V4L2设备可用的指令

在 videodev2.h 头文件中，定义了很多 ioctl()的指令，以宏定义的形式提供（VIDIOC_XXX），如下所示：
#define VIDIOC_QUERYCAP _IOR(‘V’, 0, struct v4l2_capability)
#define VIDIOC_RESERVED _IO(‘V’, 1)
#define VIDIOC_ENUM_FMT _IOWR(‘V’, 2, struct v4l2_fmtdesc)
#define VIDIOC_G_FMT _IOWR(‘V’, 4, struct v4l2_format)
#define VIDIOC_S_FMT _IOWR(‘V’, 5, struct v4l2_format)
#define VIDIOC_REQBUFS _IOWR(‘V’, 8, struct v4l2_requestbuffers)
#define VIDIOC_QUERYBUF _IOWR(‘V’, 9, struct v4l2_buffer)
#define VIDIOC_G_FBUF _IOR(‘V’, 10, struct v4l2_framebuffer)
#define VIDIOC_S_FBUF _IOW(‘V’, 11, struct v4l2_framebuffer)
#define VIDIOC_OVERLAY _IOW(‘V’, 14, int)
#define VIDIOC_QBUF _IOWR(‘V’, 15, struct v4l2_buffer)
#define VIDIOC_EXPBUF _IOWR(‘V’, 16, struct v4l2_exportbuffer)
#define VIDIOC_DQBUF _IOWR(‘V’, 17, struct v4l2_buffer)
#define VIDIOC_STREAMON _IOW(‘V’, 18, int)
#define VIDIOC_STREAMOFF _IOW(‘V’, 19, int)
#define VIDIOC_G_PARM _IOWR(‘V’, 21, struct v4l2_streamparm)
#define VIDIOC_S_PARM _IOWR(‘V’, 22, struct v4l2_streamparm)
#define VIDIOC_G_STD _IOR(‘V’, 23, v4l2_std_id)
#define VIDIOC_S_STD _IOW(‘V’, 24, v4l2_std_id)
#define VIDIOC_ENUMSTD _IOWR(‘V’, 25, struct v4l2_standard)
#define VIDIOC_ENUMINPUT _IOWR(‘V’, 26, struct v4l2_input)
#define VIDIOC_G_CTRL _IOWR(‘V’, 27, struct v4l2_control)
#define VIDIOC_S_CTRL _IOWR(‘V’, 28, struct v4l2_control)
#define VIDIOC_G_TUNER _IOWR(‘V’, 29, struct v4l2_tuner)
#define VIDIOC_S_TUNER _IOW(‘V’, 30, struct v4l2_tuner)
#define VIDIOC_G_AUDIO _IOR(‘V’, 33, struct v4l2_audio)
#define VIDIOC_S_AUDIO _IOW(‘V’, 34, struct v4l2_audio)
#define VIDIOC_QUERYCTRL _IOWR(‘V’, 36, struct v4l2_queryctrl)
#define VIDIOC_QUERYMENU _IOWR(‘V’, 37, struct v4l2_querymenu)
#define VIDIOC_G_INPUT _IOR(‘V’, 38, int)
#define VIDIOC_S_INPUT _IOWR(‘V’, 39, int)
#define VIDIOC_G_EDID _IOWR(‘V’, 40, struct v4l2_edid)
#define VIDIOC_S_EDID _IOWR(‘V’, 41, struct v4l2_edid)
#define VIDIOC_G_OUTPUT _IOR(‘V’, 46, int)
#define VIDIOC_S_OUTPUT _IOWR(‘V’, 47, int)
#define VIDIOC_ENUMOUTPUT _IOWR(‘V’, 48, struct v4l2_output)
#define VIDIOC_G_AUDOUT _IOR(‘V’, 49, struct v4l2_audioout)
#define VIDIOC_S_AUDOUT _IOW(‘V’, 50, struct v4l2_audioout)
#define VIDIOC_G_MODULATOR _IOWR(‘V’, 54, struct v4l2_modulator)
#define VIDIOC_S_MODULATOR _IOW(‘V’, 55, struct v4l2_modulator)
#define VIDIOC_G_FREQUENCY _IOWR(‘V’, 56, struct v4l2_frequency)
#define VIDIOC_S_FREQUENCY _IOW(‘V’, 57, struct v4l2_frequency)
#define VIDIOC_CROPCAP _IOWR(‘V’, 58, struct v4l2_cropcap)
#define VIDIOC_G_CROP _IOWR(‘V’, 59, struct v4l2_crop)
#define VIDIOC_S_CROP _IOW(‘V’, 60, struct v4l2_crop)
#define VIDIOC_G_JPEGCOMP _IOR(‘V’, 61, struct v4l2_jpegcompression)
#define VIDIOC_S_JPEGCOMP _IOW(‘V’, 62, struct v4l2_jpegcompression)
#define VIDIOC_QUERYSTD _IOR(‘V’, 63, v4l2_std_id)
#define VIDIOC_TRY_FMT _IOWR(‘V’, 64, struct v4l2_format)
#define VIDIOC_ENUMAUDIO _IOWR(‘V’, 65, struct v4l2_audio)
#define VIDIOC_ENUMAUDOUT _IOWR(‘V’, 66, struct v4l2_audioout)
#define VIDIOC_G_PRIORITY _IOR(‘V’, 67, __u32) /* enum v4l2_priority /
#define VIDIOC_S_PRIORITY _IOW(‘V’, 68, __u32) / enum v4l2_priority */
#define VIDIOC_G_SLICED_VBI_CAP _IOWR(‘V’, 69, struct v4l2_sliced_vbi_cap)
#define VIDIOC_LOG_STATUS _IO(‘V’, 70)
#define VIDIOC_G_EXT_CTRLS _IOWR(‘V’, 71, struct v4l2_ext_controls)
#define VIDIOC_S_EXT_CTRLS _IOWR(‘V’, 72, struct v4l2_ext_controls)
#define VIDIOC_TRY_EXT_CTRLS _IOWR(‘V’, 73, struct v4l2_ext_controls)
#define VIDIOC_ENUM_FRAMESIZES _IOWR(‘V’, 74, struct v4l2_frmsizeenum)
#define VIDIOC_ENUM_FRAMEINTERVALS _IOWR(‘V’, 75, struct v4l2_frmivalenum)
#define VIDIOC_G_ENC_INDEX _IOR(‘V’, 76, struct v4l2_enc_idx)
#define VIDIOC_ENCODER_CMD _IOWR(‘V’, 77, struct v4l2_encoder_cmd)
#define VIDIOC_TRY_ENCODER_CMD _IOWR(‘V’, 78, struct v4l2_encoder_cmd)

