[FFmpeg-trac] #4944(documentation:new): -r output option misguiding documentation

FFmpeg trac at avcodec.org
Mon Oct 19 15:34:03 CEST 2015


#4944: -r output option misguiding documentation
-------------------------------------+-------------------------------------
             Reporter:  basinilya    |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:
  documentation                      |  unspecified
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Summary of the bug:
 {{{
 doc/ffmpeg.texi:As an output option, duplicate or drop input frames to
 achieve constant output
 }}}

 In fact, that sounds more like the description of the fps filter. What
 '-r' option actually does, is set the declared fps of a video stream
 without actually duplicating frames (it may drop frames though).

 The following example produces a 2-second 4fps video and uses '-r 120'.
 The demuxer says: '120 fps', but prints only 8 frames with proper PTS.

 {{{
 $ ffmpeg -y -f lavfi -i testsrc=s=720x576:r=4:d=2 -r 120 -pix_fmt yuv422p
 -vcodec rawvideo -f matroska - 2>/dev/null | ffmpeg -f matroska -i - -vf
 "showinfo" -f null x
 ffmpeg version N-72058-g3ecc063 Copyright (c) 2000-2015 the FFmpeg
 developers
   built with gcc 4.9.2 (GCC)
   configuration: --disable-static --enable-shared --enable-gpl --enable-
 version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-
 fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass
 --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libdcadec
 --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc
 --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb
 --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-
 librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex
 --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-
 aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx
 --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265
 --enable-libxavs --enable-libxvid --enable-lzma --enable-decklink
 --enable-zlib
   libavutil      54. 23.101 / 54. 23.101
   libavcodec     56. 38.100 / 56. 38.100
   libavformat    56. 33.100 / 56. 33.100
   libavdevice    56.  4.100 / 56.  4.100
   libavfilter     5. 16.101 /  5. 16.101
   libswscale      3.  1.101 /  3.  1.101
   libswresample   1.  1.100 /  1.  1.100
   libpostproc    53.  3.100 / 53.  3.100
 Input #0, matroska,webm, from 'pipe:':
   Metadata:
     ENCODER         : Lavf56.33.100
   Duration: N/A, start: 0.000000, bitrate: N/A
     Stream #0:0: Video: rawvideo (Y42B / 0x42323459), yuv422p, 720x576,
 SAR 1:1 DAR 5:4, 120 fps, 120 tbr, 1k tbn, 1k tbc (default)
     Metadata:
       ENCODER         : Lavc56.38.100 rawvideo
 [Parsed_showinfo_0 @ 0000000002a03f20] config in time_base: 1/1000,
 frame_rate: 120/1
 [Parsed_showinfo_0 @ 0000000002a03f20] config out time_base: 0/0,
 frame_rate: 0/0
 Output #0, null, to 'x':
   Metadata:
     encoder         : Lavf56.33.100
     Stream #0:0: Video: rawvideo (Y42B / 0x42323459), yuv422p, 720x576
 [SAR 1:1 DAR 5:4], q=2-31, 200 kb/s, 120 fps, 120 tbn, 120 tbc (default)
     Metadata:
       encoder         : Lavc56.38.100 rawvideo
 Stream mapping:
   Stream #0:0 -> #0:0 (rawvideo (native) -> rawvideo (native))
 [Parsed_showinfo_0 @ 0000000002a03f20] n:   0 pts:      0 pts_time:0
 pos:      618 fmt:yuv422p sar:1/1 s:720x576 i:P iskey:1 type:I
 checksum:8B0AA2CB plane_checksum:[87271B24 F6292B83 9D3A5C24] mean:[126
 129 126] stdev:[71.4 70.2 72.6]
 [null @ 0000000002a02be0] Encoder did not produce proper pts, making some
 up.
 [Parsed_showinfo_0 @ 0000000002a03f20] n:   1 pts:    250 pts_time:0.25
 pos:   830081 fmt:yuv422p sar:1/1 s:720x576 i:P iskey:1 type:I
 checksum:5C15AB10 plane_checksum:[C538A9E0 3585795C 479987C5] mean:[126
 129 126] stdev:[71.4 70.2 72.7]
 [Parsed_showinfo_0 @ 0000000002a03f20] n:   2 pts:    500 pts_time:0.5
 pos:  1659545 fmt:yuv422p sar:1/1 s:720x576 i:P iskey:1 type:I
 checksum:B10C5D37 plane_checksum:[9A6BC88B 93E6BB84 18B8D90A] mean:[126
 129 126] stdev:[71.4 70.1 72.8]
 [Parsed_showinfo_0 @ 0000000002a03f20] n:   3 pts:    750 pts_time:0.75
 pos:  2489009 fmt:yuv422p sar:1/1 s:720x576 i:P iskey:1 type:I
 checksum:8D290D16 plane_checksum:[F3FAE338 28B7FC3F AEDA2D81] mean:[125
 129 126] stdev:[71.4 70.0 72.9]
 [Parsed_showinfo_0 @ 0000000002a03f20] n:   4 pts:   1000 pts_time:1
 pos:  3318473 fmt:yuv422p sar:1/1 s:720x576 i:P iskey:1 type:I
 checksum:11BC56BD plane_checksum:[B4839897 9F273F08 9A537F0F] mean:[124
 129 126] stdev:[71.3 69.9 72.9]
 [Parsed_showinfo_0 @ 0000000002a03f20] n:   5 pts:   1250 pts_time:1.25
 pos:  4147937 fmt:yuv422p sar:1/1 s:720x576 i:P iskey:1 type:I
 checksum:1A09A329 plane_checksum:[ADA1817E F1454629 5FF1DB73] mean:[124
 129 126] stdev:[71.2 69.9 73.0]
 [Parsed_showinfo_0 @ 0000000002a03f20] n:   6 pts:   1500 pts_time:1.5
 pos:  4977401 fmt:yuv422p sar:1/1 s:720x576 i:P iskey:1 type:I
 checksum:F5CF596F plane_checksum:[27E9F6FA 831823A8 7D483EBE] mean:[124
 129 126] stdev:[71.3 70.0 73.0]
 [Parsed_showinfo_0 @ 0000000002a03f20] n:   7 pts:   1750 pts_time:1.75
 pos:  5806865 fmt:yuv422p sar:1/1 s:720x576 i:P iskey:1 type:I
 checksum:22CD0DB6 plane_checksum:[816D6A3D 14230294 6028A0D6] mean:[125
 129 127] stdev:[71.4 70.0 72.9]
 frame=    8 fps=0.0 q=0.0 Lsize=N/A time=00:00:01.75 bitrate=N/A
 video:1kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
 muxing overhead: unknown
 }}}
 Please fix the doc.

--
Ticket URL: <https://trac.ffmpeg.org/ticket/4944>
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