view Isolated/coreaudio.c @ 73:32757e494675

Fixed bug that sets the wrong variable for fading in Pause. There still seems to be another bug related to fading though based on Johnson Lin's test case. Audio no longer stops and triggers the completion callback, but the volume doesn't seem to go up to max for long fade-ins. Still investigating.
author Eric Wing <ewing . public |-at-| gmail . com>
date Fri, 10 Aug 2012 22:53:14 -0700
parents 71b465ff0622
children
line wrap: on
line source

#ifdef ALMIXER_COMPILE_WITHOUT_SDL

/*
 * SDL_sound Core Audio backend
 * Copyright (C) 2010 Eric Wing <ewing . public @ playcontrol.net>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#if HAVE_CONFIG_H
#  include <config.h>
#endif

#ifdef __APPLE__

#include <stddef.h> /* NULL */
#include <stdio.h> /* printf */
#include <arpa/inet.h> /* htonl */
#include <AudioToolbox/AudioToolbox.h>

#include "SoundDecoder.h"

#include "SoundDecoder_Internal.h"

typedef struct CoreAudioFileContainer
{
	AudioFileID* audioFileID;
	ExtAudioFileRef extAudioFileRef;
	AudioStreamBasicDescription* outputFormat;
} CoreAudioFileContainer;

static int CoreAudio_init(void);
static void CoreAudio_quit(void);
static int CoreAudio_open(Sound_Sample *sample, const char *ext);
static void CoreAudio_close(Sound_Sample *sample);
static size_t CoreAudio_read(Sound_Sample *sample);
static int CoreAudio_rewind(Sound_Sample *sample);
static int CoreAudio_seek(Sound_Sample *sample, size_t ms);

static const char *extensions_coreaudio[] = 
{
	"aif",
	"aiff",
	"aifc",
	"wav",
	"wave",
	"mp3",
	"mp4",
	"m4a",
	"aac",
	"adts",
	"caf",
	"Sd2f",
	"Sd2",
	"au",
	"snd",
	"next",
	"mp2",
	"mp1",
	"ac3",
	"3gpp",
	"3gp",
	"3gp2",
	"3g2",
	"amrf",
	"amr",
	"ima4",
	"ima",
	NULL 
};
const Sound_DecoderFunctions __Sound_DecoderFunctions_CoreAudio =
{
    {
        extensions_coreaudio,
        "Decode audio through Core Audio through",
        "Eric Wing <ewing . public @ playcontrol.net>",
        "http://playcontrol.net"
    },
	
    CoreAudio_init,       /*   init() method */
    CoreAudio_quit,       /*   quit() method */
    CoreAudio_open,       /*   open() method */
    CoreAudio_close,      /*  close() method */
    CoreAudio_read,       /*   read() method */
    CoreAudio_rewind,     /* rewind() method */
    CoreAudio_seek        /*   seek() method */
};


static int CoreAudio_init(void)
{
    return(1);  /* always succeeds. */
} /* CoreAudio_init */


static void CoreAudio_quit(void)
{
    /* it's a no-op. */
} /* CoreAudio_quit */

