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Soundblaster Live and an Ancient Bt878
http://forum.linhes.org/viewtopic.php?f=2&t=10295		 Page 1 of 1
Author:  tecker [ Wed May 31, 2006 10:17 pm ]
Post subject:  Soundblaster Live and an Ancient Bt878
I have an old pc that i decided would be fun to turn into a mythtv backend. I have an old Pinnacle Studio PC TV card based on the 878 chipset. The card requires the pass through for the audio and has connectors for the audio to be connected internally through a cd cable. I have a Soundblaster Live card that i connected the the tv card to.

The trouble is that the tv card has no sound comming out of the SB Live. If you connect to the extrenal pass through jack there is sound there but the video and sound are nearly off by 15 seconds (approx).

I have run Aumix to try and turn anything i can up. There is a AC97 on the motherboard but it is disable in the bios and the modprobe has been configured to the SB live. I have sound when playing a dvd through the SB live.

Here is the setup.

Soundblaster Live
AUX IN four pin connector
^
|| <No sound on the internal connection
(int)
Pinnacle Studio TV (Bt878)
(ext)
^sound here on the external

Any help? Im rather confused on the problem and am worried that the sound will be faster then the video. Also the sound wont mute when you stop viewing the TV but that is something i am still looking into. Any pointer to places that my searching may have missed or ideas that you might have would be most helpful.
Author:  nickread [ Thu Jun 01, 2006 3:08 am ]
Post subject: 
The reason for the lag between the audio and the video is that the audio is coming out 'live' in real time direct from the tuner, whereas the video is being recorded to disk, buffered and played back. Thats also why you can still hear the audio when you stop watching, because the tuner card is still tuned even when Myths not using it.

Looks like you either need to find a way to enable the internal sound output from the card (are you sure the cable is wired right?) or connect the external audio out from the tuner to CD connector (assuming you have set up Myth to record from the CD in).
Author:  tecker [ Thu Jun 01, 2006 7:40 am ]
Post subject: 
The way the internal pin works is that there is a standard 1/8in jack for your regular headphones and just on the inside with little traces is the 4 pin "jack"
pins V
___. :
0)))| :


It doesnt need to be enabled on the tv card. I will need to play around with the settings but where should i start to look for that setting on the record side. That could be the problem not having that configured correctly.

The other question is that since the video is being cached like a tivo does will the audio also be cached?
Author:  nickread [ Thu Jun 01, 2006 5:13 pm ]
Post subject: 
With respect to wiring, the easiest check is to make sure the grounds are connected together, then the worst that can happen is that the channels are switched (left-right). Look at the tracks connecting each pin on the 'jack'. Probably you will find two of them directly connected by a track - these two are ground. The wires from those pins should go to the ground pins at the other end. The pins may also be labelled. I note its the Aux in input on the sound card not the CD input, sorry.

The audio will be recorded and buffered along with the video once you get Myth setup right. Otherwise you wouldn't have any audio on recordings :)

There are two places to check for audio setup - aumix, and device selection under mythtv-setup. See:
http://www.mythtv.org/docs/mythtv-HOWTO-22.html#Troubleshooting_Audio
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