tt::audio_sample_format Struct Reference

#include <ttauri/audio/audio_sample_format.hpp>

Public Member Functions
float	pack_multiplier () const noexcept
	How much to multiply float samples to create integer samples.
float	unpack_multiplier () const noexcept
	How much to multiply integer samples to create float samples.
int	num_samples_per_chunk () const noexcept
	The number of packed samples that are handled in a single 128 bit load or store.
int	chunk_stride () const noexcept
	The number of bytes to advance to the next chunk to be loaded or stored.
int	num_chunks_per_quad () const noexcept
	The number of chunks to load or store to handle 4 samples.
size_t	num_fast_quads (size_t num_samples) const noexcept
	Calculate the number of 4 sample-quads can be handled as chunked loads and stores.
i8x16	load_shuffle_indices () const noexcept
	Return a shuffle indices for loading samples into 32 bit integers.
i8x16	store_shuffle_indices () const noexcept
	Return a shuffle indices for storing 32 bit samples into packed samples.
i8x16	concat_shuffle_indices () const noexcept
	Return a shuffle indices to shift previous loaded samples for concatenation.
bool	is_valid () const noexcept
	Is the audio sample format valid.

Data Fields
int	num_bytes
	The number of bytes of the container.
int	num_guard_bits
	The number of bits used for the integer part of a fixed point number.
int	num_bits
	The number of significant bits of the sample format.
bool	is_float
	The numeric type is floating point.
std::endian	endian
	The endian order of the bytes in the container.
int	stride
	The number of bytes to step to the next sample of the same channel.

Detailed Description

Audio sample format.

Audio samples described by this type can be in three different formats.

• Signed integer PCM, which will be treated like a fixed point where the num_integer_bits is set to zero. This is the format used in most audio file formats.
• Fixed point PCM, a more generic format than signed integers which has some head-room/guard bits above normalized signed integers. The Q8.23 fixed integer format is used by iOS as a sample format.
• Floating point PCM, the floating point format used internally in ttauri, useful for doing calculations in.

Sample values are aligned to the most significant bits of the container described by num_bytes. The bottom bits are set to zero.

Member Function Documentation

chunk_stride()

int tt::audio_sample_format::chunk_stride ( ) const

noexcept

The number of bytes to advance to the next chunk to be loaded or stored.

concat_shuffle_indices()

i8x16 tt::audio_sample_format::concat_shuffle_indices ( ) const

noexcept

Return a shuffle indices to shift previous loaded samples for concatenation.

is_valid()

bool tt::audio_sample_format::is_valid ( ) const

noexcept

Is the audio sample format valid.

load_shuffle_indices()

i8x16 tt::audio_sample_format::load_shuffle_indices ( ) const

noexcept

Return a shuffle indices for loading samples into 32 bit integers.

num_chunks_per_quad()

int tt::audio_sample_format::num_chunks_per_quad ( ) const

noexcept

The number of chunks to load or store to handle 4 samples.

num_fast_quads()

size_t tt::audio_sample_format::num_fast_quads ( size_t num_samples ) const

noexcept

Calculate the number of 4 sample-quads can be handled as chunked loads and stores.

num_samples_per_chunk()

int tt::audio_sample_format::num_samples_per_chunk ( ) const

noexcept

The number of packed samples that are handled in a single 128 bit load or store.

Always one of: 1, 2 or 4.

pack_multiplier()

float tt::audio_sample_format::pack_multiplier ( ) const

noexcept

How much to multiply float samples to create integer samples.

store_shuffle_indices()

i8x16 tt::audio_sample_format::store_shuffle_indices ( ) const

noexcept

Return a shuffle indices for storing 32 bit samples into packed samples.

unpack_multiplier()

float tt::audio_sample_format::unpack_multiplier ( ) const

noexcept

How much to multiply integer samples to create float samples.

Field Documentation

endian

std::endian tt::audio_sample_format::endian

The endian order of the bytes in the container.

is_float

bool tt::audio_sample_format::is_float

The numeric type is floating point.

Otherwise it is a signed integer or fixed point number.

num_bits

int tt::audio_sample_format::num_bits

The number of significant bits of the sample format.

This value is excluding the sign. (1 << num_bits) - 1 is the maximum sample value.

Examples:

• 16 bit signed PCM -> num_bits=15
• 24 bit signed PCM -> num_bits=23
• float PCM -> num_bits=23
• Q8.23 PCM -> num_bits=23

num_bytes

int tt::audio_sample_format::num_bytes

The number of bytes of the container.

Must be either 1, 2, 3 or 4

num_guard_bits

int tt::audio_sample_format::num_guard_bits

The number of bits used for the integer part of a fixed point number.

This value is zero for signed integer and float samples.

stride

int tt::audio_sample_format::stride

The number of bytes to step to the next sample of the same channel.

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The documentation for this struct was generated from the following file:

• hikogui/src/ttauri/audio/audio_sample_format.hpp