LIBSOX_NG(3) Sound eXchange_ng LIBSOX_NG(3)

libsox_ng - another audio file format and effect library

#include <sox_ng.h>

cc -o file file.c -lsox_ng

libsox_ng is a library of sound sample file format readers/writers and sound effects processors. It is mainly developed to be used by SoX but any audio application might find it useful.

If you want to dive straight in reading and writing audio files, look at the start of GENERIC FUNCTIONS and the section on READING AND WRITING AUDIO FILES.

#include <sox_ng.h>
Declarations for all of the below (and a lot more!). However, you should only use items whose names begin with sox_ or SOX_; the lsx_ and LSX_ items are intended for internal use by SoX's format and effect handlers. They are exported by libsox so that dynamically-loaded format handlers and custom format and effect handlers can use them but should not be used by libSoX-based applications.

Programs should normally include <sox.h> to be portable to systems that have not upgraded to sox_ng yet; those that have upgraded should provide <sox.h> as an alias for <sox_ng.h> and the interface is unlikely to change.

Ensure that if a program includes <sox.h>, it is linked with -lsox, and <sox_ng.h> with -lsox_ng as some software distributions (or you) may choose to install them both side by side and the contents of their internal data structures differ.

sox_int8_t Signed twos-complement 8-bit type
sox_uint8_t Unsigned 8-bit type
sox_int16_t Signed twos-complement 16-bit type
sox_uint16_t Unsigned 16-bit type
sox_int32_t Signed twos-complement 32-bit type
sox_uint32_t Unsigned 32-bit type
sox_int64_t Signed twos-complement 64-bit type
sox_uint64_t Unsigned 64-bit type
sox_int24_t Alias for sox_int32_t (beware of the extra byte)
sox_uint24_t Alias for sox_uint32_t (beware of the extra byte)
sox_sample_t Native SoX audio sample type (alias for sox_int32_t)
sox_rate_t Samples per second are stored as a double
sox_bool Boolean type: sox_false (= 0) or sox_true (= 1)

Most of the functions in libSoX return an integer error code which is SOX_SUCCESS if the functions succeeded or a sox_error_t which can take the following values:

SOX_SUCCESS Function succeeded = 0
SOX_EOF End Of File or other error
SOX_EHDR Invalid Audio Header
SOX_EFMT Unsupported data format
SOX_ENOMEM Can't alloc memory
SOX_EPERM Operation not permitted
SOX_ENOTSUP Operation not supported
SOX_EINVAL Invalid argument
SOX_ENOKEYMAP No such keymap
SOX_ENOEFFECT No such effect
or other values mapped from errno(3).
Converts a SoX error code into an error string and returns the error string corresponding to the specified error code, or a generic message if the error code is not recognized.

Initialize the effects library. Returns SOX_SUCCESS if successful.
Find and load format handler plugins. Returns SOX_SUCCESS if successful.
Unload format handler plugins.
Close the effects library and unload format handler plugins. Returns SOX_SUCCESS if successful.
Returns the version number string of libSoX, for example, "14.4.0".
Returns information about this build of libSoX, containing:
Structure size = sizeof(sox_version_info_t)
Feature flags bits indicating whether optional features are present in this build of libSoX, the logical OR of:
No special features (= 0).
Pipes are available to fetch URLs with wget or curl, to use external codec programs like ffmpeg and for piped inputs like "|sox_ng -n -p synth 1".
libmagic is in use to autodetect the formats of files.
OpenMP support is included, so effects and channels will run in parallel if sox_get_globals()->use_threads has not been set to sox_false.
sox_open_mem_read(), sox_open_mem_write() and sox_open_memstream_write() do what it says on the box. If fmemopen(3) is not available, they fall back to sox_open_read() and sox_open_write().
Version number, for example 0x0E0402.
Version string, for example, "14.4.2".
Version extra info or NULL, set by PACKAGE_EXTRA, for example, "beta".
Distro or NULL, set by DISTRO, for example, "Debian".
Compiler info or NULL, for example, "msvc 160040219".
Architecture-dependent feature code. For example, "1248 48 44 L OMP" where the first four digits give the sizes in bytes of char, short, long and off_t, the next two the sizes of float and double, the next two the sizes of a data pointer and a function pointer, followed by L if the machine is little-endian or B if big-endian, and OMP if multi-threading is available using OpenMP.
Returns a pointer to the structure with global settings for formats and effects, containing:
The name the program was invoked as, for error reporting. sox_ng sets this to the bare program name without a directory path (or a .exe extension on Windows) as "sox_ng", "soxi_ng", "play_ng" or "rec_ng", or "sox", "soxi", "play" or "rec" when it replaces sox.

