UVC摄像头视频特定类请求

UVC摄像头特定类请求包括视频控制接口请求和视频流请求。

/* Video Class-specific Request codes */
#define SET_CUR 0x01
#define GET_CUR 0x81
#define GET_MIN 0x82
#define GET_MAX 0x83
#define GET_RES 0x84
#define GET_LEN 0x85
#define GET_INFO 0x86
#define GET_DEF 0x87

/* Video Streaming Interface Control selectors */
#define VS_PROBE_CONTROL 0x01
#define VS_COMMIT_CONTROL 0x02

在UVC视频流接口中，会处理VS_PROBE_CONTROL和VS_COMMIT_CONTROL的SET和GET请求。VS_PROBE_CONTROL和VS_COMMIT_CONTROL涉及主机和设备之间的流参数协商。下面的代码显示了与这些控件协商的流参数的结构。

/* Video Probe and Commit Controls (Table 4-47 , UVC 1.1) */
typedef struct
{
    unsigned short bmHint;
    unsigned char bFormatIndex;
    unsigned char bFrameIndex;
    unsigned int dwFrameInterval;
    unsigned short wKeyFrameRate;
    unsigned short wPFrameRate;
    unsigned short wCompQuality;
    unsigned short wCompWindowSize;
    unsigned short wDelay;
    unsigned int dwMaxVideoFrameSize;
    unsigned int dwMaxPayloadTransferSize;
    unsigned int dwClockFrequency;
    unsigned char bmFramingInfo;
    unsigned char bPreferedVersion;
    unsigned char bMinVersion;
    unsigned char bMaxVersion;
} __attribute__((packed)) UVC_ProbeCommit_Ctrl_t;