FFmpeg:改变帧速率的记录方法不起作用

Question

根据 here 上的 FFmpeg 文档，我可以使用以下方法更改视频的帧速率:

ffmpeg -i input.mkv -c:v copy -vsync drop -r 59.94 output.mkv

但我得到的只是 av_interleaved_write_frame(): Invalid argument我的机器上的错误。我究竟做错了什么？

这是日志:

ffmpeg -i noaudio.mp4 -c:v copy -vsync drop -r 160 lapse.mp4

ffmpeg version 4.1 Copyright (c) 2000-2018 the FFmpeg developers
  built with Apple LLVM version 10.0.0 (clang-1000.11.45.5)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/4.1_1 --enable-shared --enable-pthreads --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gpl --enable-libmp3lame --enable-libopus --enable-libsnappy --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxvid --enable-lzma --enable-opencl --enable-videotoolbox
  libavutil      56. 22.100 / 56. 22.100
  libavcodec     58. 35.100 / 58. 35.100
  libavformat    58. 20.100 / 58. 20.100
  libavdevice    58.  5.100 / 58.  5.100
  libavfilter     7. 40.101 /  7. 40.101
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  3.100 /  5.  3.100
  libswresample   3.  3.100 /  3.  3.100
  libpostproc    55.  3.100 / 55.  3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'noaudio.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.20.100
  Duration: 00:12:31.45, start: 0.000000, bitrate: 59950 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuvj420p(pc, bt709), 3840x2160 [SAR 1:1 DAR 16:9], 59948 kb/s, 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc (default)
    Metadata:
      handler_name    : VideoHandler
File 'lapse.mp4' already exists. Overwrite ? [y/N] y
Output #0, mp4, to 'lapse.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.20.100
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuvj420p(pc, bt709), 3840x2160 [SAR 1:1 DAR 16:9], q=2-31, 59948 kb/s, 29.97 fps, 29.97 tbr, 10240 tbn, 160 tbc (default)
    Metadata:
      handler_name    : VideoHandler
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
Press [q] to stop, [?] for help
[mp4 @ 0x7fec5400e000] Timestamps are unset in a packet for stream 0. This is deprecated and will stop working in the future. Fix your code to set the timestamps properly
av_interleaved_write_frame(): Invalid argument
frame=    1 fps=0.0 q=-1.0 Lsize=       0kB time=-577014:32:22.77 bitrate=N/A speed=N/A
video:794kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
Conversion failed!

Answer 1

如果不重新编码视频文件，您将无法更改帧速率，因此 -c:v copy 将不起作用。尝试使用 -c:v libx264 -b:v -r 59.94 和您可能需要的任何其他选项。