Upon further investigation, it turns out this bug is not related to the
linux kernel, or the saa7134 video card. If anything, it's a bug in
pulseaudio and the GNOME Sound Preferences.

1. First of all, I tested the upstream kernel 
"linux-image-2.6.34-999-generic_2.6.34-999.201005181210_i386.deb" but nothing 
changed.
2. The message "SAA7130 [0] / alsa: Encore ENLTV-FM v5.3 does not support 
digital audio" in "/var/log/kern.log" is not really important. This card is a 
cheap analog TV card, so it is quite normal that it is, well, not digital.
3. Other messages that may appear in "/var/log/user.log" pertaining to 
pulseaudio are "module-alsa-card.c: Failed to find a working profile.", and 
"module.c: Failed to load  module "module-x11-xsmp" (argument: ...)." These 
messages may be related to other bugs, such as bug #300275 and bug #382440. By 
reading those reports, it seems that some messages are harmless warnings, and 
some problems have already fixed. In any case, they aren't the source of this 
problem.

I'll give a better explanation of the bug than was given by the original
reporter.

The Encore ENLTV-FM is a cheap, analog PCI TV card based on the
"saa7130" or "saa7134" chipsets, found mostly in Latin America. A
description of this card is made in this forum post:
http://ubuntuforums.org/showthread.php?t=1042777

The card has an external "Audio Out" jack which must be connected to the
computer "Line-In" jack or to some other sound system. Some models also
permit to connect the sound internally. Normally, software in Windows
and Linux turn on the Line-In channel when a TV program is started,
being "ENLTV" in Windows, and "tvtime" or "xawtv" or other in Linux.
Then, by adjusting the volume of the Line-In channel, you can control
the TV volume without affecting the volume levels for the rest of the
system.

4. In this bug, the problem is that when starting tvtime, it is possible to 
tune the channels normally, but there is no sound present, as if the Line-In 
jack was disconnected.
5. In fact, you can open the "Sound Preferences", click on the "Input" tab, 
select "Analog Line-In / Input 1" and see there is audio in the channel.

As far as I can tell, this bug is caused by messing with the different
"Profiles" in the "Hardware" tab of the Sound Preferences. The profiles
include stuff like "Analog Stereo Duplex" (the normal setup for most
integrated audio cards), and more complicated settings like "Analog
Surround 5.1 Output + Analog Stereo Input" (for high-quality, dedicated
audio cards).

Well, since Ubuntu changed from Alsa to Pulseaudio, I had never tested
these profiles; it just worked. Then, a few days ago, I decided to try
this stuff. However, since I only have an integrated sound card (the VIA
VT8233/A/8235/8237 AC97 Audio Controller (rev 60), Realtek ALC655 rev 0,
which uses the "snd-via82xx" kernel module), the only useful profiles
are the standard Stereo or Mono setups. However, I tried the Surround
4.0, 4.1, 5.0, 5.1 anyway, and it seemed to work fine. However, when I
rebooted the PC, I found myself with the problem described here: no
sound through Line-In.

To solve this problem I used the "alsamixer" interface:

6. Open tvtime or other TV application.
7. Open a terminal and run "alsamixer".
8. Move to the right and ensure the "Line" volumen level is enabled.
9. Move further to the right where it says "Channel" (Channel Mode). With me, 
it was set to "4ch".
10. When I changed it to "2ch" it worked; sound in tvtime was back to normal.
11. When I set the Channel mode to "4ch" or "6ch" the sound disappeared again.
12. You can leave alsamixer open, and also open the GNOME Sound Preferences. 
Then, test the different profiles and see how they change to "2ch", "4ch" and 
"6ch" in alsamixer.

Therefore, it seems to me that the bug was with the Sound Preferences
interface or its pulseaudio/alsa backend changing the Channel Mode to
"4ch" or "6ch" and then being unable to reset it to "2ch", which left
the Line-In deactivated.

** Tags removed: needs-upstream-testing

-- 
saa7130[0]/alsa: Encore ENLTV-FM v5.3 doesn't support digital audio
https://bugs.launchpad.net/bugs/565895
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