/*
   http://developer.apple.com/library/ios/#documentation/MusicAudio/Reference/AudioFileConvertRef/Reference/reference.html
   kAudioFileAIFFType = 'AIFF',
   kAudioFileAIFCType            = 'AIFC',
   kAudioFileWAVEType            = 'WAVE',
   kAudioFileSoundDesigner2Type  = 'Sd2f',
   kAudioFileNextType            = 'NeXT',
   kAudioFileMP3Type             = 'MPG3',
   kAudioFileMP2Type             = 'MPG2',
   kAudioFileMP1Type             = 'MPG1',
   kAudioFileAC3Type             = 'ac-3',
   kAudioFileAAC_ADTSType        = 'adts',
   kAudioFileMPEG4Type           = 'mp4f',
   kAudioFileM4AType             = 'm4af',
   kAudioFileCAFType             = 'caff',
   kAudioFile3GPType             = '3gpp',
   kAudioFile3GP2Type            = '3gp2',
   kAudioFileAMRType             = 'amrf'
*/
static AudioFileTypeID CoreAudio_GetAudioTypeForExtension(const char* file_extension)
{
	if( (__Sound_strcasecmp(file_extension, "aif") == 0)
		|| (__Sound_strcasecmp(file_extension, "aiff") == 0)
		|| (__Sound_strcasecmp(file_extension, "aifc") == 0)
	)
	{
		return kAudioFileAIFCType;
	}
	else if( (__Sound_strcasecmp(file_extension, "wav") == 0)
		|| (__Sound_strcasecmp(file_extension, "wave") == 0)
	)
	{
		return kAudioFileWAVEType;
	}
	else if( (__Sound_strcasecmp(file_extension, "mp3") == 0)
	)
	{
		return kAudioFileMP3Type;
	}
	else if( (__Sound_strcasecmp(file_extension, "mp4") == 0)
	)
	{
		return kAudioFileMPEG4Type;
	}
	else if( (__Sound_strcasecmp(file_extension, "m4a") == 0)
	)
	{
		return kAudioFileM4AType;
	}
	else if( (__Sound_strcasecmp(file_extension, "aac") == 0)
	)
	{
		return kAudioFileAAC_ADTSType;
	}
	else if( (__Sound_strcasecmp(file_extension, "adts") == 0)
	)
	{
		return kAudioFileAAC_ADTSType;
	}
	else if( (__Sound_strcasecmp(file_extension, "caf") == 0)
		|| (__Sound_strcasecmp(file_extension, "caff") == 0)
	)
	{
		return kAudioFileCAFType;
	}
	else if( (__Sound_strcasecmp(file_extension, "Sd2f") == 0)
		|| (__Sound_strcasecmp(file_extension, "sd2") == 0)
	)
	{
		return kAudioFileSoundDesigner2Type;
	}
	else if( (__Sound_strcasecmp(file_extension, "au") == 0)
		|| (__Sound_strcasecmp(file_extension, "snd") == 0)
		|| (__Sound_strcasecmp(file_extension, "next") == 0)
	)
	{
		return kAudioFileNextType;
	}
	else if( (__Sound_strcasecmp(file_extension, "mp2") == 0)
	)
	{
		return kAudioFileMP2Type;
	}
	else if( (__Sound_strcasecmp(file_extension, "mp1") == 0)
	)
	{
		return kAudioFileMP1Type;
	}
	else if( (__Sound_strcasecmp(file_extension, "ac3") == 0)
	)
	{
		return kAudioFileAC3Type;
	}
	else if( (__Sound_strcasecmp(file_extension, "3gpp") == 0)
			|| (__Sound_strcasecmp(file_extension, "3gp") == 0)
	)
	{
		return kAudioFile3GPType;
	}
	else if( (__Sound_strcasecmp(file_extension, "3gp2") == 0)
			|| (__Sound_strcasecmp(file_extension, "3g2") == 0)
	)
	{
		return kAudioFile3GP2Type;
	}
	else if( (__Sound_strcasecmp(file_extension, "amrf") == 0)
		|| (__Sound_strcasecmp(file_extension, "amr") == 0)
	)
	{
		return kAudioFileAMRType;
	}
	else if( (__Sound_strcasecmp(file_extension, "ima4") == 0)
		|| (__Sound_strcasecmp(file_extension, "ima") == 0)
	)
	{
		/* not sure about this one */
		return kAudioFileCAFType;
	}
	else
	{
		return 0;
	}

