[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
S01E01-decimate.mp4-video.mp4
}}}
Compare against the following command line that does not use the decimate
option:
{{{
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.
decimate-allows-EIA-608-captions-to-pass-through-S01E01.vob
decimate-allows-EIA-608-captions-to-pass-through-S01E01.txt
--
Ticket URL: <https://trac.ffmpeg.org/ticket/7055>
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