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Some analog channels are bad in ivtv but OK on the analog TV
holla.net at gmail
Sep 5, 2011, 4:28 AM
Post #1 of 4 (2111 views)
Permalink
Hi,

Lately my PVR350 based mythtv setup has one major issue.
In this setup analog cable signal is fed both to the pvr350
card and the TV using a splitter.

Now the problem is there are some channels which look
good on TV but the same channel look very grainy and
blurry in mythtv. But there are also some channels which
are equally good on both TV and mythtv.

Here are few things done but no breakthrough.

- swapped the TV and the PVR inputs, but this made no difference

- Using v4l2-ctl tuned a channel from 885.25 MHz to 62.50 MHz
in steps of 1 MHz and observed the ivtv output. I was looking for
a pattern in the blurry channels frequency, but found none.

- checked the ivtv decoder output (/dev/video0) directly, Same problem
existed.

- changed the recording bitrates iin mythtv recording profiles for LiveTV

- For one grainy/blurry channel, fine tuned on either side of the frequency
using v4l2-ctl. Again no difference.

Can you please give some more ideas for debugging this ?

thanks
holla


Some system info
------------------------
kernel: 2.6.39.4 running Intel Atom based D510mo board

ivtv-related modules loaded:

ivtvfb 12085 4
ivtv 139106 1 ivtvfb
cx2341x 17783 1 ivtv
i2c_algo_bit 4857 1 ivtv
tveeprom 11113 1 ivtv
msp3400 25815 1
saa7127 8167 1
saa7115 13581 1
tuner 17420 1
tuner_simple 13140 1
tuner_types 14698 1 tuner_simple
v4l2_common 6913 6 ivtv,cx2341x,msp3400,saa7127,saa7115,tuner
videodev 79083 7
ivtv,cx2341x,msp3400,saa7127,saa7115,tuner,v4l2_common

syslog (the recursive lock warning does not seem to have any impact)

