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- .. SPDX-License-Identifier: GPL-2.0
- .. include:: <isonum.txt>
- NPCM video driver
- =================
- This driver is used to control the Video Capture/Differentiation (VCD) engine
- and Encoding Compression Engine (ECE) present on Nuvoton NPCM SoCs. The VCD can
- capture a frame from digital video input and compare two frames in memory, and
- the ECE can compress the frame data into HEXTILE format.
- Driver-specific Controls
- ------------------------
- V4L2_CID_NPCM_CAPTURE_MODE
- ~~~~~~~~~~~~~~~~~~~~~~~~~~
- The VCD engine supports two modes:
- - COMPLETE mode:
- Capture the next complete frame into memory.
- - DIFF mode:
- Compare the incoming frame with the frame stored in memory, and updates the
- differentiated frame in memory.
- Application can use ``V4L2_CID_NPCM_CAPTURE_MODE`` control to set the VCD mode
- with different control values (enum v4l2_npcm_capture_mode):
- - ``V4L2_NPCM_CAPTURE_MODE_COMPLETE``: will set VCD to COMPLETE mode.
- - ``V4L2_NPCM_CAPTURE_MODE_DIFF``: will set VCD to DIFF mode.
- V4L2_CID_NPCM_RECT_COUNT
- ~~~~~~~~~~~~~~~~~~~~~~~~
- If using V4L2_PIX_FMT_HEXTILE format, VCD will capture frame data and then ECE
- will compress the data into HEXTILE rectangles and store them in V4L2 video
- buffer with the layout defined in Remote Framebuffer Protocol:
- ::
- (RFC 6143, https://www.rfc-editor.org/rfc/rfc6143.html#section-7.6.1)
- +--------------+--------------+-------------------+
- | No. of bytes | Type [Value] | Description |
- +--------------+--------------+-------------------+
- | 2 | U16 | x-position |
- | 2 | U16 | y-position |
- | 2 | U16 | width |
- | 2 | U16 | height |
- | 4 | S32 | encoding-type (5) |
- +--------------+--------------+-------------------+
- | HEXTILE rectangle data |
- +-------------------------------------------------+
- Application can get the video buffer through VIDIOC_DQBUF, and followed by
- calling ``V4L2_CID_NPCM_RECT_COUNT`` control to get the number of HEXTILE
- rectangles in this buffer.
- References
- ----------
- include/uapi/linux/npcm-video.h
- **Copyright** |copy| 2022 Nuvoton Technologies
|
