no teletext in mythtv > 0.21

[anonymous]

If i try to use the teletext in mythtv 0.22 or 0.23 the only message i get is "Page not found". There are no other errors in the output. I also can type in some numbers, but nothing else happens. Hope you can fix it very soon. Some infos: Im using mythtv with a DVB-S-Card with

Installed versions: 0.22_p23069(22:08:34 05.01.2010)(alsa css dvb lcd lirc mmx perl python tiff vdpau video_cards_nvidia)

[stuartm]

We need more information, which country? Which satellite?

Teletext transmissions have recently ceased in the UK and probably other countries too. Are you certain that they are still broadcasting?

This is going to be difficult for the devs to fix unless we have access to sample recordings.

[frankm]

I got the same problem.

This helped me out: Index: libs/libmythtv/avformatdecoder.cpp =================================================================== --- libs/libmythtv/avformatdecoder.cpp (revision 23064) +++ libs/libmythtv/avformatdecoder.cpp (working copy) @@ -2870,6 +2870,8 @@

{

if (*buf == 0x10)

buf++; skip

+ if (*buf == 0xFF) + buf += 3; skip

if (*buf == 0x02) {

...now it's working again (I'm at DVB-T in Germany)

[danielk]

frankm, this patch doesn't make sense to me. This test & skip already exists @ line 2996:

        else if (*buf == 0xff)
        {
            buf += 3;
        }

[jochen]

I'm in germany, Astra 19,2E Program (every german one with teletext). On no one teletext is working!

[Stuart Auchterlonie]

0xFF is used as a "stuffing descriptor" all through DVB. IIRC there is nothing to stop it occuring multiple times.

The while loop that's attempting to decode streams here doesn't take into account whether or not descriptors can occur multiple times.

Stuart

[danielk]

Possible fix.

[danielk]

Frank, does the attached patch work?

It moves the buf increment inside the decode conditionals and also adds a check that we have enough bytes left to safely call TeletextDecoder::Decode(). This way we are only incrementing the pointer by a full packet size on full-sized packets and on unknown packets types, so any number of stuffing packets should get properly ignored.

I don't have any actual streams with teletext to test on, so feel free to make any corrections necessary for real data.

[jochen]

On my Sytstem the patch works, I've now teletext back again!

[danielk]

(In [23385]) Fixes #7919. Don't skip extra 46 bytes when parsing teletext data unless we actually see a teletext packet, or an unknown packet.