Mailing List Archive: Re: image quality problem with ivtv (was ivtvfb)

Re: image quality problem with ivtv (was ivtvfb)

Mar 12, 2011, 9:30 AM

Post #1 of 4 (1761 views)

On Tue, Mar 8, 2011 at 8:44 PM, Dirk Beer <rdbeer@gmail.com> wrote:
> I'm having problems with image quality with ivtvfb kernel module.

I did some more troubleshooting, and it looks like the problem is with
ivtv and the S-Video output.

dd if=/dev/video0 of=test.mpg

looks good.

dd if=/dev/video0 of=/dev/video16 bs=64k

looks bad on S-Video 1: grainy and desaturated color.
but good on Composite 1.

I'm using:
* kernel 2.6.26-ARCH i686 (old because the Arch-based LinHES R6 uses
only that kernel)
* PVR-350
* recommended firmware from ivtvdriver.org
* S-video 1 output or Composite 1 output

This identical hardware (including cables, tv, etc) gave me a nice
picture recently, so I don't think it is hardware related.

I can use Composite for now, but would like to use S-Video since it
normally has slightly better video quality. Does anyone have any
suggestions of how to fix S-Video?

Dirk

-----------------------------------------
[root@obmyth ~]# dmesg|grep ivtv
ivtv: Start initialization, version 1.4.0
ivtv0: Initializing card #0
ivtv0: Autodetected Hauppauge card (cx23415 based)
ivtv 0000:01:06.0: PCI INT A -> Link[APC3] -> GSI 18 (level, high) -> IRQ 18
ivtv0: Unreasonably low latency timer, setting to 64 (was 32)
ivtv0: Autodetected Hauppauge WinTV PVR-350
saa7115 2-0021: saa7115 found (1f7115d0e100000) @ 0x42 (ivtv i2c driver #0)
saa7127 2-0044: saa7129 found @ 0x88 (ivtv i2c driver #0)
msp3400 2-0040: MSP4448G-A2 found @ 0x80 (ivtv i2c driver #0)
tuner 2-0043: chip found @ 0x86 (ivtv i2c driver #0)
tuner 2-0061: chip found @ 0xc2 (ivtv i2c driver #0)
ivtv0: Registered device video0 for encoder MPG (4096 kB)
ivtv0: Registered device video32 for encoder YUV (2048 kB)
ivtv0: Registered device vbi0 for encoder VBI (1024 kB)
ivtv0: Registered device video24 for encoder PCM (320 kB)
ivtv0: Registered device radio0 for encoder radio
ivtv0: Registered device video16 for decoder MPG (1024 kB)
ivtv0: Registered device vbi8 for decoder VBI (64 kB)
ivtv0: Registered device vbi16 for decoder VOUT
ivtv0: Registered device video48 for decoder YUV (1024 kB)
ivtv0: Initialized card #0: Hauppauge WinTV PVR-350
ivtv: End initialization
ivtv 0000:01:06.0: firmware: requesting v4l-cx2341x-enc.fw
ivtv0: Loaded v4l-cx2341x-enc.fw firmware (376836 bytes)
ivtv 0000:01:06.0: firmware: requesting v4l-cx2341x-dec.fw
ivtv0: Loaded v4l-cx2341x-dec.fw firmware (262144 bytes)
ivtv0: Encoder revision: 0x02060039
ivtv0: Decoder revision: 0x02020023
ivtv 0000:01:06.0: firmware: requesting v4l-cx2341x-init.mpg
ivtv0: Loaded v4l-cx2341x-init.mpg firmware (155648 bytes)

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Re: image quality problem with ivtv (was ivtvfb) [ In reply to ]

awalls at md

Mar 12, 2011, 4:05 PM

Post #2 of 4 (1722 views)

Permalink

On Sat, 2011-03-12 at 09:30 -0800, Dirk Beer wrote:
> On Tue, Mar 8, 2011 at 8:44 PM, Dirk Beer <rdbeer@gmail.com> wrote:
> > I'm having problems with image quality with ivtvfb kernel module.
>
> I did some more troubleshooting, and it looks like the problem is with
> ivtv and the S-Video output.
>
> dd if=/dev/video0 of=test.mpg
>
> looks good.
>
> dd if=/dev/video0 of=/dev/video16 bs=64k
>
> looks bad on S-Video 1: grainy and desaturated color.
> but good on Composite 1.

