[mythtv-users] No video

[Bruce Markey]

Shirley, Mark R wrote:
> You were right Bruce, I made the changes I wanted to modules.conf
> to correct the broken default install of ALSA, rebooted, and suddenly 
> I had working video on Myth.  Now I need to get the recording of sound
> sorted out.  I have two sound cards in this box, and the SBLive! is the
> second card.  I am trying to work with the second card, and still haven't
> gotten any sound out of myth yet.  When I run aplay /dev/dsp when myth is
> running, I get nothing.  aplay /dev/dsp1 when myth is running, has a 
> bitstream it's trying to play, but I can't hear it.  Is there a switch 
> to change aplay's output to the second card?  I haven't had a chance to
> dig into aplay's man page yet.  Also have been playing with alsamixer
> to set the sound card inputs and outputs.  SBLive has a TON of mixer
> sliders.
> I'm not sure I'm getting the right ones.  I muted what I thought was
> line-in,
> and also set it to capture on that.  How can I be sure it's correct?


I trust you will get this all working correctly but it can
be difficult to communicate the details. Please forgive me
if I misunderstand or misinterpret something you may have
written.

I do use two configured ALSA cards for dual tuner systems. For
example, this is a system with an SB Live! and the on board
sound which I use only for capturing /dev/dsp1 for the second
tuner card.

# ALSA portion
alias char-major-116 snd
# alias snd-card-0 snd-card-via686a
alias snd-card-0 snd-emu10k1
alias snd-card-1 snd-via82xx

# OSS/Free portion
alias char-major-14 soundcore
alias sound-slot-0 snd-card-0
alias sound-service-0-0 snd-mixer-oss
alias sound-service-0-1 snd-seq-oss
alias sound-service-0-3 snd-pcm-oss
alias sound-service-0-8 snd-seq-oss
alias sound-service-0-12 snd-pcm-oss

alias sound-slot-1 snd-card-1
alias sound-service-1-0 snd-mixer-oss
alias sound-service-1-1 snd-seq-oss
alias sound-service-1-3 snd-pcm-oss
alias sound-service-1-8 snd-seq-oss
alias sound-service-1-12 snd-pcm-oss

"snd-card-0" I would refer to as the 'first card' and is the
SB Live!. My speaker cord is plugged into the the speaker jack
of this card. I also have the digital out wired to the digital
input on my stereo receiver.

"snd-card-1" I would refer to as the 'second card' and is the
on board VIA sound chip. No speakers are attached to the green
speaker jack on the motherboard.

I have the /dev/video0 patch cord attached to line in of the
SB card and the /dev/video1 patch cord to the on board blue Line-
in jack.

If I try "xawtv -c /dev/video0" and use "alsamixer" to unmute
line-in, I hear the analog passthru audio. If I try
"xawtv -c /dev/video1" and use "alsamixer -c 1" to unmute
line-in, I hear nothing(!). Why? There are no speakers attached
to the speaker out of that card.

If I run "aplay /dev/dsp1" aplay captures from dsp1 and outputs
to the default /dev/dsp so I do hear the slightly delayed recorded
sound and know that it is ready for MythTV.

So, if your "second card" is the SB Live! and the speakers are
attached to the SB Live, you would need to tell aplay to output
to /dev/dsp1 . I've never needed to do that and the man page is
a little vague.

I would suggest that life will be easier if your speakers are
attached to "snd-card-0" so if you want to take advantage of
the SB card, switch your modules.conf so that it is the first
card.


That being said, there is one other issue for capture on the
SB Live! cards. Like other ALSA drivers, it is the "Capture"
slider in "alsamixer" that sets the record level (and the Line-in
level should have no impact on the record level). However, it
also has separate sliders for different capture device types.
One of these needs to be turned up also. I have "AC97 Cap" and
"Wave Cap" turned up all the way. One of them affects the record
level but I'm recording right now so I can't test to see which
one it is ;-).

One other tool that can be helpful is "record" that comes with
xawtv. This has ASCII level meters. This can help determine if
the problem is output (meters move but no sound) or recording
(meters don't move or only show background noise). "-d" to
specify the input device "record -d /dev/dsp1".

--  bjm