Hi Andy,
I think I have good news regarding the mono out test. And I'd really like to
know if it would be a total waste of my time to test my HVR-1600 in the old
computer using WinXP and Linux with the latest drivers. If not, it's something I
can do before I hand the machine over to my sister this weekend.
> That can happen when the cx18 and/or videodev module is compiled without
> the CONFIG_VIDEO_ADV_DEBUG, or if the default /dev/video device does not
> point to a cx18 supported device. It can also happen if you are not
> root; changing registers is a privileged operation.
CONFIG_VIDEO_ADV_DEBUG was not set. Once I recompiled with it set, here's
the output of the commands.
# v4l2-dbg -d /dev/video0 -D
Driver info:
Driver name : cx18
Card type : Hauppauge HVR-1600
Bus info : PCI:0000:01:09.0
Driver version: 65792
Capabilities : 0x01030051
Video Capture
VBI Capture
Sliced VBI Capture
Tuner
Audio
Read/Write
Actually this command worked before recompiling with
CONFIG_VIDEO_ADV_DEBUG enabled.
# v4l2-dbg -d /dev/video0 -S
host0: cx23418 revision 0x01010000
host1: cx23418_843 revision 0x00008430
i2c 0x4c: cs5345 revision 0x00000000
Setting to mono:
# v4l2-dbg -c host0 -g 0x2c72014
ioctl: VIDIOC_DBG_G_REGISTER
Register 0x02c72014 = 320h (800d 00000011 00100000b)
# v4l2-dbg -c host0 -s 0x2c72014 0xb05
Register 0x02c72014 set to 0xb05
(Although I wonder if the value should have been 0xb00 since the
original register value was 0x320, not 0x325.)
# v4l2-dbg -c host0 -g 0x2c72014
ioctl: VIDIOC_DBG_G_REGISTER
Register 0x02c72014 = 305h (773d 00000011 00000101b)
Results:
No noticeable static on any channel my TV can tune! This is great news to
me. It means I might be able to work around the problem, meaning I'll have
a usable myth system and a system that I can also use to contribute some
testing on VBI, for example. You said that if the static went away, you'd
know it's a CX23418 digitizer front-end problem. I'm not quite sure what
that means. Does it mean this particular card might be sub-par and that
perhaps I should exchange it for another? If so, should I try the older
model 1178?
BTW, this test was done going through the inline amp to 8 way to 4 way
splitters. My earlier tests convince me that they are not the root cause
and I don't need to hurry up to the attic to bypass them. I'll still need
the 4 way no matter what.
There was one small issue. The sound was a lot lower with this configuration.
Normally, my TV volume is set to around 10 (maxes out at 63). This level
is appropriate for both the TV tuner and for PVR-150 recordings played
back on my old computer. The new computer seems to have a weaker audio
out, despite me cranking up the mixer volumes to the max. When I use the
new computer to play back recordings made on the old computer with the
PVR-150, I need to set the TV volume to around 15. But I had to crank up
the TV volume even higher (between 22-30 depending on channel)to get a
comparable sound level in this recent test. Not a big deal, just thought
I'd mention it. It is something I'll want to try to adjust so I don't
accidentally blast the TV if I change to the TV tuner without thinking.
One of my dogs is sound sensitive and things like that freak her out.
Restoring stereo:
# v4l2-dbg -c host0 -s 0x2c72014 0xb20
(not 0xb25, to restore original value)
Register 0x02c72014 set to 0xb20
# v4l2-dbg -c host0 -g 0x2c72014
ioctl: VIDIOC_DBG_G_REGISTER
Register 0x02c72014 = 320h (800d 00000011 00100000b)
So what are bits 0 and 2 to that register? Should I try setting the value
to 0xb25 and seeing if that allows me to get stereo without static?
>> FYI, I scanned all the channels on my old computer with the PVR-150.
>> No problems with static. However, when I got to channel 60, the video lost
>> color, although the audio was still clean. After rebooting, I continued
>> scanning. This time, I lost sound on channel 87, which follows some
>> channels that have white noise (both audio & video, and on any TV). I
>> tried unloading and reloading ivtv, which didn't restore the audio.
>> Rebooting did the trick. All but one of the remaining channels have white
>> noise, but when I did get to that one last channel, a test pattern with no
>> sound, there was no static.
>
> I've been investigating with my PVR-150MCE, HVR-1600MCE, and HVR-1600.
>
> 1. With the MCE devices where the analog tuners (LG TAPE H001F MK3 in
> the PVR-150 MCE, and TCL MFMN05 in the HVR-1600MCE) have a TDA9887
> demodulator chip, the static on channel 32 is more noticeable than on
> the HVR-1600 with a TCL M2523_5N_E tuner that has a TDA9801 demodulator.
>
> 2. Using how noisy the Raw VBI CC lines show up in osc as a qualitative
> visual measure of AM Signal to Noise ratio (SNR), Stations with a really
> high AM SNR have good sound, as do stations with a really low/poor AM
> SNR. The AM SNR on channel 32 seems to be bad, but not terrible
> (somewhere in the middle).
>
> 3. Experiments with home-made in-line attenuators of 17.5 dB and 23.5 dB
> did not improve the sound on channel 32. It only made the video signal
> worse.
>
> 4. The tuner AF out (vs the SIF out that's normally used) still exhibits
> static for the HVR-1600MCE and HVR1600
>
>
> The only conclusions I can draw are
>
> a. From 1 & 4: my static is likely originating via processes in my
> antenna amplifier and/or the analog tuner assembly and not the CX23418
> chip's front end.
>
> b. From 3: The source of my static is *not* from intermodulation
> products in the analog tuner due to signals that are too strong.
>
>
> Some speculations I can make are:
>
> c. From 2: The noise on Raw VBI lines, as is viewable with osc, *may* be
> an indicator of static appearing in the sound.
>
> d. From 2: The AGC take-over point being set in the demodulator stage of
> the analog tuner - where the demod stage takes over gain control from
> the 1st mixer/amp - may have something with why very noisy video signals
> don't experience audio static, but why mildly noisy signal do experience
> audio static.
>
> I need to look into how the analog tuner is being configured and
> experiment with some settings. Life has been very busy lately. It may
> take me a while to find what's going on.
I understand (at least the bit about life being busy). And let me take this
opportunity to say I really appreciate just how responsive you've been to my
particular issue. One thing I'm unclear about is whether you now think we have
similar root causes. If not, is there a chance that my problem is something that
can, or should, be addressed in software, either kernel or user space. IOW,
might there be an opportunity for me to help test a patch for this issue?
> I also need to look at your other email, and ask some questions about
> the cable box behavior.
Whenever life's not too busy <vbg>. Although I would like to know if it would be
a total waste of my time to test my HVR-1600 in the old computer using WinXP and
Linux with the latest drivers. If not, it's something I can do before I hand the
machine over to my sister.\ this weekend.
Regards,
Helen
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