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encode & decode 32-bit float (IEEE 754 standard) samples. #842

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11031e1
Added experimental feature to encode & decode 32-bit float (IEEE 754 …
aliheidary1381 Aug 11, 2025
48db1cc
reversed some bits in experimental floats, got 20% more compression. …
aliheidary1381 Aug 19, 2025
41998ed
minor fix in the docs
aliheidary1381 Aug 19, 2025
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3 changes: 3 additions & 0 deletions config.cmake.h.in
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Expand Up @@ -12,6 +12,9 @@
/* Set FLAC__BYTES_PER_WORD to 8 (4 is the default) */
#cmakedefine01 ENABLE_64_BIT_WORDS

/* Enable experimental feature to encode & decode 32-bit float (IEEE 754 standard) samples */
#cmakedefine01 ENABLE_EXPERIMENTAL_FLOAT_SAMPLE_CODING

/* define to align allocated memory on 32-byte boundaries */
#cmakedefine FLAC__ALIGN_MALLOC_DATA

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12 changes: 12 additions & 0 deletions configure.ac
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Expand Up @@ -275,6 +275,18 @@ else
fi
AC_SUBST(ENABLE_64_BIT_WORDS)

AC_ARG_ENABLE(experimental-float-sample-coding,
AS_HELP_STRING([--enable-experimental-float-sample-coding],[Enable experimental feature to encode & decode 32-bit float (IEEE 754 standard) samples]))
AM_CONDITIONAL([ENABLE_EXPERIMENTAL_FLOAT_SAMPLE_CODING],
[test "x$enable_experimental_float_sample_coding" = xyes])
if test "x$enable_experimental_float_sample_coding" = xyes ; then
AC_DEFINE_UNQUOTED([ENABLE_EXPERIMENTAL_FLOAT_SAMPLE_CODING],1)
else
AC_DEFINE_UNQUOTED([ENABLE_EXPERIMENTAL_FLOAT_SAMPLE_CODING],0,[Disable the feature (this is the default)])
fi
AH_TEMPLATE(ENABLE_EXPERIMENTAL_FLOAT_SAMPLE_CODING, [define to enable experimental float sample coding])
AC_SUBST(ENABLE_EXPERIMENTAL_FLOAT_SAMPLE_CODING)