}

static const char* CoreAudio_FourCCToString(int32_t error_code)
{
	static char return_string[16];
	uint32_t big_endian_code = htonl(error_code);
	char* big_endian_str = (char*)&big_endian_code;
	// see if it appears to be a 4-char-code
	if(isprint(big_endian_str[0])
	   && isprint(big_endian_str[1])
	   && isprint(big_endian_str[2])
	   && isprint (big_endian_str[3]))
	{
		return_string[0] = '\'';
		return_string[1] = big_endian_str[0];
		return_string[2] = big_endian_str[1];
		return_string[3] = big_endian_str[2];
		return_string[4] = big_endian_str[3];
		return_string[5] = '\'';
		return_string[6] = '\0';
	}
	else if(error_code > -200000 && error_code < 200000)
	{
		// no, format it as an integer
		snprintf(return_string, 16, "%d", error_code);
	}
	else
	{
		// no, format it as an integer but in hex
		snprintf(return_string, 16, "0x%x", error_code);
	}
	return return_string;
}



SInt64 CoreAudio_SizeCallback(void* inClientData)
{
	ALmixer_RWops* rw_ops = (ALmixer_RWops*)inClientData;
	SInt64 current_position = ALmixer_RWtell(rw_ops);
	SInt64 end_position = ALmixer_RWseek(rw_ops, 0, SEEK_END);
	ALmixer_RWseek(rw_ops, current_position, SEEK_SET);
//	fprintf(stderr, "CoreAudio_SizeCallback:%d\n", end_position);

	return end_position;
}

OSStatus CoreAudio_ReadCallback(
	void* inClientData,
	SInt64 inPosition,
	UInt32 requestCount,
	void* data_buffer,
	UInt32* actualCount
)
{
	ALmixer_RWops* rw_ops = (ALmixer_RWops*)inClientData;
	ALmixer_RWseek(rw_ops, inPosition, SEEK_SET);
	size_t bytes_actually_read = ALmixer_RWread(rw_ops, data_buffer, 1, requestCount);
	// Not sure how to test for a read error with ALmixer_RWops
//	fprintf(stderr, "CoreAudio_ReadCallback:%d, %d\n", requestCount, bytes_actually_read);

	*actualCount = bytes_actually_read;
	return noErr;
}


static int CoreAudio_open(Sound_Sample *sample, const char *ext)
{
	CoreAudioFileContainer* core_audio_file_container;
	AudioFileID* audio_file_id;
	OSStatus error_result;
	Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
	AudioStreamBasicDescription	actual_format;
	AudioStreamBasicDescription	output_format;
	Float64 estimated_duration;
	UInt32 format_size;
	

	core_audio_file_container = (CoreAudioFileContainer*)malloc(sizeof(CoreAudioFileContainer));
	BAIL_IF_MACRO(core_audio_file_container == NULL, ERR_OUT_OF_MEMORY, 0);


	audio_file_id = (AudioFileID*)malloc(sizeof(AudioFileID));
	BAIL_IF_MACRO(audio_file_id == NULL, ERR_OUT_OF_MEMORY, 0);

	error_result = AudioFileOpenWithCallbacks(
		internal->rw,
		CoreAudio_ReadCallback,
		NULL,
		CoreAudio_SizeCallback,
		NULL,
		CoreAudio_GetAudioTypeForExtension(ext),
		audio_file_id
	);
	if (error_result != noErr)
	{
		AudioFileClose(*audio_file_id);
		free(audio_file_id);
		free(core_audio_file_container);
		SNDDBG(("Core Audio: can't grok data. reason: [%s].\n", CoreAudio_FourCCToString(error_result)));
		BAIL_MACRO("Core Audio: Not valid audio data.", 0);
	} /* if */
	
    format_size = sizeof(actual_format);
    error_result = AudioFileGetProperty(
		*audio_file_id,
		kAudioFilePropertyDataFormat,
		&format_size,
		&actual_format
	);
    if (error_result != noErr)
	{
		AudioFileClose(*audio_file_id);
		free(audio_file_id);
		free(core_audio_file_container);
		SNDDBG(("Core Audio: AudioFileGetProperty failed. reason: [%s]", CoreAudio_FourCCToString(error_result)));
		BAIL_MACRO("Core Audio: Not valid audio data.", 0);
	} /* if */

