The pvrusb2 driver is supposed to select the audio input in conjunction with
the video choice. There is a map in the driver that, based upon the particular
model, should be selecting the correct audio input for you when you select the
"overall" input. It has always been like that. If there's a problem there now
with that, well, it is another thing that needs to be investigated.More stuff
to dig out, with no extra time in which to do it :-(Sent from my T-Mobile 4G
LTE Device
-------- Original message --------From: Jan Ceuleers
<[email protected]> Date: 4/21/19 8:21 AM (GMT-06:00) To:
[email protected] Subject: Re: [pvrusb2] Noise Mike,Thanks for your reply.Given
that in the past it was possible (in fact necessary) to select theaudio input
and that this is no longer possible/necessary now, am Iright in thinking that
the driver programs the hardware to add all audiosources together on the
assumption that only the "correct"-one willactually be producing an audio
signal and the others will be silent?If so, are there circumstances under which
this assumption might be false?Again if so, is there anything I can do about
that? For example, in myuse case (where I'm only recording from line in and
composite video in)can I disable certain components that aren't being used? For
example getrid of certain firmware images, or use certain pvrusb2 module
parameters?Thanks, JanOn 21/04/2019 14:54, [email protected] wrote:> Jan:>>
That's an odd symptom. Getting audio from an RF signal actually has a > longer
processing path than audio from the line-in port. In fact, > there should be
very little (if anything) involved with the line-in port > that isn't also
involved with processing audio from an RF signal. In > either of those two
cases, the audio is processed by a separate chip > (cx25840 IIRC) and the
result of that is what is fed into the mpeg > encoder chip. Once past the
cx25840, there's no difference in the > datapath.>> There's a separate driver
for the cx25840, which the pvrusb2 driver > employs, which is part of the v4l2
subsystem as a whole, so any problem > involving audio like you describe should
also be likely with any other > video capture driver that also happens to use a
cx25840. I know this > isn't being very helpful, but it does suggest that
looking for other > online chatter involving that part might reveal another
clue.>> -Mike>>> On Sun, 21 Apr 2019, Jan Ceuleers wrote:>>> Dear list,>>>> I
am seeking some help with an audio defect that afflicts some>> recordings made
using Hauppauge PVR 1950 devices.>>>> I have two mythtv backends:>>>> - the
slave backend has three 1950s that record from analogue cable.>> Audio recorded
from these tuners is fine.>>>> - the master backend has two 1950 PVRs that
record from set-top boxes>> (i.e. from the composite video input and line audio
inputs). All>> recordings made using these two tuners suffer from an audio
defect as>> described below.>>>> The audio defect is a clearly audible
repetitive "whistling" noise, with>> a periodicity of about 1 second. This
noise is not present on the audio>> signal that goes into the PVR.>>>> I have
tried many variations of v4l2-ctl -d$device -f $freq without>> effect (and have
settled on 450 MHz as the frequency). The point of>> doing this is that I want
to exclude noise from the channel the analogue>> tuner happens to be tuned
to.>>>> Many moons ago a pvrusb2 device had multiple audio inputs from which
one>> could select the right-one using v4l2-ctl -d$device>>
--set-audio-input=$audiodev , with valid values for audiodev being 0, 1>> and
2. The correct setting for my use case was 1. This is no longer the>> case: the
device presents only one audio input which is numbered 0.>>>> I'd be grateful
for any hints.>>>> Thanks, Jan>>>>
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