Functions
int	snd_pcm_format_signed (snd_pcm_format_t format)
	Return sign info for a PCM sample linear format. More...

int	snd_pcm_format_unsigned (snd_pcm_format_t format)
	Return sign info for a PCM sample linear format. More...

int	snd_pcm_format_linear (snd_pcm_format_t format)
	Return linear info for a PCM sample format. More...

int	snd_pcm_format_float (snd_pcm_format_t format)
	Return float info for a PCM sample format. More...

int	snd_pcm_format_little_endian (snd_pcm_format_t format)
	Return endian info for a PCM sample format. More...

int	snd_pcm_format_big_endian (snd_pcm_format_t format)
	Return endian info for a PCM sample format. More...

int	snd_pcm_format_cpu_endian (snd_pcm_format_t format)
	Return endian info for a PCM sample format. More...

int	snd_pcm_format_width (snd_pcm_format_t format)
	Return the bit-width of the format. More...

int	snd_pcm_format_physical_width (snd_pcm_format_t format)
	Return the physical bit-width of the format (bits needed to store a PCM sample) More...

snd_pcm_format_t	snd_pcm_build_linear_format (int width, int pwidth, int unsignd, int big_endian)
	Compose a PCM sample linear format. More...

ssize_t	snd_pcm_format_size (snd_pcm_format_t format, size_t samples)
	Return bytes needed to store a quantity of PCM sample. More...

uint8_t	snd_pcm_format_silence (snd_pcm_format_t format)
	Return 8 bit expressing silence for a PCM sample format. More...

uint16_t	snd_pcm_format_silence_16 (snd_pcm_format_t format)
	Return 16 bit expressing silence for a PCM sample format. More...

uint32_t	snd_pcm_format_silence_32 (snd_pcm_format_t format)
	Return 32 bit expressing silence for a PCM sample format. More...

uint64_t	snd_pcm_format_silence_64 (snd_pcm_format_t format)
	Return 64 bit expressing silence for a PCM sample format. More...

int	snd_pcm_format_set_silence (snd_pcm_format_t format, void *buf, unsigned int samples)
	Silence a PCM samples buffer. More...

snd_pcm_sframes_t	snd_pcm_bytes_to_frames (snd_pcm_t *pcm, ssize_t bytes)
	Convert bytes in frames for a PCM. More...

ssize_t	snd_pcm_frames_to_bytes (snd_pcm_t *pcm, snd_pcm_sframes_t frames)
	Convert frames in bytes for a PCM. More...

long	snd_pcm_bytes_to_samples (snd_pcm_t *pcm, ssize_t bytes)
	Convert bytes in samples for a PCM. More...

ssize_t	snd_pcm_samples_to_bytes (snd_pcm_t *pcm, long samples)
	Convert samples in bytes for a PCM. More...

int	snd_pcm_area_silence (const snd_pcm_channel_area_t *dst_channel, snd_pcm_uframes_t dst_offset, unsigned int samples, snd_pcm_format_t format)
	Silence an area. More...

int	snd_pcm_areas_silence (const snd_pcm_channel_area_t *dst_channels, snd_pcm_uframes_t dst_offset, unsigned int channels, snd_pcm_uframes_t frames, snd_pcm_format_t format)
	Silence one or more areas. More...

int	snd_pcm_area_copy (const snd_pcm_channel_area_t dst_channel, snd_pcm_uframes_t dst_offset, const snd_pcm_channel_area_t src_channel, snd_pcm_uframes_t src_offset, unsigned int samples, snd_pcm_format_t format)
	Copy an area. More...

int	snd_pcm_areas_copy (const snd_pcm_channel_area_t dst_channels, snd_pcm_uframes_t dst_offset, const snd_pcm_channel_area_t src_channels, snd_pcm_uframes_t src_offset, unsigned int channels, snd_pcm_uframes_t frames, snd_pcm_format_t format)
	Copy one or more areas. More...

int	snd_pcm_areas_copy_wrap (const snd_pcm_channel_area_t dst_channels, snd_pcm_uframes_t dst_offset, const snd_pcm_uframes_t dst_size, const snd_pcm_channel_area_t src_channels, snd_pcm_uframes_t src_offset, const snd_pcm_uframes_t src_size, const unsigned int channels, snd_pcm_uframes_t frames, const snd_pcm_format_t format)
	Copy one or more areas. More...

Detailed Description

See the PCM (digital audio) interface page for more details.

Function Documentation

◆ snd_pcm_area_copy()

int snd_pcm_area_copy	(	const snd_pcm_channel_area_t *	dst_area,
		snd_pcm_uframes_t	dst_offset,
		const snd_pcm_channel_area_t *	src_area,
		snd_pcm_uframes_t	src_offset,
		unsigned int	samples,
		snd_pcm_format_t	format
	)

Copy an area.

