Audio node types and built-in factories

Core types for audio nodes, formats, buffers, and built-in processor node factories. More...

Collaboration diagram for Audio node types and built-in factories:

Data Structures
struct	ove_audio_fmt
	Complete audio stream format descriptor. More...
struct	ove_audio_buf
	Audio buffer passed between nodes during graph processing. More...
struct	ove_audio_node_ops
	Virtual function table (vtable) for an audio processing node. More...
struct	ove_audio_node
	Descriptor for a single node in the audio graph. More...
struct	ove_audio_channel_map
	Channel routing table used by ove_audio_node_channel_map(). More...

Macros
#define	OVE_AUDIO_MAX_CHANNELS   8
	Maximum number of audio channels supported by the channel-map node.

Typedefs
typedef void(*	ove_audio_tap_fn) (const struct ove_audio_buf *buf, void *user_data)
	Callback invoked by the tap node for every processed buffer.

Enumerations
enum	ove_audio_sample_fmt { OVE_AUDIO_FMT_S16 , OVE_AUDIO_FMT_S32 , OVE_AUDIO_FMT_F32 }
	PCM sample format tag. More...
enum	ove_audio_node_type { OVE_AUDIO_NODE_SOURCE , OVE_AUDIO_NODE_PROCESSOR , OVE_AUDIO_NODE_SINK }
	Role of a node within the audio graph. More...

Functions
static unsigned int	ove_audio_sample_size (enum ove_audio_sample_fmt fmt)
	Return the size in bytes of one sample for a given format.
static int	ove_audio_fmt_equal (const struct ove_audio_fmt *a, const struct ove_audio_fmt *b)
	Test two format descriptors for equality.
int	ove_audio_node_converter (struct ove_audio_graph *g, enum ove_audio_sample_fmt target_fmt, const char *name)
	Add a sample-format converter processor node to the graph.
int	ove_audio_node_channel_map (struct ove_audio_graph *g, const struct ove_audio_channel_map *map, const char *name)
	Add a channel-mapping processor node to the graph.
int	ove_audio_node_gain (struct ove_audio_graph *g, float gain_db, const char *name)
	Add a gain processor node to the graph.
int	ove_audio_node_tap (struct ove_audio_graph *g, ove_audio_tap_fn fn, void *user_data, const char *name)
	Add a tap (observer) sink node to the graph.

Detailed Description

Core types for audio nodes, formats, buffers, and built-in processor node factories.

Defines the fundamental data types shared by every node in the audio graph: sample format, format descriptor, audio buffer, node vtable, and node descriptor. Also provides a small set of ready-made processor node factories (format converter, channel mapper, gain, and tap observer).

Note

Requires CONFIG_OVE_AUDIO.

Typedef Documentation

ove_audio_tap_fn

typedef void(* ove_audio_tap_fn) (const struct ove_audio_buf *buf, void *user_data)

Callback invoked by the tap node for every processed buffer.

Parameters

[in]	buf	Buffer containing the observed audio data.
[in]	user_data	Opaque pointer supplied at node creation.

Enumeration Type Documentation

ove_audio_sample_fmt

enum ove_audio_sample_fmt

PCM sample format tag.

Identifies the numeric type and bit-depth of each audio sample.

Enumerator
OVE_AUDIO_FMT_S16	Signed 16-bit integer (int16_t).
OVE_AUDIO_FMT_S32	Signed 32-bit integer (int32_t).
OVE_AUDIO_FMT_F32	32-bit IEEE 754 float.

ove_audio_node_type

enum ove_audio_node_type

Role of a node within the audio graph.

Enumerator
OVE_AUDIO_NODE_SOURCE	Produces audio; has no upstream connection.
OVE_AUDIO_NODE_PROCESSOR	Transforms audio; has one upstream connection.
OVE_AUDIO_NODE_SINK	Consumes audio; has no downstream connection.

Function Documentation

ove_audio_sample_size()

static unsigned int ove_audio_sample_size ( enum ove_audio_sample_fmt  fmt )

inlinestatic

Return the size in bytes of one sample for a given format.

Parameters

[in]

fmt

Sample format tag.

Returns

Byte size of one sample, or 0 for an unrecognised format.

ove_audio_fmt_equal()

static int ove_audio_fmt_equal ( const struct ove_audio_fmt *  a, const struct ove_audio_fmt *  b  )

inlinestatic

Test two format descriptors for equality.

Parameters

[in]	a	First format descriptor.
[in]	b	Second format descriptor.

Returns

Non-zero if all fields match, zero otherwise.

ove_audio_node_converter()

int ove_audio_node_converter	(	struct ove_audio_graph *	g,
		enum ove_audio_sample_fmt	target_fmt,
		const char *	name
	)

Add a sample-format converter processor node to the graph.

Inserts a processor that converts any upstream sample format to target_fmt while preserving sample rate and channel count.

Parameters

[in]	g	Graph to add the node to.
[in]	target_fmt	Desired output sample format.
[in]	name	Human-readable name for the node.

Returns

Non-negative node index on success, negative error code on failure.

Note

Requires CONFIG_OVE_AUDIO.

See also

ove_audio_graph_add_node, ove_audio_graph_connect

ove_audio_node_channel_map()

int ove_audio_node_channel_map	(	struct ove_audio_graph *	g,
		const struct ove_audio_channel_map *	map,
		const char *	name
	)

Add a channel-mapping processor node to the graph.

Inserts a processor that reorders, duplicates, or silences channels according to map. The output channel count equals map->out_channels.

Parameters

[in]	g	Graph to add the node to.
[in]	map	Channel routing descriptor.
[in]	name	Human-readable name for the node.

Returns

Non-negative node index on success, negative error code on failure.

Note

Requires CONFIG_OVE_AUDIO.

See also

ove_audio_node_converter

ove_audio_node_gain()

int ove_audio_node_gain	(	struct ove_audio_graph *	g,
		float	gain_db,
		const char *	name
	)

Add a gain processor node to the graph.

Inserts a processor that applies a fixed gain of gain_db decibels to every sample. Positive values amplify; negative values attenuate. The output format is identical to the input format.

Parameters

[in]	g	Graph to add the node to.
[in]	gain_db	Gain in decibels (e.g. -6.0f for -6 dB).
[in]	name	Human-readable name for the node.

Returns

Non-negative node index on success, negative error code on failure.

Note

Requires CONFIG_OVE_AUDIO.

ove_audio_node_tap()

int ove_audio_node_tap	(	struct ove_audio_graph *	g,
		ove_audio_tap_fn	fn,
		void *	user_data,
		const char *	name
	)

Add a tap (observer) sink node to the graph.

Inserts a sink that calls fn for every audio buffer processed. The callback receives a pointer to the upstream buffer; data must not be stored beyond the duration of the callback.

Parameters

[in]	g	Graph to add the node to.
[in]	fn	Callback invoked each processing cycle.
[in]	user_data	Opaque pointer forwarded to fn.
[in]	name	Human-readable name for the node.

Returns

Non-negative node index on success, negative error code on failure.

Note

Requires CONFIG_OVE_AUDIO.

See also

ove_audio_node_gain