1 .. SPDX-License-Identifier: GPL-2.0
3 .. include:: <isonum.txt>
8 ASPEED Video Engine found on AST2400/2500/2600 SoC supports high performance
9 video compressions with a wide range of video quality and compression ratio
10 options. The adopted compressing algorithm is a modified JPEG algorithm.
12 There are 2 types of compressions in this IP.
14 * JPEG JFIF standard mode: for single frame and management compression
15 * ASPEED proprietary mode: for multi-frame and differential compression.
16 Support 2-pass (high quality) video compression scheme (Patent pending by
17 ASPEED). Provide visually lossless video compression quality or to reduce
18 the network average loading under intranet KVM applications.
20 VIDIOC_S_FMT can be used to choose which format you want. V4L2_PIX_FMT_JPEG
21 stands for JPEG JFIF standard mode; V4L2_PIX_FMT_AJPG stands for ASPEED
24 More details on the ASPEED video hardware operations can be found in
25 *chapter 6.2.16 KVM Video Driver* of SDK_User_Guide which available on
26 `github <https://github.com/AspeedTech-BMC/openbmc/releases/>`__.
28 The ASPEED video driver implements the following driver-specific control:
30 ``V4L2_CID_ASPEED_HQ_MODE``
31 ---------------------------
32 Enable/Disable ASPEED's High quality mode. This is a private control
33 that can be used to enable high quality for aspeed proprietary mode.
41 - ASPEED HQ mode is disabled.
43 - ASPEED HQ mode is enabled.
45 ``V4L2_CID_ASPEED_HQ_JPEG_QUALITY``
46 -----------------------------------
47 Define the quality of ASPEED's High quality mode. This is a private control
48 that can be used to decide compression quality if High quality mode enabled
49 . Higher the value, better the quality and bigger the size.
65 **Copyright** |copy| 2022 ASPEED Technology Inc.