Date: Tue, 25 May 1999 06:47:32 +0100 From: Roger Hardiman <roger@cs.strath.ac.uk> To: Raul Zighelboim <raul@zighelboim.com>, multimedia@freebsd.org Subject: STB and support for DBX stereo chips Message-ID: <374A3974.A7810C55@cs.strath.ac.uk> References: <79103FDEF940D2118D9D00A0C9C9309C5FE36B@nezu.internal> <19990524194208.A7022@ipass.net> <374A1EBD.3D9D5F29@zighelboim.com>
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Raul,
I see the STB card has a DBX stereo chip.
This may be the problem.
On cheaper Mono TV cards, there is a path from the tuner's audio out
to the Audio Mux. (a selector where the audio source is chosen)
TUNER--(mono)------->AUDIO_MUX----->LINE_OUT
On DBX stereo cards, there is a channel from the DBX stereo chip to
the AUDIO_MUX
TUNER--(mono)------->AUDIO_MUX
| AUDIO_MUX----->LINE_OUT
+--DBX--(stereo)-->AUDIO_MUX
Now the FreeBSD bt848/bt878 driver does not support the DBX chip.
It simply mutes it!
If your card has the 'mono' route, you can get mono audio.
If the STB card only has the 'stereo' route, you'll get no audio
from your Tuner.
No one in the USA has bothered to write DBX support for the bt848/bt878
driver.
I live in the UK, so I cannot help.
The linux bttv drive has DBX support if people are looking for pointers.
Anyway, there are a few things to try first, assuming your card
support the 'mono' audio from the tuner.
a) have you tried speakers on the bt848 card's line out.
b) we need to check the audio mux values are right for you.
This can only be done in Windows.
Start Windows,
download bt848are.exe from somewhere on
ftp://telepresence.dmem.strath.ac.uk/pub/bt848
Run it. It monitors what the bt848 is doing.
We need to see what values the GPIO output mask and GPIO bits
do when you select Tuner Audio, Mute and External Audio.
Let me know how you get on.
Bye
Roger
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