ public:
 	bool ReadFirstPage(OggSyncState &oy);
 	bool ReadNextPage(OggSyncState &oy);
 
-	enum decoder_command HandlePackets();
-	enum decoder_command HandlePacket(const ogg_packet &packet);
-	enum decoder_command HandleBOS(const ogg_packet &packet);
-	enum decoder_command HandleTags(const ogg_packet &packet);
-	enum decoder_command HandleAudio(const ogg_packet &packet);
+	DecoderCommand HandlePackets();
+	DecoderCommand HandlePacket(const ogg_packet &packet);
+	DecoderCommand HandleBOS(const ogg_packet &packet);
+	DecoderCommand HandleTags(const ogg_packet &packet);
+	DecoderCommand HandleAudio(const ogg_packet &packet);
 };
 
 MPDOpusDecoder::~MPDOpusDecoder()
@@ -143,29 +143,29 @@ MPDOpusDecoder::ReadNextPage(OggSyncState &oy)
 	return true;
 }
 
-inline enum decoder_command
+inline DecoderCommand
 MPDOpusDecoder::HandlePackets()
 {
 	ogg_packet packet;
 	while (ogg_stream_packetout(&os, &packet) == 1) {
-		enum decoder_command cmd = HandlePacket(packet);
-		if (cmd != DECODE_COMMAND_NONE)
+		auto cmd = HandlePacket(packet);
+		if (cmd != DecoderCommand::NONE)
 			return cmd;
 	}
 
-	return DECODE_COMMAND_NONE;
+	return DecoderCommand::NONE;
 }
 
-inline enum decoder_command
+inline DecoderCommand
 MPDOpusDecoder::HandlePacket(const ogg_packet &packet)
 {
 	if (packet.e_o_s)
-		return DECODE_COMMAND_STOP;
+		return DecoderCommand::STOP;
 
 	if (packet.b_o_s)
 		return HandleBOS(packet);
 	else if (!found_opus)
-		return DECODE_COMMAND_STOP;
+		return DecoderCommand::STOP;
 
 	if (IsOpusTags(packet))
 		return HandleTags(packet);
@@ -173,18 +173,18 @@ MPDOpusDecoder::HandlePacket(const ogg_packet &packet)
 	return HandleAudio(packet);
 }
 
-inline enum decoder_command
+inline DecoderCommand
 MPDOpusDecoder::HandleBOS(const ogg_packet &packet)
 {
 	assert(packet.b_o_s);
 
 	if (found_opus || !IsOpusHead(packet))
-		return DECODE_COMMAND_STOP;
+		return DecoderCommand::STOP;
 
 	unsigned channels;
 	if (!ScanOpusHeader(packet.packet, packet.bytes, channels) ||
 	    !audio_valid_channel_count(channels))
-		return DECODE_COMMAND_STOP;
+		return DecoderCommand::STOP;
 
 	assert(opus_decoder == nullptr);
 	assert(output_buffer == nullptr);
@@ -201,7 +201,7 @@ MPDOpusDecoder::HandleBOS(const ogg_packet &packet)
 	if (opus_decoder == nullptr) {
 		g_warning("libopus error: %s",
 			  opus_strerror(opus_error));
-		return DECODE_COMMAND_STOP;
+		return DecoderCommand::STOP;
 	}
 
 	const AudioFormat audio_format(opus_sample_rate,
@@ -220,12 +220,12 @@ MPDOpusDecoder::HandleBOS(const ogg_packet &packet)
 	return decoder_get_command(decoder);
 }
 
-inline enum decoder_command
+inline DecoderCommand
 MPDOpusDecoder::HandleTags(const ogg_packet &packet)
 {
 	TagBuilder tag_builder;
 
-	enum decoder_command cmd;
+	DecoderCommand cmd;
 	if (ScanOpusTags(packet.packet, packet.bytes,
 			 &add_tag_handler, &tag_builder) &&
 	    !tag_builder.IsEmpty()) {
@@ -238,7 +238,7 @@ MPDOpusDecoder::HandleTags(const ogg_packet &packet)
 	return cmd;
 }
 
