[pvrusb2] pvrusb2-mci-20070114 radio support - stereo?

[devsk]

> Some stations broadcast mono, so signal strength
> is not necessary playing a part here (though it might).

I was tuned to a station which is known to be Stereo. In fact, I did what you said: "Just change frequencies until the ctl_audio_modes_present/cur_val is Stereo"

(96.5Mhz is the KOIT station in bay area, known to be stereo).
# start_freq=96000000

# while [ $start_freq != 108000000 ];do echo $start_freq > ctl_frequency/cur_val;sleep 2; cat ctl_audio_modes_present/cur_val;start_freq=$((start_freq+50000));done > /tmp/signal.mono 2>&1

All that I see in the /tmp/signal.mono is "Mono Lang2". That means that either 1.) I am getting all stations Mono, 2.) signal is too weak for stereo. 1.) is not really a possibility but I have no way of verifying 2.) because I can't run the mplayer test in windows? can I? What I can tell you about the sound quality in windows is very subjective, because 'it sounds stereo' is no good.

If I tune to a tv station thru mythtv, I see "Mono Lang2" for all stations. If I repeat the above with start_freq=`cat ctl_frequency/cur_val` for a known tuned channel from mythtv, I can't find a single station with stereo. That means OTA FM and analog cable both are mono.

-devsk
PS: kernel 2.6.19.2 and pvrusb2 snapshot pvrusb2-mci-20070119.

----- Original Message ----
From: Pantelis <pakt223 at freemail.gr>
To: Communications nexus for pvrusb2 driver <pvrusb2 at isely.net>
Sent: Saturday, January 27, 2007 8:47:50 AM
Subject: Re: [pvrusb2] pvrusb2-mci-20070114 radio support - stereo?

> So, if the audio mode present and settable is "Mono", how is the overall
> audio stereo? Is the value of ctl_audio_modes_present/cur_val decided by
> the signal strength? Signal strength should be same between whether I am
> booted in linux or windows, right?

Well, this is the difference between what the demodulator demodulates
and what the encoder encodes. If  ctl_audio_modes_present/cur_val
is Stereo it means a stereo signal was autodetected. This is not a user
writable setting. Some stations broadcast mono, so signal strength
is not necessary playing a part here (though it might).

So, set ctl_audio_mode/cur_val to Stereo (or just leave it alone if you
haven't touched it). Same with ctl_mpeg_audio_mode/cur_val.
Just change frequencies until the ctl_audio_modes_present/cur_val is Stereo
and then repeat the test, please :-)

>
> I did the 'mplayer -vo null -ao alsa -af pan=2:1:1:-1:-1 /dev/radio0'
> experiment and I hear "squeaking noises like from a tape bewing in
> extremely fast forwind most of the time."

Yep, but unfortunately your result is meaningless because you used
a mono source, or the signal wasn 't strong enough for the demodulator
to detect stereo.

> I wish I could  help more to find the exact cause of the audio problems, but 
> now you have another data point and tester....;-)

Thanks a lot for testing :-)
Please repeat as above :-)
Oh, and please post the kernel/driver version you are testing :-)

Btw, results from people with 29xxx devices would be nice as well ;-)

It would be great if someone found a kernel version that passes the test
(anecdotal evidence suggests 2.6.15 may actually work). If this is found
to be a regression then knowing which is the last kernel version that works
will be *huge* help!

Thanks again,
-Pantelis
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