Parameters

dst_area	destination area specification
dst_offset	offset in frames inside destination area
src_area	source area specification
src_offset	offset in frames inside source area
samples	samples to copy
format	PCM sample format

Returns: 0 on success otherwise a negative error code

◆ snd_pcm_area_silence()

int snd_pcm_area_silence	(	const snd_pcm_channel_area_t *	dst_area,
		snd_pcm_uframes_t	dst_offset,
		unsigned int	samples,
		snd_pcm_format_t	format
	)

Silence an area.

Parameters

dst_area	area specification
dst_offset	offset in frames inside area
samples	samples to silence
format	PCM sample format

Returns: 0 on success otherwise a negative error code

◆ snd_pcm_areas_copy()

int snd_pcm_areas_copy	(	const snd_pcm_channel_area_t *	dst_areas,
		snd_pcm_uframes_t	dst_offset,
		const snd_pcm_channel_area_t *	src_areas,
		snd_pcm_uframes_t	src_offset,
		unsigned int	channels,
		snd_pcm_uframes_t	frames,
		snd_pcm_format_t	format
	)

Copy one or more areas.

Parameters

dst_areas	destination areas specification (one for each channel)
dst_offset	offset in frames inside destination area
src_areas	source areas specification (one for each channel)
src_offset	offset in frames inside source area
channels	channels count
frames	frames to copy
format	PCM sample format

Returns: 0 on success otherwise a negative error code

◆ snd_pcm_areas_copy_wrap()

int snd_pcm_areas_copy_wrap	(	const snd_pcm_channel_area_t *	dst_channels,
		snd_pcm_uframes_t	dst_offset,
		const snd_pcm_uframes_t	dst_size,
		const snd_pcm_channel_area_t *	src_channels,
		snd_pcm_uframes_t	src_offset,
		const snd_pcm_uframes_t	src_size,
		const unsigned int	channels,
		snd_pcm_uframes_t	frames,
		const snd_pcm_format_t	format
	)

Copy one or more areas.

Parameters

dst_channels	destination areas specification (one for each channel)
dst_offset	offset in frames inside destination area
dst_size	size in frames of the destination buffer
src_channels	source areas specification (one for each channel)
src_offset	offset in frames inside source area
src_size	size in frames of the source buffer
channels	channels count
frames	frames to copy
format	PCM sample format

Returns: 0 on success otherwise a negative error code

◆ snd_pcm_areas_silence()

int snd_pcm_areas_silence	(	const snd_pcm_channel_area_t *	dst_areas,
		snd_pcm_uframes_t	dst_offset,
		unsigned int	channels,
		snd_pcm_uframes_t	frames,
		snd_pcm_format_t	format
	)

Silence one or more areas.

Parameters

dst_areas	areas specification (one for each channel)
dst_offset	offset in frames inside area
channels	channels count
frames	frames to silence
format	PCM sample format

Returns: 0 on success otherwise a negative error code

◆ snd_pcm_build_linear_format()

snd_pcm_format_t snd_pcm_build_linear_format	(	int	width,
		int	pwidth,
		int	unsignd,
		int	big_endian
	)

Compose a PCM sample linear format.

Parameters

width	Nominal bits per sample
pwidth	Physical bit width of the format
unsignd	Sign: 0 signed, 1 unsigned
big_endian	Endian: 0 little endian, 1 big endian

Returns: The matching format type, or SND_PCM_FORMAT_UNKNOWN if no match

◆ snd_pcm_bytes_to_frames()

snd_pcm_sframes_t snd_pcm_bytes_to_frames	(	snd_pcm_t *	pcm,
		ssize_t	bytes
	)

Convert bytes in frames for a PCM.

Parameters

pcm	PCM handle
bytes	quantity in bytes

Returns: quantity expressed in frames

◆ snd_pcm_bytes_to_samples()

long snd_pcm_bytes_to_samples	(	snd_pcm_t *	pcm,
		ssize_t	bytes
	)

Convert bytes in samples for a PCM.

Parameters

pcm	PCM handle
bytes	quantity in bytes

Returns: quantity expressed in samples

◆ snd_pcm_format_big_endian()

int snd_pcm_format_big_endian ( snd_pcm_format_t format )

Return endian info for a PCM sample format.

Parameters

format Format

Returns: 0 little endian, 1 big endian, a negative error code if endian independent

Examples: /test/pcm.c.

◆ snd_pcm_format_cpu_endian()

int snd_pcm_format_cpu_endian ( snd_pcm_format_t format )

Return endian info for a PCM sample format.

Parameters

format Format

Returns: 0 swapped, 1 CPU endian, a negative error code if endian independent

◆ snd_pcm_format_float()

int snd_pcm_format_float ( snd_pcm_format_t format )

Return float info for a PCM sample format.

Parameters

format Format

Returns: 0 non float, 1 float

◆ snd_pcm_format_linear()

int snd_pcm_format_linear ( snd_pcm_format_t format )

Return linear info for a PCM sample format.

