bash - 将 ffmpeg 控制台输出中的行保存到 bash 变量

Question

执行任何 ffmpeg 命令后

ffmpeg -i "in.mov" -c:v libx264 "out.mp4"

在控制台中输出了很多编码统计信息，例如

  ffmpeg version git-2020-07-15-a54b367 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 9.3.1 (GCC) 20200621
  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 --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. 55.100 / 56. 55.100
  libavcodec     58. 96.100 / 58. 96.100
  libavformat    58. 48.100 / 58. 48.100
  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 'in.mov':
  Metadata:
    major_brand     : qt
    minor_version   : 512
    compatible_brands: qt
    creation_time   : 2021-11-19T04:54:24.000000Z
    encoder         : Blackmagic Design DaVinci Resolve Studio
  Duration: 00:00:15.02, start: 0.000000, bitrate: 513581 kb/s
    Stream #0:0: Video: dnxhd (DNXHR SQ) (AVdh / 0x68645641), yuv422p(tv, bt709/bt709/unknown), 2560x1440, 511272 kb/s, SAR 1:1 DAR 16:9, 60 fps, 60 tbr, 15360 tbn, 15360 tbc (default)
    Metadata:
      creation_time   : 2021-11-19T04:54:24.000000Z
      handler_name    : VideoHandler
      encoder         : DNxHR SQ
      timecode        : 00:32:01:20
    Stream #0:1: Audio: pcm_s24le (lpcm / 0x6D63706C), 48000 Hz, stereo, s32 (24 bit), 2304 kb/s (default)
    Metadata:
      creation_time   : 2021-11-19T04:54:24.000000Z
      handler_name    : SoundHandler
    Stream #0:2(eng): Data: none (tmcd / 0x64636D74), 0 kb/s
    Metadata:
      creation_time   : 2021-11-19T04:54:24.000000Z
      handler_name    : TimeCodeHandler
      timecode        : 00:32:01:20
Stream mapping:
  Stream #0:0 -> #0:0 (dnxhd (native) -> h264 (libx264))
  Stream #0:1 -> #0:1 (pcm_s24le (native) -> aac (native))
Press [q] to stop, [?] for help
[libx264 @ 000001f24216e180] using SAR=1/1
[libx264 @ 000001f24216e180] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 000001f24216e180] profile High 4:2:2, level 5.1, 4:2:2, 8-bit
[libx264 @ 000001f24216e180] 264 - core 160 - H.264/MPEG-4 AVC codec - Copyleft 2003-2020 - 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=36 lookahead_threads=6 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=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, mp4, to 'out.mp4':
  Metadata:
    major_brand     : qt
    minor_version   : 512
    compatible_brands: qt
    encoder         : Lavf58.48.100
    Stream #0:0: Video: h264 (libx264) (avc1 / 0x31637661), yuv422p(progressive), 2560x1440 [SAR 1:1 DAR 16:9], q=-1--1, 0.02 fps, 15360 tbn, 60 tbc (default)
    Metadata:
      creation_time   : 2021-11-19T04:54:24.000000Z
      handler_name    : VideoHandler
      timecode        : 00:32:01:20
      encoder         : Lavc58.96.100 libx264
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
    Stream #0:1: Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp (24 bit), 128 kb/s (default)
    Metadata:
      creation_time   : 2021-11-19T04:54:24.000000Z
      handler_name    : SoundHandler
      encoder         : Lavc58.96.100 aac
frame=  901 fps= 60 q=-1.0 Lsize=   99089kB time=00:00:15.01 bitrate=54048.5kbits/s speed=   1x    
video:98829kB audio:235kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.024975%
[libx264 @ 000001f24216e180] frame I:7     Avg QP:27.22  size:382635
[libx264 @ 000001f24216e180] frame P:276   Avg QP:29.78  size:217960
[libx264 @ 000001f24216e180] frame B:618   Avg QP:33.24  size: 62079
[libx264 @ 000001f24216e180] consecutive B-frames:  8.4%  0.2%  0.3% 91.0%
[libx264 @ 000001f24216e180] mb I  I16..4:  2.8% 85.3% 11.8%
[libx264 @ 000001f24216e180] mb P  I16..4:  1.2% 24.3%  3.5%  P16..4: 28.1% 25.0% 14.0%  0.0%  0.0%    skip: 3.8%
[libx264 @ 000001f24216e180] mb B  I16..4:  0.0%  0.8%  0.2%  B16..8: 44.2% 12.3%  4.1%  direct: 6.9%  skip:31.5%  L0:38.4% L1:37.0% BI:24.7%
[libx264 @ 000001f24216e180] 8x8 transform intra:83.3% inter:52.4%
[libx264 @ 000001f24216e180] coded y,uvDC,uvAC intra: 83.2% 82.7% 23.4% inter: 33.1% 24.3% 1.9%
[libx264 @ 000001f24216e180] i16 v,h,dc,p: 13% 49%  7% 31%
[libx264 @ 000001f24216e180] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 13% 22% 14%  6%  8%  8% 11%  8% 10%
[libx264 @ 000001f24216e180] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 15% 21% 11%  7% 11% 10% 11%  7%  7%
[libx264 @ 000001f24216e180] i8c dc,h,v,p: 55% 16% 22%  7%
[libx264 @ 000001f24216e180] Weighted P-Frames: Y:5.1% UV:2.9%
[libx264 @ 000001f24216e180] ref P L0: 60.6% 17.4% 18.7%  3.2%  0.1%
[libx264 @ 000001f24216e180] ref B L0: 96.2%  3.2%  0.5%
[libx264 @ 000001f24216e180] ref B L1: 99.0%  1.0%
[libx264 @ 000001f24216e180] kb/s:53913.39
[aac @ 000001f242170dc0] Qavg: 235.206

运行 ffmpeg 命令后，我想保存以下行

Lsize=   99089kB time=00:00:15.01 bitrate=54048.5kbits/s speed=   1x

bash 变量，以便我稍后可以在脚本中使用此信息。可能吗？
我尝试使用 x=$(ffmpeg ...) 语法来做到这一点，但之后变量为空

Answer 1

尝试这样的事情:

x=$(ffmpeg... 2>&1 | grep -Eo 'Lsize=.*$')