Other programs using libsox_ng can set it to argv[0] on startup if they wish, but it is only used by libSoX when creating error messages for lsx_fail() when there are syntax errors in effects' options and leaving it NULL is harmless.

Messages are output by the default output message handler if sox_get_globals()->verbosity >= level.
The address of a client-specified message output handling function of type void message_handler(unsigned level, char *filename, char *fmt, va_list ap)
1=FAIL, 2=WARN, 3=INFO, 4=DEBUG, 5=DEBUG_MORE, 6=DEBUG_MOST.
Source code __FILENAME__ from which a message originates.
Message format string.
Message format parameters.

For examples of how to use it, see src/example3.c and demo/soxcopy.c.

Use pre-determined timestamps and random number generator seed.
Default size (in bytes) used by libSoX for blocks of sample data. Plugins should use similarly-sized buffers to get best performance.
Default size (in bytes) used by libSoX for blocks of input sample data. Plugins should use similarly-sized buffers to get best performance.
Can be used to re-seed libSoX's random number generator.
Log to base 2 of the minimum size used by libSoX for DFT filtering. Plugins should use similarly-sized DFTs to get best performance.
The frequency in Hz of A above middle C, usually 440, that is used when converting note names to frequencies.

Format handlers deal with decoding and encoding audio files and are accessed with the following types and functions:

Handler structure defined by each format, containing:
Checked when loading format handler plugins.
A short description of the format.
Null-terminated array of filename extensions handled by this format.
File flags, the logical OR of:
SOX_FILE_NOSTDIO Does not use stdio routines
SOX_FILE_DEVICE File is an audio device
SOX_FILE_PHONY Phony file/device (for example /dev/null)
SOX_FILE_REWIND File should be rewound to write header
SOX_FILE_BIT_REV Is the file bit-reversed?
SOX_FILE_NIB_REV Is the file nibble-reversed?
SOX_FILE_ENDIAN Is the file format endian?
SOX_FILE_ENDBIG For an endian file format, is it big endian?
SOX_FILE_MONO Do channel restrictions allow mono?
SOX_FILE_STEREO Do channel restrictions allow stereo?
SOX_FILE_QUAD Do channel restrictions allow quad?
SOX_FILE_LIT_END A mask to OR in if the file is little-endian
SOX_FILE_BIG_END A mask to OR in if the file is big-endian
SOX_FILE_CHANS A mask to interrogate channels restrictions. If flags & SOX_FILE_CHANS is 0, there are no restrictions.
The function to initialize the decoder. If it is NULL, the format cannot be read.
Decode a block of samples.
Close reader (decoder); NULL if no closing necessary.
The function to initialize the encoder. If it is NULL, the format cannot be written.
Encode a block of sample.
Close writer (decoder); NULL if no closing necessary.
Reposition reader; NULL if not supported.
An array of values indicating the encodings and precisions supported for writing. The data format is encoding, precision, precision, ..., 0, repeat, and end with 0. The default precision is given first. An example for a format supporting signed values at 16 and 24 bits, defaulting to 16 bits, and unsigned at 8 bits: 
  unsigned *formats = {
    SOX_ENCODING_SIGN2, 16, 24, 0,
    SOX_ENCODING_UNSIGNED, 8, 0,
    0
  }
A null-terminated array of sample rates supported for writing, NULL if all (or almost all) rates are supported.
SoX automatically allocates a buffer in which the handler can store data, of this size in bytes.
Data passed to and from format handlers, containing:
The file's name.
sox_signalinfo_t signal
Signal specifications for the reader (decoder) or the writer (encoder): sample rate, number of channels, precision, length, headroom multiplier. Info will be SOX_UNSPEC if the user provided no info.
sox_encodinginfo_t encoding
Encoding specifications for the reader or writer.
The type of the file, as determined by inspection of the file's header or by libmagic.
sox_oob_t oob
Out-Of-Band data: comments (ID3 tags), instrument info, loop info.
Can seek on this file.
The last byte written was a zero.
Read or write mode ('r' or 'w').
Samples *chans written to file.
Incremented if clipping occurs.
Failure error code.
Failure error text.
File stream pointer.
Buffer of unreturned read bytes.
Bytes read but not returned yet.
How many bytes read but not returned.
Whether this stream is a file, a pipe or a URL, one of:
Stream is a real file.
Stream is a pipe.
Stream is a URL.
Current offset within file.
Offset at which sound data begins.
sox_format_handler_t handler
The format handler for this file.
The format handler's private data area.
How samples are encoded, containing:
sox_encoding_t encoding
The encoding used for samples.
0 if unknown or variable; uncompressed value if lossless; compressed value if lossy.
Compression factor (where applicable).
sox_option_t reverse_bytes
Should bytes be reversed?
sox_option_t reverse_nibbles
Should nibbles be reversed?
sox_option_t reverse_bits
Should bits be reversed?
If set to true, the format should reverse its default endianness.

