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Add AIFF-C subformats for twos,in24,in32,42ni,23ni #916

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c69ac2d
Add AIFF-C subformats for twos,in24,in32,42ni,23ni
madah81pnz1 Jul 4, 2026
db23f7d
Add --force-aiff-c-format=raw
madah81pnz1 Jul 7, 2026
670fb30
Make AIFF-C 'raw ' be unsigned 8-bit
madah81pnz1 Jul 8, 2026
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4 changes: 4 additions & 0 deletions man/flac.md
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Expand Up @@ -601,6 +601,10 @@ found by \--keep-foreign-metadata-if-present or \--keep-foreign-metadata
: Instruct the decoder to output an AIFF-C file with format NONE and
sowt respectively.

**\--force-aiff-c-format**={none\|sowt\|twos\|in24\|42ni\|in32\|23ni}

@madah81pnz1 madah81pnz1 Jul 6, 2026

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Other format types would be 'raw ', but seems to be very rarely used.

'in16'/'61ni' is another one for 16-bit audio, which seems to be used only internally in CoreAudio, but very rarely in actual AIFF-C files.

: Instruct the decoder to output an AIFF-C file with the specified
format.

**\--force-raw-format**
: Force input (when encoding) or output (when decoding) to be treated
as raw samples (even if filename suggests otherwise).
Expand Down
7 changes: 7 additions & 0 deletions oss-fuzz/fuzzer_tool_flac.dict
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Expand Up @@ -8,6 +8,13 @@
"--force-wave64-format"
"--force-aiff-c-sowt-format"
"--force-aiff-c-none-format"
"--force-aiff-c-format=none"
"--force-aiff-c-format=sowt"
"--force-aiff-c-format=twos"
"--force-aiff-c-format=in24"
"--force-aiff-c-format=in32"
"--force-aiff-c-format=42ni"
"--force-aiff-c-format=23ni"
"--force-legacy-wave-format"
"--force-extensible-wave-format"

Expand Down
56 changes: 45 additions & 11 deletions src/flac/decode.c
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Expand Up @@ -1108,14 +1108,37 @@ FLAC__bool write_aiff_form_comm_chunk(FILE *f, FLAC__uint64 samples, uint32_t bp
return false;

if(format == FORMAT_AIFF_C) {
if(subformat == SUBFORMAT_AIFF_C_NONE) {
if(flac__utils_fwrite("NONE", 1, 4, f) != 4)
return false;
const char *compression_format = "NONE";
switch(subformat) {
case SUBFORMAT_AIFF_C_NONE:
compression_format = "NONE";
break;
case SUBFORMAT_AIFF_C_SOWT:
compression_format = "sowt";
break;
case SUBFORMAT_AIFF_C_TWOS:
compression_format = "twos";
break;
case SUBFORMAT_AIFF_C_IN24:
compression_format = "in24";
break;
case SUBFORMAT_AIFF_C_IN32:
compression_format = "in32";
break;
case SUBFORMAT_AIFF_C_42NI:
compression_format = "42ni";
break;
case SUBFORMAT_AIFF_C_23NI:
compression_format = "23ni";
break;
default:
break;
}
else if(subformat == SUBFORMAT_AIFF_C_SOWT) {
if(flac__utils_fwrite("sowt", 1, 4, f) != 4)
return false;