-inline enum decoder_command
+inline DecoderCommand
 MPDOpusDecoder::HandleAudio(const ogg_packet &packet)
 {
 	assert(opus_decoder != nullptr);
@@ -250,20 +250,19 @@ MPDOpusDecoder::HandleAudio(const ogg_packet &packet)
 				  0);
 	if (nframes < 0) {
 		g_warning("%s", opus_strerror(nframes));
-		return DECODE_COMMAND_STOP;
+		return DecoderCommand::STOP;
 	}
 
 	if (nframes > 0) {
 		const size_t nbytes = nframes * frame_size;
-		enum decoder_command cmd =
-			decoder_data(decoder, input_stream,
-				     output_buffer, nbytes,
-				     0);
-		if (cmd != DECODE_COMMAND_NONE)
+		auto cmd = decoder_data(decoder, input_stream,
+					output_buffer, nbytes,
+					0);
+		if (cmd != DecoderCommand::NONE)
 			return cmd;
 	}
 
-	return DECODE_COMMAND_NONE;
+	return DecoderCommand::NONE;
 }
 
 static void
@@ -284,8 +283,8 @@ mpd_opus_stream_decode(struct decoder *decoder,
 		return;
 
 	while (true) {
-		enum decoder_command cmd = d.HandlePackets();
-		if (cmd != DECODE_COMMAND_NONE)
+		auto cmd = d.HandlePackets();
+		if (cmd != DecoderCommand::NONE)
 			break;
 
 		if (!d.ReadNextPage(oy))
diff --git a/src/decoder/PcmDecoderPlugin.cxx b/src/decoder/PcmDecoderPlugin.cxx
index 4fccca75d..94867f01d 100644
--- a/src/decoder/PcmDecoderPlugin.cxx
+++ b/src/decoder/PcmDecoderPlugin.cxx
@@ -48,8 +48,6 @@ pcm_stream_decode(struct decoder *decoder, struct input_stream *is)
 	const bool reverse_endian = mime != nullptr &&
 		strcmp(mime, "audio/x-mpd-cdda-pcm-reverse") == 0;
 
-	enum decoder_command cmd;
-
 	const double time_to_size = audio_format.GetTimeToSize();
 
 	float total_time = -1;
@@ -60,6 +58,7 @@ pcm_stream_decode(struct decoder *decoder, struct input_stream *is)
 	decoder_initialized(decoder, audio_format,
 			    is->IsSeekable(), total_time);
 
+	DecoderCommand cmd;
 	do {
 		char buffer[4096];
 
@@ -79,7 +78,7 @@ pcm_stream_decode(struct decoder *decoder, struct input_stream *is)
 			? decoder_data(decoder, is,
 				       buffer, nbytes, 0)
 			: decoder_get_command(decoder);
-		if (cmd == DECODE_COMMAND_SEEK) {
+		if (cmd == DecoderCommand::SEEK) {
 			goffset offset = (goffset)(time_to_size *
 						   decoder_seek_where(decoder));
 
@@ -91,9 +90,9 @@ pcm_stream_decode(struct decoder *decoder, struct input_stream *is)
 				decoder_seek_error(decoder);
 			}
 
-			cmd = DECODE_COMMAND_NONE;
+			cmd = DecoderCommand::NONE;
 		}
-	} while (cmd == DECODE_COMMAND_NONE);
+	} while (cmd == DecoderCommand::NONE);
 }
 
 static const char *const pcm_mime_types[] = {
diff --git a/src/decoder/SndfileDecoderPlugin.cxx b/src/decoder/SndfileDecoderPlugin.cxx
index 252e88df5..56853958c 100644
--- a/src/decoder/SndfileDecoderPlugin.cxx
+++ b/src/decoder/SndfileDecoderPlugin.cxx
@@ -119,7 +119,6 @@ sndfile_stream_decode(struct decoder *decoder, struct input_stream *is)
 	size_t frame_size;
 	sf_count_t read_frames, num_frames;
 	int buffer[4096];
-	enum decoder_command cmd;
 
 	info.format = 0;
 
@@ -147,6 +146,7 @@ sndfile_stream_decode(struct decoder *decoder, struct input_stream *is)
 	frame_size = audio_format.GetFrameSize();
 	read_frames = sizeof(buffer) / frame_size;
 