If the reverse_ fields are sox_option_default during sox_open_read() or sox_open_write(), libSoX will set them to either sox_option_no or sox_option_yes according to the default of the machine or format.

The type of the sox_encodinginfo_t.reverse_* fields, one of:
Option specified as no (= 0).
Option specified as yes.
Option unspecified, usually implies some kind of auto-detect logic.
Returns a null-terminated table of information about the loaded format handlers, of which each entry contains:
The name of the format handler.
sox_format_handler_t *(*fn)(void)
The function to call to get a pointer to the format handler's data.
sox_format_handler_t *sox_find_format(char *name, sox_bool ignore_devices)
Finds a format handler by name and returns it, or NULL if it is not found.
Path to file to be examined (required if filetype is NULL).
A previously-determined file type, or NULL to use the extension of path.
Encoding for which the format handler should be queried.

Returns true if the format handler for the specified file type supports the specified encoding.

sox_format_handler_t sox_write_handler(char *path, char *filetype, char **filetype1)
Gets the format handler for a specified file type. Returns the found format handler, or NULL if not found.
Path to file (required if filetype is NULL).
Filetype for which handler is needed, or NULL to use the extension from path.
Receives the filetype that was detected. Pass NULL if not needed.

The format of encoded sample data, one of:
SOX_ENCODING_UNKNOWN Encoding has not yet been determined
SOX_ENCODING_SIGN2 Signed linear 2's compliment
SOX_ENCODING_UNSIGNED Unsigned linear: Sound Blaster
SOX_ENCODING_FLOAT Floating point (binary format)
SOX_ENCODING_FLOAT_TEXT Floating point (text format)
SOX_ENCODING_FLAC FLAC compression
SOX_ENCODING_HCOM Mac FSSD files with Huffman compression
SOX_ENCODING_WAVPACK WavPack with integer samples
SOX_ENCODING_WAVPACKF WavPack with float samples
SOX_ENCODING_ULAW Mu-law signed logs: US telephony
SOX_ENCODING_ALAW A-law signed logs: non-US telephony
SOX_ENCODING_G721 G.721 4-bit ADPCM
SOX_ENCODING_G723 G.723 3 or 5 bit ADPCM
SOX_ENCODING_CL_ADPCM Creative Labs 8->2,3,4 bit compressed PCM
SOX_ENCODING_CL_ADPCM16 Creative Labs 16->4 bit compressed PCM
SOX_ENCODING_MS_ADPCM Microsoft Compressed PCM
SOX_ENCODING_IMA_ADPCM IMA Compressed PCM
SOX_ENCODING_OKI_ADPCM Dialogic/OKI Compressed PCM
SOX_ENCODING_DPCM Differential PCM: Fasttracker 2 (xi format)
SOX_ENCODING_DWVW Delta Width Variable Word
SOX_ENCODING_DWVWN Delta Width Variable Word N-bit
SOX_ENCODING_GSM GSM 6.10 33byte frame lossy compression
SOX_ENCODING_MP1 MPEG 1 Layer 1 compression
SOX_ENCODING_MP2 MPEG 1 Layer 2 compression
SOX_ENCODING_MP3 MPEG 1 Layer 3 compression
SOX_ENCODING_VORBIS Vorbis compression
SOX_ENCODING_AMR_WB AMR-WB compression
SOX_ENCODING_AMR_NB AMR-NB compression
