[pvrusb2] Noise

[Jan Ceuleers]

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