source-engine/engine/audio/snd_wave_mixer_xma.cpp

//========= Copyright Valve Corporation, All rights reserved. ============//
//
// Purpose: XMA Decoding
//
//=====================================================================================//

#include "audio_pch.h"
#include "tier1/mempool.h"
#include "circularbuffer.h"
#include "tier1/utllinkedlist.h"

// memdbgon must be the last include file in a .cpp file!!!
#include "tier0/memdbgon.h"

//#define DEBUG_XMA

// Failed attempt to allow mixer to request data that is immediately discarded
// to support < 0 delay samples
//#define ALLOW_SKIP_SAMPLES

// XMA is supposed to decode at an ideal max of 512 mono samples every 4msec.
// XMA can only peel a max of 1984 stereo samples per poll request (if available).
// Max is not achievable and degrades based on quality settings, stereo, etc, but using these numbers for for calcs.
// 1984 stereo samples should be decoded by xma in 31 msec.
// 1984 stereo samples at 44.1Khz dictates a request every 45 msec.
// GetOutputData() must be clocked faster than 45 msec or samples will not be available.
// However, the XMA decoder must be serviced much faster. It was designed for 5 msec.
// 15 msec seems to be fast enough for XMA to decode enough to keep the smaller buffer sizes satisfied, and have slop for +/- 5 msec swings.

// Need at least this amount of decoded pcm samples before mixing can commence.
// This needs to be able to cover the initial mix request, while a new decode cycle is in flight.
#define MIN_READYTOMIX	( ( 2 * XMA_POLL_RATE ) * 0.001f )

// number of samples that xma decodes
// must be 128 aligned for mono (1984 is hw max for stereo)
#define XMA_MONO_OUTPUT_BUFFER_SAMPLES		2048
#define XMA_STEREO_OUTPUT_BUFFER_SAMPLES	1920

// for decoder input
// xma blocks are fetched from the datacache into one of these hw buffers for decoding
// must be in quantum units of XMA_BLOCK_SIZE
#define XMA_INPUT_BUFFER_SIZE		( 8 * XMA_BLOCK_SIZE )

// circular staging buffer to drain xma decoder and stage until mixer requests
// must be large enough to hold the slowest expected mixing frame worth of samples
#define PCM_STAGING_BUFFER_TIME		200

// xma physical heap, supplies xma input buffers for hw decoder
// each potential channel must be able to peel 2 buffers for driving xma decoder
#define XMA_PHYSICAL_HEAP_SIZE		( 2 * MAX_CHANNELS * XMA_INPUT_BUFFER_SIZE )

// in millseconds
#define MIX_IO_DATA_TIMEOUT			2000	// async i/o from dvd could be very late
#define MIX_DECODER_TIMEOUT			3000	// decoder might be very busy
#define MIX_DECODER_POLLING_LATENCY	5		// not faster than 5ms, or decoder will sputter

// diagnostic errors
#define ERROR_IO_DATA_TIMEOUT		-1	// async i/o taking too long to deliver xma blocks
#define ERROR_IO_TRUNCATED_BLOCK	-2	// async i/o failed to deliver complete blocks
#define ERROR_IO_NO_XMA_DATA		-3	// async i/o failed to deliver any block
#define ERROR_DECODER_TIMEOUT		-4	// decoder taking too long to decode xma blocks
#define ERROR_OUT_OF_MEMORY			-5	// not enough physical memory for xma blocks
#define ERROR_XMA_PARSE				-6	// decoder barfed on xma blocks
#define ERROR_XMA_CANTLOCK			-7	// hw not acting as expected
#define ERROR_XMA_CANTSUBMIT		-8	// hw not acting as expected
#define ERROR_XMA_CANTRESUME		-9	// hw not acting as expected
#define ERROR_XMA_NO_PCM_DATA		-10	// no xma decoded pcm data ready
#define ERROR_NULL_BUFFER			-11	// logic flaw, expected buffer is null 

const char *g_XMAErrorStrings[] =
{
	"Unknown Error Code",
	"Async I/O Data Timeout",		// ERROR_IO_DATA_TIMEOUT
	"Async I/O Truncated Block",	// ERROR_IO_TRUNCATED_BLOCK
	"Async I/O Data Not Ready",		// ERROR_IO_NO_XMA_DATA
	"Decoder Timeout",				// ERROR_DECODER_TIMEOUT
	"Out Of Memory",				// ERROR_OUT_OF_MEMORY
	"XMA Parse",					// ERROR_XMA_PARSE
	"XMA Cannot Lock",				// ERROR_XMA_CANTLOCK
	"XMA Cannot Submit",			// ERROR_XMA_CANTSUBMIT
	"XMA Cannot Resume",			// ERROR_XMA_CANTRESUME
	"XMA No PCM Data Ready",		// ERROR_XMA_NO_PCM_DATA
	"NULL Buffer",					// ERROR_NULL_BUFFER
};