SOX_ENCODING_CVSD Continuously Variable Slope Delta
SOX_ENCODING_LPC10 Linear Predictive Coding
SOX_ENCODING_OPUS Opus compression
SOX_ENCODING_DSD Direct Stream Digital
SOX_ENCODINGS End of list marker
Returns a pointer to a null-terminated list of available encodings, containing:
How lossy the format is, one of:
No flags specified (implies lossless encoding).
Encode, decode: lossy once.
Encode, decode, encode, decode: lossy twice.
Short name for the encoding.
Description of the encoding.
Fills in a sox_encodinginfo_t with default values.
Given an encoding and the encoded bits_per_sample, returns the number of useful bits per sample in the decoded data, or 0 to indicate that the value returned by the format handler should be used instead of a pre-determined precision.
Encoding for which to lookup precision information.
The number of encoded bits per sample.

sox_format_t *sox_open_read(char *path, sox_signalinfo_t *signal, sox_encodinginfo_t *encoding, char *filetype)
Opens a decoding session for a file.
Path to file to be opened (required).
Information already known about audio stream, or NULL if none.
Information already known about sample encoding, or NULL if none.
Previously-determined file type, or NULL to auto-detect.

Returns the handle for the new session, which must be closed with sox_close(), or NULL on failure.

sox_format_t *sox_open_mem_read(void *buffer, size_t size, sox_signalinfo_t *signal, sox_encodinginfo_t *encoding, char *filetype)
Opens a decoding session for a memory buffer.
Pointer to audio data buffer (required).
Number of bytes to read from audio data buffer.
Information already known about audio stream, or NULL if none.
Information already known about sample encoding, or NULL if none.
Previously-determined file type, or NULL to auto-detect.

Returns a handle for the new session, which must be closed with sox_close(), or NULL on failure.

Reads samples from a decoding session into a sample buffer.
Buffer from which to read samples.
Number of samples available in buf.

Returns the number of samples decoded, or 0 on EOF or a read error. If it was the end of the file, errno will be zero, non-zero if there was a read error.

Sets the location at which the next samples will be decoded.
Sample offset at which to position reader.
Only SOX_SEEK_SET is currently supported.

Returns SOX_SUCCESS if successful.

sox_format_t *sox_open_write(char *path, sox_signalinfo_t *signal, sox_encodinginfo_t *encoding, char *filetype, sox_oob_t *oob, sox_bool (*overwrite)(char *filename))
Opens an encoding session for a file.
Path to file to be written (required).
Information about desired audio stream (required).
Information about desired sample encoding, or NULL to use defaults.
Previously-determined file type, or NULL to auto-detect.
Out-of-band data to add to file, or NULL if none.
Called if file exists to determine whether overwrite is ok.

