Implement Get MIDI Ticks for non-MIDI formats by returning the playba…

…ck position in seconds.

Implemented for mpg123, libvorbisfile and libopusfile.
Works for EmptyAudio and SDLAudio by approximating it through the frame count.

When no BGM is playing the returned value is 0.

Fix EasyRPG#1517

src/audio.cpp

@@ -20,6 +20,7 @@
 #include "system.h"
 #include "baseui.h"
 #include "player.h"
+#include "graphics.h"
 
 AudioInterface& Audio() {
 	static EmptyAudio default_;
@@ -32,12 +33,23 @@ AudioInterface& Audio() {
 
 void EmptyAudio::BGM_Play(std::string const&, int, int, int) {
 	bgm_starttick = Player::GetFrames();
+	playing = true;
+}
+
+void EmptyAudio::BGM_Stop() {
+	playing = false;
 }
 
 unsigned EmptyAudio::BGM_GetTicks() const {
-	return (Player::GetFrames() - bgm_starttick) * 500; // Arbitrary
+	if (!playing) {
+		return 0;
+	}
+
+	// Time since BGM_Play was called, works for everything except MIDI
+	return (Player::GetFrames() - bgm_starttick + 1) / Graphics::GetDefaultFps();
 }
 
 bool EmptyAudio::BGM_PlayedOnce() const {
-	return BGM_GetTicks() > 5000; // Arbitrary
+	// 5 seconds, arbitrary
+	return BGM_GetTicks() > (Graphics::GetDefaultFps() * 5);
 }

src/audio.h

@@ -51,10 +51,10 @@ struct AudioInterface {
 	 * Returns whether the background music has played at least once.
 	 */
 	virtual bool BGM_PlayedOnce() const = 0;
-	
+
 	/**
 	 * Reports if a music file is currently being played.
-	 * 
+	 *
 	 * @return true when BGM is playing
 	 */
 	virtual bool BGM_IsPlaying() const = 0;
@@ -112,10 +112,11 @@ struct AudioInterface {
 };
 
 struct EmptyAudio : public AudioInterface {
+public:
 	void BGM_Play(std::string const&, int, int, int) override;
 	void BGM_Pause() override {}
 	void BGM_Resume() override {}
-	void BGM_Stop() override {}
+	void BGM_Stop() override;
 	bool BGM_PlayedOnce() const override;
 	bool BGM_IsPlaying() const override { return false; }
 	unsigned BGM_GetTicks() const override;
@@ -126,7 +127,10 @@ struct EmptyAudio : public AudioInterface {
 	void SE_Stop() override {}
 	void Update() override {}
 
+private:
 	unsigned bgm_starttick = 0;
+
+	bool playing = false;
 };
 
 AudioInterface& Audio();

src/audio_decoder.h

@@ -249,7 +249,7 @@ class AudioDecoder {
 	 * 200 = double speed and so on
 	 * Not all audio decoders support this. Using the audio hardware is
 	 * recommended.
-	 * 
+	 *
 	 * @param pitch Pitch multiplier to use
 	 * @return true if pitch was set, false otherwise
 	 */
@@ -275,9 +275,11 @@ class AudioDecoder {
 	virtual size_t Tell() const;
 
 	/**
-	 * Returns amount of executed ticks. Only useful for MIDI format.
+	 * Returns a value suitable for the GetMidiTicks command.
+	 * For MIDI this is the amount of MIDI ticks, for other
+	 * formats usually the playback position in seconds.
 	 *
-	 * @return Amount of MIDI ticks.
+	 * @return Amount of MIDI ticks or position in seconds
 	 */
 	virtual int GetTicks() const;
 

src/audio_generic.cpp

@@ -113,6 +113,7 @@ unsigned GenericAudio::BGM_GetTicks() const {
 	for (unsigned i = 0; i < nr_of_bgm_channels; i++) {
 		if (BGM_Channels[i].decoder) {
 			ticks = BGM_Channels[i].decoder->GetTicks();
+			break;
 		}
 	}
 	UnlockMutex();

src/audio_sdl_mixer.cpp

@@ -455,12 +455,16 @@ bool SdlMixerAudio::BGM_IsPlaying() const {
 }
 
 unsigned SdlMixerAudio::BGM_GetTicks() const {
+	if (!BGM_IsPlaying()) {
+		return 0;
+	}
+
 	if (audio_decoder) {
 		return audio_decoder->GetTicks();
 	}
 