    format_size = sizeof(estimated_duration);
    error_result = AudioFileGetProperty(
		*audio_file_id,
		kAudioFilePropertyEstimatedDuration,
		&format_size,
		&estimated_duration
	);
    if (error_result != noErr)
	{
		AudioFileClose(*audio_file_id);
		free(audio_file_id);
		free(core_audio_file_container);
		SNDDBG(("Core Audio: AudioFileGetProperty failed. reason: [%s].\n", CoreAudio_FourCCToString(error_result)));
		BAIL_MACRO("Core Audio: Not valid audio data.", 0);
	} /* if */


	core_audio_file_container->audioFileID = audio_file_id;
	
	internal->decoder_private = core_audio_file_container;
	
	sample->flags = SOUND_SAMPLEFLAG_CANSEEK;
	sample->actual.rate = (UInt32) actual_format.mSampleRate;
	sample->actual.channels = (UInt8)actual_format.mChannelsPerFrame;
	internal->total_time = (SInt32)(estimated_duration * 1000.0 + 0.5);

#if 0
	/* FIXME: Both Core Audio and SDL 1.3 support float and 32-bit formats */
	if(actual_format.mFormatFlags & kAudioFormatFlagIsBigEndian)
	{
		if(16 == actual_format.mBitsPerChannel)
		{
			if(kAudioFormatFlagIsSignedInteger & actual_format.mFormatFlags)
			{
				sample->actual.format = AUDIO_S16MSB;
			}
			else
			{
				sample->actual.format = AUDIO_U16MSB;				
			}
		}
		else if(8 == actual_format.mBitsPerChannel)
		{
			if(kAudioFormatFlagIsSignedInteger & actual_format.mFormatFlags)
			{
				sample->actual.format = AUDIO_S8;
			}
			else
			{
				sample->actual.format = AUDIO_U8;				
			}
		}
		else // might be 0 for undefined? 
		{
			// This case seems to come up a lot for me. Maybe for file types like .m4a?
			sample->actual.format = AUDIO_S16SYS;
			SNDDBG(("Core Audio: Unsupported actual_format.mBitsPerChannel: [%d].\n", actual_format.mBitsPerChannel));
			
		}
	}
	else // little endian
	{
		if(16 == actual_format.mBitsPerChannel)
		{
			if(kAudioFormatFlagIsSignedInteger & actual_format.mFormatFlags)
			{
				sample->actual.format = AUDIO_S16LSB;
			}
			else
			{
				sample->actual.format = AUDIO_U16LSB;				
			}
		}
		else if(8 == actual_format.mBitsPerChannel)
		{
			if(kAudioFormatFlagIsSignedInteger & actual_format.mFormatFlags)
			{
				sample->actual.format = AUDIO_S8;
			}
			else
			{
				sample->actual.format = AUDIO_U8;				
			}
		}
		else // might be 0 for undefined? 
		{
			sample->actual.format = AUDIO_S16SYS;
			
			SNDDBG(("Core Audio: Unsupported actual_format.mBitsPerChannel: [%d].\n", actual_format.mBitsPerChannel));
		}

	}
#else
	
	
	
    /*
     * I want to use Core Audio to do conversion and decoding for performance reasons.
	 * This is particularly important on mobile devices like iOS.
	 * Taking from the Ogg Vorbis decode, I pretend the "actual" format is the same 
	 * as the desired format. 
     */
    sample->actual.format = (sample->desired.format == 0) ?
	AUDIO_S16SYS : sample->desired.format;
#endif	


