[linux-dvb] Re: DVICO HDTV PCI and MythTV issue

Andy myidea72bvdl at straymail.com
Sat Feb 10 08:36:48 CET 2007


Well, I have found the answer to my question below. So I might as well 
let everybody else know. The solution comes from Michael C. (Thanks 
Michael).

Is this a bug? Or an unhandled corner case?

Note: I am very new to DVB reception, so forgive (or correct) my 
incorrect terminology.

When scanning free-to-air channels scandvb "appears" to be outputting 
the wrong audio ID for channels that are broadcasting AC3 audio.

If you use the scandvb output ("scandvb au-sydney_north_shore > 
channels.conf") as a "channels.conf" import file for MythTV, then MythTV 
will be unable to receive audio on those channels. (Xine appears to not 
use the incorrect audio ID's in a channels.conf file.)

I have only tested on a DVICO Fusion HDTV PCI card on Fedora Core 6. 
Your mileage may vary.

The solution is to use tzap to tune each frequency/multiplex (correct 
terminology??) and then to use "scandvb -c" to display the available 
channels on that frequency. Find the AC3 code for each channel 
(displayed in Hex), convert to decimal. Change the ID in the 
channels.conf generated originally by scandvb. Usually the audio ID will 
be zero, especially if only AC3 is available. (In Australia all our HD 
channels only have AC3 audio - hence the audio ID will be zero and great 
disappointment when trying to watch TV!)

Is it possible to modify scandvb to fix this??? Maybe add an option to 
specify a preferred audio type, or an ordered list of preferred audio 
types? Maybe default to choosing the best audio stream based on quality?

Andy.

> Date: Thu, 08 Feb 2007 11:30:43 +1100
> From: Andy <myidea72bvdl at straymail.com>
> Subject: [linux-dvb] DVICO HDTV PCI and MythTV issue
> To: linux-dvb at linuxtv.org
> Message-ID: <45CA6F33.7040006 at straymail.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Hi All,
>
>   I am hoping somebody on this list can help with a very annoying 
> problem using a DVICO HDTV PCI card with MythTV.
>
>   The card works perfectly with Xine, but MythTV receives corrupted 
> audio (continuous machine gun like noise) with a good picture ONLY on 
> certain channels. Is anybody else experiencing this problem???
>
>   I am in Sydney, Australia. The free to air stations that don't work 
> are all the Nine Network (Chn 9, 90, 99), Ten Network (Chn 1, 10 but 11 
> works!) and ABC Network (only 2 doesn't work). All other 15 or so 
> channels are received beautifully.
>
>   Note, I used the "add 166667" trick on the frequency file for the Nine 
> Network in "dvb-t/au-sydney_north_shore" file of dvb-utils in order to 
> get a valid channels.conf. Xine uses this file perfectly receiving all 
> stations. I have let MythTV do it's own scan - it finds all stations. It 
> just can't receive the particular stations above. I have also tried 
> importing the above channels.conf file - exactly the same result.
>
>   Is their a difference between the way Xine would tune the card and the 
> way MythTV would tune the card?
>  
>   I am using Fedora Core 6 (2.6.19-1.2895.fc6 #1 SMP i686 athlon i386) 
> and I am running MythTV installed using Yum from ATrpms 
> (mythtv-backend-0.20-151.fc6.at).
>
> Many thanks,
> Andy.
>
>
>
> ------------------------------



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