Returns the new session handle, which must be closed with sox_close(), or NULL on failure.

sox_format_t *sox_open_mem_write(void *buffer, size_t size, sox_signalinfo_t *signal, sox_encodinginfo_t *encoding, char *filetype, sox_oob_t *oob)
Opens an encoding session for a memory buffer.
A pointer to the audio data buffer that receives data (required).
The maximum number of bytes to write to audio data buffer.
Information about the desired audio stream (required).
Information about the desired sample encoding, or NULL to use defaults.
The previously-determined file type, or NULL to auto-detect.
Out-of-band data to add to file, or NULL if none.

Returns the new session handle, which must be closed with sox_close(), or NULL on failure.

sox_format_t *sox_open_memstream_write(char **buffer_p, size_t *size_p, sox_signalinfo_t *signal, sox_encodinginfo_t *encoding, char *filetype, sox_oob_t *oob)
Opens an encoding session for a memstream buffer.
Receives pointer to audio data buffer that receives data (required).
Receives size of data written to audio data buffer (required).
Information about desired audio stream (required).
Information about desired sample encoding, or NULL to use defaults.
Previously-determined file type, or NULL to auto-detect.
Out-of-band data to add to file, or NULL if none.

Returns the new session handle, which must be closed with sox_close(), or NULL on failure.

Writes samples to an encoding session from a sample buffer.
Buffer from which to read samples.
Number of samples available in buf.

Returns the number of samples encoded, or zero if a write error occurred (for the reason, check errno(3).)

Closes an encoding or decoding session. Returns SOX_SUCCESS if successful.

The following types and functions are used to access libSoX's powerful effects.

Effect information, containing:
Global effects parameters, containing:
The type of plot requested, one of:
No plot.
Octave plot.
Gnuplot plot.
Output the plot data as text.
A pointer to the associated sox_globals_t.
sox_signalinfo_t in_signal
Info about the incoming data stream.
sox_signalinfo_t out_signal
Info about the outgoing data stream.
sox_encodinginfo_t *in_encoding
Info about the incoming data encoding.
sox_encodinginfo_t *out_encoding
Info about the outgoing data encoding.
sox_effect_handler_t handler
The handler for this effect.
Incremented when clipping occurs.
1 if handler.flags & SOX_EFF_MCHAN, or the number of channels otherwise.
Flow number.
The effect's private data area (each flow has a separate copy).
Signal parameters, containing:
Samples per second, 0 if unknown.
Number of sound channels, 0 if unknown.
Bits per sample, 0 if unknown.
Samples in the file (sample frames × channels), SOX_UNSPEC (= 0) if the actual value is not yet known, SOX_UNKNOWN_LEN is used within the effects chain if the actual length is not known. Format handlers use SOX_UNSPEC instead. SOX_IGNORE_LENGTH to indicate that a format handler should ignore length information in file headers.
Effects headroom multiplier; may be NULL.

Members are SOX_UNSPEC (= 0) if the actual value is not yet known.

