[FFmpeg-user] Can extract DVB-Sub, cannot extract DVB-T

[Brian Enigma]

So I have two sets of transport stream files, one with a DVB-Sub subtitle
track and one with a DVB-T Teletext track.  In both instances, there's an
audio track, a video track, and a data track and ffmpeg recognizes all of
them correctly.  What I'd like to do is extract out just the data track
(i.e. strip out the audio and video tracks) for analysis and
post-processing.

In the DVB-Sub case, I can do something like this (with both ffmpeg 0.8.4
and the latest git) and everything works as expected:

    ffmpeg -i file1.ts -vn -an -scodec copy -f rawvideo dvbsub.dat

When I try to do the very same thing for the DVB-Teletext track, I always
end up with a zero-length file.  I know there should be data in there, as
I've looked at the data PID in an analyzer and can see the content of the
teletext payloads.  Ffmpeg sees and recognizes the stream as dvb_teletext,
but it doesn't seem to want to export it.

Am I doing something wrong?  Am I missing something?  Or is this something
that ffmpeg does not support?

 ～Brian