The PVR-350 defaults to outputting on both CVBS and S-Video. Could you
test with v4l2-ctl to set the output explciitly to S-Video only?

> I'm using:
> * kernel 2.6.26-ARCH i686 (old because the Arch-based LinHES R6 uses
> only that kernel)
> * PVR-350
> * recommended firmware from ivtvdriver.org
> * S-video 1 output or Composite 1 output
>
> This identical hardware (including cables, tv, etc) gave me a nice
> picture recently, so I don't think it is hardware related.

Please try and test these things if you can (maybe you already have):

1. The PVR-350 S-Video output quality using Windows
2. A different S-Video receiving device (another TV, VCR, or even a
PVR-150)
3. A different S-Video cable

Most PVR-350's are getting old, so a partial failure of the SAA7129 chip
due to age would not be surprising.

If you look at page 47 of the SAA7129 datasheet:

http://dl.ivtvdriver.org/datasheets/video/SAA7128H_SAA7129H_3.pdf

it is possible for the DAC and output amplifier for CVBS to be fine,
while the DAC and output amplifier for C is failing.

> I can use Composite for now, but would like to use S-Video since it
> normally has slightly better video quality. Does anyone have any
> suggestions of how to fix S-Video?

The SAA7129 isn't a terribly complicated chip, so if you really do
beleive it is just a register being set wrong, you can examine and
twiddle the registers of the SAA7129 yourself using v4l2-dbg.
(Your ivtv & saa7127 modules, and mabye other core videodev and v4l2
related modules, will need to be built with the CONFIG_VIDEO_ADV_DEBUG
kernel configuration option for v4l2-dbg to work.)

The registers of the SAA7129 are documented on pages 15-35 of the
datasheet. A simple register to play with, to get an obvious effect, is
register 0x3a, where the state of bit 7 controls whether the SAA7129
displays normal video or a color bar pattern.

I'm really busy for the next 2 weeks, so I won't be able to look into
any possible problem myself until then. Even then I'll have to jump
through hoops to get a device that can receive S-Video near my PVR-350.

Regards,
Andy

> Dirk
>
> -----------------------------------------
> [root@obmyth ~]# dmesg|grep ivtv
> ivtv: Start initialization, version 1.4.0
> ivtv0: Initializing card #0
> ivtv0: Autodetected Hauppauge card (cx23415 based)
> ivtv 0000:01:06.0: PCI INT A -> Link[APC3] -> GSI 18 (level, high) -> IRQ 18
> ivtv0: Unreasonably low latency timer, setting to 64 (was 32)
> ivtv0: Autodetected Hauppauge WinTV PVR-350
> saa7115 2-0021: saa7115 found (1f7115d0e100000) @ 0x42 (ivtv i2c driver #0)
> saa7127 2-0044: saa7129 found @ 0x88 (ivtv i2c driver #0)
> msp3400 2-0040: MSP4448G-A2 found @ 0x80 (ivtv i2c driver #0)
> tuner 2-0043: chip found @ 0x86 (ivtv i2c driver #0)
> tuner 2-0061: chip found @ 0xc2 (ivtv i2c driver #0)
> ivtv0: Registered device video0 for encoder MPG (4096 kB)
> ivtv0: Registered device video32 for encoder YUV (2048 kB)
> ivtv0: Registered device vbi0 for encoder VBI (1024 kB)
> ivtv0: Registered device video24 for encoder PCM (320 kB)
> ivtv0: Registered device radio0 for encoder radio
> ivtv0: Registered device video16 for decoder MPG (1024 kB)
> ivtv0: Registered device vbi8 for decoder VBI (64 kB)
> ivtv0: Registered device vbi16 for decoder VOUT
> ivtv0: Registered device video48 for decoder YUV (1024 kB)
> ivtv0: Initialized card #0: Hauppauge WinTV PVR-350
> ivtv: End initialization
> ivtv 0000:01:06.0: firmware: requesting v4l-cx2341x-enc.fw
> ivtv0: Loaded v4l-cx2341x-enc.fw firmware (376836 bytes)
> ivtv 0000:01:06.0: firmware: requesting v4l-cx2341x-dec.fw
> ivtv0: Loaded v4l-cx2341x-dec.fw firmware (262144 bytes)
> ivtv0: Encoder revision: 0x02060039
> ivtv0: Decoder revision: 0x02020023
> ivtv 0000:01:06.0: firmware: requesting v4l-cx2341x-init.mpg
> ivtv0: Loaded v4l-cx2341x-init.mpg firmware (155648 bytes)
>
> _______________________________________________
> ivtv-users mailing list
> ivtv-users@ivtvdriver.org
> http://ivtvdriver.org/mailman/listinfo/ivtv-users

