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

[Reimar Döffinger]

On Sun, Sep 06, 2009 at 06:00:35PM +0200, Francesco Lavra wrote:
> On Sun, 2009-08-30 at 20:58 +0200, Reimar Döffinger wrote:
> > On Sun, Aug 30, 2009 at 06:47:48PM +0000, Carl Eugen Hoyos wrote:
> > > Francesco Lavra <francescolavra <at> interfree.it> writes:
> > > 
> > > > I tried playing a DVB stream using the libavformat demuxer, and it
> > > > doesn't work. Using the command
> > > > mplayer -demuxer lavf dvb://<channel_name>
> > > > it hangs in av_open_input_stream(), while if I dump a DVB stream in a
> > > > file and try to play it with -demuxer lavf MPlayer exits with "LAVF: no
> > > > audio or video headers found - broken file?". Of course, in both cases
> > > > playing with the native TS demuxer works fine.
> > > 
> > > demuxer lavf does not work on ts files for some time.
> > 
> > It does work for me both with dvb directly and with captured files,
> > though not reliably.
> 
> Even with the latest patches from Carl Eugen, the lavf demuxer doesn't
> demux my DVB streams.
> The changes to update_teletext() attached by Reimar don't work with the
> native TS demuxer for DVB teletext decoding, and trying to implement the
> necessary changes to the TS demuxer (in a way that would be welcome for
> inclusion in the MPlayer tree) I figured out that it's not an easy task.
> So, I will try to fix the lavf demuxer to make it work with my streams,
> and then I will come back to DVB teletext...

I know it is a lot to ask, and I appreciate that you intend to try
anyways. I'll try to help where I can.
Do you have a sample file that shows the issues you have with the lavf
issues? mplayer -dumpsteam works for me on DVB streams for creating
samples. I might be able to fix it faster and easier than you (though I
don't like the lavf demuxer much either).

> > I attached the results of my hacks, but I am stuck since what comes out
> > of the demuxer (whether native or lavf) is not even slightly similar
> > to teletext data...
> 
> If you take a look at the patches I sent on August 16 (especially
> 03_dvb_teletext.patch), you will see how DVB teletext data must be
> decoded.

Oh crap, so they have reversed bit order? That's something I indeed
never thought of.
libavcodec/get_bits.h defines a ff_reverse array that does that btw.
(though I admit it is questionable if that should be used from MPlayer).