[FFmpeg-user] proper metadata key=value for default/nondefault subtitles

[Elias Fries]

On Tue, Oct 30, 2012 at 7:37 AM, Roger Pack <rogerdpack2 at gmail.com> wrote:

> > But how to set whether the stream is on by default?  The  subtitle
> stream has
> > the default flag, and ffmpeg recognizes it.  I've tried to turn it off
>
> So basically you want to tweak the file so that its subtitle stream is
> set to default "on"?
> -r
>

Thanks for reply.  Well in this case the subtitle stream is already set to
"default",
meaning that a player should play that stream automatically.  I want to
turn off
the default flag, so (assuming the player respects it), it would not play
unless the
user chose the subtitle track and turned it on in the player.

Alternatively, in other files I might have several audio tracks and several
subtitle tracks.
I want to know how to control the default flag, telling the player which
track, if any,
should be played by default.

Actually, I noticed Carl had a related ticket recently
(https://ffmpeg.org/trac/ffmpeg/ticket/1815; the issue was only asking
that ffmpeg faithfully copied such flags as "default" and "forced").
ffmpeg must know how to set/unset these
flags, I'm just wondering how to control that.  It is probably
container-dependent,
and I am currently working with mkv.

Jim