ioctl VIDIOC_ENUMOUTPUT &manvol; VIDIOC_ENUMOUTPUT Enumerate video outputs int ioctl int fd int request struct v4l2_output *argp fd &fd; request VIDIOC_ENUMOUTPUT argp To query the attributes of a video outputs applications initialize the index field of &v4l2-output; and call the VIDIOC_ENUMOUTPUT ioctl with a pointer to this structure. Drivers fill the rest of the structure or return an &EINVAL; when the index is out of bounds. To enumerate all outputs applications shall begin at index zero, incrementing by one until the driver returns EINVAL. &cs-str; __u32 index Identifies the output, set by the application. __u8 name[32] Name of the video output, a NUL-terminated ASCII string, for example: "Vout". This information is intended for the user, preferably the connector label on the device itself. __u32 type Type of the output, see . __u32 audioset Drivers can enumerate up to 32 video and audio outputs. This field shows which audio outputs were selectable as the current output if this was the currently selected video output. It is a bit mask. The LSB corresponds to audio output 0, the MSB to output 31. Any number of bits can be set, or none.When the driver does not enumerate audio outputs no bits must be set. Applications shall not interpret this as lack of audio support. Drivers may automatically select audio outputs without enumerating them.For details on audio outputs and how to select the current output see . __u32 modulator Output devices can have zero or more RF modulators. When the type is V4L2_OUTPUT_TYPE_MODULATOR this is an RF connector and this field identifies the modulator. It corresponds to &v4l2-modulator; field index. For details on modulators see . &v4l2-std-id; std Every video output supports one or more different video standards. This field is a set of all supported standards. For details on video standards and how to switch see . __u32 reserved[4] Reserved for future extensions. Drivers must set the array to zero. &cs-def; V4L2_OUTPUT_TYPE_MODULATOR 1 This output is an analog TV modulator. V4L2_OUTPUT_TYPE_ANALOG 2 Analog baseband output, for example Composite / CVBS, S-Video, RGB. V4L2_OUTPUT_TYPE_ANALOGVGAOVERLAY 3 [?] &return-value; EINVAL The &v4l2-output; index is out of bounds.