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- .. SPDX-License-Identifier: GPL-2.0
- .. include:: <isonum.txt>
- ASPEED video driver
- ===================
- ASPEED Video Engine found on AST2400/2500/2600 SoC supports high performance
- video compressions with a wide range of video quality and compression ratio
- options. The adopted compressing algorithm is a modified JPEG algorithm.
- There are 2 types of compressions in this IP.
- * JPEG JFIF standard mode: for single frame and management compression
- * ASPEED proprietary mode: for multi-frame and differential compression.
- Support 2-pass (high quality) video compression scheme (Patent pending by
- ASPEED). Provide visually lossless video compression quality or to reduce
- the network average loading under intranet KVM applications.
- VIDIOC_S_FMT can be used to choose which format you want. V4L2_PIX_FMT_JPEG
- stands for JPEG JFIF standard mode; V4L2_PIX_FMT_AJPG stands for ASPEED
- proprietary mode.
- More details on the ASPEED video hardware operations can be found in
- *chapter 6.2.16 KVM Video Driver* of SDK_User_Guide which available on
- `github <https://github.com/AspeedTech-BMC/openbmc/releases/>`__.
- The ASPEED video driver implements the following driver-specific control:
- ``V4L2_CID_ASPEED_HQ_MODE``
- ---------------------------
- Enable/Disable ASPEED's High quality mode. This is a private control
- that can be used to enable high quality for aspeed proprietary mode.
- .. flat-table::
- :header-rows: 0
- :stub-columns: 0
- :widths: 1 4
- * - ``(0)``
- - ASPEED HQ mode is disabled.
- * - ``(1)``
- - ASPEED HQ mode is enabled.
- ``V4L2_CID_ASPEED_HQ_JPEG_QUALITY``
- -----------------------------------
- Define the quality of ASPEED's High quality mode. This is a private control
- that can be used to decide compression quality if High quality mode enabled
- . Higher the value, better the quality and bigger the size.
- .. flat-table::
- :header-rows: 0
- :stub-columns: 0
- :widths: 1 4
- * - ``(1)``
- - minimum
- * - ``(12)``
- - maximum
- * - ``(1)``
- - step
- * - ``(1)``
- - default
- **Copyright** |copy| 2022 ASPEED Technology Inc.
|