class CXMAAllocator
{
public:
	static void *Alloc( int bytes )
	{
		MEM_ALLOC_CREDIT();

		return XMemAlloc( bytes, 
			MAKE_XALLOC_ATTRIBUTES( 
				0, 
				false, 
				TRUE, 
				FALSE, 
				eXALLOCAllocatorId_XAUDIO,
				XALLOC_PHYSICAL_ALIGNMENT_4K, 
				XALLOC_MEMPROTECT_WRITECOMBINE_LARGE_PAGES, 
				FALSE,
				XALLOC_MEMTYPE_PHYSICAL ) );
	}

	static void Free( void *p )
	{
		XMemFree( p, 
			MAKE_XALLOC_ATTRIBUTES( 
				0, 
				false, 
				TRUE, 
				FALSE, 
				eXALLOCAllocatorId_XAUDIO,
				XALLOC_PHYSICAL_ALIGNMENT_4K, 
				XALLOC_MEMPROTECT_WRITECOMBINE_LARGE_PAGES, 
				FALSE,
				XALLOC_MEMTYPE_PHYSICAL ) );
	}
};

// for XMA decoding, fixed size allocations aligned to 4K from a single physical heap
CAlignedMemPool< XMA_INPUT_BUFFER_SIZE, 4096, XMA_PHYSICAL_HEAP_SIZE, CXMAAllocator > g_XMAMemoryPool;

ConVar snd_xma_spew_warnings( "snd_xma_spew_warnings", "0" );
ConVar snd_xma_spew_startup( "snd_xma_spew_startup", "0" );
ConVar snd_xma_spew_mixers( "snd_xma_spew_mixers", "0" );
ConVar snd_xma_spew_decode( "snd_xma_spew_decode", "0" );
ConVar snd_xma_spew_drain( "snd_xma_spew_drain", "0" );
#ifdef DEBUG_XMA
ConVar snd_xma_record( "snd_xma_record", "0" );
ConVar snd_xma_spew_errors( "snd_xma_spew_errors", "0" );
#endif

//-----------------------------------------------------------------------------
// Purpose: Mixer for ADPCM encoded audio
//-----------------------------------------------------------------------------
class CAudioMixerWaveXMA : public CAudioMixerWave
{
public:
	typedef CAudioMixerWave BaseClass;

	CAudioMixerWaveXMA( IWaveData *data, int initialStreamPosition );
	~CAudioMixerWaveXMA( 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] );

	virtual void			SetSampleStart( int newPosition );
	virtual int				GetPositionForSave();
	virtual void			SetPositionFromSaved( int savedPosition );

	virtual int				GetMixSampleSize() { return CalcSampleSize( 16, m_NumChannels ); }

	virtual bool			IsReadyToMix();
	virtual bool			ShouldContinueMixing();

private:
	int						GetXMABlocksAndSubmitToDecoder( bool bDecoderLocked );
	int						UpdatePositionForLooping( int *pNumRequestedSamples );
	int						ServiceXMADecoder( bool bForceUpdate );
	int						GetPCMSamples( int numRequested, char *pData );

	XMAPLAYBACK				*m_pXMAPlayback;

	// input buffers, encoded xma
	byte					*m_pXMABuffers[2];
	int						m_XMABufferIndex;

	// output buffer, decoded pcm samples, a staging circular buffer, waiting for mixer requests
	// due to staging nature, contains decoded samples from multiple input buffers
	CCircularBuffer			*m_pPCMSamples;

	int						m_SampleRate;
	int						m_NumChannels;
	// maximum possible decoded samples
	int						m_SampleCount;

	// decoded sample position
	int						m_SamplePosition;
	// current data marker
	int						m_LastDataOffset;
	int						m_DataOffset;
	// total bytes of data
	int						m_TotalBytes;

#if defined( ALLOW_SKIP_SAMPLES )
	// number of samples to throwaway
	int						m_SkipSamples;
#endif

	// timers
	unsigned int			m_StartTime;
	unsigned int			m_LastDrainTime;
	unsigned int			m_LastPollTime;

	int						m_hMixerList;
	int						m_Error;

	unsigned int			m_bStartedMixing : 1;
	unsigned int			m_bFinished : 1;
	unsigned int			m_bLooped : 1;
};

CUtlFixedLinkedList< CAudioMixerWaveXMA * >	g_XMAMixerList;