+	DecoderCommand cmd;
 	do {
 		num_frames = sf_readf_int(sf, buffer, read_frames);
 		if (num_frames <= 0)
@@ -155,7 +155,7 @@ sndfile_stream_decode(struct decoder *decoder, struct input_stream *is)
 		cmd = decoder_data(decoder, is,
 				   buffer, num_frames * frame_size,
 				   0);
-		if (cmd == DECODE_COMMAND_SEEK) {
+		if (cmd == DecoderCommand::SEEK) {
 			sf_count_t c =
 				time_to_frame(decoder_seek_where(decoder),
 					      &audio_format);
@@ -164,9 +164,9 @@ sndfile_stream_decode(struct decoder *decoder, struct input_stream *is)
 				decoder_seek_error(decoder);
 			else
 				decoder_command_finished(decoder);
-			cmd = DECODE_COMMAND_NONE;
+			cmd = DecoderCommand::NONE;
 		}
-	} while (cmd == DECODE_COMMAND_NONE);
+	} while (cmd == DecoderCommand::NONE);
 
 	sf_close(sf);
 }
diff --git a/src/decoder/VorbisDecoderPlugin.cxx b/src/decoder/VorbisDecoderPlugin.cxx
index 2b175912d..a4a938aa8 100644
--- a/src/decoder/VorbisDecoderPlugin.cxx
+++ b/src/decoder/VorbisDecoderPlugin.cxx
@@ -83,7 +83,7 @@ static int ogg_seek_cb(void *data, ogg_int64_t offset, int whence)
 
 	Error error;
 	return vis->seekable &&
-		(!vis->decoder || decoder_get_command(vis->decoder) != DECODE_COMMAND_STOP) &&
+		(!vis->decoder || decoder_get_command(vis->decoder) != DecoderCommand::STOP) &&
 		vis->input_stream->LockSeek(offset, whence, error)
 		? 0 : -1;
 }
@@ -143,7 +143,7 @@ vorbis_is_open(struct vorbis_input_stream *vis, OggVorbis_File *vf,
 	int ret = ov_open_callbacks(vis, vf, NULL, 0, vorbis_is_callbacks);
 	if (ret < 0) {
 		if (decoder == NULL ||
-		    decoder_get_command(decoder) == DECODE_COMMAND_NONE)
+		    decoder_get_command(decoder) == DecoderCommand::NONE)
 			g_warning("Failed to open Ogg Vorbis stream: %s",
 				  vorbis_strerror(ret));
 		return false;
@@ -221,8 +221,6 @@ vorbis_stream_decode(struct decoder *decoder,
 
 	decoder_initialized(decoder, audio_format, vis.seekable, total_time);
 
-	enum decoder_command cmd = decoder_get_command(decoder);
-
 #ifdef HAVE_TREMOR
 	char buffer[4096];
 #else
@@ -235,8 +233,9 @@ vorbis_stream_decode(struct decoder *decoder,
 	int prev_section = -1;
 	unsigned kbit_rate = 0;
 
+	DecoderCommand cmd = decoder_get_command(decoder);
 	do {
-		if (cmd == DECODE_COMMAND_SEEK) {
+		if (cmd == DecoderCommand::SEEK) {
 			double seek_where = decoder_seek_where(decoder);
 			if (0 == ov_time_seek_page(&vf, seek_where)) {
 				decoder_command_finished(decoder);
@@ -302,7 +301,7 @@ vorbis_stream_decode(struct decoder *decoder,
 		cmd = decoder_data(decoder, input_stream,
 				   buffer, nbytes,
 				   kbit_rate);
-	} while (cmd != DECODE_COMMAND_STOP);
+	} while (cmd != DecoderCommand::STOP);
 
 	ov_clear(&vf);
 }
diff --git a/src/decoder/WavpackDecoderPlugin.cxx b/src/decoder/WavpackDecoderPlugin.cxx
index d0122ad87..ecabafefe 100644
--- a/src/decoder/WavpackDecoderPlugin.cxx
+++ b/src/decoder/WavpackDecoderPlugin.cxx
@@ -177,9 +177,9 @@ wavpack_decode(struct decoder *decoder, WavpackContext *wpc, bool can_seek)
 
 	decoder_initialized(decoder, audio_format, can_seek, total_time);
 
