ioctl VIDIOC_G_AUDIO, VIDIOC_S_AUDIO

&manvol;

VIDIOC_G_AUDIO

VIDIOC_S_AUDIO

Query or select the current audio input and its attributes

    	int ioctl
    	int fd
    	int request
    	struct v4l2_audio *argp

    	int ioctl
    	int fd
    	int request
    	const struct v4l2_audio *argp

## Arguments

`fd`

- &fd;

`request`

- VIDIOC_G_AUDIO, VIDIOC_S_AUDIO

`argp`

## Description

To query the current audio input applications zero out the reserved array of a &v4l2-audio; and call the `VIDIOC_G_AUDIO` ioctl with a pointer to this structure. Drivers fill the rest of the structure or return an &EINVAL; when the device has no audio inputs, or none which combine with the current video input.

Audio inputs have one writable property, the audio mode. To select the current audio input and change the audio mode, applications initialize the index and mode fields, and the reserved array of a v4l2_audio structure and call the `VIDIOC_S_AUDIO` ioctl. Drivers may switch to a different audio mode if the request cannot be satisfied. However, this is a write-only ioctl, it does not return the actual new audio mode.

## struct v4l2_audio

&cs-str;
__u32 | index | Identifies the audio input, set by the driver or application.
__u8 | name[32] | Name of the audio input, a NUL-terminated ASCII string, for example: "Line In". This information is intended for the user, preferably the connector label on the device itself.
__u32 | capability | Audio capability flags, see audio-capability.
__u32 | mode | Audio mode flags set by drivers and applications (on `VIDIOC_S_AUDIO` ioctl), see audio-mode.
__u32 | reserved[2] | Reserved for future extensions. Drivers and applications must set the array to zero.

## Audio Capability Flags

&cs-def;
`V4L2_AUDCAP_STEREO` | 0x00001 | This is a stereo input. The flag is intended to automatically disable stereo recording etc. when the signal is always monaural. The API provides no means to detect if stereo is received, unless the audio input belongs to a tuner.
`V4L2_AUDCAP_AVL` | 0x00002 | Automatic Volume Level mode is supported.

## Audio Mode Flags

&cs-def;
`V4L2_AUDMODE_AVL` | 0x00001 | AVL mode is on.

&return-value;

EINVAL

- No audio inputs combine with the current video input, or the number of the selected audio input is out of bounds or it does not combine.