CON_COMMAND( snd_xma_info, "Spew XMA Info" )
{
	Msg( "XMA Memory:\n" );
	Msg( " Blocks Allocated: %d\n", g_XMAMemoryPool.NumAllocated() );
	Msg( " Blocks Free:      %d\n", g_XMAMemoryPool.NumFree() );
	Msg( " Total Bytes:      %d\n", g_XMAMemoryPool.BytesTotal() );
	Msg( "Active XMA Mixers: %d\n", g_XMAMixerList.Count() );
	for ( int hMixer = g_XMAMixerList.Head(); hMixer != g_XMAMixerList.InvalidIndex(); hMixer = g_XMAMixerList.Next( hMixer ) )
	{
		CAudioMixerWaveXMA *pXMAMixer = g_XMAMixerList[hMixer];
		Msg( "  rate:%5d ch:%1d '%s'\n", pXMAMixer->GetSource()->SampleRate(), pXMAMixer->GetSource()->IsStereoWav() ? 2 : 1, pXMAMixer->GetSource()->GetFileName() );
	}
}

CAudioMixerWaveXMA::CAudioMixerWaveXMA( IWaveData *data, int initialStreamPosition ) : CAudioMixerWave( data ) 
{
	Assert( dynamic_cast<CAudioSourceWave *>(&m_pData->Source()) != NULL );

	m_Error = 0;

	m_NumChannels = m_pData->Source().IsStereoWav() ? 2 : 1;
	m_SampleRate = m_pData->Source().SampleRate();
	m_bLooped = m_pData->Source().IsLooped();
	m_SampleCount = m_pData->Source().SampleCount();
	m_TotalBytes = m_pData->Source().DataSize();

#if defined( ALLOW_SKIP_SAMPLES )
	m_SkipSamples = 0;
#endif

	m_LastDataOffset = initialStreamPosition;
	m_DataOffset = initialStreamPosition;
	m_SamplePosition = 0;
	if ( initialStreamPosition )
	{
		m_SamplePosition = m_pData->Source().StreamToSamplePosition( initialStreamPosition );

		CAudioMixerWave::m_sample_loaded_index = m_SamplePosition;
		CAudioMixerWave::m_sample_max_loaded = m_SamplePosition + 1;
	}

	m_bStartedMixing = false;
	m_bFinished = false;

	m_StartTime = 0;
	m_LastPollTime = 0;
	m_LastDrainTime = 0;

	m_pXMAPlayback = NULL;
	m_pPCMSamples = NULL;

	m_pXMABuffers[0] = NULL;
	m_pXMABuffers[1] = NULL;
	m_XMABufferIndex = 0;

	m_hMixerList = g_XMAMixerList.AddToTail( this );

#ifdef DEBUG_XMA
	if ( snd_xma_record.GetBool() )
	{
		WaveCreateTmpFile( "debug.wav", m_SampleRate, 16, m_NumChannels );
	}
#endif

	if ( snd_xma_spew_mixers.GetBool() )
	{
		Msg( "XMA: 0x%8.8x (%2d), Mixer Alloc, '%s'\n", (unsigned int)this, g_XMAMixerList.Count(), m_pData->Source().GetFileName() );
	}
}

CAudioMixerWaveXMA::~CAudioMixerWaveXMA( void )
{
	if ( m_pXMAPlayback )
	{
		XMAPlaybackDestroy( m_pXMAPlayback );

		g_XMAMemoryPool.Free( m_pXMABuffers[0] );
		if ( m_pXMABuffers[1] )
		{
			g_XMAMemoryPool.Free( m_pXMABuffers[1] );
		}
	}

	if ( m_pPCMSamples )
	{
		FreeCircularBuffer( m_pPCMSamples );
	}

	g_XMAMixerList.Remove( m_hMixerList );

	if ( snd_xma_spew_mixers.GetBool() )
	{
		Msg( "XMA: 0x%8.8x (%2d), Mixer Freed, '%s'\n", (unsigned int)this, g_XMAMixerList.Count(), m_pData->Source().GetFileName() );
	}
}

void CAudioMixerWaveXMA::Mix( IAudioDevice *pDevice, channel_t *pChannel, void *pData, int outputOffset, int inputOffset, fixedint fracRate, int outCount, int timecompress )
{
	if ( m_NumChannels == 1 )
	{
		pDevice->Mix16Mono( pChannel, (short *)pData, outputOffset, inputOffset, fracRate, outCount, timecompress );
	}
	else
	{
		pDevice->Mix16Stereo( pChannel, (short *)pData, outputOffset, inputOffset, fracRate, outCount, timecompress );
	}
}

