ffmpeg sdl输出帧率太高

Question

我正在使用以下命令行通过SDL播放视频：

ffmpeg -i input.mkv -f sdl "Video"

视频播放太快，ffmpeg打印出帧率约为500（不是恒定的，只是尽可能快地播放），我尝试如下限制帧率，但是这些都没有任何效果：

ffmpeg -i input.mkv -r 25 -f sdl "Video"  
ffmpeg -i input.mkv -f sdl -r 25 "Video"  
ffmpeg -i input.mkv -framerate 25 -f sdl "Video"  
ffmpeg -i input.mkv -f sdl -framerate 25 "Video"  

我在Windows 7上使用ffmpeg版本ffmpeg-20150605-git-7be0f48-win64-static
ffplay input.mkv效果很好。

谢谢！

编辑： ffmpeg -i input.mkv -r 25 -f sdl "Video"控制台输出如下：

ffmpeg version N-72662-g7be0f48 Copyright (c) 2000-2015 the FFmpeg developers
  built with gcc 4.9.2 (GCC)
  configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-av
isynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enab
le-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --
enable-libdcadec --enable-libfreetype --enable-libgme --enable-libgsm --enable-l
ibilbc --enable-libmodplug --enable-libmfx --enable-libmp3lame --enable-libopenc
ore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --ena
ble-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable
-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-aacenc --enabl
e-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable
-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --e
nable-lzma --enable-decklink --enable-zlib
  libavutil      54. 26.101 / 54. 26.101
  libavcodec     56. 41.101 / 56. 41.101
  libavformat    56. 34.100 / 56. 34.100
  libavdevice    56.  4.100 / 56.  4.100
  libavfilter     5. 16.101 /  5. 16.101
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  2.100 /  1.  2.100
  libpostproc    53.  3.100 / 53.  3.100
Input #0, matroska,webm, from 'input.mkv':
  Metadata:
    ENCODER         : Lavf56.34.100
  Duration: 00:20:00.20, start: 0.000000, bitrate: 1006 kb/s
    Stream #0:0: Video: h264 (High), yuv420p, 720x304, SAR 1:1 DAR 45:19, 23.98
fps, 23.98 tbr, 1k tbn, 47.95 tbc (default)
    Metadata:
      BPS             : 813254
      BPS-eng         : 813254
      DURATION        : 02:13:35.090000000
      DURATION-eng    : 02:13:35.090000000
      NUMBER_OF_FRAMES: 192170
      NUMBER_OF_FRAMES-eng: 192170
      NUMBER_OF_BYTES : 814788601
      NUMBER_OF_BYTES-eng: 814788601
      _STATISTICS_WRITING_APP: mkvmerge v7.0.0 ('Where We Going') 32bit built on
 Jun  9 2014 15:08:34
      _STATISTICS_WRITING_APP-eng: mkvmerge v7.0.0 ('Where We Going') 32bit buil
t on Jun  9 2014 15:08:34
      _STATISTICS_WRITING_DATE_UTC: 2015-01-07 06:01:37
      _STATISTICS_WRITING_DATE_UTC-eng: 2015-01-07 06:01:37
      _STATISTICS_TAGS: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
      _STATISTICS_TAGS-eng: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
    Stream #0:1(eng): Audio: aac (LC), 48000 Hz, 5.1, fltp (default)
    Metadata:
      LANGUAGE        : eng
      BPS             : 185184
      BPS-eng         : 185184
      DURATION        : 02:13:35.125000000
      DURATION-eng    : 02:13:35.125000000
      NUMBER_OF_FRAMES: 375709
      NUMBER_OF_FRAMES-eng: 375709
      NUMBER_OF_BYTES : 185534548
      NUMBER_OF_BYTES-eng: 185534548
      _STATISTICS_WRITING_APP: mkvmerge v7.0.0 ('Where We Going') 32bit built on
 Jun  9 2014 15:08:34
      _STATISTICS_WRITING_APP-eng: mkvmerge v7.0.0 ('Where We Going') 32bit buil
t on Jun  9 2014 15:08:34
      _STATISTICS_WRITING_DATE_UTC: 2015-01-07 06:01:37
      _STATISTICS_WRITING_DATE_UTC-eng: 2015-01-07 06:01:37
      _STATISTICS_TAGS: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
      _STATISTICS_TAGS-eng: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
Output #0, sdl, to 'Video':
  Metadata:
    encoder         : Lavf56.34.100
    Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 720x304 [SAR 1:1
DAR 45:19], q=2-31, 200 kb/s, 25 fps, 25 tbn, 25 tbc (default)
    Metadata:
      BPS             : 813254
      BPS-eng         : 813254
      DURATION        : 02:13:35.090000000
      DURATION-eng    : 02:13:35.090000000
      NUMBER_OF_FRAMES: 192170
      NUMBER_OF_FRAMES-eng: 192170
      NUMBER_OF_BYTES : 814788601
      NUMBER_OF_BYTES-eng: 814788601
      _STATISTICS_WRITING_APP: mkvmerge v7.0.0 ('Where We Going') 32bit built on
 Jun  9 2014 15:08:34
      _STATISTICS_WRITING_APP-eng: mkvmerge v7.0.0 ('Where We Going') 32bit buil
t on Jun  9 2014 15:08:34
      _STATISTICS_WRITING_DATE_UTC: 2015-01-07 06:01:37
      _STATISTICS_WRITING_DATE_UTC-eng: 2015-01-07 06:01:37
      _STATISTICS_TAGS: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
      _STATISTICS_TAGS-eng: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
      encoder         : Lavc56.41.101 rawvideo
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> rawvideo (native))
Press [q] to stop, [?] for help
frame=28726 fps=244 q=0.0 Lsize=N/A time=00:20:00.20 bitrate=N/A
video:9210274kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxi
ng overhead: unknown

Answer 1

经过实验和阅读文档，我终于找到了我的问题的答案：

ffmpeg -re -i input.mkv -f sdl "Video"

说明 ： -r ， -framerate选项以及fps过滤器均会影响产生的视频帧率，并将其作为元数据写入输出文件，以供以后由视频播放器使用。 对于sdl （和其他一些）而言，这是无效的，因为视频只是逐帧输出到OpenGL表面。 执行此操作的速度仅取决于ffmpeg处理速度（在我的情况下约为500fps）。 为了限制这一点，存在-re选项，该选项将处理速度设置为输入所定义的速度。