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

["Haber, Thomas" <THaber@tee.toshiba.de>]

Where do you want to transfer the parameters beside the pids.
You still want to keep the set ?

tom

> -----Original Message-----
> From: Johannes Stezenbach [mailto:js@convergence.de]
> Sent: Dienstag, 7. Oktober 2003 13:27
> To: Rob.McConnell@Zarlink.Com
> Cc: Haber, Thomas; linux-dvb@linuxtv.org; Ralph Metzler
> Subject: Re: [linux-dvb] Re: Linux DVB API 4 Q's
> 
> 
> Rob.McConnell@Zarlink.Com wrote:
> > 
> > 1)  DVB_DMX_START and DVB_DMX_STOP ioctls will globally 
> work on any filters
> > attached to a single fd.  I guess the advantage of keeping 
> the DVB_DMX_STOP
> > ioctl is to reduce any time required to do an "open" on a 
> new fd after you
> > did a "close".
> > 
> > 2) To individually ADD & START a filter issue the 
> DVB_DMX_ADD_PID_FILTER
> > ioctl with the DVB_DMX_IMMEDIATE_START flag set.
> > 
> > 3) To START a group of filters at once, issue the 
> DVB_DMX_START ioctl on
> > the required fd.
> > 
> > 4) To STOP a group of filters (e.g. pausing), issue the 
> DVB_DMX_STOP ioctl
> > on the required fd.
> > 
> > 5) To individually STOP and remove a filter issue the
> > DVB_DMX_DEL_PID_FILTER ioctl.
> > 
> > 
> > OK, does this look reasonable?
> 
> Maybe it's just a matter of taste, but I think that sucks :-(
> 
> o at open() time we don't know what the user is going to do with the
>   new file descriptor, hence there isn't much overhead in open() /
>   close(); all the work is in starting and stopping the filters
> o state handling in the driver *and* in the application will be more
>   complicated when we have to deal with filters which are set but not
>   started
> o if you want to start a number of filters at once, you might also
>   want to stop then together (symmetry)
> 
> 
> I would prefer to:
> 
> - pass an array of PIDs to ADD/DEL
> - remove the DVB_DMX_IMMEDIATE_START, DVB_DMX_START and 
> DVB_DMX_STOP ioctls
> 
> While I don't think that it's important for me to set a number of
> filters at exactly the same time, this would simplify error handling
> because we can make setting all filters together either 
> succeed or fail
> (atomicity).
> 
> I think this a simple and efficient API. Don't you?
> 
> 
> Johannes
> 


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