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SDL_wave.h (5582B)

      1 /*
      2   Simple DirectMedia Layer
      3   Copyright (C) 1997-2020 Sam Lantinga <slouken@libsdl.org>
      4 
      5   This software is provided 'as-is', without any express or implied
      6   warranty.  In no event will the authors be held liable for any damages
      7   arising from the use of this software.
      8 
      9   Permission is granted to anyone to use this software for any purpose,
     10   including commercial applications, and to alter it and redistribute it
     11   freely, subject to the following restrictions:
     12 
     13   1. The origin of this software must not be misrepresented; you must not
     14      claim that you wrote the original software. If you use this software
     15      in a product, an acknowledgment in the product documentation would be
     16      appreciated but is not required.
     17   2. Altered source versions must be plainly marked as such, and must not be
     18      misrepresented as being the original software.
     19   3. This notice may not be removed or altered from any source distribution.
     20 */
     21 #include "../SDL_internal.h"
     22 
     23 /* RIFF WAVE files are little-endian */
     24 
     25 /*******************************************/
     26 /* Define values for Microsoft WAVE format */
     27 /*******************************************/
     28 /* FOURCC */
     29 #define RIFF            0x46464952      /* "RIFF" */
     30 #define WAVE            0x45564157      /* "WAVE" */
     31 #define FACT            0x74636166      /* "fact" */
     32 #define LIST            0x5453494c      /* "LIST" */
     33 #define BEXT            0x74786562      /* "bext" */
     34 #define JUNK            0x4B4E554A      /* "JUNK" */
     35 #define FMT             0x20746D66      /* "fmt " */
     36 #define DATA            0x61746164      /* "data" */
     37 /* Format tags */
     38 #define UNKNOWN_CODE    0x0000
     39 #define PCM_CODE        0x0001
     40 #define MS_ADPCM_CODE   0x0002
     41 #define IEEE_FLOAT_CODE 0x0003
     42 #define ALAW_CODE       0x0006
     43 #define MULAW_CODE      0x0007
     44 #define IMA_ADPCM_CODE  0x0011
     45 #define MPEG_CODE       0x0050
     46 #define MPEGLAYER3_CODE 0x0055
     47 #define EXTENSIBLE_CODE 0xFFFE
     48 
     49 /* Stores the WAVE format information. */
     50 typedef struct WaveFormat
     51 {
     52     Uint16 formattag;       /* Raw value of the first field in the fmt chunk data. */
     53     Uint16 encoding;        /* Actual encoding, possibly from the extensible header. */
     54     Uint16 channels;        /* Number of channels. */
     55     Uint32 frequency;       /* Sampling rate in Hz. */
     56     Uint32 byterate;        /* Average bytes per second. */
     57     Uint16 blockalign;      /* Bytes per block. */
     58     Uint16 bitspersample;   /* Currently supported are 8, 16, 24, 32, and 4 for ADPCM. */
     59 
     60     /* Extra information size. Number of extra bytes starting at byte 18 in the
     61      * fmt chunk data. This is at least 22 for the extensible header.
     62      */
     63     Uint16 extsize;
     64 
     65     /* Extensible WAVE header fields */
     66     Uint16 validsamplebits;
     67     Uint32 samplesperblock; /* For compressed formats. Can be zero. Actually 16 bits in the header. */
     68     Uint32 channelmask;
     69     Uint8 subformat[16];    /* A format GUID. */
     70 } WaveFormat;
     71 
     72 /* Stores information on the fact chunk. */
     73 typedef struct WaveFact {
     74     /* Represents the state of the fact chunk in the WAVE file.
     75      * Set to -1 if the fact chunk is invalid.
     76      * Set to 0 if the fact chunk is not present
     77      * Set to 1 if the fact chunk is present and valid.
     78      * Set to 2 if samplelength is going to be used as the number of sample frames.
     79      */
     80     Sint32 status;
     81 
     82     /* Version 1 of the RIFF specification calls the field in the fact chunk
     83      * dwFileSize. The Standards Update then calls it dwSampleLength and specifies
     84      * that it is 'the length of the data in samples'. WAVE files from Windows
     85      * with this chunk have it set to the samples per channel (sample frames).
     86      * This is useful to truncate compressed audio to a specific sample count
     87      * because a compressed block is usually decoded to a fixed number of
     88      * sample frames.
     89      */
     90     Uint32 samplelength; /* Raw sample length value from the fact chunk. */
     91 } WaveFact;
     92 
     93 /* Generic struct for the chunks in the WAVE file. */
     94 typedef struct WaveChunk
     95 {
     96     Uint32 fourcc;   /* FOURCC of the chunk. */
     97     Uint32 length;   /* Size of the chunk data. */
     98     Sint64 position; /* Position of the data in the stream. */
     99     Uint8 *data;     /* When allocated, this points to the chunk data. length is used for the malloc size. */
    100     size_t size;     /* Number of bytes in data that could be read from the stream. Can be smaller than length. */
    101 } WaveChunk;
    102 
    103 /* Controls how the size of the RIFF chunk affects the loading of a WAVE file. */
    104 typedef enum WaveRiffSizeHint {
    105     RiffSizeNoHint,
    106     RiffSizeForce,
    107     RiffSizeIgnoreZero,
    108     RiffSizeIgnore,
    109     RiffSizeMaximum
    110 } WaveRiffSizeHint;
    111 
    112 /* Controls how a truncated WAVE file is handled. */
    113 typedef enum WaveTruncationHint {
    114     TruncNoHint,
    115     TruncVeryStrict,
    116     TruncStrict,
    117     TruncDropFrame,
    118     TruncDropBlock
    119 } WaveTruncationHint;
    120 
    121 /* Controls how the fact chunk affects the loading of a WAVE file. */
    122 typedef enum WaveFactChunkHint {
    123     FactNoHint,
    124     FactTruncate,
    125     FactStrict,
    126     FactIgnoreZero,
    127     FactIgnore
    128 } WaveFactChunkHint;
    129 
    130 typedef struct WaveFile
    131 {
    132     WaveChunk chunk;
    133     WaveFormat format;
    134     WaveFact fact;
    135 
    136     /* Number of sample frames that will be decoded. Calculated either with the
    137      * size of the data chunk or, if the appropriate hint is enabled, with the
    138      * sample length value from the fact chunk.
    139      */
    140     Sint64 sampleframes;
    141 
    142     void *decoderdata;   /* Some decoders require extra data for a state. */
    143 
    144     WaveRiffSizeHint riffhint;
    145     WaveTruncationHint trunchint;
    146     WaveFactChunkHint facthint;
    147 } WaveFile;
    148 
    149 /* vi: set ts=4 sw=4 expandtab: */