Dear all, I'm using ffmpeg (4.3.1-2020-11-19-full_build-www.gyan.dev) on Windows 7 to mux video, audio and subtitles streams in a mp4 container. I'd like to force the subtitles stream to be displayed by default, so I use the "-disposition:s:0 forced" option. However ffmpeg fails to properly set the "disposition" option for the subtitles stream to "forced" so I need to manually enable the subtitle when the video is played by VLC media player 3.0.11. The exact command is: ffmpeg -i Video.mp4 -i Audio.mp4 -i Sub.vtt -map 0 -map 1 -map 2 -metadata:s:a:0 language=jpn -metadata:s:s:0 language=ita -c:v copy -c:a copy -c:s mov_text -disposition:a:0 default -disposition:s:0 forced Video_Audio_Sub.mp4 The relevant part of the command output for the subtitle stream is:     Stream #0:2(ita): Subtitle: mov_text (tx3g / 0x67337874) (forced) While the subtitles stream is tagged as "(forced)", in the resulting muxed video the subtitle stream is only tagged as "default" as reported by ffprobe and mediainfo and is not automatically displayed in VLC: ffprobe Video_Audio_Sub.mp4 [...]     Stream #0:2(ita): Subtitle: mov_text (tx3g / 0x67337874), 0 kb/s (default) mediainfo Video_Audio_Sub.mp4 [...] Text ID                                       : 3 Format                                   : Timed Text Muxing mode                              : sbtl Codec ID                                 : tx3g Default                                  : Yes Forced                                   : No Is this a bug or did I miss something? For comparison, using mp4box -add Video_Audio.mp4 -add Sub.srt:txtflags=0xC0000000 -new Video_Audio_Sub.mp4 the subtitles stream is correctly recognized as "forced" by mediainfo (and as "default" by ffprobe) and is automatically displayed in VLC: mediainfo Video_Audio_Sub.mp4 Text ID                                       : 3 Format                                   : Timed Text Codec ID                                 : tx3g Forced                                   : Yes Thank you in advance for the help. Regards. Andrea