-	enum decoder_command cmd = decoder_get_command(decoder);
-	while (cmd != DECODE_COMMAND_STOP) {
-		if (cmd == DECODE_COMMAND_SEEK) {
+	DecoderCommand cmd = decoder_get_command(decoder);
+	while (cmd != DecoderCommand::STOP) {
+		if (cmd == DecoderCommand::SEEK) {
 			if (can_seek) {
 				unsigned where = decoder_seek_where(decoder) *
 					audio_format.sample_rate;
diff --git a/src/decoder/WildmidiDecoderPlugin.cxx b/src/decoder/WildmidiDecoderPlugin.cxx
index daa0e0cc9..3a057ca2c 100644
--- a/src/decoder/WildmidiDecoderPlugin.cxx
+++ b/src/decoder/WildmidiDecoderPlugin.cxx
@@ -72,7 +72,6 @@ wildmidi_file_decode(struct decoder *decoder, const char *path_fs)
 	};
 	midi *wm;
 	const struct _WM_Info *info;
-	enum decoder_command cmd;
 
 	wm = WildMidi_Open(path_fs);
 	if (wm == nullptr)
@@ -87,6 +86,7 @@ wildmidi_file_decode(struct decoder *decoder, const char *path_fs)
 	decoder_initialized(decoder, audio_format, true,
 			    info->approx_total_samples / WILDMIDI_SAMPLE_RATE);
 
+	DecoderCommand cmd;
 	do {
 		char buffer[4096];
 		int len;
@@ -101,7 +101,7 @@ wildmidi_file_decode(struct decoder *decoder, const char *path_fs)
 
 		cmd = decoder_data(decoder, nullptr, buffer, len, 0);
 
-		if (cmd == DECODE_COMMAND_SEEK) {
+		if (cmd == DecoderCommand::SEEK) {
 			unsigned long seek_where = WILDMIDI_SAMPLE_RATE *
 				decoder_seek_where(decoder);
 
@@ -111,10 +111,10 @@ wildmidi_file_decode(struct decoder *decoder, const char *path_fs)
 			WildMidi_FastSeek(wm, &seek_where);
 #endif
 			decoder_command_finished(decoder);
-			cmd = DECODE_COMMAND_NONE;
+			cmd = DecoderCommand::NONE;
 		}
 
-	} while (cmd == DECODE_COMMAND_NONE);
+	} while (cmd == DecoderCommand::NONE);
 
 	WildMidi_Close(wm);
 }
diff --git a/src/decoder/sidplay_decoder_plugin.cxx b/src/decoder/sidplay_decoder_plugin.cxx
index 19969c00a..fed0476ec 100644
--- a/src/decoder/sidplay_decoder_plugin.cxx
+++ b/src/decoder/sidplay_decoder_plugin.cxx
@@ -290,7 +290,7 @@ sidplay_file_decode(struct decoder *decoder, const char *path_fs)
 	const unsigned timebase = player.timebase();
 	song_len *= timebase;
 
-	enum decoder_command cmd;
+	DecoderCommand cmd;
 	do {
 		char buffer[4096];
 		size_t nbytes;
@@ -303,7 +303,7 @@ sidplay_file_decode(struct decoder *decoder, const char *path_fs)
 
 		cmd = decoder_data(decoder, NULL, buffer, nbytes, 0);
 
-		if(cmd==DECODE_COMMAND_SEEK) {
+		if (cmd == DecoderCommand::SEEK) {
 			unsigned data_time = player.time();
 			unsigned target_time = (unsigned)
 				(decoder_seek_where(decoder) * timebase);
@@ -328,7 +328,7 @@ sidplay_file_decode(struct decoder *decoder, const char *path_fs)
 		if (song_len > 0 && player.time() >= (unsigned)song_len)
 			break;
 
-	} while (cmd != DECODE_COMMAND_STOP);
+	} while (cmd != DecoderCommand::STOP);
 }
 
 static bool
diff --git a/test/dump_playlist.cxx b/test/dump_playlist.cxx
index 45719fab0..af73ed4e7 100644
--- a/test/dump_playlist.cxx
+++ b/test/dump_playlist.cxx
@@ -59,10 +59,10 @@ decoder_initialized(gcc_unused struct decoder *decoder,
 {
 }
 