if(flac__utils_fwrite(compression_format, 1, 4, f) != 4) {
return false;
}

for(i = 34; i < comm_length; i++) {
if(flac__utils_fwrite("\x00", 1, 1, f) != 1)
return false;
Expand Down Expand Up @@ -1248,11 +1271,22 @@ FLAC__StreamDecoderWriteStatus write_callback(const FLAC__StreamDecoder *decoder
FILE *fout = decoder_session->fout;
const uint32_t bps = frame->header.bits_per_sample, channels = frame->header.channels;
const uint32_t shift = (bps%8)? 8-(bps%8): 0;
FLAC__bool is_big_endian = (
(decoder_session->format == FORMAT_AIFF || (decoder_session->format == FORMAT_AIFF_C && decoder_session->subformat == SUBFORMAT_AIFF_C_NONE)) ? true : (
decoder_session->format == FORMAT_WAVE || decoder_session->format == FORMAT_WAVE64 || decoder_session->format == FORMAT_RF64 || (decoder_session->format == FORMAT_AIFF_C && decoder_session->subformat == SUBFORMAT_AIFF_C_SOWT) ? false :
decoder_session->is_big_endian
));
FLAC__bool is_big_endian = ((decoder_session->format == FORMAT_AIFF ||
(decoder_session->format == FORMAT_AIFF_C &&
((decoder_session->subformat == SUBFORMAT_AIFF_C_NONE) ||
(decoder_session->subformat == SUBFORMAT_AIFF_C_TWOS) ||
(decoder_session->subformat == SUBFORMAT_AIFF_C_IN24) ||
(decoder_session->subformat == SUBFORMAT_AIFF_C_IN32))))
? true
: (
decoder_session->format == FORMAT_WAVE || decoder_session->format == FORMAT_WAVE64 ||
decoder_session->format == FORMAT_RF64 ||
(decoder_session->format == FORMAT_AIFF_C &&
((decoder_session->subformat == SUBFORMAT_AIFF_C_SOWT) ||
(decoder_session->subformat == SUBFORMAT_AIFF_C_42NI) ||
(decoder_session->subformat == SUBFORMAT_AIFF_C_23NI)))
? false
: decoder_session->is_big_endian));
FLAC__bool is_unsigned_samples = (
decoder_session->format == FORMAT_AIFF || decoder_session->format == FORMAT_AIFF_C ? false : (
decoder_session->format == FORMAT_WAVE || decoder_session->format == FORMAT_WAVE64 || decoder_session->format == FORMAT_RF64 ? bps<=8 :
Expand Down
59 changes: 55 additions & 4 deletions src/flac/encode.c
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Expand Up @@ -575,10 +575,15 @@ static FLAC__bool get_sample_info_wave(EncoderSession *e, encode_options_t optio
return true;
}

static inline char get_printable_char(const FLAC__uint8 byte)
{
return ((byte >= 0x20) && (byte <= 0x7E)) ? (char)byte : '?';
}

static FLAC__bool get_sample_info_aiff(EncoderSession *e, encode_options_t options)
{
FLAC__bool got_comm_chunk = false, got_ssnd_chunk = false;
uint32_t sample_rate = 0, channels = 0, bps = 0, shift = 0;
uint32_t sample_rate = 0, channels = 0, bps = 0, original_bps = 0, shift = 0;
FLAC__uint64 sample_frames = 0;
FLAC__uint32 channel_mask = 0;

Expand Down Expand Up @@ -641,6 +646,7 @@ static FLAC__bool get_sample_info_aiff(EncoderSession *e, encode_options_t optio
if(!read_uint16(e->fin, /*big_endian=*/true, &x, e->inbasefilename))
return false;
bps = (uint32_t)x;
original_bps = bps;
shift = (bps%8)? 8-(bps%8) : 0; /* SSND data is always byte-aligned, left-justified but format_input() will double-check */
bps += shift;

Expand All @@ -651,14 +657,59 @@ static FLAC__bool get_sample_info_aiff(EncoderSession *e, encode_options_t optio

/* check compression type for AIFF-C */
if(is_aifc) {
const FLAC__uint32 AIFF_C_COMPRESSION_TYPE_NONE = 0x4E4F4E45; /* "NONE" */
const FLAC__uint32 AIFF_C_COMPRESSION_TYPE_SOWT = 0x736F7774; /* "sowt" */
const FLAC__uint32 AIFF_C_COMPRESSION_TYPE_TWOS = 0x74776F73; /* "twos" */
const FLAC__uint32 AIFF_C_COMPRESSION_TYPE_IN24 = 0x696E3234; /* "in24" */
const FLAC__uint32 AIFF_C_COMPRESSION_TYPE_IN32 = 0x696E3332; /* "in32" */
const FLAC__uint32 AIFF_C_COMPRESSION_TYPE_42NI = 0x34326E69; /* "42ni" */
const FLAC__uint32 AIFF_C_COMPRESSION_TYPE_23NI = 0x32336E69; /* "23ni" */

if(!read_uint32(e->fin, /*big_endian=*/true, &xx, e->inbasefilename))
return false;
if(xx == 0x736F7774) /* "sowt" */
if((xx == AIFF_C_COMPRESSION_TYPE_SOWT) ||
(xx == AIFF_C_COMPRESSION_TYPE_42NI) ||
(xx == AIFF_C_COMPRESSION_TYPE_23NI)) {
e->info.is_big_endian = false;
else if(xx == 0x4E4F4E45) /* "NONE" */
}
else if((xx == AIFF_C_COMPRESSION_TYPE_NONE) ||
(xx == AIFF_C_COMPRESSION_TYPE_TWOS) ||
(xx == AIFF_C_COMPRESSION_TYPE_IN24) ||
(xx == AIFF_C_COMPRESSION_TYPE_IN32)) {
; /* nothing to do, we already default to big-endian */
}
else {
flac__utils_printf(stderr, 1, "%s: ERROR: can't handle AIFF-C compression type \"%c%c%c%c\"\n", e->inbasefilename, (char)(xx>>24), (char)((xx>>16)&8), (char)((xx>>8)&8), (char)(xx&8));

