[MPlayer-dev-eng] [PATCH] Add DVB teletext support

[Nico Sabbi]

Il giorno lun, 29/06/2009 alle 19.41 +0200, Francesco Lavra ha scritto:
> On Sat, 2009-06-27 at 21:57 +0200, Nico Sabbi wrote:
> > Il giorno sab, 27/06/2009 alle 19.03 +0200, Francesco Lavra ha scritto:
> > > Hi,
> > > This patch adds support for DVB teletext decoding and display (parts of
> > > code have been taken from the DVB patch of AleVT).
> > > Teletext support is limited to DVB-T (because I could test it only with
> > > a DVB-T card), but adding support for DVB-C and DVB-S should be fairly
> > > trivial.
> > > A new field needs to be added to the channels definition file (typically
> > > found at ~/.mplayer/channels.conf[.ter]), which specifies the Packet ID
> > > (PID) of the teletext stream, just after the audio PIDs field; if there
> > > is not teletext on a given program, a negative value must be provided as
> > > teletext PID. This can break compatibility with previous versions, so if
> > > this is too much of a concern I could insert code which detects
> > > automatically the teletext PID of a given program (I could take it from
> > > the DVB patch of AleVT). Let me know.
> > 
> > not the slightest change is needed in the stream code: multiple pids can
> > be selected by means of pid+pid+pid... syntax, or using a plain 8192 pid
> > (that selects the whole TS).
> > Moreover, the meaning of those changes in the stream code is obscure and
> > would need a serious documentation, but I'll repeat it: the stream layer
> > doesn't need any change. The only changes needed are
> > 1) a decoder that I won't review ;)
> > 2) *eventually* something in demux_ts.c
> 
> OK, it makes sense to specify the teletext PID with pid+pid syntax,
> although it's not technically correct, because teletext is neither video
> nor audio...
> Re-implementing DVB teletext support without touching the stream layer
> could be done as follows:
> - Add DVB teletext decoding capability to stream/tvi_vbi.c.
> - Add teletext support to libmpdemux/demux_ts.c (by means of code which
> detects teletext packets and passes them to teletext_control() in
> tvi_vbi.c)

demuxers ddmux, decoders decode, so ... al the code belongs to decoders'
files.

> - Modify update_teletext() in mpcommon.c and some functions in command.c
> such that they call directly teletext_control() in tvi_vbi.c
> 
> It could be worthwhile moving teletext-related definitions outside the
> stream/ directory, maybe in libmpcodecs/, renaming tvi_vbi.c to
> something like dec_teletext.c, and adding in the same directory
> libmpcodecs/ an header file (dec_teletext.h?) containing all the
> teletext-related definitions currently split between stream/tv.h and
> stream/tvi_def.h.
> 
> What do you think?
> 

most likely yes, but I'm not familiar with decoders; better wait for
someone else.