说明：  当前我所使用的ffmpeg的版本是3.2，支持dxva2硬件加速的有以下几种文件格式： AV_CODEC_ID_MPEG2VIDEO、AV_CODEC_ID_H264、AV_CODEC_ID_VC1、AV_CODEC_ID_WMV3、AV_CODEC_ID_HEVC、AV_CODEC_ID_VP9。ffmpeg识别为这几种格式的文件都可以尝试使用dxva2做硬件加速。但这并不代表是这几种格式的文件就一定支持dxva2硬件加速，因为我就遇到了一个AV_CODEC_ID_HEVC文件在初始化配置dxva2的过程中会失败，PotPlayer在播放这个文件时也不能用dxva2硬件加速
(The current version of ffmpeg I'm using is 3.2. Dxva2 hardware acceleration is supported in the following file formats: AV_CODEC_ID_MPEG2VIDEO, AV_CODEC_ID_H264, AV_CODEC_ID_VC1, AV_CODEC_ID_WMV3, AV_CODEC_ID_HEVC, AV_CODEC_ID_VP9. Ffmpeg recognizes files in any of these formats and can try to use dxva2 for hardware acceleration. However, this does not mean that files in these formats must support dxva2 hardware acceleration, because I encountered an AV_CODEC_ID_HEVC file that failed to initialize the configuration of dxva2, and PotPlayer could not use dxva2 hardware acceleration when playing this file)