@madah81pnz1 madah81pnz1 Jul 6, 2026 •
edited
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This & 8 seems to be a very old bug, all the way from the original implementation in 2005 (commit 15acb69).
It would print either a NUL character or a BS (backspace) character.

I added get_printable_char() to avoid printing garbage characters to the terminal or log file, as this could potentially be exploited in some way wit, e.g. unicode right-to-left override or escape sequence.

flac__utils_printf(stderr, 1, "%s: ERROR: can't handle AIFF-C compression type \"%c%c%c%c\"\n",
e->inbasefilename,
get_printable_char(xx >> 24),
get_printable_char(xx >> 16),
get_printable_char(xx >> 8),
get_printable_char(xx));
return false;
}

if(((xx == AIFF_C_COMPRESSION_TYPE_IN24) ||
(xx == AIFF_C_COMPRESSION_TYPE_42NI)) &&
(original_bps != 24)) {
flac__utils_printf(stderr, 1, "%s: ERROR: invalid bits per sample %u, expected 24 for AIFF-C compression type \"%c%c%c%c\"\n",
e->inbasefilename,
original_bps,
get_printable_char(xx >> 24),
get_printable_char(xx >> 16),
get_printable_char(xx >> 8),
get_printable_char(xx));
return false;
}
else if(((xx == AIFF_C_COMPRESSION_TYPE_IN32) ||
(xx == AIFF_C_COMPRESSION_TYPE_23NI)) &&
(original_bps != 32)) {
flac__utils_printf(stderr, 1, "%s: ERROR: invalid bits per sample %u, expected 32 for AIFF-C compression type \"%c%c%c%c\"\n",
e->inbasefilename,
original_bps,
get_printable_char(xx >> 24),
get_printable_char(xx >> 16),
get_printable_char(xx >> 8),
get_printable_char(xx));
return false;
}
}
Expand Down
4 changes: 2 additions & 2 deletions src/flac/foreign_metadata.c
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Expand Up @@ -551,7 +551,7 @@ static FLAC__bool read_from_flac_(foreign_metadata_t *fm, FILE *f, FLAC__Metadat
/* Initialize bools */
fm->is_wavefmtex = 0;
fm->is_aifc = 0;
fm->is_sowt = 0;
memset(fm->aifc_comm_compression_type, 0, sizeof(fm->aifc_comm_compression_type));
fm->is_rf64 = 0 == memcmp(buffer, "RF64", 4);

