1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 2 3.. _v4l2-meta-fmt-uvc: 4 5******************************* 6V4L2_META_FMT_UVC ('UVCH') 7******************************* 8 9UVC Payload Header Data 10 11 12Description 13=========== 14 15This format describes standard UVC metadata, extracted from UVC packet headers 16and provided by the UVC driver through metadata video nodes. That data includes 17exact copies of the standard part of UVC Payload Header contents and auxiliary 18timing information, required for precise interpretation of timestamps, contained 19in those headers. See section "2.4.3.3 Video and Still Image Payload Headers" of 20the "UVC 1.5 Class specification" for details. 21 22Each UVC payload header can be between 2 and 12 bytes large. Buffers can 23contain multiple headers, if multiple such headers have been transmitted by the 24camera for the respective frame. However, the driver may drop headers when the 25buffer is full, when they contain no useful information (e.g. those without the 26SCR field or with that field identical to the previous header), or generally to 27perform rate limiting when the device sends a large number of headers. 28 29Each individual block contains the following fields: 30 31.. flat-table:: UVC Metadata Block 32 :widths: 1 4 33 :header-rows: 1 34 :stub-columns: 0 35 36 * - Field 37 - Description 38 * - __u64 ts; 39 - system timestamp in host byte order, measured by the driver upon 40 reception of the payload 41 * - __u16 sof; 42 - USB Frame Number in host byte order, also obtained by the driver as 43 close as possible to the above timestamp to enable correlation between 44 them 45 * - :cspan:`1` *The rest is an exact copy of the UVC payload header:* 46 * - __u8 length; 47 - length of the rest of the block, including this field 48 * - __u8 flags; 49 - Flags, indicating presence of other standard UVC fields 50 * - __u8 buf[]; 51 - The rest of the header, possibly including UVC PTS and SCR fields 52