1.. Permission is granted to copy, distribute and/or modify this 2.. document under the terms of the GNU Free Documentation License, 3.. Version 1.1 or any later version published by the Free Software 4.. Foundation, with no Invariant Sections, no Front-Cover Texts 5.. and no Back-Cover Texts. A copy of the license is included at 6.. Documentation/media/uapi/fdl-appendix.rst. 7.. 8.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections 9 10.. _v4l2-meta-fmt-uvc: 11 12******************************* 13V4L2_META_FMT_UVC ('UVCH') 14******************************* 15 16UVC Payload Header Data 17 18 19Description 20=========== 21 22This format describes standard UVC metadata, extracted from UVC packet headers 23and provided by the UVC driver through metadata video nodes. That data includes 24exact copies of the standard part of UVC Payload Header contents and auxiliary 25timing information, required for precise interpretation of timestamps, contained 26in those headers. See section "2.4.3.3 Video and Still Image Payload Headers" of 27the "UVC 1.5 Class specification" for details. 28 29Each UVC payload header can be between 2 and 12 bytes large. Buffers can 30contain multiple headers, if multiple such headers have been transmitted by the 31camera for the respective frame. However, the driver may drop headers when the 32buffer is full, when they contain no useful information (e.g. those without the 33SCR field or with that field identical to the previous header), or generally to 34perform rate limiting when the device sends a large number of headers. 35 36Each individual block contains the following fields: 37 38.. flat-table:: UVC Metadata Block 39 :widths: 1 4 40 :header-rows: 1 41 :stub-columns: 0 42 43 * - Field 44 - Description 45 * - __u64 ts; 46 - system timestamp in host byte order, measured by the driver upon 47 reception of the payload 48 * - __u16 sof; 49 - USB Frame Number in host byte order, also obtained by the driver as 50 close as possible to the above timestamp to enable correlation between 51 them 52 * - :cspan:`1` *The rest is an exact copy of the UVC payload header:* 53 * - __u8 length; 54 - length of the rest of the block, including this field 55 * - __u8 flags; 56 - Flags, indicating presence of other standard UVC fields 57 * - __u8 buf[]; 58 - The rest of the header, possibly including UVC PTS and SCR fields 59