[pulseaudio-discuss] problems with KWorld DVB-T 323UR tuner sound quality&volume

[Laszlo Kustan]

Hi,
Thanks for your answer.

> Assuming that other sound producing programs output with a normal
> volume, the tuner record level (and/or its master volume) is probably
> low. Run "alsamixer -c1" to find out and fix the situation. If this is
> not the problem, I don't know what might be.

Yes, other sounds are ok. The difference between the sound levels is
big, I must turn off all other sounds when watching TV because other
sounds are much louder (as my speakers are at max volume level).
alsamixer -c1 says "No mixer elems found".
In pavucontrol everything is at maximum and if I change at input
devices the em28xx capture slider does not change tuner volume.
I also tried paman, Em28xx Audio - Empia 28xx Capture volume slider
does not change tuner volume.
In paman if I change the alsa playback volume from 100% to 400%, the
volume increases but of course the background noise is amplified also.
>
> An addition: I just noticed that you claimed the mixer settings seemed
> fine. Did you perhaps only look at the sound card mixer and not the
> tuner's mixer? Have you noticed that alsamixer shows mixer controls
> separately for playback and record? The mode can be switched with the
> tab key. With the tuner you're interested only in the recording
> controls, maybe except for the Master control which might also affect
> recording levels (or might not, I don't really know if it's possible).
>
Yes, I verified the capture volumes too.
>> - slight delay between A/V
>
> It seems that this kind of hook-tuner-to-sound-card setup is rather
> common with analog tv cards. In this situation the playback program has
> no information about how audio and video should be synchronized.
> Therefore I would guess that tvtime would offer the possibility to add
> delay to the video playback. I've never used the program, so I don't
> know if that's the case.
>
> If a delay can't be added, you can only try minimizing buffering (which
> may cause drop-outs). aplay and arecord seem to have several buffering
> options, --buffer-time being perhaps the easiest to use. I assume aplay
> in your example plays through pulseaudio - I don't know how well the
> buffer size request is respected by the pulse alsa plugin.
>
I already tried sox with minimum buffering and the delay was the same.

>
> Hangs up as in you need to reboot? I don't know what might cause that -
> maybe a buggy sound card or tuner driver?
complete system freeze, I can only reboot with the reset button.
Sometimes it happens when I try to start the routing also.

>
> A fourth problem that you didn't mention, but I think is quite likely to
> occur, is that raw piping from the tuner to the sound card causes
> glitches as the tuner and the sound card don't share the clock and due
> to clock drift you get buffer over- or underruns. I don't know any good
> solution for this.
yes, there are glitches too, but with the background noise I have they
are not so annoying.
This means that no usb tuner can work normally under Linux? I did not
see so much complaints on forums, so I guess most of the people can
use normally their tuners.
I also wrote to the linux-dvb mailing list and according to them tuner
driver seems to work correctly at me, the problems should be
pulseaudio related.
The tuner was tried on Windows too and there were no problems.
Laszlo Kustan