/* Experimental, meant for debugging, testing and internal use.
Only implemented if CONFIG_VIDEO_ADV_DEBUG is defined.
You must be root to use these ioctls. Never use these in applications! */
#define VIDIOC_DBG_S_REGISTER _IOW(‘V’, 79, struct v4l2_dbg_register)
#define VIDIOC_DBG_G_REGISTER _IOWR(‘V’, 80, struct v4l2_dbg_register)

/* Experimental, meant for debugging, testing and internal use.
Never use this ioctl in applications!
Note: this ioctl is deprecated in favor of VIDIOC_DBG_G_CHIP_INFO and
will go away in the future. */
#define VIDIOC_DBG_G_CHIP_IDENT _IOWR(‘V’, 81, struct v4l2_dbg_chip_ident)

#define VIDIOC_S_HW_FREQ_SEEK _IOW(‘V’, 82, struct v4l2_hw_freq_seek)

#define VIDIOC_S_DV_TIMINGS _IOWR(‘V’, 87, struct v4l2_dv_timings)
#define VIDIOC_G_DV_TIMINGS _IOWR(‘V’, 88, struct v4l2_dv_timings)
#define VIDIOC_DQEVENT _IOR(‘V’, 89, struct v4l2_event)
#define VIDIOC_SUBSCRIBE_EVENT _IOW(‘V’, 90, struct v4l2_event_subscription)
#define VIDIOC_UNSUBSCRIBE_EVENT _IOW(‘V’, 91, struct v4l2_event_subscription)

/* Experimental, the below two ioctls may change over the next couple of kernel
versions */
#define VIDIOC_CREATE_BUFS _IOWR(‘V’, 92, struct v4l2_create_buffers)
#define VIDIOC_PREPARE_BUF _IOWR(‘V’, 93, struct v4l2_buffer)

/* Experimental selection API */
#define VIDIOC_G_SELECTION _IOWR(‘V’, 94, struct v4l2_selection)
#define VIDIOC_S_SELECTION _IOWR(‘V’, 95, struct v4l2_selection)

/* Experimental, these two ioctls may change over the next couple of kernel
versions. */
#define VIDIOC_DECODER_CMD _IOWR(‘V’, 96, struct v4l2_decoder_cmd)
#define VIDIOC_TRY_DECODER_CMD _IOWR(‘V’, 97, struct v4l2_decoder_cmd)

/* Experimental, these three ioctls may change over the next couple of kernel
versions. */
#define VIDIOC_ENUM_DV_TIMINGS _IOWR(‘V’, 98, struct v4l2_enum_dv_timings)
#define VIDIOC_QUERY_DV_TIMINGS _IOR(‘V’, 99, struct v4l2_dv_timings)
#define VIDIOC_DV_TIMINGS_CAP _IOWR(‘V’, 100, struct v4l2_dv_timings_cap)

/* Experimental, this ioctl may change over the next couple of kernel
versions. */
#define VIDIOC_ENUM_FREQ_BANDS _IOWR(‘V’, 101, struct v4l2_frequency_band)

/* Experimental, meant for debugging, testing and internal use.
Never use these in applications! */
#define VIDIOC_DBG_G_CHIP_INFO _IOWR(‘V’, 102, struct v4l2_dbg_chip_info)

#define VIDIOC_QUERY_EXT_CTRL _IOWR(‘V’, 103, struct v4l2_query_ext_ctrl)