-	// TODO: Implement properly. This is an approximation.
-	return SDL_GetTicks() - bgm_starttick;
+	// Should work for everything except MIDI
+	return SDL_GetTicks() + 1 - bgm_starttick;
 }
 
 void SdlMixerAudio::BGM_Volume(int volume) {

src/decoder_mpg123.cpp

@@ -94,6 +94,11 @@ bool Mpg123Decoder::Open(FILE* file) {
 		return false;
 	}
 
+	// Samplerate cached, regularly needed for Ticks function
+	int ch;
+	int fmt;
+	mpg123_getformat(handle.get(), &samplerate, &ch, &fmt);
+
 	return true;
 }
 
@@ -185,6 +190,15 @@ bool Mpg123Decoder::SetFormat(int freq, AudioDecoder::Format fmt, int channels)
 	return err == MPG123_OK;
 }
 
+int Mpg123Decoder::GetTicks() const {
+	if (samplerate == 0) {
+		return 0;
+	}
+
+	off_t pos = mpg123_tell(handle.get());
+	return pos / samplerate;
+}
+
 bool Mpg123Decoder::IsMp3(FILE* stream) {
 	Mpg123Decoder decoder;
 	// Prevent stream handle destruction
@@ -199,7 +213,7 @@ bool Mpg123Decoder::IsMp3(FILE* stream) {
 	int err = 0;
 	size_t done = 0;
 	int err_count = 0;
-	
+
 	// Read beginning of assumed MP3 file and count errors as an heuristic to detect MP3
 	for (int i = 0; i < 10; ++i) {
 		err = mpg123_read(decoder.handle.get(), buffer, 1024, &done);

src/decoder_mpg123.h

@@ -47,6 +47,8 @@ class Mpg123Decoder : public AudioDecoder {
 
 	bool SetFormat(int frequency, AudioDecoder::Format format, int channels) override;
 
+	int GetTicks() const override;
+
 	static bool IsMp3(FILE* stream);
 private:
 	int FillBuffer(uint8_t* buffer, int length) override;
@@ -56,6 +58,8 @@ class Mpg123Decoder : public AudioDecoder {
 #endif
 	int err = 0;
 	bool finished = false;
+
+	long samplerate = 0;
 };
 
 #endif

src/decoder_oggvorbis.cpp

@@ -68,7 +68,6 @@ bool OggVorbisDecoder::Open(FILE* file) {
 		return false;
 	}
 
-	// (long)ov_pcm_total(ovf, -1)) -> decoded length in samples, maybe useful for ticks later?
 	frequency = vi->rate;
 	channels = vi->channels;
 
@@ -107,6 +106,14 @@ bool OggVorbisDecoder::SetFormat(int freq, AudioDecoder::Format format, int chan
 	return true;
 }
 
+int OggVorbisDecoder::GetTicks() const {
+	if (!ovf) {
+		return 0;
+	}
+
+	return (int)ov_time_tell(ovf);
+}
+
 int OggVorbisDecoder::FillBuffer(uint8_t* buffer, int length) {
 	if (!ovf)
 		return -1;

src/decoder_oggvorbis.h

@@ -49,6 +49,8 @@ class OggVorbisDecoder : public AudioDecoder {
 	void GetFormat(int& frequency, AudioDecoder::Format& format, int& channels) const override;
 
 	bool SetFormat(int frequency, AudioDecoder::Format format, int channels) override;
+
+	int GetTicks() const override;
 private:
 	int FillBuffer(uint8_t* buffer, int length) override;
 

src/decoder_opus.cpp

@@ -103,6 +103,15 @@ bool OpusDecoder::SetFormat(int freq, AudioDecoder::Format format, int chans) {
 	return true;
 }
 
+int OpusDecoder::GetTicks() const {
+	if (!oof) {
+		return 0;
+	}
+
+	// According to the docs it is number of samples at 48 kHz
+	return op_pcm_tell(oof) / 48000;
+}
+
 int OpusDecoder::FillBuffer(uint8_t* buffer, int length) {
 	if (!oof)
 		return -1;

src/decoder_opus.h

@@ -42,6 +42,8 @@ class OpusDecoder : public AudioDecoder {
 	void GetFormat(int& frequency, AudioDecoder::Format& format, int& channels) const override;
 
 	bool SetFormat(int frequency, AudioDecoder::Format format, int channels) override;
+
+	int GetTicks() const override;
 private:
 	int FillBuffer(uint8_t* buffer, int length) override;