[mythtv-users] MythTV w/o a sound card

[Johannes Niess]

Am Montag, 19. Januar 2004 16:09 schrieb David Kim:
> I'm a linux newbie and a MythTV newbie.
>
> I'm in the process of building my HTPC from
> scratch and successfully loaded Redhat 9 and
> MythTV.
>
> I am trying to run the frontend and backend from
> the same machine and I think I have all the
> software configured properly.
>
> However, when I try to run mythbackend, I don't
> get any responses back on the command prompt. It
> just hangs.
>
> I am wondering if this is caused by the lack of a
> sound card in my system. I have not put in a
> sound card to my HTPC because I haven't sound a
> compatible one yet.
>
> Bottom line...
>
> Do I need a working sound card to be able to run MythTV???

David,

AFAIR the backend is just waiting for connections from frontends. It is 
designed to run as a "daemon" in the background. If you start it from the 
command line, it does not move itself to the background. That's usefull for 
debugging. You can see what's going on inside the backend by starting it as 
"mythbackend --verbose all".

Now you should open another command line and start "mythfrontend --verbose 
all". Now you should see the full screen menues.

Most backends don't need a soundcard. They can record sound directly from the 
capture card if you load the corresponding modules. E. g. btaudio for analog 
capture cards with a btxxx chipset. Just look at the boot messages. I first 
load the modules for my "normal" sound card, so it gets the device 
name /dev/dsp0. TV sound output is next, so it gets /dev/dsp1.

This is the relevant part of my output from "dmesg | less" on the command 
line. i810 is my real sound card and the btaudio lines are from the TV audio 
out:

Intel 810 + AC97 Audio, version 0.24, 10:38:18 Dec 24 2003
i810: SiS 7012 found at IO 0xd800 and 0xd400, MEM 0x0000 and 0x0000, IRQ 18
i810_audio: Audio Controller supports 6 channels.
i810_audio: Defaulting to base 2 channel mode.
i810_audio: Resetting connection 0
ac97_codec: AC97 Audio codec, id: ALG32 (ALC650)
i810_audio: AC'97 codec 0, new EID value = 0x05c7
i810_audio: AC'97 codec 0, DAC map configured, total channels = 6
btaudio: driver version 0.7 loaded [digital+analog]
btaudio: Bt878 (rev 17) at 00:0a.1, irq: 17, latency: 32, mmio: 0xdc005000
btaudio: using card config "default"
btaudio: registered device dsp1 [digital]
btaudio: registered device dsp2 [analog]
btaudio: registered device mixer1

An alternative backend setup uses an external "loop back" cable from the TV 
card to the sound card. In this case the "classical" sound card does the 
sound recording.

Frontends should have a sound card to play sound. Unless your frontend box is 
quite old, it has a (onboard) sound card. It's years ago that there were no 
drivers for some sound cards. Nowadays almost everything is supported.

Hope that helps,

Johannes Nieß