-enum decoder_command
+DecoderCommand
 decoder_get_command(gcc_unused struct decoder *decoder)
 {
-	return DECODE_COMMAND_NONE;
+	return DecoderCommand::NONE;
 }
 
 void
@@ -96,22 +96,22 @@ decoder_timestamp(gcc_unused struct decoder *decoder,
 {
 }
 
-enum decoder_command
+DecoderCommand
 decoder_data(gcc_unused struct decoder *decoder,
 	     gcc_unused struct input_stream *is,
 	     const void *data, size_t datalen,
 	     gcc_unused uint16_t kbit_rate)
 {
 	gcc_unused ssize_t nbytes = write(1, data, datalen);
-	return DECODE_COMMAND_NONE;
+	return DecoderCommand::NONE;
 }
 
-enum decoder_command
+DecoderCommand
 decoder_tag(gcc_unused struct decoder *decoder,
 	    gcc_unused struct input_stream *is,
 	    gcc_unused Tag &&tag)
 {
-	return DECODE_COMMAND_NONE;
+	return DecoderCommand::NONE;
 }
 
 void
diff --git a/test/read_tags.cxx b/test/read_tags.cxx
index de100134b..d7f2f38d9 100644
--- a/test/read_tags.cxx
+++ b/test/read_tags.cxx
@@ -47,10 +47,10 @@ decoder_initialized(gcc_unused struct decoder *decoder,
 {
 }
 
-enum decoder_command
+DecoderCommand
 decoder_get_command(gcc_unused struct decoder *decoder)
 {
-	return DECODE_COMMAND_NONE;
+	return DecoderCommand::NONE;
 }
 
 void decoder_command_finished(gcc_unused struct decoder *decoder)
@@ -81,22 +81,22 @@ decoder_timestamp(gcc_unused struct decoder *decoder,
 {
 }
 
-enum decoder_command
+DecoderCommand
 decoder_data(gcc_unused struct decoder *decoder,
 	     gcc_unused struct input_stream *is,
 	     const void *data, size_t datalen,
 	     gcc_unused uint16_t bit_rate)
 {
 	gcc_unused ssize_t nbytes = write(1, data, datalen);
-	return DECODE_COMMAND_NONE;
+	return DecoderCommand::NONE;
 }
 
-enum decoder_command
+DecoderCommand
 decoder_tag(gcc_unused struct decoder *decoder,
 	    gcc_unused struct input_stream *is,
 	    gcc_unused Tag &&tag)
 {
-	return DECODE_COMMAND_NONE;
+	return DecoderCommand::NONE;
 }
 
 void
diff --git a/test/run_decoder.cxx b/test/run_decoder.cxx
index ed29c1880..794302b5d 100644
--- a/test/run_decoder.cxx
+++ b/test/run_decoder.cxx
@@ -68,10 +68,10 @@ decoder_initialized(struct decoder *decoder,
 	decoder->initialized = true;
 }
 
-enum decoder_command
+DecoderCommand
 decoder_get_command(gcc_unused struct decoder *decoder)
 {
-	return DECODE_COMMAND_NONE;
+	return DecoderCommand::NONE;
 }
 
 void decoder_command_finished(gcc_unused struct decoder *decoder)
@@ -101,22 +101,22 @@ decoder_timestamp(gcc_unused struct decoder *decoder,
 {
 }
 
-enum decoder_command
+DecoderCommand
 decoder_data(gcc_unused struct decoder *decoder,
 	     gcc_unused struct input_stream *is,
 	     const void *data, size_t datalen,
 	     gcc_unused uint16_t kbit_rate)
 {
 	gcc_unused ssize_t nbytes = write(1, data, datalen);
-	return DECODE_COMMAND_NONE;
+	return DecoderCommand::NONE;
 }
 
-enum decoder_command
+DecoderCommand
 decoder_tag(gcc_unused struct decoder *decoder,
 	    gcc_unused struct input_stream *is,
 	    gcc_unused Tag &&tag)
 {
-	return DECODE_COMMAND_NONE;
+	return DecoderCommand::NONE;
 }
 
 void