//-----------------------------------------------------------------------------
// Looping is achieved in two passes to provide a circular view of the linear data.
// Pass1: Clamps a sample request to the end of data.
// Pass2: Snaps to the loop start, and returns the number of samples to discard, could be 0,
// up to the expected loop sample position.
// Returns the number of samples to discard, or 0.
//-----------------------------------------------------------------------------
int CAudioMixerWaveXMA::UpdatePositionForLooping( int *pNumRequestedSamples )
{
	if ( !m_bLooped )
	{
		// not looping, no fixups
		return 0;
	}

	int numLeadingSamples;
	int numTrailingSamples;
	CAudioSourceWave &source = reinterpret_cast<CAudioSourceWave &>(m_pData->Source());
	int loopSampleStart = source.GetLoopingInfo( NULL, &numLeadingSamples, &numTrailingSamples );

	int numRemainingSamples = ( m_SampleCount - numTrailingSamples ) - m_SamplePosition;

	// possibly straddling the end of data (and thus about to loop)
	// want to split the straddle into two regions, due to loops possibly requiring a trailer and leader of discarded samples
	if ( numRemainingSamples > 0 )
	{
		// first region, all the remaining samples, clamped until end of desired data
		*pNumRequestedSamples = min( *pNumRequestedSamples, numRemainingSamples );

		// nothing to discard
		return 0;
	}
	else if ( numRemainingSamples == 0 )
	{
		// at exact end of desired data, snap the sample position back
		// the position will be correct AFTER discarding decoded trailing and leading samples
		m_SamplePosition = loopSampleStart;

		// clamp the request
		numRemainingSamples = ( m_SampleCount - numTrailingSamples ) - m_SamplePosition;
		*pNumRequestedSamples = min( *pNumRequestedSamples, numRemainingSamples );

		// flush these samples so the sample position is the real loop sample starting position
		return numTrailingSamples + numLeadingSamples;
	}

	return 0;
}

//-----------------------------------------------------------------------------
// Get and submit XMA block(s). The decoder must stay blocks ahead of mixer
// so the decoded samples are available for peeling.
// An XMA file is thus treated as a series of fixed size large buffers (multiple xma blocks),
// which are streamed in sequentially. The XMA buffers may be delayed from the 
// audio data cache due to async i/o latency.
// Returns < 0 if error, 0 if no decode started, 1 if decode submitted.
//-----------------------------------------------------------------------------
int CAudioMixerWaveXMA::GetXMABlocksAndSubmitToDecoder( bool bDecoderIsLocked )
{
	int status = 0;

	if ( m_DataOffset >= m_TotalBytes )
	{
		if ( !m_bLooped )
		{
			// end of file, no more data to decode
			// not an error, because decoder finishes long before samples drained
			return 0;
		}

		// start from beginning of loop
		CAudioSourceWave &source = reinterpret_cast<CAudioSourceWave &>(m_pData->Source());
		source.GetLoopingInfo( &m_DataOffset, NULL, NULL ); 
		m_DataOffset *= XMA_BLOCK_SIZE;
	}

	HRESULT hr;
	bool bLocked = false;
	if ( !bDecoderIsLocked )
	{
		// decoder must be locked before any access
		hr = XMAPlaybackRequestModifyLock( m_pXMAPlayback );
		if ( FAILED( hr ) )
		{
			status = ERROR_XMA_CANTLOCK;
			goto cleanUp;
		}

		hr = XMAPlaybackWaitUntilModifyLockObtained( m_pXMAPlayback );
		if ( FAILED( hr ) )
		{
			status = ERROR_XMA_CANTLOCK;
			goto cleanUp;
		}
		bLocked = true;
	}

	// the input buffer can never be less than a single xma block (buffer size is multiple blocks)
	int bufferSize = min( m_TotalBytes - m_DataOffset, XMA_INPUT_BUFFER_SIZE );
	if ( !bufferSize )
	{
		// EOF
		goto cleanUp;
	}
	Assert( !( bufferSize % XMA_BLOCK_SIZE ) );

	byte *pXMABuffer = m_pXMABuffers[m_XMABufferIndex & 0x01];
	if ( !pXMABuffer )
	{
		// shouldn't happen, buffer should have been allocated
		Assert( 0 );
		status = ERROR_NULL_BUFFER;
		goto cleanUp;
	}

	if ( !XMAPlaybackQueryReadyForMoreData( m_pXMAPlayback, 0 ) || XMAPlaybackQueryInputDataPending( m_pXMAPlayback, 0, pXMABuffer ) )
	{
		// decoder too saturated for more data or 
		// decoder still decoding from input hw buffer
		goto cleanUp;
	}

	// get xma block(s)
	// pump to get all of requested data
	char *pData;
	int total = 0;
	while ( total < bufferSize )
	{
		int available = m_pData->ReadSourceData( (void **)&pData, m_DataOffset, bufferSize - total, NULL );
		if ( !available )
			break;

