atscscan (was Re: [linux-dvb] Re: Fusion HDTV 5)

Patrick Boettcher patrick.boettcher at
Tue Aug 16 22:33:22 CEST 2005


On Tue, 16 Aug 2005, Alan Fry wrote:

> 1. I see similar behaviour, which I think is "on demand" programming.  I 
> sometimes can see menu's
> that look like they are actively being clicked to select progams. I haven't 
> yet found any stable in the clear programming,  but I think it will only take 
> time on my part.
> 2. A question:  whenever atscscan  actually discovers a signal I get the 
> message "filter timeout".  Is this
> an mpeg2 filter that is crashing when it tries to process the incoming 
> signal?

Don't worry about the signal so much:

atscscan tries to use the PSIP section to gather informations about the 
channel-constellation of a channel. Unfortunately (especially in cable 
networks, ATSC is better) the broadcasters don't maintain the PSIP 
section. Or there is a different method they keep the names in the stream.

In case atscscan doesn't find a PSIP section (which is the case when the 
timeout occurs) it sets the service_id (from PAT) in hex as name.

In very short, this is how atscscan works: Scanning PAT+PMT for services 
and theirs streams + PSIP TVCT or CVCT to get names and additional 

MichaelK told me that his settopbox is able get more channel names, so 
there has to be a way of getting the channel name, I just don't know. 
Maybe via the EIT.

That sometimes the vpid is not set can be because either the service is a 
radio channel or the vpid was in some descriptor (in PMT) which is not 
known by atscscan (because of an unexpected stream-type or so).

> 3.  Another question:  for the few channels I have successfully "azap-ped" so 
> far, the captured .mpg or .TS
> will crash mplayer after a short time (10 seconds of video)...same thing if I 
> cat /dvr0 into mplayer. any ideas what is going on here?

Try to increase the cache of mplayer to 4MB (-cache 4096).

best regards,

   Mail: patrick.boettcher at

More information about the linux-dvb mailing list