	SNDDBG(("CoreAudio: channels == (%d).\n", sample->actual.channels));
	SNDDBG(("CoreAudio: sampling rate == (%d).\n",sample->actual.rate));
	SNDDBG(("CoreAudio: total seconds of sample == (%d).\n", internal->total_time));
	SNDDBG(("CoreAudio: sample->actual.format == (%d).\n", sample->actual.format));


	
	error_result = ExtAudioFileWrapAudioFileID(*audio_file_id,
		false, // set to false for read-only
		&core_audio_file_container->extAudioFileRef
	);
	if(error_result != noErr)
	{
		AudioFileClose(*audio_file_id);
		free(audio_file_id);
		free(core_audio_file_container);
		SNDDBG(("Core Audio: can't wrap data. reason: [%s].\n", CoreAudio_FourCCToString(error_result)));
		BAIL_MACRO("Core Audio: Failed to wrap data.", 0);
	} /* if */


	/* The output format must be linear PCM because that's the only type OpenAL knows how to deal with.
	 * Set the client format to 16 bit signed integer (native-endian) data because that is the most
	 * optimal format on iPhone/iPod Touch hardware.
	 * Maintain the channel count and sample rate of the original source format.
	 */
	output_format.mSampleRate = actual_format.mSampleRate; // preserve the original sample rate
	output_format.mChannelsPerFrame = actual_format.mChannelsPerFrame; // preserve the number of channels
	output_format.mFormatID = kAudioFormatLinearPCM; // We want linear PCM data
	output_format.mFramesPerPacket = 1; // We know for linear PCM, the definition is 1 frame per packet

	if(sample->desired.format == 0)
	{
		// do AUDIO_S16SYS
		output_format.mFormatFlags = kAudioFormatFlagsNativeEndian | kAudioFormatFlagIsSignedInteger | kAudioFormatFlagIsPacked; // I seem to read failures problems without kAudioFormatFlagIsPacked. From a mailing list post, this seems to be a Core Audio bug.
		output_format.mBitsPerChannel = 16; // We know we want 16-bit
	}
	else
	{
		output_format.mFormatFlags = 0; // clear flags
		output_format.mFormatFlags |= kAudioFormatFlagIsPacked; // I seem to read failures problems without kAudioFormatFlagIsPacked. From a mailing list post, this seems to be a Core Audio bug.
		// Mask against bitsize
		if(0xFF & sample->desired.format)
		{
			output_format.mBitsPerChannel = 16; /* 16-bit */
		}
		else
		{
			output_format.mBitsPerChannel = 8; /* 8-bit */
		}

		// Mask for signed/unsigned
		if((1<<15) & sample->desired.format)
		{
			output_format.mFormatFlags = output_format.mFormatFlags | kAudioFormatFlagIsSignedInteger;

		}
		else
		{
			// no flag set for unsigned
		}
		// Mask for big/little endian
		if((1<<12) & sample->desired.format)
		{
			output_format.mFormatFlags = output_format.mFormatFlags | kAudioFormatFlagIsBigEndian;
		}
		else
		{
			// no flag set for little endian 
		}
	}

	output_format.mBytesPerPacket = output_format.mBitsPerChannel/8 * output_format.mChannelsPerFrame; // e.g. 16-bits/8 * channels => so 2-bytes per channel per frame
	output_format.mBytesPerFrame = output_format.mBitsPerChannel/8 * output_format.mChannelsPerFrame; // For PCM, since 1 frame is 1 packet, it is the same as mBytesPerPacket