Effect handler information, containing:
The effect's name.
One-line effect usage and parameters.
Additional lines of usage, null-terminated.
The logical OR of:
The effect might alter the number of channels.
The effect might alter sample rate.
The effect does its own calculation of output sample precision (otherwise a default value is taken, depending on the presence of SOX_EFF_MODIFY).
The effect might alter audio length (as measured in time units, not necessarily in samples).
The effect handles multiple channels internally.
The effect does nothing and can be optimized out of the chain.
The effect does not support gain -r.
The effect does not modify sample values (but it might remove or duplicate samples or insert zeros).
The effect is present in libSoX but is not valid for use by SoX command-line tools.
The effect's function to parse command-line arguments, called once per effect.
The function to initialize effect, called once per flow.
The function to process samples.
Buffer from which to read samples
Buffer to which samples are written.
On entry, contains the capacity of ibuf in samples; on exit, contains the number of samples consumed.
On entry, contains the capacity of obuf in samples; on exit, contains the number of samples written.
The function to output after input is complete. Parameters are as for flow.
The function to shut the effect down (called once per flow).
The function to shut the effect down (called once per effect).
Pointer to a function to read the current value of an effect's parameter, returning NULL if there is no readable parameter of that name, or a pointer to mallocked memory containing a string value sprintfed with "%g" which it is the caller's responsibility to free.
Pointer to a function to set the value of an effect's parameter, returning NULL if that parameter cannot be set or if the value is garbage, or a pointer to mallocked memory containing the new value sprintfed with "%g". Values outside the parameter's range set the minimum or maximum value and return that.
The size of the effect's private data.
A chain of effects to be applied to a stream, containing:
sox_effect_t **effects
Table of effects to be applied to a stream.
Number of effects to be applied.
Copy of global effects settings.
sox_encodinginfo_t *in_enc
Input encoding.
sox_encodinginfo_t *out_enc
Output encoding.
Returns global parameters for effects.
sox_effect_handler_t *sox_find_effect(char *name)
Finds the effect handler with the given name. Returns an effect pointer, or NULL if not found.
sox_effect_t *sox_create_effect(sox_effect_handler_t *eh)
Creates an effect using the given handler. Returns the new effect, or NULL if not found.
Applies the command-line options to the effect. Returns the number of arguments consumed.
sox_effect_handler_t *sox_get_effect_fns(void)
Returns an null-terminated array of the known effect handlers.
sox_effects_chain_t *sox_create_effects_chain(sox_encodinginfo_t *in_enc, sox_encodinginfo_t *out_enc)
Initializes an effects chain.
Input encoding.
Output encoding.

Returns a handle, which must be closed with sox_delete_effects_chain(). or NULL on failure.

Closes an effects chain and deletes all the effects in it.
Adds an effect to the end of the effects chain. Returns SOX_SUCCESS if successful.
Characteristics of the input signal to the chain.
Characteristics of the output signal from the chain.
Runs the effects chain. Returns SOX_SUCCESS if successful.
Effects chain to run.
If not NULL, a pointer to a function for monitoring flow progress, called between processing each block of data. It is handed a copy of the client_data pointer that was passed to sox_flow_effects and if the callback returns anything other than SOX_SUCCESS, the flow is stopped.
A pointer that is pass to the callback.
Returns the number of clips that occurred while running an effects chain.
Shuts down an effect (calls stop on each of its flows) and returns the number of clips from all flows.
Adds an already-initialized effect to the end of the chain.
sox_effect_t *sox_pop_effect_last(sox_effects_chain_t *chain)
Removes and returns an effect from the end of the chain. Returns the removed effect, or NULL if the chain has no effects.
Shut down and delete an effect.
Shut down and delete the last effect in the chain.
Shut down and delete all effects in the chain.

For both of these, *effp should be a trim effect.

Gets the sample offset of the start of the trim, useful for efficiently skipping the part that will be trimmed anyway (get trim start, seek, then clear trim start). Returns the sample offset of the start of the trim.
Clears the start of the trim to 0.

Out-Of-Band data: comments, instrument info and loop info, containing:
File's metadata as comment strings in id=value format, accessed via the sox_*_comments functions below.
Instrument specification, containing:
For unity pitch playback.
MIDI pitch-bend low range.
MIDI pitch-bend high range.
Loop modes: the lower 4 bits describe the loop behaviour, one of:
Single-shot.
Forward loop.
Forward/back loop.
and the upper 4 bits mask the loop blass, the logical OR of
8 loops (??).
AIFF style, one sustain & one decay loop.
Number of active loops (max SOX_MAX_NLOOPS = 8).
Looping specifications, containing:
First sample.
Length of loop.
Number of repeats, 0=forever.
Bits with the same meaning as loopmode above.

