1 .. SPDX-License-Identifier: GPL-2.0 2 3 .. include:: <isonum.txt> 4 5 ASPEED video driver 6 =================== 7 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. 11 12 There are 2 types of compressions in this IP. 13 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. 19 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 22 proprietary mode. 23 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/>`__. 27 28 The ASPEED video driver implements the following driver-specific control: 29 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. 34 35 .. flat-table:: 36 :header-rows: 0 37 :stub-columns: 0 38 :widths: 1 4 39 40 * - ``(0)`` 41 - ASPEED HQ mode is disabled. 42 * - ``(1)`` 43 - ASPEED HQ mode is enabled. 44 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. 50 51 .. flat-table:: 52 :header-rows: 0 53 :stub-columns: 0 54 :widths: 1 4 55 56 * - ``(1)`` 57 - minimum 58 * - ``(12)`` 59 - maximum 60 * - ``(1)`` 61 - step 62 * - ``(1)`` 63 - default 64 65 **Copyright** |copy| 2022 ASPEED Technology Inc.
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