	
/*
	output_format.mSampleRate = actual_format.mSampleRate; // preserve the original sample rate
	output_format.mChannelsPerFrame = actual_format.mChannelsPerFrame; // preserve the number of channels
	output_format.mFormatID = kAudioFormatLinearPCM; // We want linear PCM data
//	output_format.mFormatFlags = kAudioFormatFlagsNativeEndian | kAudioFormatFlagIsPacked | kAudioFormatFlagIsSignedInteger;
	output_format.mFormatFlags = kAudioFormatFlagsNativeEndian |  kAudioFormatFlagIsSignedInteger;
	output_format.mFramesPerPacket = 1; // We know for linear PCM, the definition is 1 frame per packet
	output_format.mBitsPerChannel = 16; // We know we want 16-bit
	output_format.mBytesPerPacket = 2 * output_format.mChannelsPerFrame; // We know we are using 16-bit, so 2-bytes per channel per frame
	output_format.mBytesPerFrame = 2 * output_format.mChannelsPerFrame; // For PCM, since 1 frame is 1 packet, it is the same as mBytesPerPacket
*/
	SNDDBG(("output_format: mSampleRate: %lf\n", output_format.mSampleRate)); 
	SNDDBG(("output_format: mChannelsPerFrame: %d\n", output_format.mChannelsPerFrame)); 
	SNDDBG(("output_format: mFormatID: %d\n", output_format.mFormatID)); 
	SNDDBG(("output_format: mFormatFlags: %d\n", output_format.mFormatFlags)); 
	SNDDBG(("output_format: mFramesPerPacket: %d\n", output_format.mFramesPerPacket)); 
	SNDDBG(("output_format: mBitsPerChannel: %d\n", output_format.mBitsPerChannel)); 
	SNDDBG(("output_format: mBytesPerPacket: %d\n", output_format.mBytesPerPacket)); 
	SNDDBG(("output_format: mBytesPerFrame: %d\n", output_format.mBytesPerFrame)); 
	
	
	/* Set the desired client (output) data format */
	error_result = ExtAudioFileSetProperty(core_audio_file_container->extAudioFileRef, kExtAudioFileProperty_ClientDataFormat, sizeof(output_format), &output_format);
	if(noErr != error_result)
	{
		ExtAudioFileDispose(core_audio_file_container->extAudioFileRef);
		AudioFileClose(*audio_file_id);
		free(audio_file_id);
		free(core_audio_file_container);
		SNDDBG(("Core Audio: ExtAudioFileSetProperty(kExtAudioFileProperty_ClientDataFormat) failed, reason: [%s].\n", CoreAudio_FourCCToString(error_result)));
		BAIL_MACRO("Core Audio: Not valid audio data.", 0);
	}	


	core_audio_file_container->outputFormat = (AudioStreamBasicDescription*)malloc(sizeof(AudioStreamBasicDescription));
	BAIL_IF_MACRO(core_audio_file_container->outputFormat == NULL, ERR_OUT_OF_MEMORY, 0);


	
	/* Copy the output format to the audio_description that was passed in so the 
	 * info will be returned to the user.
	 */
	memcpy(core_audio_file_container->outputFormat, &output_format, sizeof(AudioStreamBasicDescription));

	

	return(1);
} /* CoreAudio_open */


static void CoreAudio_close(Sound_Sample *sample)
{
	Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
	CoreAudioFileContainer* core_audio_file_container = (CoreAudioFileContainer *) internal->decoder_private;
	
	free(core_audio_file_container->outputFormat);
	ExtAudioFileDispose(core_audio_file_container->extAudioFileRef);
	AudioFileClose(*core_audio_file_container->audioFileID);
	free(core_audio_file_container->audioFileID);
	free(core_audio_file_container);
		
} /* CoreAudio_close */


static size_t CoreAudio_read(Sound_Sample *sample)
{
	OSStatus error_result = noErr;	
	/* Documentation/example shows SInt64, but is problematic for big endian
	 * on 32-bit cast for ExtAudioFileRead() because it takes the upper
	 * bits which turn to 0.
	 */
	UInt32 buffer_size_in_frames = 0;
	UInt32 buffer_size_in_frames_remaining = 0;
	UInt32 total_frames_read = 0;
	UInt32 data_buffer_size = 0;
	UInt32 bytes_remaining = 0;
	size_t total_bytes_read = 0;
	Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
	CoreAudioFileContainer* core_audio_file_container = (CoreAudioFileContainer *) internal->decoder_private;
	UInt32 max_buffer_size = internal->buffer_size;

