UVC规范(USB摄像头)
UVC 负载格式描述符（数据格式）
2020-10-20
2301
0
UVC已经定义的数据格式类型见下表（以VS_FORMAT开头）：
| 描述符类型 | 值 |
|---|---|
| VS_UNDEFINED | 0x00 |
| VS_INPUT_HEADER | 0x01 |
| VS_OUTPUT_HEADER | 0x02 |
| VS_STILL_IMAGE_FRAME | 0x03 |
| VS_FORMAT_UNCOMPRESSED | 0x04 |
| VS_FRAME_UNCOMPRESSED | 0x05 |
| VS_FORMAT_MJPEG | 0x06 |
| VS_FRAME_MJPEG | 0x07 |
| Reserved | 0x08 |
| Reserved | 0x09 |
| VS_FORMAT_MPEG2TS | 0x0A |
| Reserved | 0x0B |
| VS_FORMAT_DV | 0x0C |
| VS_COLORFORMAT | 0x0D |
| Reserved | 0x0E |
| Reserved | 0x0F |
| VS_FORMAT_FRAME_BASED | 0x10 |
| VS_FRAME_FRAME_BASED | 0x11 |
| VS_FORMAT_STREAM_BASED | 0x12 |
| VS_FORMAT_H264 | 0x13 |
| VS_FRAME_H264 | 0x14 |
| VS_FORMAT_H264_SIMULCAST | 0x15 |
| VS_FORMAT_VP8 | 0x16 |
| VS_FRAME_VP8 | 0x17 |
| VS_FORMAT_VP8_SIMULCAST | 0x18 |
如我们支持MJPG数据格式：
bLength: 0x0B
bDescriptorType: 0x24
bDescriptorSubtype: 0x06
bFormatIndex: 0x01
bNumFrameDescriptors: 0x03
bmFlags: 0x00 -> Sample Size is Not Fixed
bDefaultFrameIndex: 0x03
bAspectRatioX: 0x00
bAspectRatioY: 0x00
bmInterlaceFlags: 0x00
D00 = 0 non-Interlaced stream or variable
D01 = 0 2 fields per frame
D02 = 0 Field 1 not first
D03 = 0 Reserved
D4..5 = 0 Field patterns -> Field 1 only
D6..7 = 0 Display Mode -> Bob only
bCopyProtect: 0x00 -> Duplication Unrestricted
如bDescriptorSubtype=VS_FORMAT_MJPEG表示数据帧格式为MJPG。关于同数据格式但帧格式不同（如分辨率不同），可见下节视频帧格式。
关于不同格式的数据帧相关的详细，可在https://www.usb.org/sites/default/files/USB_Video_Class_1_5.zip 处下载对应的文档。
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