[FFmpeg-trac] #7055(ffmpeg:new): Using decimate allows EIA-608 captions to pass through to MP4 file even when the -sn option is uses

FFmpeg trac at avcodec.org
Sun Mar 4 02:56:08 EET 2018

#7055: Using decimate allows EIA-608 captions to pass through to MP4 file even
when the -sn option is uses
             Reporter:  navilor      |                     Type:  defect
               Status:  new          |                 Priority:  minor
            Component:  ffmpeg       |                  Version:  3.4
             Keywords:  decimate,    |               Blocked By:
  captions                           |  Reproduced by developer:  0
             Blocking:               |
Analyzed by developer:  0            |
 '''Summary of the bug:'''

 I am currently using FFmpeg build number N-89980-ge752da5464. This issue
 also reproduces using build number N-87130-g2b9fd15 which is much older.

 I have some MPEG-PS content that is behind NTSC hard telecine. As such I
 am using both yadif and decimate to remove that. If I use decimate then
 EIA-608 captions pass through even when the -sn option is in place. If I
 do not use decimate then captions, as expected, do not pass through
 because the -sn option is in place.

 Note that the size of the data stream reported by MediaInfo is zero in
 both the source media as well as the output MP4 file. The data stream
 plays back as expected in the VOB file but not in the MP4 file.

 '''How to reproduce:'''
 ffmpeg -t 00:01:00 -fpsprobesize 48 -i decimate-allows-EIA-608-captions-
 to-pass-through-S01E01.vob -vf
 yadif,decimate,crop=720:480:0:0,scale=720:480 -pix_fmt yuv420p -vsync 1
 -sn -map 0:1 -r 23.976 -threads 0 -vcodec libx264 -b:v:0:1 803752 -bufsize
 1410194 -maxrate 1004690 -an  -preset medium -profile:v high -g 48 -tune
 film -x264opts no-scenecut -map_metadata -1 -f mp4 -y

 Compare against the following command line that does not use the decimate
 ffmpeg -t 00:01:00 -fpsprobesize 60 -i decimate-allows-EIA-608-captions-
 to-pass-through-S01E01.vob -vf yadif,crop=720:480:0:0,scale=720:480
 -pix_fmt yuv420p -vsync 1 -sn -map 0:1 -r 29.970 -threads 0 -vcodec
 libx264 -b:v:0:1 818252 -bufsize 1428319 -maxrate 1022815 -an -preset
 medium -profile:v high -g 60 -tune film -x264opts no-scenecut
 -map_metadata -1 -f mp4 -y S01E01.mp4-video.mp4

 It is important to either have full subtitles in a file or none at all
 especially when delivering streaming media compliant content. I always use
 a sidecar file for my VOD captions.

 I am currently attempting to upload a copy of the sample media and the
 associated text file to [ftp://upload.ffmpeg.org] per your bug report
 documentation at [https://ffmpeg.org/bugreports.html], however I am unable
 to connect to upload.ffmpeg.org via either WinSCP's FTP or Windows 7's
 command line FTP.

 The names of the files I plan to upload for replication will be named as
 following provided I can establish communication with the server.


Ticket URL: <https://trac.ffmpeg.org/ticket/7055>
FFmpeg <https://ffmpeg.org>
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