[mythtv] Re: Adding DVB-T support to MythTV

[jng_junk at greenmail.demon.co.uk]

Hi there.

> Yep, I think MJPeg tools would definitely do the conversion to various 
> different video formats, while ts2ps would demultiplex the initial 
> transport stream.

Demultiplexing the initial transport stream isn't too much of a problem. 
As somebody pointed out there are many streams transmitted on a single 
frequency but there is some example DVB source code that shows how to get 
the stream(s) you are interested in. It is not difficult to get to a 
situation where you have a single MPEG stream (audio and video) that you 
can output to a file or pipe or whatever. It is what you do with it 
afterwards that is the problem. :)

> The only problem then is to get this stream into a virtual v4l interface
> ( if indeed this is possible ). I did look around on the web to try and
> find out if it's possible to pipe a stream in this way but couldn't find
> anything referring to similar stuff - if anyone knows how to do this I
> will certainly test it out. I would also imagine there would be timing
> and synchronising issues.

I'm new to this v4l stuff, I'm going to have to read up on it before I can
comment on any of the above. But I don't know how synchronisation issues
would occur since the audio and video in the initial MPEG stream are
already synchronised. Wouldn't you have to work pretty hard to get them
out of sync?

> As I said in my previous mail the channel changing would require a script 
> and a config file. The config file lists the channel frequencies on the 
> dvb signal, and cross references them to the mythtv epg. This would need 
> to be filled somehow by tv_grab_uk, or perhaps generated automatically by 
> another script. The channel change script would then convert the mythtv 
> channels to the correct frequency and call dvbtune.

This is not a problem. I've already sussed the tuning problems. I have 
written/stolen some code that is able change channel on demand. And it 
would be easy to incorporate this functionality in MythTV.

> However, even on the initial feedback to this post it certainly looks like 
> there is some interest so here's hoping someone picks this up and runs 
> with it. I'm available for testing, documentation and other non-programmer 
> type stuff .....

If I could only get on top of the video stuff, I'd be well on the way...

James.