		// aggregate into hw buffer
		V_memcpy( pXMABuffer + total, pData, available );

		m_DataOffset += available;
		total += available;
	}	
	if ( total != bufferSize )
	{
		if ( !total )
		{
			// failed to get any data, could be async latency or file error
			status = ERROR_IO_NO_XMA_DATA;
		}
		else
		{
			// failed to get complete xma block(s)
			status = ERROR_IO_TRUNCATED_BLOCK;
		}
		goto cleanUp;
	}

	// track the currently submitted offset
	// this is used as a cheap method for save/restore because an XMA seek table is not available
	m_LastDataOffset = m_DataOffset - total;

	// start decoding the block(s) in the hw buffer
	hr = XMAPlaybackSubmitData( m_pXMAPlayback, 0, pXMABuffer, bufferSize );
	if ( FAILED( hr ) )
	{
		// failed to start decoder
		status = ERROR_XMA_CANTSUBMIT;
		goto cleanUp;
	}

	// decode submitted
	status = 1;

	// advance to next buffer
	m_XMABufferIndex++;

	if ( snd_xma_spew_decode.GetBool() )
	{
		Msg( "XMA: 0x%8.8x, XMABuffer: 0x%8.8x, BufferSize: %d, NextDataOffset: %d, %s\n", (unsigned int)this, pXMABuffer, bufferSize, m_DataOffset, m_pData->Source().GetFileName() );
	}

cleanUp:
	if ( bLocked )
	{
		// release the lock and let the decoder run
		hr = XMAPlaybackResumePlayback( m_pXMAPlayback );
 		if ( FAILED( hr ) )
		{
			status = ERROR_XMA_CANTRESUME;
		}
	}
	
	return status;
}

//-----------------------------------------------------------------------------
// Drain the XMA Decoder into the staging circular buffer of PCM for mixer.
// Fetch new XMA samples for the decoder.
//-----------------------------------------------------------------------------
int CAudioMixerWaveXMA::ServiceXMADecoder( bool bForceUpdate )
{
	// allow decoder to work without being polled (lock causes a decoding stall)
	// decoder must be allowed minimum operating latency
	// the buffers are sized to compensate for the operating latency
	if ( !bForceUpdate && ( Plat_MSTime() - m_LastPollTime <= MIX_DECODER_POLLING_LATENCY ) )
	{
		return 0;
	}
	m_LastPollTime = Plat_MSTime();

	// lock and pause the decoder to gain access
	HRESULT hr = XMAPlaybackRequestModifyLock( m_pXMAPlayback );
	if ( FAILED( hr ) )
	{
		m_Error = ERROR_XMA_CANTLOCK;
		return -1;
	}

	hr = XMAPlaybackWaitUntilModifyLockObtained( m_pXMAPlayback );
	if ( FAILED( hr ) )
	{
		m_Error = ERROR_XMA_CANTLOCK;
		return -1;
	}

	DWORD dwParseError = XMAPlaybackGetParseError( m_pXMAPlayback, 0 );
	if ( dwParseError )
	{
		if ( snd_xma_spew_warnings.GetBool() )
		{
			Warning( "XMA: 0x%8.8x, Decoder Error, Parse: %d, '%s'\n", (unsigned int)this, dwParseError, m_pData->Source().GetFileName() );
		}
		m_Error = ERROR_XMA_PARSE;
		return -1;
	}

#ifdef DEBUG_XMA
	if ( snd_xma_spew_errors.GetBool() )
	{
		DWORD dwError = XMAPlaybackGetErrorBits( m_pXMAPlayback, 0 );
		if ( dwError )
		{
			Warning( "XMA: 0x%8.8x, Playback Error: %d, '%s'\n", (unsigned int)this, dwError, m_pData->Source().GetFileName() );
		}
	}
#endif

	int numNewSamples = XMAPlaybackQueryAvailableData( m_pXMAPlayback, 0 );
	int numMaxSamples = m_pPCMSamples->GetWriteAvailable()/( m_NumChannels*sizeof( short ) );
	int numSamples = min( numNewSamples, numMaxSamples );
	while ( numSamples )
	{
		char *pPCMData = NULL;
		int numSamplesDecoded = XMAPlaybackConsumeDecodedData( m_pXMAPlayback, 0, numSamples, (void**)&pPCMData );

		// put into staging buffer, ready for mixer to drain
		m_pPCMSamples->Write( pPCMData, numSamplesDecoded*m_NumChannels*sizeof( short ) );
		
		numSamples -= numSamplesDecoded;
		numNewSamples -= numSamplesDecoded;
	}

	// queue up more blocks for the decoder
	// the decoder will always finish ahead of the mixer, submit nothing, and the mixer will still be draining
	int decodeStatus = GetXMABlocksAndSubmitToDecoder( true );
	if ( decodeStatus < 0 )
	{
		m_Error = decodeStatus;
		return -1;
	}

	m_bFinished = ( numNewSamples == 0 ) && ( decodeStatus == 0 ) && XMAPlaybackIsIdle( m_pXMAPlayback, 0 );