if(fm->type == FOREIGN_BLOCK_TYPE__RIFF && (0 == memcmp(buffer, "RIFF", 4) || fm->is_rf64))
Expand Down Expand Up @@ -653,7 +653,7 @@ static FLAC__bool read_from_flac_(foreign_metadata_t *fm, FILE *f, FLAC__Metadat
if(error) *error = "read error (020)";
return false;
}
fm->is_sowt = 0 == memcmp(buffer+26, "sowt", 2);
memcpy(fm->aifc_comm_compression_type, buffer + 26, sizeof(fm->aifc_comm_compression_type));
fm->aifc_comm_length = length;
}
}
Expand Down
2 changes: 1 addition & 1 deletion src/flac/foreign_metadata.h
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Expand Up @@ -62,7 +62,7 @@ typedef struct {
FLAC__bool is_rf64; /* always false if type!=RIFF */
FLAC__bool is_wavefmtex; /* always false if type!=RIFF */
FLAC__bool is_aifc; /* always false if type!=AIFF */
FLAC__bool is_sowt; /* always false if type!=AIFF */
char aifc_comm_compression_type[4]; /* always empty if type!=AIFF */
FLAC__uint32 aifc_comm_length;
FLAC__uint32 ssnd_offset_size; /* 0 if type!=AIFF */
} foreign_metadata_t;
Expand Down
78 changes: 67 additions & 11 deletions src/flac/main.c
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Expand Up @@ -154,6 +154,7 @@ static struct share__option long_options_[] = {
{ "force-extensible-wave-format",share__no_argument,0, 0 },
{ "force-aiff-c-none-format" , share__no_argument, 0, 0 },
{ "force-aiff-c-sowt-format" , share__no_argument, 0, 0 },
{ "force-aiff-c-format" , share__required_argument, 0, 0 },
{ "lax" , share__no_argument, 0, 0 },
{ "replay-gain" , share__no_argument, 0, 0 },
{ "ignore-chunk-sizes" , share__no_argument, 0, 0 },
Expand Down Expand Up @@ -257,6 +258,7 @@ static struct {
FLAC__bool force_extensible_wave_format;
FLAC__bool force_aiff_c_none_format;
FLAC__bool force_aiff_c_sowt_format;
FileSubFormat force_aiff_c_format;
FLAC__bool delete_input;
FLAC__bool preserve_modtime;
FLAC__bool keep_foreign_metadata;
Expand Down Expand Up @@ -443,15 +445,16 @@ int do_it(void)
if(!FLAC__format_sample_rate_is_valid(option_values.format_sample_rate))
return usage_error("ERROR: invalid sample rate '%u', must be > 0 and <= %u\n", option_values.format_sample_rate, FLAC__MAX_SAMPLE_RATE);
}
if((option_values.force_raw_format?1:0) +
(option_values.force_aiff_format?1:0) +
(option_values.force_rf64_format?1:0) +
(option_values.force_wave64_format?1:0) +
(option_values.force_legacy_wave_format?1:0) +
(option_values.force_extensible_wave_format?1:0) +
(option_values.force_aiff_c_none_format?1:0) +
(option_values.force_aiff_c_sowt_format?1:0)
> 1)
if((option_values.force_raw_format ? 1 : 0) +
(option_values.force_aiff_format ? 1 : 0) +
(option_values.force_rf64_format ? 1 : 0) +
(option_values.force_wave64_format ? 1 : 0) +
(option_values.force_legacy_wave_format ? 1 : 0) +
(option_values.force_extensible_wave_format ? 1 : 0) +
(option_values.force_aiff_c_none_format ? 1 : 0) +
(option_values.force_aiff_c_sowt_format ? 1 : 0) +
((option_values.force_aiff_c_format != SUBFORMAT_UNSPECIFIED) ? 1 : 0) >
1)
return usage_error("ERROR: only one of force format options allowed\n");
if(option_values.mode_decode) {
if(!option_values.force_raw_format) {
Expand Down Expand Up @@ -623,6 +626,7 @@ FLAC__bool init_options(void)
option_values.force_extensible_wave_format = false;
option_values.force_aiff_c_none_format = false;
option_values.force_aiff_c_sowt_format = false;
option_values.force_aiff_c_format = SUBFORMAT_UNSPECIFIED;
option_values.delete_input = false;
option_values.preserve_modtime = true;
option_values.keep_foreign_metadata = false;
Expand Down Expand Up @@ -839,6 +843,33 @@ int parse_option(int short_option, const char *long_option, const char *option_a
else if(0 == strcmp(long_option, "force-aiff-c-sowt-format")) {
option_values.force_aiff_c_sowt_format = true;
}
else if(0 == strcmp(long_option, "force-aiff-c-format")) {
FLAC__ASSERT(0 != option_argument);
if(0 == strcmp(option_argument, "none")) {
option_values.force_aiff_c_format = SUBFORMAT_AIFF_C_NONE;
}
else if(0 == strcmp(option_argument, "sowt")) {
option_values.force_aiff_c_format = SUBFORMAT_AIFF_C_SOWT;
}
else if(0 == strcmp(option_argument, "twos")) {
option_values.force_aiff_c_format = SUBFORMAT_AIFF_C_TWOS;
}
else if(0 == strcmp(option_argument, "in24")) {
option_values.force_aiff_c_format = SUBFORMAT_AIFF_C_IN24;
}
else if(0 == strcmp(option_argument, "in32")) {
option_values.force_aiff_c_format = SUBFORMAT_AIFF_C_IN32;
}
else if(0 == strcmp(option_argument, "42ni")) {
option_values.force_aiff_c_format = SUBFORMAT_AIFF_C_42NI;
}
else if(0 == strcmp(option_argument, "23ni")) {
option_values.force_aiff_c_format = SUBFORMAT_AIFF_C_23NI;
}
else {
return usage_error("ERROR: argument to --force-aiff-c-format must be \"none\", \"sowt\", \"twos\", \"in24\", \"42ni\", \"in32\", or \"23ni\"\n");
}
}
else if(0 == strcmp(long_option, "lax")) {
option_values.lax = true;
}
Expand Down Expand Up @@ -1409,6 +1440,7 @@ void show_help(void)
printf(" --force-extensible-wave-format Decode to extensible wave format\n");
printf(" --force-aiff-c-none-format Decode to AIFF-C NONE format\n");
printf(" --force-aiff-c-sowt-format Decode to AIFF-C sowt format\n");
printf(" --force-aiff-c-format=FORMAT Decode to AIFF-C format (none,sowt,twos,in24,42ni,in32,23ni)\n");
printf(" --force-raw-format Treat input or output as raw samples\n");
printf("raw format options:\n");
printf(" --sign={signed|unsigned} Sign of samples (input/output) \n");
Expand Down Expand Up @@ -1922,16 +1954,40 @@ int decode_file(const char *infilename)
output_format = FORMAT_AIFF_C;
output_subformat = SUBFORMAT_AIFF_C_SOWT;
}
else if(option_values.force_aiff_c_format != SUBFORMAT_UNSPECIFIED) {
output_format = FORMAT_AIFF_C;
output_subformat = option_values.force_aiff_c_format;
}
else if(foreign_metadata != NULL) {
if(foreign_metadata->is_wavefmtex)
output_subformat = SUBFORMAT_WAVE_EXTENSIBLE;
else if(output_format == FORMAT_WAVE)
output_subformat = SUBFORMAT_WAVE_PCM;
else if(foreign_metadata->is_aifc) {
if(foreign_metadata->is_sowt)
if(memcmp(foreign_metadata->aifc_comm_compression_type, "NONE", 4) == 0) {
output_subformat = SUBFORMAT_AIFF_C_NONE;
}
else if(memcmp(foreign_metadata->aifc_comm_compression_type, "sowt", 4) == 0) {
output_subformat = SUBFORMAT_AIFF_C_SOWT;
else
}
else if(memcmp(foreign_metadata->aifc_comm_compression_type, "twos", 4) == 0) {
output_subformat = SUBFORMAT_AIFF_C_TWOS;
}
else if(memcmp(foreign_metadata->aifc_comm_compression_type, "in24", 4) == 0) {
output_subformat = SUBFORMAT_AIFF_C_IN24;
}
else if(memcmp(foreign_metadata->aifc_comm_compression_type, "in32", 4) == 0) {
output_subformat = SUBFORMAT_AIFF_C_IN32;
}
else if(memcmp(foreign_metadata->aifc_comm_compression_type, "42ni", 4) == 0) {
output_subformat = SUBFORMAT_AIFF_C_42NI;
}
else if(memcmp(foreign_metadata->aifc_comm_compression_type, "23ni", 4) == 0) {
output_subformat = SUBFORMAT_AIFF_C_23NI;
}
else {
output_subformat = SUBFORMAT_AIFF_C_NONE;
}
}
}

