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engine/audio/private/snd_wave_mixer_mp3.h

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+//========= Copyright Valve Corporation, All rights reserved. ============//
+//
+// Purpose: Mixer for ADPCM encoded audio
+//
+//=============================================================================//
+
+#ifndef SND_WAVE_MIXER_MP3_H
+#define SND_WAVE_MIXER_MP3_H
+#pragma once
+
+#include "vaudio/ivaudio.h"
+
+static const int MP3_BUFFER_SIZE = 16384;
+
+class CAudioMixerWaveMP3 : public CAudioMixerWave, public IAudioStreamEvent
+{
+public:
+	CAudioMixerWaveMP3( IWaveData *data );
+	~CAudioMixerWaveMP3( void );
+
+	virtual void Mix( IAudioDevice *pDevice, channel_t *pChannel, void *pData, int outputOffset, int inputOffset, fixedint fracRate, int outCount, int timecompress );
+	virtual int	 GetOutputData( void **pData, int sampleCount, char copyBuf[AUDIOSOURCE_COPYBUF_SIZE] );
+
+	// need to override this to fixup blocks
+	// UNDONE: This doesn't quite work with MP3 - we need a MP3 position, not a sample position
+	void SetSampleStart( int newPosition );
+
+	int GetPositionForSave() { return GetStream() ? GetStream()->GetPosition() : 0; }
+	void SetPositionFromSaved(int position) { if ( GetStream() ) GetStream()->SetPosition(position); }
+
+	// IAudioStreamEvent
+	virtual int StreamRequestData( void *pBuffer, int bytesRequested, int offset );
+
+	virtual void SetStartupDelaySamples( int delaySamples );
+	virtual int GetMixSampleSize() { return CalcSampleSize( 16, m_channelCount ); }
+
+	virtual int GetStreamOutputRate() { return GetStream() ? GetStream()->GetOutputRate() : 0; }
+
+private:
+	IAudioStream			*GetStream();
+	bool					DecodeBlock( void );
+	void					GetID3HeaderOffset();
+
+	// Lazily initialized, use GetStream
+	IAudioStream			*m_pStream;
+	bool					m_bStreamInit;
+
+	char					m_samples[MP3_BUFFER_SIZE];
+	int						m_sampleCount;
+	int						m_samplePosition;
+	int						m_channelCount;
+	int						m_offset;
+	int						m_delaySamples;
+	int						m_headerOffset;
+};
+
+CAudioMixerWaveMP3 *CreateMP3Mixer( IWaveData *data );
+
+#endif // SND_WAVE_MIXER_MP3_H