	// decoder was paused for access, let the decoder run
	hr = XMAPlaybackResumePlayback( m_pXMAPlayback );
 	if ( FAILED( hr ) )
	{
		m_Error = ERROR_XMA_CANTRESUME;
		return -1;
	}

	return 1;
}

//-----------------------------------------------------------------------------
// Drain the PCM staging buffer.
// Copy samples (numSamplesToCopy && pData). Return actual copied.
// Flush Samples (numSamplesToCopy && !pData). Return actual flushed.
// Query available number of samples (!numSamplesToCopy && !pData). Returns available.
//-----------------------------------------------------------------------------
int CAudioMixerWaveXMA::GetPCMSamples( int numSamplesToCopy, char *pData )
{
	int numReadySamples = m_pPCMSamples->GetReadAvailable()/( m_NumChannels*sizeof( short ) );

	// peel sequential samples from the stream's staging buffer
	int numCopiedSamples = 0;
	int numRequestedSamples = min( numSamplesToCopy, numReadySamples );
	if ( numRequestedSamples )
	{
		if ( pData )
		{
			// copy to caller
			m_pPCMSamples->Read( pData, numRequestedSamples*m_NumChannels*sizeof( short ) );
			pData += numRequestedSamples*m_NumChannels*sizeof( short );
		}
		else
		{
			// flush
			m_pPCMSamples->Advance( numRequestedSamples*m_NumChannels*sizeof( short ) );
		}

		numCopiedSamples += numRequestedSamples;
	}

	if ( snd_xma_spew_drain.GetBool() )
	{
		char *pOperation = ( numSamplesToCopy && !pData ) ? "Flushed" : "Copied";
		Msg( "XMA: 0x%8.8x, SamplePosition: %d, Ready: %d, Requested: %d, %s: %d, Elapsed: %d ms '%s'\n", 
			(unsigned int)this, m_SamplePosition, numReadySamples, numSamplesToCopy, pOperation, numCopiedSamples, Plat_MSTime() - m_LastDrainTime, m_pData->Source().GetFileName() );
	}
	m_LastDrainTime = Plat_MSTime();

	if ( numSamplesToCopy )
	{
		// could be actual flushed or actual copied
		return numCopiedSamples;
	}
	
	if ( !pData )
	{
		// satify query for available
		return numReadySamples;
	}

	return 0;
}

//-----------------------------------------------------------------------------
// Stall mixing until initial buffer of decoded samples are available.
//-----------------------------------------------------------------------------
bool CAudioMixerWaveXMA::IsReadyToMix()
{
	// XMA mixing cannot be driven from the main thread
	Assert( ThreadInMainThread() == false );

	if ( m_Error )
	{
		// error has been set
		// let mixer try to get unavailable samples, which casues the real abort
		return true;
	}

	if ( m_bStartedMixing )
	{
		// decoding process has started
		return true;
	}

	if ( !m_pXMAPlayback )
	{
		// first time, finish setup
		int numBuffers;
		if ( m_bLooped || m_TotalBytes > XMA_INPUT_BUFFER_SIZE )
		{
			// data will cascade through multiple buffers
			numBuffers = 2;
		}
		else
		{
			// data can fit into a single buffer
			numBuffers = 1;
		}

		// xma data must be decoded from a hw friendly buffer
		// pool should have buffers available
		if ( g_XMAMemoryPool.BytesAllocated() != numBuffers * g_XMAMemoryPool.ChunkSize() )
		{
			for ( int i = 0; i < numBuffers; i++ )
			{
				m_pXMABuffers[i] = (byte*)g_XMAMemoryPool.Alloc();
			}

			XMA_PLAYBACK_INIT xmaPlaybackInit = { 0 };
			xmaPlaybackInit.sampleRate = m_SampleRate;
			xmaPlaybackInit.channelCount = m_NumChannels;
			xmaPlaybackInit.subframesToDecode = 4;
			xmaPlaybackInit.outputBufferSizeInSamples = ( m_NumChannels == 2 ) ? XMA_STEREO_OUTPUT_BUFFER_SAMPLES : XMA_MONO_OUTPUT_BUFFER_SAMPLES;
			XMAPlaybackCreate( 1, &xmaPlaybackInit, 0, &m_pXMAPlayback );

			int stagingSize = PCM_STAGING_BUFFER_TIME * m_SampleRate * m_NumChannels * sizeof( short ) * 0.001f;
			m_pPCMSamples = AllocateCircularBuffer( AlignValue( stagingSize, 4 ) );
		}
		else
		{
			// too many sounds playing, no xma buffers free
			m_Error = ERROR_OUT_OF_MEMORY;
			return true;
		}

		m_StartTime = Plat_MSTime();
	}

	// waiting for samples
	// allow decoder to work without being polled (lock causes a decoding stall)
	if ( Plat_MSTime() - m_LastPollTime <= MIX_DECODER_POLLING_LATENCY )
	{
		return false;
	}
	m_LastPollTime = Plat_MSTime();

