ffmpeg:-copyts 使 -t 停止在时间戳，而不是持续时间

Question

从

-t duration (input/output)

When used as an input option (before -i), limit the duration of data read from the input file.

When used as an output option (before an output url), stop writing the output after its duration reaches duration.

所以这应该产生一个 1 分钟的文件，时间戳从 1:49 开始，对吧？

ffmpeg -y -copyts -ss 1:49 -i ~/Videos/input.mkv -c copy -t 1:00 timing-1m49s.mkv 
ffmpeg version 3.3.2 Copyright (c) 2000-2017 the FFmpeg developers
  built with gcc 7 (SUSE Linux)
  configuration: --prefix=/usr --libdir=/usr/lib64 --shlibdir=/usr/lib64 --incdir=/usr/include/ffmpeg --extra-cflags='-fmessage-length=0 -grecord-gcc-switches -O2 -Wall -D_FORTIFY_SOURCE=2 -fstack-protector-strong -funwind-tables -fasynchronous-unwind-tables -g' --optflags='-fmessage-length=0 -grecord-gcc-switches -O2 -Wall -D_FORTIFY_SOURCE=2 -fstack-protector-strong -funwind-tables -fasynchronous-unwind-tables -g' --disable-htmlpages --enable-pic --disable-stripping --enable-shared --disable-static --enable-gpl --disable-openssl --enable-avresample --enable-libcdio --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libcelt --enable-libcdio --enable-libdc1394 --enable-libfreetype --enable-libgsm --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libwebp --enable-netcdf --enable-vaapi --enable-vdpau --enable-libfdk_aac --enable-nonfree --enable-libmp3lame --enable-libtwolame --enable-libx264 --enable-libx265 --enable-libxvid
  libavutil      55. 58.100 / 55. 58.100
  libavcodec     57. 89.100 / 57. 89.100
  libavformat    57. 71.100 / 57. 71.100
  libavdevice    57.  6.100 / 57.  6.100
  libavfilter     6. 82.100 /  6. 82.100
  libavresample   3.  5.  0 /  3.  5.  0
  libswscale      4.  6.100 /  4.  6.100
  libswresample   2.  7.100 /  2.  7.100
  libpostproc    54.  5.100 / 54.  5.100
Input #0, matroska,webm, from '/home/ariel/Videos/input.mkv':
  Metadata:
    encoder         : libebml v0.7.7 + libmatroska v0.8.0
    creation_time   : 2006-07-20T03:07:03.000000Z
  Duration: 00:23:57.06, start: 0.000000, bitrate: 1983 kb/s
    Stream #0:0: Video: h264 (High), yuv420p(progressive), 720x480, SAR 37:30 DAR 37:20, 29.97 fps, 29.97 tbr, 1k tbn, 59.94 tbc (default)
    Stream #0:1(eng): Audio: ac3, 48000 Hz, stereo, fltp, 192 kb/s (default)
    Stream #0:2(jpn): Audio: ac3, 48000 Hz, stereo, fltp, 192 kb/s
    Stream #0:3(eng): Subtitle: dvd_subtitle, 720x480 (default)
    Metadata:
      title           : English Audio
    Stream #0:4(eng): Subtitle: dvd_subtitle, 720x480
    Metadata:
      title           : Japanese Audio
Output #0, matroska, to 'timing-1m49s.mkv':
  Metadata:
    encoder         : Lavf57.71.100
    Stream #0:0: Video: h264 (High) (H264 / 0x34363248), yuv420p(progressive), 720x480 [SAR 37:30 DAR 37:20], q=2-31, 29.97 fps, 29.97 tbr, 1k tbn, 1k tbc (default)
    Stream #0:1(eng): Audio: ac3 ([0] [0][0] / 0x2000), 48000 Hz, stereo, fltp, 192 kb/s (default)
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
frame=    0 fps=0.0 q=-1.0 Lsize=       1kB time=00:00:00.00 bitrate=N/A speed=   0x    
video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown

错误的。它输出一个没有帧的文件:

-rwxrwx--- 1 root users 805 Jul 30 01:36 timing-1m49s.mkv

我必须指定 -t 1:49或更多，例如 -t 1:55生成一个从 0:00 开始的 6 秒文件，根据元数据应该持续 1:55。

我到了这一点，试图在同一命令中提取剪辑并添加字幕，但这种最小的情况在我看来与文档相反。

Answer 1

是的，-t用作输出选项查看通常从零开始的时间戳。除了 -copyts 时这样的情况。用来。使用-t作为输入选项:

ffmpeg -y -copyts -ss 1:49 -t 1:00 -i ~/Videos/input.mkv -c copy timing-1m49s.mkv