[mythtv] DSM-CC object carousel parser and storage patch for0.18.1

Stuart Auchterlonie stuarta at squashedfrog.net
Sat Oct 1 11:48:41 UTC 2005

On Sat, Oct 01, 2005 at 12:07:54PM +0100, Neil Davidson wrote:
> > > On Sat 1 October 2005 10:47, Stuart Auchterlonie wrote:
> > >> Have looked at this. If you let the DSMCC streams get 
> > recorded then 
> > >> the size of the recordings blows out by an average of 30%. 
> > Not good.
> > >
> > > Would it not be a good idea to let people choose if the stream is 
> > > recorded, even on a per schedule basis? There are some good reasons 
> > > why it might be desired - for example many BBC programs have added 
> > > information broadcast along with them (e.g. "For more information 
> > > press the red button"). As many myth users watch everything 
> > recorded 
> > > they would miss-out on that extra and sometimes useful facility.
> > 

We'll call this next bit idea #1.

> > Perhaps it's possible to find some kind of hybrid between #1 
> > and #2 originally suggested - the recorder could perhaps 
> > parse the stream and only record one copy of each object, to 
> > keep file size down...
> > 

We'll call this next bit idea #2.

> I've also seen Additional programming on the Interactive stream. For
> example, How TO Start Your Own Country had a (semi)live broadcast after the
> program on BBC2, would be cool if you could record things like that.

The problem with these ideas is that the DSMCC streams are only a
transport mechanism. They have no knowledge of what they carry.

For idea #1 we would have to download the entire carousel and then
re-encode it and stick it back into the data stream. Messy.

With idea #2 the mheg applications that are running (ie. the stuff
behind the red button) are able to select a completely different set
of PIDs, to what you currently have to show you what you want to look

An example would help.

BBC News has a multiscreen news facility. When you start the multiscreen
news what happens is you are tuned to the BBC Parliment channel, and
various boxes and text are rendered over the top of the BBC Parliment
content, and depending on which of the two news items you want to look
at, a different audio PID is selected.

So to get the multiscreen news you would have to record 2 different
video stream, 3 different audio stream + up to 6 data streams to glue
it all together.

Guess that's why it's called interactive....


More information about the mythtv-dev mailing list