ALACAudioTypes.h

/*
 * Copyright (c) 2011 Apple Inc. All rights reserved.
 *
 * @APPLE_APACHE_LICENSE_HEADER_START@
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * 
 * @APPLE_APACHE_LICENSE_HEADER_END@
 */
 
/*
    File:       ALACAudioTypes.h
*/
 
#ifndef ALACAUDIOTYPES_H
#define ALACAUDIOTYPES_H
 
#if PRAGMA_ONCE
#pragma once
#endif
 
#ifdef __cplusplus
extern "C" {
#endif
 
#if PRAGMA_STRUCT_ALIGN
    #pragma options align=mac68k
#elif PRAGMA_STRUCT_PACKPUSH
    #pragma pack(push, 2)
#elif PRAGMA_STRUCT_PACK
    #pragma pack(2)
#endif
 
#include <stdint.h>
 
#if defined(__ppc__)
#define TARGET_RT_BIG_ENDIAN 1
#elif defined(__ppc64__)
#define TARGET_RT_BIG_ENDIAN 1
#endif
 
#define kChannelAtomSize 12
    
enum 
{
    kALAC_UnimplementedError   = -4,
    kALAC_FileNotFoundError    = -43,
    kALAC_ParamError           = -50,
    kALAC_MemFullError         = -108
};
 
enum
{
    kALACFormatAppleLossless = 'alac',
    kALACFormatLinearPCM = 'lpcm'
};
 
enum
{
    kALACMaxChannels    = 8,
    kALACMaxEscapeHeaderBytes = 8,
    kALACMaxSearches    = 16,
    kALACMaxCoefs       = 16,
    kALACDefaultFramesPerPacket = 4096
};
 
typedef uint32_t ALACChannelLayoutTag;
 
enum
{
    kALACFormatFlagIsFloat                     = (1 << 0),     // 0x1
    kALACFormatFlagIsBigEndian                 = (1 << 1),     // 0x2
    kALACFormatFlagIsSignedInteger             = (1 << 2),     // 0x4
    kALACFormatFlagIsPacked                    = (1 << 3),     // 0x8
    kALACFormatFlagIsAlignedHigh               = (1 << 4),     // 0x10
};
 
enum
{
#if TARGET_RT_BIG_ENDIAN
    kALACFormatFlagsNativeEndian       = kALACFormatFlagIsBigEndian
#else
    kALACFormatFlagsNativeEndian       = 0
#endif
};
 
// this is required to be an IEEE 64bit float
typedef double alac_float64_t;
 
// These are the Channel Layout Tags used in the Channel Layout Info portion of the ALAC magic cookie
enum
{
    kALACChannelLayoutTag_Mono          = (100<<16) | 1,    // C
    kALACChannelLayoutTag_Stereo        = (101<<16) | 2,    // L R
    kALACChannelLayoutTag_MPEG_3_0_B    = (113<<16) | 3,    // C L R
    kALACChannelLayoutTag_MPEG_4_0_B    = (116<<16) | 4,    // C L R Cs
    kALACChannelLayoutTag_MPEG_5_0_D    = (120<<16) | 5,    // C L R Ls Rs
    kALACChannelLayoutTag_MPEG_5_1_D    = (124<<16) | 6,    // C L R Ls Rs LFE
    kALACChannelLayoutTag_AAC_6_1       = (142<<16) | 7,    // C L R Ls Rs Cs LFE
    kALACChannelLayoutTag_MPEG_7_1_B    = (127<<16) | 8     // C Lc Rc L R Ls Rs LFE    (doc: IS-13818-7 MPEG2-AAC)
};
 
// ALAC currently only utilizes these channels layouts. There is a one for one correspondance between a
// given number of channels and one of these layout tags
static const ALACChannelLayoutTag   ALACChannelLayoutTags[kALACMaxChannels] =
{
    kALACChannelLayoutTag_Mono,         // C
    kALACChannelLayoutTag_Stereo,       // L R
    kALACChannelLayoutTag_MPEG_3_0_B,   // C L R
    kALACChannelLayoutTag_MPEG_4_0_B,   // C L R Cs
    kALACChannelLayoutTag_MPEG_5_0_D,   // C L R Ls Rs
    kALACChannelLayoutTag_MPEG_5_1_D,   // C L R Ls Rs LFE
    kALACChannelLayoutTag_AAC_6_1,      // C L R Ls Rs Cs LFE
    kALACChannelLayoutTag_MPEG_7_1_B    // C Lc Rc L R Ls Rs LFE    (doc: IS-13818-7 MPEG2-AAC)
};
 
// AudioChannelLayout from CoreAudioTypes.h. We never need the AudioChannelDescription so we remove it
struct ALACAudioChannelLayout
{
    ALACChannelLayoutTag          mChannelLayoutTag;
    uint32_t                      mChannelBitmap;
    uint32_t                      mNumberChannelDescriptions;
};
typedef struct ALACAudioChannelLayout ALACAudioChannelLayout;
 
struct AudioFormatDescription
{
    alac_float64_t mSampleRate;
    uint32_t  mFormatID;
    uint32_t  mFormatFlags;
    uint32_t  mBytesPerPacket;
    uint32_t  mFramesPerPacket;
    uint32_t  mBytesPerFrame;
    uint32_t  mChannelsPerFrame;
    uint32_t  mBitsPerChannel;
    uint32_t  mReserved;
};
typedef struct AudioFormatDescription  AudioFormatDescription;
 
/* Lossless Definitions */
 
enum
{
    kALACCodecFormat        = 'alac',
    kALACVersion            = 0,
    kALACCompatibleVersion  = kALACVersion,
    kALACDefaultFrameSize   = 4096
};
 
// note: this struct is wrapped in an 'alac' atom in the sample description extension area
// note: in QT movies, it will be further wrapped in a 'wave' atom surrounded by 'frma' and 'term' atoms
typedef struct ALACSpecificConfig
{
    uint32_t                frameLength;
    uint8_t                 compatibleVersion;
    uint8_t                 bitDepth;                           // max 32
    uint8_t                 pb;                                 // 0 <= pb <= 255
    uint8_t                 mb;
    uint8_t                 kb;
    uint8_t                 numChannels;
    uint16_t                maxRun;
    uint32_t                maxFrameBytes;
    uint32_t                avgBitRate;
    uint32_t                sampleRate;
 
} ALACSpecificConfig;
 
 
// The AudioChannelLayout atom type is not exposed yet so define it here
enum
{
    AudioChannelLayoutAID = 'chan'
};
 
#if PRAGMA_STRUCT_ALIGN
    #pragma options align=reset
#elif PRAGMA_STRUCT_PACKPUSH
    #pragma pack(pop)
#elif PRAGMA_STRUCT_PACK
    #pragma pack()
#endif
 
#ifdef __cplusplus
}
#endif
 
#endif  /* ALACAUDIOTYPES_H */