//	printf("internal->buffer_size=%d, internal->buffer=0x%x, sample->buffer_size=%d\n", internal->buffer_size, internal->buffer, sample->buffer_size); 
//	printf("internal->max_buffer_size=%d\n", max_buffer_size); 

	/* Compute how many frames will fit into our max buffer size */
	/* Warning: If this is not evenly divisible, the buffer will not be completely filled which violates the SDL_sound assumption. */
	buffer_size_in_frames = max_buffer_size / core_audio_file_container->outputFormat->mBytesPerFrame;
//	printf("buffer_size_in_frames=%ld, internal->buffer_size=%d, internal->buffer=0x%x outputFormat->mBytesPerFrame=%d, sample->buffer_size=%d\n", buffer_size_in_frames, internal->buffer_size, internal->buffer, core_audio_file_container->outputFormat->mBytesPerFrame, sample->buffer_size); 


//	void* temp_buffer = malloc(max_buffer_size);
	
	AudioBufferList audio_buffer_list;
	audio_buffer_list.mNumberBuffers = 1;
	audio_buffer_list.mBuffers[0].mDataByteSize = max_buffer_size;
	audio_buffer_list.mBuffers[0].mNumberChannels = core_audio_file_container->outputFormat->mChannelsPerFrame;
	audio_buffer_list.mBuffers[0].mData = internal->buffer;


	bytes_remaining = max_buffer_size;
	buffer_size_in_frames_remaining = buffer_size_in_frames;
	
	// oops. Due to the kAudioFormatFlagIsPacked bug, 
	// I was misled to believe that Core Audio
	// was not always filling my entire requested buffer. 
	// So this while-loop might be unnecessary.
	// However, I have not exhaustively tested all formats, 
	// so maybe it is possible this loop is useful.
	// It might also handle the not-evenly disvisible case above.
	while(buffer_size_in_frames_remaining > 0 && !(sample->flags & SOUND_SAMPLEFLAG_EOF))
	{
		
		data_buffer_size = (UInt32)(buffer_size_in_frames * core_audio_file_container->outputFormat->mBytesPerFrame);
//		printf("data_buffer_size=%d\n", data_buffer_size); 

		buffer_size_in_frames = buffer_size_in_frames_remaining;
		
//		printf("reading buffer_size_in_frames=%"PRId64"\n", buffer_size_in_frames); 


		audio_buffer_list.mBuffers[0].mDataByteSize = bytes_remaining;
		audio_buffer_list.mBuffers[0].mData = &(((UInt8*)internal->buffer)[total_bytes_read]);

		
		/* Read the data into an AudioBufferList */
		error_result = ExtAudioFileRead(core_audio_file_container->extAudioFileRef, &buffer_size_in_frames, &audio_buffer_list);
		if(error_result == noErr)
		{
		
		
			/* Success */
			
			total_frames_read += buffer_size_in_frames;
			buffer_size_in_frames_remaining = buffer_size_in_frames_remaining - buffer_size_in_frames;
			
//			printf("read buffer_size_in_frames=%"PRId64", buffer_size_in_frames_remaining=%"PRId64"\n", buffer_size_in_frames, buffer_size_in_frames_remaining); 

			/* ExtAudioFileRead returns the number of frames actually read. Need to convert back to bytes. */
			data_buffer_size = (UInt32)(buffer_size_in_frames * core_audio_file_container->outputFormat->mBytesPerFrame);
//			printf("data_buffer_size=%d\n", data_buffer_size); 

			total_bytes_read += data_buffer_size;
			bytes_remaining = bytes_remaining - data_buffer_size;

			/* Note: 0 == buffer_size_in_frames is a legitimate value meaning we are EOF. */
			if(0 == buffer_size_in_frames)
			{
				sample->flags |= SOUND_SAMPLEFLAG_EOF;			
			}

		}
		else 
		{
			SNDDBG(("Core Audio: ExtAudioFileReadfailed, reason: [%s].\n", CoreAudio_FourCCToString(error_result)));

			sample->flags |= SOUND_SAMPLEFLAG_ERROR;
			break;
			