Returns the number of items in the metadata block.
Adds an item to the metadata block, in "id=value" format.
Adds a newline-separated list of "id=value" items to the metadata block, for example "id1=value1\nid2=value2".
Duplicates the metadata block and returns the copy.
Frees the metadata block.
If "id=value" is found in the comments, returns a pointer to its value, or NULL if the id was not found.

Returns true if the specified file is a known playlist file type.
Parses the specified playlist file. Returns SOX_SUCCESS if successful.
The function to call for each item in the playlist.
A pointer to client data, passed to the callback function.
The name of the playlist file.

Keymaps are the mechanism by which SoX allows you to modify effects' internal parameters on the fly by mapping keys with --keymap and then pressing them while in --interactive mode (e.g. when using play or with -d as the output filename.)

Add a keymap.
The string name of the key to map, for example "D".
The name of the effect to affect. "echo" will affect all echoes in the effects chain; "echo2" will only affect the second instance of it.
The name of the parameter in the effect's priv_t to change. For effects with multiple stages, "decay" will affect the decay of all stages and "decay2" will only affect the decay of the scond stage.
How to affect the parameter: '+', '−', '*', '/' or '='.
How much to add or subtract from the parameter, to muliply or divide it by, or to set its value to.
See if a key or an effect.field is used in a keymap
Apply a keymap. Returns SOX_SUCCESS on successful application, SOX_ENOEFFECT if the effect was not found in the chain or it was found but doesn't have a keymappable parameter of that name, SOX_ENOKEYMAP if the key was not mapped to anything.
Forget all keymaps.

Gets the basename of the specified file; for example, the basename of "/a/b/c.d" would be "c". Returns the number of characters written to the buffer, excluding the final nul character, or 0 on failure.
Buffer into which basename should be written.
Size of buffer, in bytes.
Filename from which to extract basename.

Compute a 32-bit integer API version from three 8-bit parts. a is the major version number, b the minor version and c the micro or bugfix version. Returns a 32-bit integer API version like 0x000a0b0c.
The current API version as a 32-bit integer which follows the version number of SoX.
Returns the smallest (most negative) value storable in a twos-complement signed integer with the specified number of bits, cast to an unsigned integer. For example, SOX_INT_MIN(8) = 0x80, SOX_INT_MIN(16) = 0x8000, etc.
The size of value for which to calculate minimum and maximum values.
Returns the largest (positive) value storable in a twos-complement signed integer with the specified number of bits, cast to an unsigned integer for example, SOX_INT_MAX(8) = 0x7F, SOX_INT_MAX(16) = 0x7FFF, etc.
Returns the largest value storable in an unsigned integer with the specified number of bits; for example, SOX_UINT_MAX(8) = 0xFF, SOX_UINT_MAX(16) = 0xFFFF, etc.
Returns 0x7F.
Returns 0x7FFF.
Returns 0x7FFFFF.
Returns 0x7FFFFFFF.
Bits in a sox_sample_t (= 32).
The maximum value of a sox_sample_t (= 0x7FFFFFFF).
The minimum (most negative) value of a sox_sample_t (= 0x80000000).
The sign bit for sox_sample_t (= 0x80000000).
The maximum value of a size_t.

Linear PCM <--> sox_sample_t
I/O Input sox_sample_t Clips Input sox_sample_t Clips
Format Minimum Minimum I O Maximum Maximum I O
Float −inf −1 y n inf 1 − 5e−10 y n
Int8 −128 −128 n n 127 127.9999999 n y
Int16 −32768 −32768 n n 32767 32767.99998 n y
Int24 −8388608 −8388608 n n 8388607 8388607.996 n y
Int32 −2147483648 −2147483648 n n 2147483647 2147483647 n n

Conversions are as accurate as possible (with rounding).

Halves are rounded toward +infinity, all others to nearest integer.

Clips shows whether on not there is the possibility of a conversion clipping to the minimum or maximum value when inputting from or outputting to a given type.

