Audio API. More...

#include <muteki/common.h>
#include <muteki/devio.h>
#include <muteki/threading.h>

Data Structures
struct	pcm_config_s
	The PCM codec configuration. More...

struct	pcm_codec_context_s
	The PCM codec context. More...

struct	device_service_pcm_s

struct	pcm_state_s

struct	pcm_frame_s
	PCM frame data structure. Used internally. More...

struct	pcm_decoder_buffer_s
	Codec buffer descriptor. Used Internally. More...

Typedefs
typedef struct device_service_pcm_s	device_service_pcm_t

typedef struct pcm_config_s	pcm_config_t

typedef struct pcm_codec_context_s	pcm_codec_context_t

typedef struct pcm_state_s	pcm_state_t

typedef struct pcm_frame_s	pcm_frame_t

typedef struct pcm_decoder_buffer_s	pcm_decoder_buffer_t

typedef void(*	pcm_codec_func_t) (device_service_pcm_t pcm, pcm_decoder_buffer_t src, pcm_decoder_buffer_t *dest)

Enumerations
enum	pcm_direction_e { DIRECTION_DEFAULT , DIRECTION_OUT , DIRECTION_IN }
	PCM codec direction/mode. More...

enum	pcm_format_e { FORMAT_AUTO = -1 , FORMAT_PCM_MONO = 1 , FORMAT_PCM_STEREO = 3 }
	Sample format. More...

Functions
pcm_codec_context_t *	OpenPCMCodec (int direction, int sample_rate, int format)
	Create PCM codec context.

void	ClosePCMCodec (pcm_codec_context_t *ctx)
	Destroy a PCM codec context.

Variables
const int	SAMPLE_RATE_AUTO = -1
	Use the default sample rate. Usually this is equivalent to 44100Hz.

Detailed Description

Audio API.

Enumeration Type Documentation

◆ pcm_direction_e

enum pcm_direction_e

PCM codec direction/mode.

Enumerator
DIRECTION_DEFAULT	Default direction. Usually DIRECTION_OUT.
DIRECTION_OUT	Output/playback mode.
DIRECTION_IN	Input/recording mode.

◆ pcm_format_e

enum pcm_format_e

Sample format.

Enumerator
FORMAT_AUTO	Use the default format. Usually FORMAT_PCM_STEREO.
FORMAT_PCM_MONO	PCM mono.
FORMAT_PCM_STEREO	PCM stereo.

Function Documentation

◆ ClosePCMCodec()

void ClosePCMCodec ( pcm_codec_context_t * ctx )

extern

Destroy a PCM codec context.

Syscall Number: 0x10251

Parameters

ctx	The context.

◆ OpenPCMCodec()

pcm_codec_context_t * OpenPCMCodec	(	int	direction,
		int	sample_rate,
		int	format
	)

extern

Create PCM codec context.

Use this to play/record audio in a streaming manner.

This changes the configuration of the \\?\PCM service. More details TBA.

The context object can be used directly, but it's recommended to open another descriptor using the CreateFile() syscall, and use ReadFile() / WriteFile() / DeviceIoControl() to access the device.

For example, below is a simple loop that uses both the PCM and the device IO syscalls together to play samples:

char sample[0x2000]; // Write audio data to this buffer periodically
size_t num_bytes, actual_bytes;
 
pcm_codec_context_t *pcmdesc = OpenPCMCodec(DIRECTION_OUT, SAMPLE_RATE_AUTO, FORMAT_AUTO);
if (pcmdesc == NULL) {
    // TODO fail
}
 
devio_descriptor_t *pcmdev = CreateFile("\\\\?\\PCM", 0, 0, NULL, 3, 0, NULL);
if (pcmdev == NULL || pcmdev == DEVIO_DESC_INVALID) {
    ClosePCMCodec(pcmdesc);
    // TODO fail
}
 
while (true) {
    // TODO populate the samples and set num_bytes to how many bytes to play
    WriteFile(pcmdev, sample, num_bytes, &actual_bytes, NULL);
    if (num_bytes != actual_bytes) {
        // TODO optionally report error
    }
}
 
CloseHandle(pcmdev);
ClosePCMCodec(pcmdesc);

Syscall Number: 0x10250

Parameters

direction	Direction. Can either be input (record) or output (playback).
sample_rate	Sample rate.
format	Sample format.

Returns: The context.

See also: pcm_direction_e Predefined values for codec direction.; pcm_format_e Supported sample formats.

Data Structures

Typedefs

Enumerations

Functions