		}
	}
	
	if( (!(sample->flags & SOUND_SAMPLEFLAG_EOF)) && (total_bytes_read < max_buffer_size))
	{
		SNDDBG(("Core Audio: ExtAudioFileReadfailed SOUND_SAMPLEFLAG_EAGAIN, reason: [total_bytes_read < max_buffer_size], %d, %d.\n", total_bytes_read , max_buffer_size));
		
		/* Don't know what to do here. */
		sample->flags |= SOUND_SAMPLEFLAG_EAGAIN;
	}
	return total_bytes_read;
} /* CoreAudio_read */


static int CoreAudio_rewind(Sound_Sample *sample)
{
	OSStatus error_result = noErr;	
	Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
	CoreAudioFileContainer* core_audio_file_container = (CoreAudioFileContainer *) internal->decoder_private;
	
	error_result = ExtAudioFileSeek(core_audio_file_container->extAudioFileRef, 0);
	if(error_result != noErr)
	{
		sample->flags |= SOUND_SAMPLEFLAG_ERROR;
	}
	return(1);
} /* CoreAudio_rewind */

/* Note: I found this tech note:
 http://developer.apple.com/library/mac/#qa/qa2009/qa1678.html
 I don't know if this applies to us. So far, I haven't noticed the problem,
 so I haven't applied any of the techniques.
 */
static int CoreAudio_seek(Sound_Sample *sample, size_t ms)
{
	OSStatus error_result = noErr;	
	Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
	CoreAudioFileContainer* core_audio_file_container = (CoreAudioFileContainer *) internal->decoder_private;
	SInt64 frame_offset = 0;

	/* I'm confused. The Apple documentation says this:
	 "Seek position is specified in the sample rate and frame count of the file’s audio data format
	 — not your application’s audio data format."
	 My interpretation is that I want to get the "actual format of the file and compute the frame offset.
	 But when I try that, seeking goes to the wrong place.
	 When I use outputFormat, things seem to work correctly.
	 I must be misinterpreting the documentation or doing something wrong.
	 */
#if 0 /* not working */
	AudioStreamBasicDescription	actual_format;
	UInt32 format_size;
    format_size = sizeof(AudioStreamBasicDescription);
    error_result = AudioFileGetProperty(
		*core_audio_file_container->audioFileID,
		kAudioFilePropertyDataFormat,
		&format_size,
		&actual_format
	);
    if(error_result != noErr)
	{
		sample->flags |= SOUND_SAMPLEFLAG_ERROR;
		BAIL_MACRO("Core Audio: Could not GetProperty for kAudioFilePropertyDataFormat.", 0);
	} /* if */

	// packetIndex = (pos * sampleRate) / framesPerPacket
	frame_offset = (SInt64)((ms/1000.0 * actual_format.mSampleRate) / actual_format.mFramesPerPacket);
	// computed against actual format and not the client format

	// packetIndex = (pos * sampleRate) / framesPerPacket
	//	frame_offset = (SInt64)((ms/1000.0 * actual_format.mSampleRate) / actual_format.mFramesPerPacket);
#else /* seems to work, but I'm confused */
	// packetIndex = (pos * sampleRate) / framesPerPacket
	frame_offset = (SInt64)((ms/1000.0 * core_audio_file_container->outputFormat->mSampleRate) / core_audio_file_container->outputFormat->mFramesPerPacket);	
#endif
	
	// computed against actual format and not the client format
	error_result = ExtAudioFileSeek(core_audio_file_container->extAudioFileRef, frame_offset);
	if(error_result != noErr)
	{
		sample->flags |= SOUND_SAMPLEFLAG_ERROR;
	}
	return(1);
} /* CoreAudio_seek */

#endif /* __APPLE__ */


#endif /* ALMIXER_COMPILE_WITHOUT_SDL */