[Discuss] line in for Intel sound chipset apparently has quit working with Debian Jessie kernel upgrade

Alan W. Irwin irwin at beluga.phys.uvic.ca
Mon Jun 5 16:02:59 PDT 2017

On 2017-06-05 13:16-0700 Alan W. Irwin wrote:

> On 2017-06-05 12:15-0700 Alan W. Irwin wrote:
> [...]
>> This issue came to my attention because my ancient analog TV card (a
>> Hauppauge WINTV-GO) was working fine yesterday morning, but after a
>> system upgrade it quit delivering sound yesterday afternoon.  For this
>> TV card, the sound is delivered via an external cable from the TV card
>> to line-in (the blue connector) for the Intel audio chipset.
> P.S.  Another possibility is to test whether that sound output from
> the TV card is fine (which if that worked would prove by elimination
> that there was now something wrong with line in).  Would someone be
> willing to loan me the appropriate sound hardware to make such a test?
> Normally such sound hardware would be used to connect to line out of a
> sound card, but in this case it would connect to the analog audio
> output of my TV card to test that.  As far as I can tell both ends of
> my external sound cable are identical (i.e., are single male sound
> plugs of the same size) and thus would be compatible with either line
> in or line out jacks for a sound card and also compatible with any
> sound equipment that connects to those.

After posting the above, I found a post suggesting making the above
test using the computer speakers.  So I did that by connecting my
computer speakers (normally connected to line-out in the sound card)
directly to the analog sound output of the TV card.  The male plug on
the speaker line was compatible with the female plug for the analog
sound output from the TV card (as assumed above).  However, the result
was no sound at all coming out of the speakers!  Is that an expected
result if the analog audio out from the TV card is working properly?  If the conclusion is that
TV card audio is not working properly, I don't see how that
relates to the system update I did since my mental model (which could
be wrong) is that analog sound output from that card is essentially a
pure hardware function with the computer completely unaware of it
except by what happens with line-in on the sound card.

Of course the computer (and also alsamixer) is aware of the audio
capture capabilities of the bt878 chipset in the WINTV-GO card.  So
naively I should be able to access audio information that way instead
of via the external audio cable, but as far as I can tell nobody has
ever recommended that method on Linux, and I am not sure how that
would work (or if it works at all) on that platform.

After the above test, I reconnected the speaker sound cable as per
normal (with the line out of the sound card, color-coded lime green),
and aplay worked again (proving the speakers were OK after that
experiment).  I then reconnected TV card analog sound out with
sound-card line-in, but the result was the same; no sound from tvtime
(although the video was fine proving the current kernel at least
enables the video capabilities of that card without issues).

Alan W. Irwin

Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).

Programming affiliations with the FreeEOS equation-of-state
implementation for stellar interiors (freeeos.sf.net); the Time
Ephemerides project (timeephem.sf.net); PLplot scientific plotting
software package (plplot.sf.net); the libLASi project
(unifont.org/lasi); the Loads of Linux Links project (loll.sf.net);
and the Linux Brochure Project (lbproject.sf.net).

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