AUDIO: Split the seeking MP3 class from the base decoding stream

1 files changed, 135 insertions, 102 deletions

diff --git a/audio/decoders/mp3.cpp b/audio/decoders/mp3.cpp
index feb531f5ae..8550d9116d 100644
--- a/audio/decoders/mp3.cpp
+++ b/audio/decoders/mp3.cpp
@@ -27,6 +27,7 @@
 #include "common/debug.h"
 #include "common/ptr.h"
 #include "common/stream.h"
+#include "common/substream.h"
 #include "common/textconsole.h"
 #include "common/util.h"
 
@@ -45,20 +46,34 @@ namespace Audio {
 #pragma mark -
 
 
-class MP3Stream : public SeekableAudioStream {
+class BaseMP3Stream : public virtual AudioStream {
+public:
+	BaseMP3Stream();
+	virtual ~BaseMP3Stream();
+
+	bool endOfData() const		{ return _state == MP3_STATE_EOS; }
+	bool isStereo() const		{ return MAD_NCHANNELS(&_frame.header) == 2; }
+	int getRate() const			{ return _frame.header.samplerate; }
+
 protected:
+	void decodeMP3Data(Common::ReadStream &stream);
+	void readMP3Data(Common::ReadStream &stream);
+
+	void initStream(Common::ReadStream &stream);
+	void readHeader(Common::ReadStream &stream);
+	void deinitStream();
+
+	int fillBuffer(Common::ReadStream &stream, int16 *buffer, const int numSamples);
+
 	enum State {
 		MP3_STATE_INIT,	// Need to init the decoder
 		MP3_STATE_READY,	// ready for processing data
 		MP3_STATE_EOS		// end of data reached (may need to loop)
 	};
 
-	Common::DisposablePtr<Common::SeekableReadStream> _inStream;
-
 	uint _posInFrame;
 	State _state;
 
-	Timestamp _length;
 	mad_timer_t _curTime;
 
 	mad_stream _stream;
@@ -71,81 +86,54 @@ protected:
 
 	// This buffer contains a slab of input data
 	byte _buf[BUFFER_SIZE + MAD_BUFFER_GUARD];
+};
 
+class MP3Stream : public BaseMP3Stream, public SeekableAudioStream {
 public:
 	MP3Stream(Common::SeekableReadStream *inStream,
 	               DisposeAfterUse::Flag dispose);
-	~MP3Stream();
+	virtual ~MP3Stream() {}
 
 	int readBuffer(int16 *buffer, const int numSamples);
-
-	bool endOfData() const		{ return _state == MP3_STATE_EOS; }
-	bool isStereo() const		{ return MAD_NCHANNELS(&_frame.header) == 2; }
-	int getRate() const			{ return _frame.header.samplerate; }
-
 	bool seek(const Timestamp &where);
 	Timestamp getLength() const { return _length; }
+
 protected:
-	void decodeMP3Data();
-	void readMP3Data();
+	Common::ScopedPtr<Common::SeekableReadStream> _inStream;
 
-	void initStream();
-	void readHeader();
-	void deinitStream();
+	Timestamp _length;
+
+private:
+	static Common::SeekableReadStream *skipID3(Common::SeekableReadStream *stream, DisposeAfterUse::Flag dispose);
 };
 
-MP3Stream::MP3Stream(Common::SeekableReadStream *inStream, DisposeAfterUse::Flag dispose) :
-	_inStream(inStream, dispose),
+
+BaseMP3Stream::BaseMP3Stream() :
 	_posInFrame(0),
 	_state(MP3_STATE_INIT),
-	_length(0, 1000),
 	_curTime(mad_timer_zero) {
 
