video - FFMPEG 编码视频文件所需的时间

Question

我最近一直在使用 FFMPEG 对视频文件进行一些操作，了解语法等，并发现它非常有帮助。我正在寻找一些关于编码文件速度的反馈。例如，我对一个长度为 1 小时、文件扩展名为 .mov 且大小为 4GB 的视频文件运行以下命令，而该命令只需要 4 个多小时即可运行。它会生成一个 2.2GB 大小的文件。我在高规范 i7 笔记本电脑上运行它。

    ffmpeg -i "C:\MyInputFile.mov" -b:v 4500k -bufsize 4500k -r 50 -bsf:a aac_adtstoasc -vf scale=1920:1080 "C:\MyOutputFile.mp4"

Please see following the log created at the start of the encoding. I dont have the full log unless I let it run again for 4 hours!

    -i "C:\MyInputFile.mov" -b:v 4500k -bufsize 4500k -r 50 -bsf:a aac_adtstoasc -vf scale=1920:1080 "C:\MyOutputFile.mp4"
ffmpeg version 4.2.2 Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 9.2.1 (GCC) 20200122
  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-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-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-amf --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'C:\MyInputFile.mov':
  Metadata:
    major_brand     : qt
    minor_version   : 537199360
    compatible_brands: qt
    creation_time   : 2019-06-24T18:14:35.000000Z
    timecode        : 10:00:00:00
  Duration: 01:09:20.12, start: 0.000000, bitrate: 8092 kb/s
    Stream #0:0(eng): Video: mpeg4 (Advanced Simple Profile) (mp4v / 0x7634706D), yuv420p(pc, smpte170m/unknown/smpte170m), 1024x576 [SAR 1:1 DAR 16:9], 6553 kb/s, 25 fps, 25 tbr, 25k tbn, 1k tbc (default)
    Metadata:
      creation_time   : 2019-06-24T18:14:35.000000Z
      handler_name    : Apple Video Media Handler
      encoder         : MPEG-4 Video
    Stream #0:1(eng): Audio: pcm_s16le (sowt / 0x74776F73), 48000 Hz, stereo, s16, 1536 kb/s (default)
    Metadata:
      creation_time   : 2019-06-24T18:14:36.000000Z
      handler_name    : Apple Sound Media Handler
    Stream #0:2(eng): Data: none (tmcd / 0x64636D74) (default)
    Metadata:
      creation_time   : 2019-06-24T19:32:28.000000Z
      handler_name    : Time Code Media Handler
      timecode        : 10:00:00:00
Stream mapping:
  Stream #0:0 -> #0:0 (mpeg4 (native) -> h264 (libx264))
  Stream #0:1 -> #0:1 (pcm_s16le (native) -> aac (native))
Press [q] to stop, [?] for help
[libx264 @ 000001d8655322c0] VBV maxrate unspecified, assuming CBR
[libx264 @ 000001d8655322c0] using SAR=1/1
[libx264 @ 000001d8655322c0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 000001d8655322c0] profile High, level 4.2, 4:2:0, 8-bit
[libx264 @ 000001d8655322c0] 264 - core 159 - H.264/MPEG-4 AVC codec - Copyleft 2003-2019 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1
chroma_qp_offset=-2 threads=6 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=cbr mbtree=1 bitrate=4500 ratetol=1.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 vbv_maxrate=4500 vbv_bufsize=4500 nal_hrd=none filler=0 ip_ratio=1.40 aq=1:1.00
Output #0, mp4, to ' C:\MyOutputFile.mp4':
  Metadata:
    major_brand     : qt
    minor_version   : 537199360
    compatible_brands: qt
    timecode        : 10:00:00:00
    encoder         : Lavf58.29.100
    Stream #0:0(eng): Video: h264 (libx264) (avc1 / 0x31637661), yuv420p(progressive), 1920x1080 [SAR 1:1 DAR 16:9], q=-1--1, 4500 kb/s, 0.02 fps, 12800 tbn, 50 tbc (default)
    Metadata:
      creation_time   : 2019-06-24T18:14:35.000000Z
      handler_name    : Apple Video Media Handler
      encoder         : Lavc58.54.100 libx264
    Side data:
      cpb: bitrate max/min/avg: 0/0/4500000 buffer size: 4500000 vbv_delay: -1
    Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 128 kb/s (default)
    Metadata:
      creation_time   : 2019-06-24T18:14:36.000000Z
      handler_name    : Apple Sound Media Handler
      encoder         : Lavc58.54.100 aac
frame=  273 fps= 21 q=31.0 size=    2048kB time=00:00:05.44 bitrate=3084.1kbits/s dup=136 drop=0 speed=0.415x

我可以对命令进行任何修改以在更短的时间内对其进行编码吗？

Answer 1

流复制

I need to recnode it so that software I have can work with it - will only work with mp4 files.

您的输入视频是 MPEG-4 视频。音频是 PCM。 MP4 接受 MPEG-4 视频，因此您可以 stream copy视频，只重新编码音频:

ffmpeg -i input.mov -c:v copy -c:a aac output.mp4

如果“mp4 文件”是指“H.264 视频”，那么您的软件当然可能不支持 MPEG-4 视频，您必须将其重新编码为 H.264。

如果你必须重新编码

您的命令使用编码器 libx264 输出 H.264 视频。使用更快的 libx264 -preset .

除非需要，否则不要将帧速率加倍。删除 -r 50 .

通常不建议升级。删除 -vf scale=1920:1080 .

对速度没有影响，但删除 -bsf:a aac_adtstoasc因为它会在需要时自动应用。

using cpu capabilities在你的日志中没有说none!这很好。

调查hardware accelerated decoding/filtering/encoding .这些编码器针对速度进行了优化，对于 H.264 编码可能比 x264 更快，但在相同比特率的情况下，它们无法匹配 x264 质量。