[mythtv-users] MythTV 0.24.1, Ubuntu 11.04 and MHEG on Freeview UK

Lawrence Rust lvr at softsystem.co.uk
Sun Oct 2 11:54:52 UTC 2011

On Sun, 2011-10-02 at 11:19 +0100, Paul wrote:
> >It's possible that another re-tune is necessary to get the correct
> >associations.  The BBC are moving a number of services around at the
> >moment.  Just recently BBC News, Alba and Parliament moved on satellite.
> I did another retune but that I truncated the mythconverg tables related to 
> tuning and channel information. Usually I just truncate the following:
> program, channel, channelscan, channelscan_channel, 
> channelscan_dtv_multiplex, dtv_multiplex
> but this time I also truncated:
> eit_cache (empty), pid_cache (empty) and dtv_privatetypes
> After that I did a full scan for all channels and the 'red button' came back 
> up.

That's good to hear.

>  So I can only think that the table 'dtv_privatetypes' held some 
> redundant information which mythtv (this is a database I've been using since 
> 0.21) was still reading and applying. I have also noticed that the table 
> dtv_privatetypes no longer has any information in it (likewise with 
> pid_cache and eit_cache).
> I now have the 'red button' back but it still consumes a lot of CPU which 
> causes the video to stop / start everytime I use the 'red button'.

The current MHEG implementation is extremely inefficient in handling
fonts and graphics.  It rarely caches anything and performs a lot of
unnecessary copies.  The biggest hit though is the interpreter which
could do with something like JIT compiling.

Unfortunately most desktop CPUs are capable of shrugging off these
inefficiencies so the pressure to improve is low.  Another case where it
would have been preferable to develop the original code on the lowest
spec machine.  As you can gather I'm not keen on giving developers high
spec machines because code efficiency suffers.

> I was also going to re-compile fixes/0.24 with the iplayer.diff file but the 
> lastest version on your website is coming up as a binary file.

Thanks for the report, looks like the patch got screwed somehow.  I have
updated the link.

> Anyway thanks for all the help,

Glad to be of help.


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