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 fd &fd; request VIDIOC_G_AUDIO, VIDIOC_S_AUDIO argp 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. &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 . __u32 mode Audio mode flags set by drivers and applications (on VIDIOC_S_AUDIO ioctl), see . __u32 reserved[2] Reserved for future extensions. Drivers and applications must set the array to zero. &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. &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, or there are no audio inputs at all and the ioctl is not supported. EBUSY I/O is in progress, the input cannot be switched.