[FFmpeg-trac] #3968(undetermined:new): fieldmatch with decimate generates out-of-sync video

[FFmpeg]

#3968: fieldmatch with decimate generates out-of-sync video
-------------------------------------+-------------------------------------
             Reporter:  myleal       |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:
  undetermined                       |  unspecified
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 When using fieldmatch on some interlaced mpeg video (ntsc dvd source), the
 output was generated with out-of-sync video.

 The input sample has 120 seconds of video + audio, and is available on:

 https://docs.google.com/file/d/0B4PVnH9qRoFRSlRGT19VZ3Zpbmc/edit?pli=1

 After reencoding, The output has 97 seconds of video and 120 seconds of
 audio.

 How to reproduce:

 C:\Temp>"c:\Program Files\ffmpeg\ffmpeg.exe" -i sample.mpg -vf
 fieldmatch,decimate output.mp4

 Output of ffmpeg log 99:

 C:\Temp>"c:\Program Files\ffmpeg\ffmpeg.exe" -v 9 -loglevel 99 -i
 sample.mpg
 ffmpeg version 2.2.4 Copyright (c) 2000-2014 the FFmpeg developers
   built on Jul  7 2014 19:32:48 with gcc 4.8.2 (GCC)
   configuration: --extra-ldflags=-L/usr/local/x86_64-w64-mingw32/lib
 --prefix=/u
 sr/local/x86_64-w64-mingw32 --cross-prefix=x86_64-w64-mingw32- --target-
 os=mingw
 32 --enable-w32threads --enable-memalign-hack --arch=x86_64 --enable-
 runtime-cpu
 detect --disable-debug --enable-static --disable-shared --disable-ffplay
 --disab
 le-ffserver --enable-gpl --enable-version3 --enable-nonfree --enable-
 libmp3lame
 --enable-libfdk-aac --enable-libx264 --enable-libopenjpeg
   libavutil      52. 66.100 / 52. 66.100
   libavcodec     55. 52.102 / 55. 52.102
   libavformat    55. 33.100 / 55. 33.100
   libavdevice    55. 10.100 / 55. 10.100
   libavfilter     4.  2.100 /  4.  2.100
   libswscale      2.  5.102 /  2.  5.102
   libswresample   0. 18.100 /  0. 18.100
   libpostproc    52.  3.100 / 52.  3.100
 Splitting the commandline.
 Reading option '-v' ... matched as option 'v' (set logging level) with
 argument
 '9'.
 Reading option '-loglevel' ... matched as option 'loglevel' (set logging
 level)
 with argument '99'.
 Reading option '-i' ... matched as input file with argument 'sample.mpg'.
 Finished splitting the commandline.
 Parsing a group of options: global .
 Applying option v (set logging level) with argument 9.
 Successfully parsed a group of options.
 Parsing a group of options: input file sample.mpg.
 Successfully parsed a group of options.
 Opening an input file: sample.mpg.
 [mpeg @ 0000000001b17780] Format mpeg probed with size=16384 and score=52
 [mpeg @ 0000000001b17780] Before avformat_find_stream_info() pos: 0 bytes
 read:3
 2768 seeks:0
 [mpeg @ 0000000001b17780] probing stream 0 pp:2500
 [mpeg @ 0000000001b17780] Probe with size=2002, packets=1 detected
 mpegvideo wit
 h score=25
 [mpeg @ 0000000001b17780] probed stream 0
 [mpeg @ 0000000001b17780] max_analyze_duration 5000000 reached at 5005000
 micros
 econds
 rfps: 29.916667 0.005978
     Last message repeated 1 times
 rfps: 30.000000 0.002044
 rfps: 59.916667 0.001354
     Last message repeated 1 times
 rfps: 60.000000 0.008178
 rfps: 29.970030 0.000076
     Last message repeated 1 times
 rfps: 59.940060 0.000304
     Last message repeated 1 times
 [mpeg @ 0000000001b17780] After avformat_find_stream_info() pos: 0 bytes
 read:29
 69744 seeks:2 frames:298
 Input #0, mpeg, from 'sample.mpg':
   Duration: 00:02:00.10, start: 0.600000, bitrate: 6081 kb/s
     Stream #0:0[0x1e0], 152, 1/90000: Video: mpeg2video (Main),
 yuv420p(tv), 720
 x480 [SAR 8:9 DAR 4:3], 1001/60000, max. 8801 kb/s, 29.97 fps, 29.97 tbr,
 90k tb
 n, 59.94 tbc
     Stream #0:1[0x80], 146, 1/90000: Audio: ac3, 48000 Hz, 5.1(side),
 fltp, 384
 kb/s
 Successfully opened the file.
 At least one output file must be specified
 [AVIOContext @ 0000000001b1fee0] Statistics: 2969744 bytes read, 2 seeks
 Conversion failed!

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Ticket URL: <https://trac.ffmpeg.org/ticket/3968>
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