framerate filter duplicates last frame when converting 25 to 24 fps

[rmk]

Execute the command line below and look at the last two frames of the output and its duration (is one frame too many, because it should be 1s as the input (24 frames width duration 1/24)).

Command line (adjust the font file path for your os) and output:

ffmpeg -f lavfi -i testsrc=640x480:d=1:r=25 -vcodec mpeg4 -vf drawtext="fontfile=/System/Library/Fonts/Courier.dfont:text='Frame %{n}':x=85:y=H/2+lh/2+descent-ascent:fontsize=48:fontcolor=black",framerate=fps=24 -q:v 1 -y 25_to_24_1s.mov
ffmpeg version git-2015-09-15-f6ef8f2 Copyright (c) 2000-2015 the FFmpeg developers
  built with Apple LLVM version 6.0 (clang-600.0.57) (based on LLVM 3.5svn)
  configuration: --enable-shared --disable-static --disable-doc --disable-devices --enable-indev=lavfi --prefix=/Users/teamcity/buildAgent/work/3b1b1b1b725f407e/build/ffmpeg --extra-cflags=-I/Users/teamcity/buildAgent/work/3b1b1b1b725f407e/build/libmp3lame/include/ --extra-ldflags=-L/Users/teamcity/buildAgent/work/3b1b1b1b725f407e/build/libmp3lame/lib/ --extra-ldflags='-Wl,-rpath,@loader_path/../lib' --enable-libmp3lame --enable-libopenh264 --enable-libfreetype
  libavutil      55.  2.100 / 55.  2.100
  libavcodec     57.  1.100 / 57.  1.100
  libavformat    57.  0.100 / 57.  0.100
  libavdevice    57.  0.100 / 57.  0.100
  libavfilter     6.  3.100 /  6.  3.100
  libswscale      4.  0.100 /  4.  0.100
  libswresample   2.  0.100 /  2.  0.100
Input #0, lavfi, from 'testsrc=640x480:d=1:r=25':
  Duration: N/A, start: 0.000000, bitrate: N/A
    Stream #0:0: Video: rawvideo (RGB[24] / 0x18424752), rgb24, 640x480 [SAR 1:1 DAR 4:3], 25 tbr, 25 tbn, 25 tbc
[Parsed_framerate_1 @ 0x101f03640] time base:1/25 -> 1/600 exact:1
[Parsed_framerate_1 @ 0x101f03640] fps -> fps:24/1 scene score:7.000000 interpolate start:15 end:240
Output #0, mov, to '25_to_24_1s.mov':
  Metadata:
    encoder         : Lavf57.0.100
    Stream #0:0: Video: mpeg4 (mp4v / 0x7634706D), yuv420p, 640x480 [SAR 1:1 DAR 4:3], q=2-31, 200 kb/s, 24 fps, 12288 tbn, 24 tbc
    Metadata:
      encoder         : Lavc57.1.100 mpeg4
Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo (native) -> mpeg4 (native))
Press [q] to stop, [?] for help
frame=   25 fps=0.0 q=1.0 Lsize=     100kB time=00:00:01.04 bitrate= 787.9kbits/s    
video:99kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.922774%

[Marton Balint]

Fixed in 0c31a3876d9a522add43ab62a9bcd3d857b28436.