1、原始视频信息

通过ffmpeg -i命令查看视频基本信息

 ffmpeg -i input.mp4
ffmpeg version 6.1-essentials_build-www.gyan.dev Copyright (c) 2000-2023 the FFmpeg developersbuilt with gcc 12.2.0 (Rev10, Built by MSYS2 project)configuration: --enable-gpl --enable-version3 --enable-static --pkg-config=pkgconf --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-bzlib --enable-lzma --enable-zlib --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-sdl2 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-libaom --enable-libopenjpeg --enable-libvpx --enable-mediafoundation --enable-libass --enable-libfreetype --enable-libfribidi --enable-libharfbuzz --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc --enable-dxva2 --enable-d3d11va --enable-libvpl --enable-libgme --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libtheora --enable-libvo-amrwbenc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-librubberbandlibavutil      58. 29.100 / 58. 29.100libavcodec     60. 31.102 / 60. 31.102libavformat    60. 16.100 / 60. 16.100libavdevice    60.  3.100 / 60.  3.100libavfilter     9. 12.100 /  9. 12.100libswscale      7.  5.100 /  7.  5.100libswresample   4. 12.100 /  4. 12.100libpostproc    57.  3.100 / 57.  3.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0000024c98921a00] st: 0 edit list: 1 Missing key frame while searching for timestamp: 1000
[mov,mp4,m4a,3gp,3g2,mj2 @ 0000024c98921a00] st: 0 edit list 1 Cannot find an index entry before timestamp: 1000.
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'input.mp4':Metadata:major_brand     : mp42minor_version   : 1compatible_brands: mp42hvc1CAEPmake            :make-eng        :model           :model-eng       :creation_time   : 2023-09-14T07:26:06.000000Ztimecode        : 00:25:37:02Duration: 00:07:01.44, start: 0.000000, bitrate: 214391 kb/sStream #0:0[0x1](eng): Video: hevc (Rext) (hvc1 / 0x31637668), yuv422p10le(tv, bt709), 4096x2160, 214092 kb/s, 50 fps, 50 tbr, 50k tbn (default)Metadata:creation_time   : 2023-09-14T07:26:06.000000Zvendor_id       : [0][0][0][0]Stream #0:1[0x2](eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 253 kb/s (default)Metadata:creation_time   : 2023-09-14T07:26:06.000000Zvendor_id       : [0][0][0][0]Stream #0:2[0x3](eng): Data: none (tmcd / 0x64636D74), 1 kb/s (default)Metadata:creation_time   : 2023-09-14T07:26:06.000000Ztimecode        : 00:25:37:02
At least one output file must be specified

通过命令查看，原始视频信息

Video: hevc (Rext) (hvc1 / 0x31637668), yuv422p10le(tv, bt709), 4096x2160, 214092 kb/s, 50 fps, 50 tbr, 50k tbn (default)

2、ffmpeg视频转换-保持清晰度

ffmpeg -i input.mp4 -r 25 -qscale 0 -q:v 1 -c:a aac -b:v 20000k -vf scale=2048:-1 output.mp4

-qscale value：使用固定的视频量化标度(VBR)，以value质量为基础的VBR，取值0.01-255，越小质量越好

-q:v：表示存储jpeg的图像质量

-b:v：设置输出文件的视频比特率（码率）

-c:a：指定音频编码器

-r 输出帧率

-vf：设置视频滤镜，scale=2048:-1，宽度为2048，保持长宽比

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参考自：https://blog.csdn.net/lsb2002/article/details/135276109