Re: [xine-devel] input_dvb.c questions

[Mike L. <mi...@se...>]

Hi Barry, All

Firstly, I apologise for not replying sooner to your questions.

On Tuesday 14 June 2005 00:36, Barry Scott wrote:
> I'm getting to know input_dvb.c better now and have some questions
> about how it operates.
>
> Why does it scan the PMT to get the video and audio PIDs rather then
> use the PIDs from the channels.conf file?
>
> Is it to adapt to changes in PID assignment after the channels.conf
> file is created?

Primarily, yes.  the dvb plugin also recognises teletext, dvb subtitles, and 
AC3 audio, whose pids aren't available in the zap format channels.conf, and 
therefore the PAT/PMT require parsing (as per the DVB spec)

> This adds 1 to 2 seconds before the MRL plays so I'm experimenting
> with eliminating this step.

hmm..  I've had reports that this is so with some cards, (the driver times 
out), however I've not been able to repeat it with my twinhan based cards - 
can you tell me what version of the kernel/driver and the make/model of card 
you're using?  I'd really like to track down the cause of this.... and create 
a workaround too, of course :)

> Making a number of the usleeps a lot shorter has pulled in the time
> to notice FE_HAS_LOCK.

unfortunately, quite a number of cards appear to need the additional time, 
certainly dvb-s cards at least

> There seems to be around 3 seconds delay from first video/audio received
> until anything is shown on screen. Is this expected? Can I tune to
> shorten this delay?

This is a known issue, due to the way xine buffers streams.  I've experimented 
with removing the buffering - you can play with this by uncommenting the 
#define DVB_NO_BUFFERING
around line 133 in input_dvb.c, this has been known to work for some people, 
and will shave a couple of seconds delay.

Regards
Mike

>
> Barry
>
>
>
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