 	// The MAD_BUFFER_GUARD must always contain zeros (the reason
 	// for this is that the Layer III Huffman decoder of libMAD
 	// may read a few bytes beyond the end of the input buffer).
 	memset(_buf + BUFFER_SIZE, 0, MAD_BUFFER_GUARD);
-
-	// Calculate the length of the stream
-	initStream();
-
-	while (_state != MP3_STATE_EOS)
-		readHeader();
-
-	// To rule out any invalid sample rate to be encountered here, say in case the
-	// MP3 stream is invalid, we just check the MAD error code here.
-	// We need to assure this, since else we might trigger an assertion in Timestamp
-	// (When getRate() returns 0 or a negative number to be precise).
-	// Note that we allow "MAD_ERROR_BUFLEN" as error code here, since according
-	// to mad.h it is also set on EOF.
-	if ((_stream.error == MAD_ERROR_NONE || _stream.error == MAD_ERROR_BUFLEN) && getRate() > 0)
-		_length = Timestamp(mad_timer_count(_curTime, MAD_UNITS_MILLISECONDS), getRate());
-
-	deinitStream();
-
-	// Reinit stream
-	_state = MP3_STATE_INIT;
-
-	// Decode the first chunk of data. This is necessary so that _frame
-	// is setup and isStereo() and getRate() return correct results.
-	decodeMP3Data();
 }
 
-MP3Stream::~MP3Stream() {
+BaseMP3Stream::~BaseMP3Stream() {
 	deinitStream();
 }
 
-void MP3Stream::decodeMP3Data() {
+void BaseMP3Stream::decodeMP3Data(Common::ReadStream &stream) {
 	do {
 		if (_state == MP3_STATE_INIT)
-			initStream();
+			initStream(stream);
 
 		if (_state == MP3_STATE_EOS)
 			return;
 
 		// If necessary, load more data into the stream decoder
 		if (_stream.error == MAD_ERROR_BUFLEN)
-			readMP3Data();
+			readMP3Data(stream);
 
 		while (_state == MP3_STATE_READY) {
 			_stream.error = MAD_ERROR_NONE;
@@ -179,11 +167,11 @@ void MP3Stream::decodeMP3Data() {
 		_state = MP3_STATE_EOS;
 }
 
-void MP3Stream::readMP3Data() {
+void BaseMP3Stream::readMP3Data(Common::ReadStream &stream) {
 	uint32 remaining = 0;
 
 	// Give up immediately if we already used up all data in the stream
-	if (_inStream->eos()) {
+	if (stream.eos()) {
 		_state = MP3_STATE_EOS;
 		return;
 	}
@@ -198,7 +186,7 @@ void MP3Stream::readMP3Data() {
 	}
 
 	// Try to read the next block
-	uint32 size = _inStream->read(_buf + remaining, BUFFER_SIZE - remaining);
+	uint32 size = stream.read(_buf + remaining, BUFFER_SIZE - remaining);
 	if (size <= 0) {
 		_state = MP3_STATE_EOS;
 		return;
@@ -209,31 +197,7 @@ void MP3Stream::readMP3Data() {
 	mad_stream_buffer(&_stream, _buf, size + remaining);
 }
 
-bool MP3Stream::seek(const Timestamp &where) {
-	if (where == _length) {
-		_state = MP3_STATE_EOS;
-		return true;
-	} else if (where > _length) {
-		return false;
-	}
-
-	const uint32 time = where.msecs();
-
-	mad_timer_t destination;
-	mad_timer_set(&destination, time / 1000, time % 1000, 1000);
-
-	if (_state != MP3_STATE_READY || mad_timer_compare(destination, _curTime) < 0)
-		initStream();
-
-	while (mad_timer_compare(destination, _curTime) > 0 && _state != MP3_STATE_EOS)
-		readHeader();
-
-	decodeMP3Data();
-
-	return (_state != MP3_STATE_EOS);
-}
-
-void MP3Stream::initStream() {
+void BaseMP3Stream::initStream(Common::ReadStream &stream) {
 	if (_state != MP3_STATE_INIT)
 		deinitStream();
 
@@ -243,41 +207,23 @@ void MP3Stream::initStream() {
 	mad_synth_init(&_synth);
 