AC_ARG_ENABLE(valgrind-testing,
AS_HELP_STRING([--enable-valgrind-testing],[Run all tests inside Valgrind]),
[case "${enableval}" in
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3 changes: 3 additions & 0 deletions include/FLAC++/decoder.h
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Expand Up @@ -139,6 +139,9 @@ namespace FLAC {
virtual FLAC__uint64 get_total_samples() const; ///< See FLAC__stream_decoder_get_total_samples()
virtual FLAC__uint64 find_total_samples(); ///< See FLAC__stream_decoder_find_total_samples()
virtual uint32_t get_channels() const; ///< See FLAC__stream_decoder_get_channels()
#if ENABLE_EXPERIMENTAL_FLOAT_SAMPLE_CODING
virtual SampleType get_sample_type() const; ///< See FLAC__stream_decoder_get_is_float_samples()
#endif
virtual ::FLAC__ChannelAssignment get_channel_assignment() const; ///< See FLAC__stream_decoder_get_channel_assignment()
virtual uint32_t get_bits_per_sample() const; ///< See FLAC__stream_decoder_get_bits_per_sample()
virtual uint32_t get_sample_rate() const; ///< See FLAC__stream_decoder_get_sample_rate()
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6 changes: 6 additions & 0 deletions include/FLAC++/encoder.h
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Expand Up @@ -129,6 +129,9 @@ namespace FLAC {
virtual bool set_verify(bool value); ///< See FLAC__stream_encoder_set_verify()
virtual bool set_streamable_subset(bool value); ///< See FLAC__stream_encoder_set_streamable_subset()
virtual bool set_channels(uint32_t value); ///< See FLAC__stream_encoder_set_channels()
#if ENABLE_EXPERIMENTAL_FLOAT_SAMPLE_CODING
virtual bool set_sample_type(SampleType value); ///< See FLAC__stream_encoder_set_sample_type()
#endif
virtual bool set_bits_per_sample(uint32_t value); ///< See FLAC__stream_encoder_set_bits_per_sample()
virtual bool set_sample_rate(uint32_t value); ///< See FLAC__stream_encoder_set_sample_rate()
virtual bool set_compression_level(uint32_t value); ///< See FLAC__stream_encoder_set_compression_level()
Expand Down Expand Up @@ -159,6 +162,9 @@ namespace FLAC {
virtual bool get_do_mid_side_stereo() const; ///< See FLAC__stream_encoder_get_do_mid_side_stereo()
virtual bool get_loose_mid_side_stereo() const; ///< See FLAC__stream_encoder_get_loose_mid_side_stereo()
virtual uint32_t get_channels() const; ///< See FLAC__stream_encoder_get_channels()
#if ENABLE_EXPERIMENTAL_FLOAT_SAMPLE_CODING
virtual SampleType get_sample_type() const; ///< See FLAC__stream_encoder_get_is_float_samples()
#endif
virtual uint32_t get_bits_per_sample() const; ///< See FLAC__stream_encoder_get_bits_per_sample()
virtual uint32_t get_sample_rate() const; ///< See FLAC__stream_encoder_get_sample_rate()
virtual uint32_t get_blocksize() const; ///< See FLAC__stream_encoder_get_blocksize()
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6 changes: 6 additions & 0 deletions include/FLAC++/metadata.h
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Expand Up @@ -330,6 +330,9 @@ namespace FLAC {
uint32_t get_max_framesize() const;
uint32_t get_sample_rate() const;
uint32_t get_channels() const;
#if ENABLE_EXPERIMENTAL_FLOAT_SAMPLE_CODING
SampleType get_sample_type() const;
#endif
uint32_t get_bits_per_sample() const;
FLAC__uint64 get_total_samples() const;
const FLAC__byte *get_md5sum() const;
Expand All @@ -340,6 +343,9 @@ namespace FLAC {
void set_max_framesize(uint32_t value);
void set_sample_rate(uint32_t value);
void set_channels(uint32_t value);
#if ENABLE_EXPERIMENTAL_FLOAT_SAMPLE_CODING
void set_sample_type(SampleType value);
#endif
void set_bits_per_sample(uint32_t value);
void set_total_samples(FLAC__uint64 value);
void set_md5sum(const FLAC__byte value[16]);
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11 changes: 11 additions & 0 deletions include/FLAC/format.h
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Expand Up @@ -178,6 +178,9 @@ extern FLAC_API const uint32_t FLAC__STREAM_SYNC_LEN; /* = 32 bits */
/** The length of the FLAC signature in bytes. */
#define FLAC__STREAM_SYNC_LENGTH (4u)

typedef enum { NOT_SPECIFIED = -1,
INT = 0,
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@madah81pnz1 madah81pnz1 Mar 9, 2026

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Since this is put into the global scope/namespace, I suggest to add a prefix like SAMPLE_TYPE_ for all enum values, or even FLAC__SAMPLE_TYPE_.
Especially INT is a bit too short and too common name as to not be confusing.

FLOAT = 1 } SampleType; // TODO: merge with endian & unsigned
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@madah81pnz1 madah81pnz1 Mar 9, 2026

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The name of the type should be FLAC__SampleType, to follow naming style


/*****************************************************************************
*
Expand Down Expand Up @@ -431,6 +434,11 @@ typedef struct {
uint32_t bits_per_sample;
/**< The sample resolution. */

#if ENABLE_EXPERIMENTAL_FLOAT_SAMPLE_CODING
SampleType sample_type;
/**< FLOAT if the samples are IEEE 754 binary32 (32-bit floating point) */
#endif

FLAC__FrameNumberType number_type;
/**< The numbering scheme used for the frame. As a convenience, the
* decoder will always convert a frame number to a sample number because
Expand Down Expand Up @@ -539,6 +547,9 @@ typedef struct {
uint32_t sample_rate;
uint32_t channels;
uint32_t bits_per_sample;
#if ENABLE_EXPERIMENTAL_FLOAT_SAMPLE_CODING
SampleType sample_type;
#endif
FLAC__uint64 total_samples;
FLAC__byte md5sum[16];
} FLAC__StreamMetadata_StreamInfo;
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14 changes: 14 additions & 0 deletions include/FLAC/stream_decoder.h
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Expand Up @@ -1033,6 +1033,20 @@ FLAC_API FLAC__uint64 FLAC__stream_decoder_find_total_samples(FLAC__StreamDecode
*/
FLAC_API uint32_t FLAC__stream_decoder_get_channels(const FLAC__StreamDecoder *decoder);