[ 69.220797] Linux video capture interface: v2.00
[ 69.264828] i2c-core: driver [tuner] using legacy suspend method
[ 69.264839] i2c-core: driver [tuner] using legacy resume method
[ 69.297763] i2c-core: driver [msp3400] using legacy suspend method
[ 69.297773] i2c-core: driver [msp3400] using legacy resume method
[ 69.348542] ivtv: Start initialization, version 1.4.2
[ 69.348721] ivtv0: Initializing card 0
[ 69.348731] ivtv0: Autodetected Hauppauge card (cx23415 based)
[ 69.350466] ACPI: PCI Interrupt Link [LNKF] enabled at IRQ 11
[ 69.350481] ivtv 0000:05:00.0: PCI INT A -> Link[LNKF] -> GSI 11
(level, low) -> IRQ 11
[ 69.422441] tveeprom 0-0050: Hauppauge model 48134, rev J321, serial# 2764033
[ 69.422452] tveeprom 0-0050: tuner model is Philips FM1216 (idx 21, type 5)
[ 69.422460] tveeprom 0-0050: TV standards PAL(B/G) (eeprom 0x04)
[ 69.422466] tveeprom 0-0050: audio processor is MSP4418 (idx 25)
[ 69.422473] tveeprom 0-0050: decoder processor is SAA7115 (idx 19)
[ 69.422479] tveeprom 0-0050: has radio, has IR receiver, has no IR
transmitter
[ 69.422486] ivtv0: Autodetected Hauppauge WinTV PVR-350
[ 69.455442] saa7115 0-0021: saa7115 found (1f7115d0e100000) @ 0x42
(ivtv i2c driver #0)
[ 69.591207]
[ 69.591210] =============================================
[ 69.591291] [ INFO: possible recursive locking detected ]
[ 69.591340] 2.6.39.4 #1
[ 69.591375] ---------------------------------------------
[ 69.591441] modprobe/226 is trying to acquire lock:
[ 69.591505] (&hdl->lock){+.+.+.}, at: [<f81a8202>]
handler_new_ref+0xa2/0x1d0 [videodev]
[ 69.591683]
[ 69.591685] but task is already holding lock:
[ 69.591790] (&hdl->lock){+.+.+.}, at: [<f81a8919>]
v4l2_ctrl_add_handler+0x59/0xc0 [videodev]
[ 69.591965]
[ 69.591967] other info that might help us debug this:
[ 69.592009] 3 locks held by modprobe/226:
[ 69.592009] #0: (&__lockdep_no_validate__){+.+.+.}, at:
[<c042d350>] __driver_attach+0x50/0x90
[ 69.592009] #1: (&__lockdep_no_validate__){+.+.+.}, at:
[<c042d35c>] __driver_attach+0x5c/0x90
[ 69.592009] #2: (&hdl->lock){+.+.+.}, at: [<f81a8919>]
v4l2_ctrl_add_handler+0x59/0xc0 [videodev]
[ 69.592009]
[ 69.592009] stack backtrace:
[ 69.592009] Pid: 226, comm: modprobe Not tainted 2.6.39.4 #1
[ 69.592009] Call Trace:
[ 69.592009] [<c0603062>] ? printk+0x19/0x1f
[ 69.592009] [<c01743e5>] __lock_acquire+0x11b5/0x1860
[ 69.592009] [<c0173030>] ? mark_lock+0x190/0x390
[ 69.592009] [<c0174fcd>] lock_acquire+0x7d/0x100
[ 69.592009] [<f81a8202>] ? handler_new_ref+0xa2/0x1d0 [videodev]
[ 69.592009] [<c01394eb>] ? get_parent_ip+0xb/0x40
[ 69.592009] [<f81a8202>] ? handler_new_ref+0xa2/0x1d0 [videodev]
[ 69.592009] [<c060484c>] mutex_lock_nested+0x5c/0x330
[ 69.592009] [<f81a8202>] ? handler_new_ref+0xa2/0x1d0 [videodev]
[ 69.592009] [<f81a81db>] ? handler_new_ref+0x7b/0x1d0 [videodev]
[ 69.592009] [<f81a8202>] handler_new_ref+0xa2/0x1d0 [videodev]
[ 69.592009] [<f81a8919>] ? v4l2_ctrl_add_handler+0x59/0xc0 [videodev]
[ 69.592009] [<f81a8949>] v4l2_ctrl_add_handler+0x89/0xc0 [videodev]
[ 69.592009] [<f81a5019>] v4l2_device_register_subdev+0xd9/0x1b0 [videodev]
[ 69.592009] [<c01394eb>] ? get_parent_ip+0xb/0x40
[ 69.592009] [<f80194d3>] v4l2_i2c_new_subdev_board+0x103/0x1a0 [v4l2_common]
[ 69.592009] [<c0397bea>] ? strlcpy+0x3a/0x50
[ 69.592009] [<f80195bf>] v4l2_i2c_new_subdev+0x4f/0x60 [v4l2_common]
[ 69.592009] [<f873babc>] ivtv_i2c_register+0x27c/0x3c0 [ivtv]
[ 69.592009] [<f874a9bb>] ivtv_probe+0x105f/0x15ee [ivtv]
[ 69.592009] [<c01394eb>] ? get_parent_ip+0xb/0x40
[ 69.592009] [<c0139593>] ? sub_preempt_count+0x73/0xb0
[ 69.592009] [<c0606c89>] ? _raw_spin_unlock_irqrestore+0x39/0x70
[ 69.592009] [<c0430f84>] ? pm_runtime_enable+0x44/0x70
[ 69.592009] [<c03ade13>] local_pci_probe+0x43/0xb0
[ 69.592009] [<c03ae0f0>] pci_device_probe+0x60/0x80
[ 69.592009] [<c042d1ea>] driver_probe_device+0x7a/0x190
[ 69.592009] [<c042d389>] __driver_attach+0x89/0x90
[ 69.592009] [<c042d300>] ? driver_probe_device+0x190/0x190
[ 69.592009] [<c042c1b2>] bus_for_each_dev+0x42/0x70
[ 69.592009] [<c042ceda>] driver_attach+0x1a/0x20
[ 69.592009] [<c042d300>] ? driver_probe_device+0x190/0x190
[ 69.592009] [<c042cb17>] bus_add_driver+0xb7/0x280
[ 69.592009] [<c03ae570>] ? store_new_id+0x100/0x100
[ 69.592009] [<c042d686>] driver_register+0x66/0x110
[ 69.592009] [<c03a05d3>] ? __raw_spin_lock_init+0x33/0x60
[ 69.592009] [<c03ae335>] __pci_register_driver+0x55/0xc0
[ 69.592009] [<f875a073>] module_start+0x73/0x9a [ivtv]
[ 69.592009] [<c0101101>] do_one_initcall+0x31/0x170
[ 69.592009] [<f875a000>] ? 0xf8759fff
[ 69.592009] [<c017e996>] sys_init_module+0x116/0x19c0
[ 69.592009] [<c0607790>] sysenter_do_call+0x12/0x36
[ 69.607742] saa7127 0-0044: saa7127 found @ 0x88 (ivtv i2c driver #0)
[ 69.661646] msp3400 0-0040: MSP4418G-A2 found @ 0x80 (ivtv i2c driver #0)
[ 69.661725] msp3400 0-0040: msp3400 supports nicam and radio, mode
is autodetect and autoselect
[ 69.685194] tuner 0-0061: Tuner -1 found with type(s) Radio TV.
[ 69.687530] tuner-simple 0-0061: creating new instance
[ 69.687624] tuner-simple 0-0061: type set to 5 (Philips PAL_BG
(FI1216 and compatibles))
[ 69.703132] ivtv0: Registered device video0 for encoder MPG (16384 kB)
[ 69.703482] ivtv0: Registered device video32 for encoder YUV (2048 kB)
[ 69.703735] ivtv0: Registered device vbi0 for encoder VBI (8192 kB)
[ 69.703979] ivtv0: Registered device video24 for encoder PCM (320 kB)
[ 69.705327] ivtv0: Registered device radio0 for encoder radio
[ 69.705917] ivtv0: Registered device video16 for decoder MPG (1024 kB)
[ 69.706200] ivtv0: Registered device vbi8 for decoder VBI (64 kB)
[ 69.707902] ivtv0: Registered device vbi16 for decoder VOUT
[ 69.710185] ivtv0: Registered device video48 for decoder YUV (1024 kB)
[ 69.710264] ivtv0: Initialized card: Hauppauge WinTV PVR-350
[ 69.710395] ivtv: End initialization
[ 70.383320] ivtv0: Loaded v4l-cx2341x-enc.fw firmware (376836 bytes)
[ 70.412114] ivtv0: Loaded v4l-cx2341x-dec.fw firmware (262144 bytes)
[ 70.612502] ivtv0: Encoder revision: 0x02060039
[ 70.612746] ivtv0: Decoder revision: 0x02020023
[ 70.692074] ivtv0: Loaded v4l-cx2341x-init.mpg firmware (155648 bytes)
[ 70.873745] ivtvfb0: Framebuffer at 0xe1510000, mapped to
0xf9510000, size 1665k
[ 71.169245] Console: switching to colour frame buffer device 90x36
[ 71.280594] ivtvfb0: Framebuffer registered on ivtv0

