DecoderControl: use std::chrono::duration for Seek()

src/PlayerThread.cxx

@@ -567,7 +567,7 @@ Player::SeekDecoder()
 	if (where < 0.0)
 		where = 0.0;
 
-	if (!dc.Seek(where + start_ms / 1000.0)) {
+	if (!dc.Seek(SongTime::FromS(where) + SongTime::FromMS(start_ms))) {
 		/* decoder failure */
 		player_command_finished(pc);
 		return false;

src/decoder/DecoderAPI.cxx

@@ -196,7 +196,7 @@ decoder_command_finished(Decoder &decoder)
 
 		dc.pipe->Clear(*dc.buffer);
 
-		decoder.timestamp = dc.seek_where;
+		decoder.timestamp = dc.seek_time.ToDoubleS();
 	}
 
 	dc.command = DecoderCommand::NONE;
@@ -218,7 +218,7 @@ decoder_seek_time(Decoder &decoder)
 
 	decoder.seeking = true;
 
-	return SongTime::FromS(dc.seek_where);
+	return dc.seek_time;
 }
 
 uint64_t
@@ -236,7 +236,7 @@ decoder_seek_where_frame(Decoder &decoder)
 
 	decoder.seeking = true;
 
-	return uint64_t(dc.seek_where * dc.in_audio_format.sample_rate);
+	return dc.seek_time.ToScale<uint64_t>(dc.in_audio_format.sample_rate);
 }
 
 void decoder_seek_error(Decoder & decoder)

src/decoder/DecoderControl.cxx

@@ -105,16 +105,15 @@ DecoderControl::Stop()
 }
 
 bool
-DecoderControl::Seek(double where)
+DecoderControl::Seek(SongTime t)
 {
 	assert(state != DecoderState::START);
-	assert(where >= 0.0);
 
 	if (state == DecoderState::STOP ||
 	    state == DecoderState::ERROR || !seekable)
 		return false;
 
-	seek_where = where;
+	seek_time = t;
 	seek_error = false;
 	LockSynchronousCommand(DecoderCommand::SEEK);
 

src/decoder/DecoderControl.hxx

@@ -26,6 +26,7 @@
 #include "thread/Mutex.hxx"
 #include "thread/Cond.hxx"
 #include "thread/Thread.hxx"
+#include "Chrono.hxx"
 #include "util/Error.hxx"
 
 #include <assert.h>
@@ -107,7 +108,7 @@ struct DecoderControl {
 
 	bool seek_error;
 	bool seekable;
-	double seek_where;
+	SongTime seek_time;
 
 	/** the format of the song file */
 	AudioFormat in_audio_format;
@@ -365,7 +366,7 @@ public:
 
 	void Stop();
 
-	bool Seek(double where);
+	bool Seek(SongTime t);
 
 	void Quit();
 

src/decoder/DecoderInternal.hxx

@@ -57,7 +57,7 @@ struct Decoder {
 	bool initial_seek_running;
 
 	/**
-	 * This flag is set by decoder_seek_where(), and checked by
+	 * This flag is set by decoder_seek_time(), and checked by
 	 * decoder_command_finished().  It is used to clean up after
 	 * seeking.
 	 */