 	// Reset the stream data
-	_inStream->seek(0, SEEK_SET);
 	_curTime = mad_timer_zero;
 	_posInFrame = 0;
-	
-	// Skip ID3 TAG if any
-	// ID3v1 (beginning with with 'TAG') is located at the end of files. So we can ignore those.
-	// ID3v2 can be located at the start of files and begins with a 10 bytes header, the first 3 bytes being 'ID3'.
-	// The tag size is coded on the last 4 bytes of the 10 bytes header as a 32 bit synchsafe integer.
-	// See http://id3.org/id3v2.4.0-structure for details.
-	char data[10];
-	_inStream->read(data, 10);
-	if (data[0] == 'I' && data[1] == 'D' && data[2] == '3') {
-		uint32 size = data[9] + 128 * (data[8] + 128 * (data[7] + 128 * data[6]));
-		// This size does not include an optional 10 bytes footer. Check if it is present.
-		if (data[5] & 0x10)
-			size += 10;
-		debug("Skipping ID3 TAG (%d bytes)", size + 10);
-		_inStream->seek(size, SEEK_CUR);
-	} else
-		_inStream->seek(0, SEEK_SET);
 
 	// Update state
 	_state = MP3_STATE_READY;
 
 	// Read the first few sample bytes
-	readMP3Data();
+	readMP3Data(stream);
 }
 
-void MP3Stream::readHeader() {
+void BaseMP3Stream::readHeader(Common::ReadStream &stream) {
 	if (_state != MP3_STATE_READY)
 		return;
 
 	// If necessary, load more data into the stream decoder
 	if (_stream.error == MAD_ERROR_BUFLEN)
-		readMP3Data();
+		readMP3Data(stream);
 
 	while (_state != MP3_STATE_EOS) {
 		_stream.error = MAD_ERROR_NONE;
@@ -287,7 +233,7 @@ void MP3Stream::readHeader() {
 		// be far too slow). Hence we perform this explicitly in a separate step.
 		if (mad_header_decode(&_frame.header, &_stream) == -1) {
 			if (_stream.error == MAD_ERROR_BUFLEN) {
-				readMP3Data();  // Read more data
+				readMP3Data(stream);  // Read more data
 				continue;
 			} else if (MAD_RECOVERABLE(_stream.error)) {
 				debug(6, "MP3Stream: Recoverable error in mad_header_decode (%s)", mad_stream_errorstr(&_stream));
@@ -307,7 +253,7 @@ void MP3Stream::readHeader() {
 		_state = MP3_STATE_EOS;
 }
 
-void MP3Stream::deinitStream() {
+void BaseMP3Stream::deinitStream() {
 	if (_state == MP3_STATE_INIT)
 		return;
 
@@ -319,7 +265,7 @@ void MP3Stream::deinitStream() {
 	_state = MP3_STATE_EOS;
 }
 
-static inline int scale_sample(mad_fixed_t sample) {
+static inline int scaleSample(mad_fixed_t sample) {
 	// round
 	sample += (1L << (MAD_F_FRACBITS - 16));
 
@@ -333,28 +279,115 @@ static inline int scale_sample(mad_fixed_t sample) {
 	return sample >> (MAD_F_FRACBITS + 1 - 16);
 }
 
-int MP3Stream::readBuffer(int16 *buffer, const int numSamples) {
+int BaseMP3Stream::fillBuffer(Common::ReadStream &stream, int16 *buffer, const int numSamples) {
 	int samples = 0;
 	// Keep going as long as we have input available
 	while (samples < numSamples && _state != MP3_STATE_EOS) {
 		const int len = MIN(numSamples, samples + (int)(_synth.pcm.length - _posInFrame) * MAD_NCHANNELS(&_frame.header));
 		while (samples < len) {
-			*buffer++ = (int16)scale_sample(_synth.pcm.samples[0][_posInFrame]);
+			*buffer++ = (int16)scaleSample(_synth.pcm.samples[0][_posInFrame]);
 			samples++;
 			if (MAD_NCHANNELS(&_frame.header) == 2) {
-				*buffer++ = (int16)scale_sample(_synth.pcm.samples[1][_posInFrame]);
+				*buffer++ = (int16)scaleSample(_synth.pcm.samples[1][_posInFrame]);
 				samples++;
 			}
 			_posInFrame++;
 		}
 		if (_posInFrame >= _synth.pcm.length) {
 			// We used up all PCM data in the current frame -- read & decode more
-			decodeMP3Data();
+			decodeMP3Data(stream);
 		}
 	}
 	return samples;
 }
 
