[linux-dvb] Re: Linux DVB API 4 Q's

[Rob.McConnell@Zarlink.Com]

> Rob.McConnell@Zarlink.Com wrote:
> >
> > As I understand the current API version 3 implementation allows you to
> > attach multiple section filters to a single fd, so I think we should
keep
> > this in V4.

> Nope. Only one filter per fd.

I beg to differ on this.  If you have a look at dvb_demux.c there is the
function "dvb_dmx_swfilter_section_feed" that gets called when we have some
section data available from the h/w.  In this function we have a pointer to
a "dvb_demux_filter" that is set from "dvb_demux_feed->filter".  Now each
"dvb_demux_filter" has a "next" field that points to another
"dvb_demux_filter".  So we have a feed that can have multiple
"dvb_demux_filters" attached to it.  The function then calls
"dvb_dmx_swfilter_sectionfilter" for each available "dvb_demux_filter"
attached to the feed.  This called function then parses the data returned
by the h/w for each section filter attached to the feed to check whether a
match has been found.  You can attach multiple section filters to a single
fd by calling "DMX_SET_FILTER" multiple times on the already opened fd.

> > What about leaving the demux device alone and allowing it to choose say
> > front_end x = C/A module input.  Then we
> > need a C/A device that can set it's source to say external demod #1.
In
> > this case, h/w that does have the ability to route an input TS from say
an
> > external demod to a C/A module and then into the logical demux device
is
> > covered.  Also, h/w that does not have a C/A or C/I router will still
> > function the same i.e. demux selects the required front_end.

> If we'd use the "general input device" model, you could have
> e.g. two frontend input devices and two CI input devices. Then add
> a DVB_CI_SET_INPUT ioctl which allows simply to select frontend0/1. OK?

Yes, I agree - this was my thoughts exactly.  Having a SET_INPUT ioctl
would be similar to the way the video and audio devices api works as well
(I like to keep things consistent). : )


Cheers,

Rob : )








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