Unsigned integers are converted to and from signed integers by flipping the uppermost bit then treating them as signed integers.

Before you use the following SoX sample conversion macros in a function, SOX_SAMPLE_LOCALS declares the temporary local variables they require. For example:

   sox_int16_t sox_sample_to_CD(sox_sample_t sample)
   {
     SOX_SAMPLE_LOCALS
     unsigned clips = 0;
     return SOX_SAMPLE_TO_SIGNED(16, sample, clips);
   }

The following macros return a SoX native sample value and parameters are:

The width of the resulting sample (1 through 32).
The value to be converted.
A variable that is incremented if the result is too big.
These macros are largely agnostic to the numeric types of their arguments.
Converts a signed integer of width bits to sox_sample_t.
Converts an unsigned integer of width bits to sox_sample_t.
Converts an unsigned 8-bit integer to sox_sample_t. The clips parameter is not used.
Converts a signed 8-bit integer to sox_sample_t. The clips parameter is not used.
Converts an unsigned 16-bit integer to sox_sample_t. The clips parameter is not used.
Converts a signed 16-bit integer to sox_sample_t. The clips parameter is not used.
Converts an unsigned 24-bit integer to sox_sample_t. The clips parameter is not used.
Converts a signed 24-bit integer to sox_sample_t. The clips parameter is not used.
Converts an unsigned 32-bit integer to sox_sample_t. The clips parameter is not used.
Converts a signed 32-bit integer to sox_sample_t. The clips parameter is not used.
Converts a 32-bit float to sox_sample_t.
Converts a 64-bit float to sox_sample_t.
Converts a SoX native sample to an unsigned integer of width bits.
Converts a SoX native sample to a signed integer of width bits.
Converts a SoX native sample to an unsigned 8-bit integer.
Converts a SoX native sample to an signed 8-bit integer.
Converts a SoX native sample to an unsigned 16-bit integer.
Converts a SoX native sample to a signed 16-bit integer.
Converts a SoX native sample to an unsigned 24-bit integer.
Converts a SoX native sample to a signed 24-bit integer.
Converts a SoX native sample to an unsigned 32-bit integer. The clips parameter is not used.
Converts a SoX native sample to a signed 32-bit integer. The clips parameter is not used.
Converts a SoX native sample to a 32-bit float.
Converts a SoX native sample to a 64-bit float. The clips parameter is not used.
Clips a value of a type that is larger then sox_sample_t (for example, sox_int64_t) to sox_sample_t's limits and increment a counter if clipping occurs. d is the value (an lvalue) to be clipped, updated as necessary.
Clips a value of a type that is larger then sox_sample_t (for example, sox_int64_t) to sox_sample_t's limits and increment a counter if clipping occurs. Returns the clipped value.
Clips a value to the limits of a signed integer of the specified width and increment a counter if clipping occurs. Returns the clipped value.
Clips a value to the limits of a 16-bit signed integer and increment a counter if clipping occurs. Returns the clipped value.
Clips a value to the limits of a 24-bit signed integer and increments a counter if clipping occurs. Returns the clipped value.
The default channel count is 2 (stereo).
The default sample rate is 48000Hz.
The default precision is 16 bits per sample.
The default encoding is SOX_ENCODING_SIGN2 (linear 2's complement PCM).

How you link against libsox_ng depends on how SoX was built on your system. For a static build, just link against the library. For a dynamic build, use libtool to link with the correct linker flags. See the libtool manual for details; basically, you use it like this:

   libtool --mode=link gcc -o prog /path/to/libsox_ng.la

Copyright 1991-2015 Lance Norskog, Chris Bagwell and sundry contributors.

This library is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License version 2 as published by the Free Software Foundation.

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 General Public License for more details.

The many authors and contributors are listed in the README file that is distributed with the source code.

sox_ng(1), libsoxeffect_ng(3), soxformat_ng(7), src/example*.c and demo/*.c in the SoX source distribution.

August 11, 2024 SoX