+MP3Stream::MP3Stream(Common::SeekableReadStream *inStream, DisposeAfterUse::Flag dispose) :
+		BaseMP3Stream(),
+		_inStream(skipID3(inStream, dispose)),
+		_length(0, 1000) {
+
+	// Initialize the stream with some data
+	decodeMP3Data(*_inStream);
+
+	// Calculate the length of the stream
+	while (_state != MP3_STATE_EOS)
+		readHeader(*_inStream);
+
+	// To rule out any invalid sample rate to be encountered here, say in case the
+	// MP3 stream is invalid, we just check the MAD error code here.
+	// We need to assure this, since else we might trigger an assertion in Timestamp
+	// (When getRate() returns 0 or a negative number to be precise).
+	// Note that we allow "MAD_ERROR_BUFLEN" as error code here, since according
+	// to mad.h it is also set on EOF.
+	if ((_stream.error == MAD_ERROR_NONE || _stream.error == MAD_ERROR_BUFLEN) && getRate() > 0)
+		_length = Timestamp(mad_timer_count(_curTime, MAD_UNITS_MILLISECONDS), getRate());
+
+	deinitStream();
+
+	// Reinit stream
+	_state = MP3_STATE_INIT;
+	_inStream->seek(0);
+
+	// Decode the first chunk of data. This is necessary so that _frame
+	// is setup and isStereo() and getRate() return correct results.
+	decodeMP3Data(*_inStream);
+}
+
+int MP3Stream::readBuffer(int16 *buffer, const int numSamples) {
+	return fillBuffer(*_inStream, buffer, numSamples);
+}
+
+bool MP3Stream::seek(const Timestamp &where) {
+	if (where == _length) {
+		_state = MP3_STATE_EOS;
+		return true;
+	} else if (where > _length) {
+		return false;
+	}
+
+	const uint32 time = where.msecs();
+
+	mad_timer_t destination;
+	mad_timer_set(&destination, time / 1000, time % 1000, 1000);
+
+	if (_state != MP3_STATE_READY || mad_timer_compare(destination, _curTime) < 0) {
+		_inStream->seek(0);
+		initStream(*_inStream);
+	}
+
+	while (mad_timer_compare(destination, _curTime) > 0 && _state != MP3_STATE_EOS)
+		readHeader(*_inStream);
+
+	decodeMP3Data(*_inStream);
+
+	return (_state != MP3_STATE_EOS);
+}
+
+Common::SeekableReadStream *MP3Stream::skipID3(Common::SeekableReadStream *stream, DisposeAfterUse::Flag dispose) {
+	// Skip ID3 TAG if any
+	// ID3v1 (beginning with with 'TAG') is located at the end of files. So we can ignore those.
+	// ID3v2 can be located at the start of files and begins with a 10 bytes header, the first 3 bytes being 'ID3'.
+	// The tag size is coded on the last 4 bytes of the 10 bytes header as a 32 bit synchsafe integer.
+	// See http://id3.org/id3v2.4.0-structure for details.
+	char data[10];
+	stream->read(data, sizeof(data));
+
+	uint32 offset = 0;
+	if (!stream->eos() && data[0] == 'I' && data[1] == 'D' && data[2] == '3') {
+		uint32 size = data[9] + 128 * (data[8] + 128 * (data[7] + 128 * data[6]));
+		// This size does not include an optional 10 bytes footer. Check if it is present.
+		if (data[5] & 0x10)
+			size += 10;
+
+		// Add in the 10 bytes we read in
+		size += sizeof(data);
+		debug("Skipping ID3 TAG (%d bytes)", size);
+		offset = size;
+	}
+
+	return new Common::SeekableSubReadStream(stream, offset, stream->size(), dispose);
+}
+
 
 #pragma mark -
 #pragma mark --- MP3 factory functions ---