52 lines · plain
1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later2 3.. _v4l2-meta-fmt-uvc:4 5*******************************6V4L2_META_FMT_UVC ('UVCH')7*******************************8 9UVC Payload Header Data10 11 12Description13===========14 15This format describes standard UVC metadata, extracted from UVC packet headers16and provided by the UVC driver through metadata video nodes. That data includes17exact copies of the standard part of UVC Payload Header contents and auxiliary18timing information, required for precise interpretation of timestamps, contained19in those headers. See section "2.4.3.3 Video and Still Image Payload Headers" of20the "UVC 1.5 Class specification" for details.21 22Each UVC payload header can be between 2 and 12 bytes large. Buffers can23contain multiple headers, if multiple such headers have been transmitted by the24camera for the respective frame. However, the driver may drop headers when the25buffer is full, when they contain no useful information (e.g. those without the26SCR field or with that field identical to the previous header), or generally to27perform 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 Block32 :widths: 1 433 :header-rows: 134 :stub-columns: 035 36 * - Field37 - Description38 * - __u64 ts;39 - system timestamp in host byte order, measured by the driver upon40 reception of the payload41 * - __u16 sof;42 - USB Frame Number in host byte order, also obtained by the driver as43 close as possible to the above timestamp to enable correlation between44 them45 * - :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 field48 * - __u8 flags;49 - Flags, indicating presence of other standard UVC fields50 * - __u8 buf[];51 - The rest of the header, possibly including UVC PTS and SCR fields52