	// must have buffers in flight before mixing can begin
	if ( m_DataOffset == m_LastDataOffset )
	{
		// keep trying to get data, async i/o has some allowable latency
		int decodeStatus = GetXMABlocksAndSubmitToDecoder( false );
		if ( decodeStatus < 0 && decodeStatus != ERROR_IO_NO_XMA_DATA )
		{
			m_Error = decodeStatus;
			return true;
		}
		else if ( !decodeStatus || decodeStatus == ERROR_IO_NO_XMA_DATA )
		{
			// async streaming latency could be to blame, check watchdog
			if ( Plat_MSTime() - m_StartTime >= MIX_IO_DATA_TIMEOUT )
			{
				m_Error = ERROR_IO_DATA_TIMEOUT;
			}
			return false;
		}
	}

	// get the available samples ready for immediate mixing
	if ( ServiceXMADecoder( true ) < 0 )
	{
		return true;
	}

	// can't mix until we have a minimum threshold of data or the decoder is finished
	int minSamplesNeeded = m_bFinished ? 0 : MIN_READYTOMIX * m_SampleRate;
#if defined( ALLOW_SKIP_SAMPLES )
	minSamplesNeeded += m_bFinished ? 0 : m_SkipSamples;
#endif

	int numReadySamples = GetPCMSamples( 0, NULL );
	if ( numReadySamples > minSamplesNeeded )
	{
		// decoder has samples ready for draining
		m_bStartedMixing = true;
		if ( snd_xma_spew_startup.GetBool() )
		{
			Msg( "XMA: 0x%8.8x, Startup Latency: %d ms, Samples Ready: %d, '%s'\n", (unsigned int)this, Plat_MSTime() - m_StartTime, numReadySamples, m_pData->Source().GetFileName() );
		}
		return true;
	}

	if ( Plat_MSTime() - m_StartTime >= MIX_DECODER_TIMEOUT )
	{
		m_Error = ERROR_DECODER_TIMEOUT;
	}

	// on startup error, let mixer start and get unavailable samples, and abort
	// otherwise hold off mixing until samples arrive
	return ( m_Error != 0 );
}

//-----------------------------------------------------------------------------
// Returns true to mix, false to stop mixer completely. Called after
// mixer requests samples.
//-----------------------------------------------------------------------------
bool CAudioMixerWaveXMA::ShouldContinueMixing()
{
	if ( !IsRetail() && m_Error && snd_xma_spew_warnings.GetBool() )
	{
		const char *pErrorString;
		if ( m_Error < 0 && -m_Error < ARRAYSIZE( g_XMAErrorStrings ) )
		{
			pErrorString = g_XMAErrorStrings[-m_Error];
		}
		else
		{
			pErrorString = g_XMAErrorStrings[0];
		}
		Warning( "XMA: 0x%8.8x, Mixer Aborted: %s, SamplePosition: %d/%d, DataOffset: %d/%d, '%s'\n", 
			(unsigned int)this, pErrorString, m_SamplePosition, m_SampleCount, m_DataOffset, m_TotalBytes, m_pData->Source().GetFileName() );
	}

	// an error condition is fatal to mixer
	return ( m_Error == 0 && BaseClass::ShouldContinueMixing() );
}

//-----------------------------------------------------------------------------
// Read existing buffer or decompress a new block when necessary.
// If no samples can be fetched, returns 0, which hints the mixer to a pending shutdown state.
// This routines operates in large buffer quantums, and nothing smaller.
// XMA decode performance severly degrades if the lock is too frequent.
//-----------------------------------------------------------------------------
int CAudioMixerWaveXMA::GetOutputData( void **pData, int numSamplesToCopy, char copyBuf[AUDIOSOURCE_COPYBUF_SIZE] )
{
	if ( m_Error )
	{
		// mixer will eventually shutdown
		return 0;
	}

	if ( !m_bStartedMixing )
	{
#if defined( ALLOW_SKIP_SAMPLES )
		int numMaxSamples =  AUDIOSOURCE_COPYBUF_SIZE/( m_NumChannels * sizeof( short ) );
		numSamplesToCopy = min( numSamplesToCopy, numMaxSamples );
		m_SkipSamples += numSamplesToCopy;