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Re: image quality problem with ivtv (was ivtvfb) [ In reply to ]

dheitmueller at kernellabs

Mar 12, 2011, 4:36 PM

Post #3 of 4 (1738 views)

Permalink

On Sat, Mar 12, 2011 at 7:05 PM, Andy Walls <awalls@md.metrocast.net> wrote:
> I'm really busy for the next 2 weeks, so I won't be able to look into
> any possible problem myself until then. Even then I'll have to jump
> through hoops to get a device that can receive S-Video near my PVR-350.

Or just spend $20.00 and buy an Nvidia card with VDPAU and S-video
output. Given how cheap they are nowadays, it probably isn't worth
the effort to debug.

Devin

--
Devin J. Heitmueller - Kernel Labs
http://www.kernellabs.com

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Re: image quality problem with ivtv (was ivtvfb) [ In reply to ]

rdbeer at gmail

Mar 14, 2011, 12:40 PM

Post #4 of 4 (1719 views)

Permalink

Andy, all,

thanks very much for the replies. Sorry it's taken me a while to respond.

>> looks bad on S-Video 1: grainy and desaturated color.
>> but good on Composite 1.
>
> The PVR-350 defaults to outputting on both CVBS and S-Video. Could you
> test with v4l2-ctl to set the output explciitly to S-Video only?

Yes, I did try that, but it didn't help.

> Please try and test these things if you can (maybe you already have):
>
> 1. The PVR-350 S-Video output quality using Windows
> 2. A different S-Video receiving device (another TV, VCR, or even a
> PVR-150)
> 3. A different S-Video cable

Ok, I will try those as next steps.

>
> Most PVR-350's are getting old, so a partial failure of the SAA7129 chip
> due to age would not be surprising.
>
> If you look at page 47 of the SAA7129 datasheet:
<snip>
> The registers of the SAA7129 are documented on pages 15-35 of the
> datasheet. A simple register to play with, to get an obvious effect, is
> register 0x3a, where the state of bit 7 controls whether the SAA7129
> displays normal video or a color bar pattern.
Good to know, thank you. By the way, you might be surprised to know
that when my old PVR-350 burned up about a year ago, Hauppauge sent me
a brand new one as a replacement at no cost. Very generous of them.

> I'm really busy for the next 2 weeks, so I won't be able to look into
> any possible problem myself until then. Even then I'll have to jump
> through hoops to get a device that can receive S-Video near my PVR-350.

Please don't bother on my account. At this point with Composite out
working, I'm not willing to put much time into troubleshooting it
myself :)

Thanks again, I appreciate your detailed reply.

Dirk

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