#if ENABLE_EXPERIMENTAL_FLOAT_SAMPLE_CODING
/** Get the current sample type in the stream being decoded.
* Will only be valid after decoding has started and will contain the
* value from the most recently decoded frame header.
*
* \param decoder A decoder instance to query.
* \assert
* \code decoder != NULL \endcode
* \retval SampleType
* FLOAT if samples are in IEEE 754 binary32 format, INT otherwise.
*/
FLAC_API SampleType FLAC__stream_decoder_get_sample_type(const FLAC__StreamDecoder *decoder);
#endif

/** Get the current channel assignment in the stream being decoded.
* Will only be valid after decoding has started and will contain the
* value from the most recently decoded frame header.
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26 changes: 26 additions & 0 deletions include/FLAC/stream_encoder.h
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Expand Up @@ -783,6 +783,20 @@ FLAC_API FLAC__bool FLAC__stream_encoder_set_streamable_subset(FLAC__StreamEncod
*/
FLAC_API FLAC__bool FLAC__stream_encoder_set_channels(FLAC__StreamEncoder *encoder, uint32_t value);

#if ENABLE_EXPERIMENTAL_FLOAT_SAMPLE_CODING
/** Set the sample type of the input to be encoded.
*
* \default \c false
* \param encoder An encoder instance to set.
* \param value FLOAT for IEEE 754 binary32, INT otherwise.
* \assert
* \code encoder != NULL \endcode
* \retval FLAC__bool
* \c false if the encoder is already initialized, else \c true.
*/
FLAC_API FLAC__bool FLAC__stream_encoder_set_sample_type(FLAC__StreamEncoder *encoder, SampleType value);
#endif

/** Set the sample resolution of the input to be encoded.
*
* \warning
Expand Down Expand Up @@ -1372,6 +1386,18 @@ FLAC_API FLAC__bool FLAC__stream_encoder_get_streamable_subset(const FLAC__Strea
*/
FLAC_API uint32_t FLAC__stream_encoder_get_channels(const FLAC__StreamEncoder *encoder);

#if ENABLE_EXPERIMENTAL_FLOAT_SAMPLE_CODING
/** Get the input sample type setting.
*
* \param encoder An encoder instance to query.
* \assert
* \code encoder != NULL \endcode
* \retval SampleType
* FLOAT if samples are in IEEE 754 binary32 format, INT otherwise.
*/
FLAC_API SampleType FLAC__stream_encoder_get_sample_type(const FLAC__StreamEncoder *encoder);
#endif

/** Get the input sample resolution setting.
*
* \param encoder An encoder instance to query.
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3 changes: 3 additions & 0 deletions man/flac.md
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Expand Up @@ -615,6 +615,9 @@ When encoding from or decoding to raw PCM, format must be specified.
**\--endian**={big\|little}
: Specify the byte order for samples

**\--sample-type**={int\|float}
: Specify the sample types.

**\--channels**=\#
: (Input only) specify number of channels. The channels must be
interleaved, and in the order of the FLAC format (see the format
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3 changes: 3 additions & 0 deletions man/metaflac.md
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Expand Up @@ -103,6 +103,9 @@ modification time is set to the current time):
**\--show-channels**
: Show the number of channels from the STREAMINFO block.

**\--show-sample-type**
: Show if the audio samples are integer or floating-point from the STREAMINFO block.

**\--show-bps**
: Show the \# of bits per sample from the STREAMINFO block.

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1 change: 1 addition & 0 deletions src/CMakeLists.txt
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@@ -1,4 +1,5 @@
option(ENABLE_64_BIT_WORDS "Set FLAC__BYTES_PER_WORD to 8, for 64-bit machines. For 32-bit machines, turning this off might give a tiny speed improvement" ON)
option(ENABLE_EXPERIMENTAL_FLOAT_SAMPLE_CODING "Enable experimental feature to encode & decode 32-bit float (IEEE 754 standard) samples" ON)
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@madah81pnz1 madah81pnz1 Mar 9, 2026

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Should be OFF by default?

option(BUILD_UTILS "Build utils" OFF)

add_subdirectory("libFLAC")
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