Expand Down
14 changes: 12 additions & 2 deletions src/flac/utils.h
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Expand Up @@ -31,8 +31,18 @@
typedef enum { FORMAT_RAW, FORMAT_WAVE, FORMAT_WAVE64, FORMAT_RF64, FORMAT_AIFF, FORMAT_AIFF_C, FORMAT_FLAC, FORMAT_OGGFLAC } FileFormat;
static const char * const FileFormatString[] = { " raw", " WAVE", " Wave64", "n RF64", "n AIFF", "n AIFF-C", " FLAC", "n Ogg FLAC" };

typedef enum { SUBFORMAT_UNSPECIFIED = 0, SUBFORMAT_WAVE_PCM, SUBFORMAT_WAVE_EXTENSIBLE, SUBFORMAT_AIFF_C_NONE, SUBFORMAT_AIFF_C_SOWT } FileSubFormat;

typedef enum {
SUBFORMAT_UNSPECIFIED = 0,
SUBFORMAT_WAVE_PCM,
SUBFORMAT_WAVE_EXTENSIBLE,
SUBFORMAT_AIFF_C_NONE,
SUBFORMAT_AIFF_C_SOWT,
SUBFORMAT_AIFF_C_TWOS,
SUBFORMAT_AIFF_C_IN24,
SUBFORMAT_AIFF_C_IN32,
SUBFORMAT_AIFF_C_42NI,
SUBFORMAT_AIFF_C_23NI
} FileSubFormat;

typedef struct {
FLAC__bool is_relative; /* i.e. specification string started with + or - */
Expand Down
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