		// caller requesting data before mixing has commenced
		V_memset( copyBuf, 0, numSamplesToCopy );
		*pData = (void*)copyBuf;
		return numSamplesToCopy;
#else
		// not allowed, GetOutputData() should only be called by the mixing loop
		Assert( 0 );
		return 0;
#endif
	}

	// XMA mixing cannot be driven from the main thread
	Assert( ThreadInMainThread() == false );

	// needs to be clocked at regular intervals
	if ( ServiceXMADecoder( false ) < 0 )
	{
		return 0;
	}

#if defined( ALLOW_SKIP_SAMPLES )
	if ( m_SkipSamples > 0 )
	{		
		// flush whatever is available
		// ignore
		m_SkipSamples -= GetPCMSamples( m_SkipSamples, NULL );
		if ( m_SkipSamples != 0 )
		{
			// not enough decoded data ready to flush
			// must flush these samples to maintain proper position
			m_Error = ERROR_XMA_NO_PCM_DATA;
			return 0;
		}
	}
#endif

	// loopback may require flushing some decoded samples
	int numRequestedSamples = numSamplesToCopy;
	int numDiscardSamples = UpdatePositionForLooping( &numRequestedSamples );
	if ( numDiscardSamples > 0 )
	{
		// loopback requires discarding samples to converge to expected looppoint
		numDiscardSamples -= GetPCMSamples( numDiscardSamples, NULL );
		if ( numDiscardSamples != 0 )
		{
			// not enough decoded data ready to flush
			// must flush these samples to achieve looping
			m_Error = ERROR_XMA_NO_PCM_DATA;
			return 0;
		}
	}

	// can only drain as much as can be copied to caller		
	int numMaxSamples =  AUDIOSOURCE_COPYBUF_SIZE/( m_NumChannels * sizeof( short ) );
	numRequestedSamples = min( numRequestedSamples, numMaxSamples );

	int numCopiedSamples = GetPCMSamples( numRequestedSamples, copyBuf );
	if ( numCopiedSamples )
	{
		CAudioMixerWave::m_sample_max_loaded += numCopiedSamples;
		CAudioMixerWave::m_sample_loaded_index += numCopiedSamples;

		// advance position by valid samples
		m_SamplePosition += numCopiedSamples;

		*pData = (void*)copyBuf;

#ifdef DEBUG_XMA
		if ( snd_xma_record.GetBool() )
		{
			WaveAppendTmpFile( "debug.wav", copyBuf, 16, numCopiedSamples * m_NumChannels );
			WaveFixupTmpFile( "debug.wav" );
		}
#endif
	}
	else
	{
		// no samples copied
		if ( !m_bFinished && numRequestedSamples )
		{
			// XMA latency error occurs when decoder not finished (not at EOF) and caller wanted samples but can't get any
			if ( snd_xma_spew_warnings.GetInt() )
			{
				Warning( "XMA: 0x%8.8x, No Decoded Data Ready: %d samples needed, '%s'\n", (unsigned int)this, numSamplesToCopy, m_pData->Source().GetFileName() );
			}
			m_Error = ERROR_XMA_NO_PCM_DATA;
		}
	}

	return numCopiedSamples;
}

//-----------------------------------------------------------------------------
// Purpose: Seek to a new position in the file
//			NOTE: In most cases, only call this once, and call it before playing
//			any data.
// Input  : newPosition - new position in the sample clocks of this sample
//-----------------------------------------------------------------------------
void CAudioMixerWaveXMA::SetSampleStart( int newPosition )
{
	// cannot support this
	// this should be unused and thus not supporting
	Assert( 0 );
}


int CAudioMixerWaveXMA::GetPositionForSave()
{
	if ( m_bLooped )
	{
		// A looped sample cannot be saved/restored because the decoded sample position,
		// which is needed for loop calc, cannot ever be correctly restored without
		// the XMA seek table. 
		return 0;
	}

	// This is silly and totally wrong, but doing it anyways.
	// The correct thing was to have the XMA seek table and use
	// that to determine the correct packet. This is just a hopeful
	// nearby approximation. Music did not have the seek table at
	// the time of this code. The Seek table was added for vo
	// restoration later.
	return m_LastDataOffset;
}

void CAudioMixerWaveXMA::SetPositionFromSaved( int savedPosition )
{
	// Not used here. The Mixer creation will be given the initial startup offset.
}

//-----------------------------------------------------------------------------
// Purpose: Abstract factory function for XMA mixers
//-----------------------------------------------------------------------------
CAudioMixer *CreateXMAMixer( IWaveData *data, int initialStreamPosition )
{
	return new CAudioMixerWaveXMA( data, initialStreamPosition );
}