Parameters

format Format

Returns: 0 non linear, 1 linear

Examples: /test/pcm.c.

◆ snd_pcm_format_little_endian()

int snd_pcm_format_little_endian ( snd_pcm_format_t format )

Return endian info for a PCM sample format.

Parameters

format Format

Returns: 0 big endian, 1 little endian, a negative error code if endian independent

◆ snd_pcm_format_physical_width()

int snd_pcm_format_physical_width ( snd_pcm_format_t format )

Return the physical bit-width of the format (bits needed to store a PCM sample)

Parameters

format Sample format

Returns: the physical bit-width of the format, or a negative error code if not applicable

Examples: /test/latency.c, and /test/pcm.c.

◆ snd_pcm_format_set_silence()

int snd_pcm_format_set_silence	(	snd_pcm_format_t	format,
		void *	data,
		unsigned int	samples
	)

Silence a PCM samples buffer.

Parameters

format	Sample format
data	Buffer
samples	Samples count

Returns: 0 if successful or a negative error code

Examples: /test/latency.c.

◆ snd_pcm_format_signed()

int snd_pcm_format_signed ( snd_pcm_format_t format )

Return sign info for a PCM sample linear format.

Parameters

format Format

Returns: 0 unsigned, 1 signed, a negative error code if format is not linear

◆ snd_pcm_format_silence()

uint8_t snd_pcm_format_silence ( snd_pcm_format_t format )

Return 8 bit expressing silence for a PCM sample format.

Parameters

format Sample format

Returns: silence 8 bit word

◆ snd_pcm_format_silence_16()

uint16_t snd_pcm_format_silence_16 ( snd_pcm_format_t format )

Return 16 bit expressing silence for a PCM sample format.

Parameters

format Sample format

Returns: silence 16 bit word

◆ snd_pcm_format_silence_32()

uint32_t snd_pcm_format_silence_32 ( snd_pcm_format_t format )

Return 32 bit expressing silence for a PCM sample format.

Parameters

format Sample format

Returns: silence 32 bit word

◆ snd_pcm_format_silence_64()

uint64_t snd_pcm_format_silence_64 ( snd_pcm_format_t format )

Return 64 bit expressing silence for a PCM sample format.

Parameters

format Sample format

Returns: silence 64 bit word

◆ snd_pcm_format_size()

ssize_t snd_pcm_format_size	(	snd_pcm_format_t	format,
		size_t	samples
	)

Return bytes needed to store a quantity of PCM sample.

Parameters

format	Sample format
samples	Samples count

Returns: bytes needed, a negative error code if not integer or unknown

◆ snd_pcm_format_unsigned()

int snd_pcm_format_unsigned ( snd_pcm_format_t format )

Return sign info for a PCM sample linear format.

Parameters

format Format

Returns: 0 signed, 1 unsigned, a negative error code if format is not linear

Examples: /test/pcm.c.

◆ snd_pcm_format_width()

int snd_pcm_format_width ( snd_pcm_format_t format )

Return the bit-width of the format.

Parameters

format Sample format

Returns: the bit-width of the format, or a negative error code if not applicable

Examples: /test/pcm.c.

◆ snd_pcm_frames_to_bytes()

ssize_t snd_pcm_frames_to_bytes	(	snd_pcm_t *	pcm,
		snd_pcm_sframes_t	frames
	)

Convert frames in bytes for a PCM.

Parameters

pcm	PCM handle
frames	quantity in frames

Returns: quantity expressed in bytes

◆ snd_pcm_samples_to_bytes()

ssize_t snd_pcm_samples_to_bytes	(	snd_pcm_t *	pcm,
		long	samples
	)

Convert samples in bytes for a PCM.

Parameters

pcm	PCM handle
samples	quantity in samples

Returns: quantity expressed in bytes

Functions

Detailed Description

Function Documentation

◆ snd_pcm_area_copy()

◆ snd_pcm_area_silence()

◆ snd_pcm_areas_copy()

◆ snd_pcm_areas_copy_wrap()

◆ snd_pcm_areas_silence()

◆ snd_pcm_build_linear_format()

◆ snd_pcm_bytes_to_frames()

◆ snd_pcm_bytes_to_samples()

◆ snd_pcm_format_big_endian()

◆ snd_pcm_format_cpu_endian()

◆ snd_pcm_format_float()

◆ snd_pcm_format_linear()

◆ snd_pcm_format_little_endian()

◆ snd_pcm_format_physical_width()

◆ snd_pcm_format_set_silence()

◆ snd_pcm_format_signed()

◆ snd_pcm_format_silence()

◆ snd_pcm_format_silence_16()

◆ snd_pcm_format_silence_32()

◆ snd_pcm_format_silence_64()

◆ snd_pcm_format_size()

◆ snd_pcm_format_unsigned()

◆ snd_pcm_format_width()

◆ snd_pcm_frames_to_bytes()

◆ snd_pcm_samples_to_bytes()