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Re: Some analog channels are bad in ivtv but OK on the analog TV [ In reply to ]
rdmisc at dahlsys
Sep 5, 2011, 7:19 AM
Post #2 of 4 (2067 views)
Permalink
On 2011-09-05 05:28, Sathish Vasudevaiah wrote:
> Hi,
>
> Lately my PVR350 based mythtv setup has one major issue.
> In this setup analog cable signal is fed both to the pvr350
> card and the TV using a splitter.
>
> Now the problem is there are some channels which look
> good on TV but the same channel look very grainy and
> blurry in mythtv. But there are also some channels which
> are equally good on both TV and mythtv.
>
> Here are few things done but no breakthrough.
>
> - swapped the TV and the PVR inputs, but this made no difference
>
> - Using v4l2-ctl tuned a channel from 885.25 MHz to 62.50 MHz
> in steps of 1 MHz and observed the ivtv output. I was looking for
> a pattern in the blurry channels frequency, but found none.
>
> - checked the ivtv decoder output (/dev/video0) directly, Same problem
> existed.
>
> - changed the recording bitrates iin mythtv recording profiles for LiveTV
>
> - For one grainy/blurry channel, fine tuned on either side of the frequency
> using v4l2-ctl. Again no difference.
>
> Can you please give some more ideas for debugging this ?
>
> thanks
> holla

