Audio 如何在不改变质量和帧率的情况下压缩视频大小（Ffmpeg）？

我正在使用此命令压缩我的视频：

ffmpeg -y -i video.mp4 -vcodec libx264 -crf 24 -preset ultrafast compressed.mp4

虽然它工作正常，但是持续时间略有增加，因为我正在更改视频的帧率，我们需要视频的精确持续时间。有没有一种方法可以在不改变帧率的情况下压缩视频？任何帮助都将不胜感激。多谢各位

日志：

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我看不到您的命令中使用了

-r

选项或fps过滤器来更改帧速率。你怎么知道帧速率在变化？我想我在什么地方读到crf代表24 fps。抱歉，如果我错了，但是压缩时持续时间仍然会增加。CRF是恒定速率因子，这是控制比特率和质量的几种方法之一。我建议阅读更多信息。你怎么知道持续时间在变化？请复制并粘贴命令中的完整日志。谢谢，我们将对此进行更多检查。当我在10秒视频上应用该命令时，压缩后的时间变为11秒，但这种情况只发生了几次，这就是为什么我要求使用该命令的替代方法。没有，我只是使用文件属性（Windows）检查了持续时间

ffmpeg version git-2020-08-31-4a11a6f Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 10.2.1 (GCC) 20200805
  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libsrt --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libgsm --enable-librav1e --enable-libsvtav1 --disable-w32threads --enable-libmfx --enable-ffnvcodec --enable-cuda-llvm --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
  libavutil      56. 58.100 / 56. 58.100
  libavcodec     58.101.101 / 58.101.101
  libavformat    58. 51.101 / 58. 51.101
  libavdevice    58. 11.101 / 58. 11.101
  libavfilter     7. 87.100 /  7. 87.100
  libswscale      5.  8.100 /  5.  8.100
  libswresample   3.  8.100 /  3.  8.100
  libpostproc    55.  8.100 / 55.  8.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '1600498063375.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isommp42
    creation_time   : 2020-09-19T06:47:54.000000Z
    com.android.version: 10
  Duration: 00:00:10.53, start: 0.000000, bitrate: 4613 kb/s
    Stream #0:0(eng): Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p(tv, bt709), 776x1440, 4611 kb/s, SAR 1:1 DAR 97:180, 19.11 fps, 16.42 tbr, 90k tbn, 180k tbc (default)
    Metadata:
      creation_time   : 2020-09-19T06:47:54.000000Z
      handler_name    : VideoHandle
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
Press [q] to stop, [?] for help
[libx264 @ 000001e25a673ac0] using SAR=1/1
[libx264 @ 000001e25a673ac0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 000001e25a673ac0] profile Constrained Baseline, level 3.2, 4:2:0, 8-bit
[libx264 @ 000001e25a673ac0] 264 - core 161 - H.264/MPEG-4 AVC codec - Copyleft 2003-2020 - http://www.videolan.org/x264.html - options: cabac=0 ref=1 deblock=0:0:0 analyse=0:0 me=dia subme=0 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=0 threads=6 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=0 keyint=250 keyint_min=16 scenecut=0 intra_refresh=0 rc=crf mbtree=0 crf=24.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=0
Output #0, mp4, to 'compressed.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isommp42
    com.android.version: 10
    encoder         : Lavf58.51.101
    Stream #0:0(eng): Video: h264 (libx264) (avc1 / 0x31637661), yuv420p, 776x1440 [SAR 1:1 DAR 97:180], q=-1--1, 16.42 fps, 12608 tbn, 16.42 tbc (default)
    Metadata:
      creation_time   : 2020-09-19T06:47:54.000000Z
      handler_name    : VideoHandle
      encoder         : Lavc58.101.101 libx264
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
frame=  181 fps= 95 q=-1.0 Lsize=    5244kB time=00:00:10.96 bitrate=3918.2kbits/s dup=1 drop=29 speed=5.76x
video:5243kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.030269%
[libx264 @ 000001e25a673ac0] frame I:1     Avg QP:21.00  size: 92845
[libx264 @ 000001e25a673ac0] frame P:180   Avg QP:22.42  size: 29306
[libx264 @ 000001e25a673ac0] mb I  I16..4: 100.0%  0.0%  0.0%
[libx264 @ 000001e25a673ac0] mb P  I16..4: 35.6%  0.0%  0.0%  P16..4: 39.9%  0.0%  0.0%  0.0%  0.0%    skip:24.6%
[libx264 @ 000001e25a673ac0] coded y,uvDC,uvAC intra: 34.6% 31.8% 2.5% inter: 28.7% 17.1% 0.7%
[libx264 @ 000001e25a673ac0] i16 v,h,dc,p: 38% 18% 20% 23%
[libx264 @ 000001e25a673ac0] i8c dc,h,v,p: 48% 17% 25%  9%
[libx264 @ 000001e25a673ac0] kb/s:3894.93