Problems on recording of teletext subtitles of an iptv stream after a large amount of time.

[agrafiods]

We have a system using ffmpeg to record and segment incoming iptv streams with teletext subtitles and then feed the generated files for further processing. After about 25-27 hours of continuous recording without any issues (both logwise and in processing) ffmpeg starts generating systematic DTS discontinuities on the subtitle stream (on every packet actually) and the subtitles of the generated files cannot be correctly parsed on the later steps, either they do not appear at all, or a few lines appear collapsed on the beginning of the clip. Simply stopping and starting the ffmpeg will fix the issue for the previously mentioned period. Source streams are local tvheadend streams (with pass profile). This happens on every source stream and only appears to be affected by the time the process is continuously running (that is, sources started at different times will each start failing after the above time has passed since its beginning).

command is: ffmpeg -fix_sub_duration -i <ipstream> -map 0 - c:v copy -c:a copy -c:s copy -f segment -segment_time 180 -reset_timestamps 1 -strftime 1 someid_%Y-%m-%d-%H-%M-%S.ts

Tested this with versions 3.3.8 (via deb.multimedia), several static builds of November 2018 and a compilation of ffmpeg on 2018-12-05 as per ​https://trac.ffmpeg.org/wiki/CompilationGuide/Ubuntu
Compilation configuration was "configuration: --prefix=/home/user/ffmpeg_compile_2018_12_05 --pkg-config-flags=--static --extra-cflags=-I/home/user/ffmpeg_compile_2018_12_05/include --extra-ldflags=-L/home/user/ffmpeg_compile_2018_12_05/lib --extra-libs='-lpthread -lm' --bindir=/home/user/ffmpeg_compile_2018_12_05/bin --enable-gpl --enable-openssl --enable-version3 --enable-static --enable-fontconfig --enable-frei0r --enable-gray --enable-libfribidi --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librubberband --enable-libsoxr --enable-libspeex --enable-libopus --enable-libvorbis --enable-libtheora --enable-libvidstab --enable-libvpx --enable-libvo-amrwbenc --enable-libwebp --enable-libxml2 --enable-libx264 --enable-libx265 --enable-libxvid --enable-libzvbi --enable-nonfree"

[Carl Eugen Hoyos]

Please test current FFmpeg git head - nothing else is supported here - and attach the complete, uncut console output for such a failing conversion to make this a valid ticket.

Not related: FFmpeg is mostly a transcoding tool, looking at your command line, tcpdump, mplayer -dumpstream or FFmpeg's aviocat may show better results for your task.