Could be a heat issue. Try turning the computer off for a while, then
turn it on and tune directly to one of the channels on which you get
poor quality on the PVR 350.

The splitter probably drops the signal strength equally across both
legs. Try removing it altogether and use a plain coax connector to hook
your PVR 350 up directly to see if the improved signal strength helps
the card.

Could be interference that the card picks up inside the computer. Could
also be a poor quality power supply in the computer. Try the card in
another computer to check these. You could also try rearranging the
expansion cards in the computer to move the PVR 350 away from other cards.

Roger



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Re: Some analog channels are bad in ivtv but OK on the analog TV [ In reply to ]
holla.net at gmail
Sep 5, 2011, 5:49 PM
Post #3 of 4 (2062 views)
Permalink
Thanks, I will investigate these three points.

In my case, I do not have a regular cabinet instead a custom made with
everything tightly packed around a mini-ITX board. There is only one PCI
slot on the board. I will especially check up on the power supply.

One thing that confuses me is that there are some channels which are
equally good on both the legs of the splitter. If it is heat or the power
supply problem, I guess it would have affected these channels also, no ?

> Could be a heat issue. Try turning the computer off for a while, then turn
> it on and tune directly to one of the channels on which you get poor quality
> on the PVR 350.
>
> The splitter probably drops the signal strength equally across both legs.
> Try removing it altogether and use a plain coax connector to hook your PVR
> 350 up directly to see if the improved signal strength helps the card.
>
> Could be interference that the card picks up inside the computer. Could also
> be a poor quality power supply in the computer. Try the card in another
> computer to check these. You could also try rearranging the expansion cards
> in the computer to move the PVR 350 away from other cards.
>
> Roger
>
>
>
> _______________________________________________
> ivtv-users mailing list
> ivtv-users@ivtvdriver.org
> http://ivtvdriver.org/mailman/listinfo/ivtv-users
>

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Re: Some analog channels are bad in ivtv but OK on the analog TV [ In reply to ]
rdmisc at dahlsys
Sep 5, 2011, 9:57 PM
Post #4 of 4 (2062 views)
Permalink
There's some fine tuned analog circuitry inside the RF tuner box on the
card, and I think it's possible that heat or voltages that are too high
or too low could cause the components to go out of spec in such a way
that there is signal loss only at specific locations in the spectrum.

If RF noise makes it into the tuner, it could cause problems at the
frequency the noise is at and all harmonic frequencies as well, causing
seemingly random channels to have issues. Noise could come in via the
power from the power supply or via electromagnetic radiation.

It could also be that the signal strength on the channels you're having
trouble with are low, and your TV is able to handle it, while the PVR
350 is not. A signal amplifier might help then.

On 2011-09-05 18:49, Sathish Vasudevaiah wrote:
> Thanks, I will investigate these three points.
>
> In my case, I do not have a regular cabinet instead a custom made with
> everything tightly packed around a mini-ITX board. There is only one PCI
> slot on the board. I will especially check up on the power supply.
>
> One thing that confuses me is that there are some channels which are
> equally good on both the legs of the splitter. If it is heat or the power
> supply problem, I guess it would have affected these channels also, no ?
>


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