how to solve black screen?

supwin · Post by **supwin** » Tue Dec 08, 2009 3:09 am

Hi every one

I have so tried to solve a black screen but it still be.
I use Ubuntu 9.04 + Zoneminder v1.23.3 and tv tuner Saa7134.
Saa7134 is working with xawtv or other except Zoneminder.

this is a Screen shot xawtv play with Saa7134.

this is a Screen shot Zoneminder's list camera. Is it ok? Source and Function are orange.

this is a Screen shot viewer camera. Look at it ....... BLANK SCREEN
I try click "Setting" for the camera Setting I wonder why every value is -1
and then I try change to other value such as 50 and click save. It will be back to -1.

please ......... help me
what can I do? and what should I check? or where should I find down any information to solve this?
please........................

thank you in advance

Post by **cordel** » Tue Dec 08, 2009 10:40 am

Have you checked the logs and gone through the troubleshooting as described in both the Documentation and FAQ in the wiki?
What have you done?
What are the errors in the logs and which ones?

supwin · Post by **supwin** » Fri Dec 11, 2009 1:40 am

Thank you for you reply
I have set it up step by step as wiki (link below)
http://www.zoneminder.com/wiki/index.ph ... _interface

and I check logs

12/11/09 08:36:28.788329 zmwatch[2671].ERR [Can't get shared memory id '7a6d0001', 1: No such file or directory]
12/11/09 08:36:28.788741 zmwatch[2671].INF [Restarting capture daemon for Camera1, shared memory not valid]
12/11/09 08:36:29.166929 zmwatch[2671].INF ['zmc -d /dev/video' starting at 09/12/11 08:36:29, pid = 4224]

it say "Can't get shared memory id '7a6d0001'"
So I try with this

kernel.shmmax = 167772160

but it still be black screen and there is few topic about "black screen" but they can't help me.

I don't know what I miss.
help me please

thank you.

whatboy · Post by **whatboy** » Fri Dec 11, 2009 3:18 am

Did you read carfully here http://www.zoneminder.com/wiki/index.ph ... esolutions.

kernel.shmall should be in pages not in bytes... like if you have 4 Gb, then 4000 x 1024 x 1024 / 4096

and kernel.shmmax (height x width x Colorscheme x Bufferring x numberofcameras) + 10% / 8

supwin · Post by **supwin** » Fri Dec 11, 2009 3:42 am

whatboy wrote:Did you read carfully here http://www.zoneminder.com/wiki/index.ph ... esolutions.

kernel.shmall should be in pages not in bytes... like if you have 4 Gb, then 4000 x 1024 x 1024 / 4096

and kernel.shmmax (height x width x Colorscheme x Bufferring x numberofcameras) + 10% / 8

Thank you whatboy
I now don't understand what is meaning.
but I try first. may I ask you If I can't, please...

thank you.

whatboy · Post by **whatboy** » Fri Dec 11, 2009 4:21 am

HUH???

kernel.shmall is the total physical memory your PC have but in pages... like if you have 4Gb of total memory you just do this...

4000 x 1024 x 1024 / 4096 = 1024000

And kernel.shmmax

supposed you capture image is 320 x 200 and is RGB24 and you have 2 cameras with the same resolution/color and you have a buffer ring of 40 then

320 x 200 x 24 x 40 x 2 = 122880000 + 10% of 122880000
122880000 + 12288000 = 135168000 / 8 = 16896000

So you put in the /etc/sysctl.conf file
kernel.shmall = 1024000
kernel.shmmax = 16896000

Then you execute as root
sysctl -p
ipcs -l

and restart zoneminder...

supwin · Post by **supwin** » Sat Dec 12, 2009 1:46 am

whatboy wrote:HUH???

kernel.shmall is the total physical memory your PC have but in pages... like if you have 4Gb of total memory you just do this...

4000 x 1024 x 1024 / 4096 = 1024000

And kernel.shmmax

supposed you capture image is 320 x 200 and is RGB24 and you have 2 cameras with the same resolution/color and you have a buffer ring of 40 then

320 x 200 x 24 x 40 x 2 = 122880000 + 10% of 122880000
122880000 + 12288000 = 135168000 / 8 = 16896000

So you put in the /etc/sysctl.conf file
kernel.shmall = 1024000
kernel.shmmax = 16896000

Then you execute as root
sysctl -p
ipcs -l

and restart zoneminder...

Thank you Mr.whatboy
I'm going to make as you teach me.
I'll report how is success.
Thank you so much

Post by **cordel** » Mon Dec 14, 2009 6:40 am

[Restarting capture daemon for Camera1, shared memory not valid]

Is not the same as a "Can''t shmget"

Shared Memory Not Valid usually means that the initial capture failed which results in no image to put into shared memory which in turn means that there is nothing in shared memory to retrieve.

You need to raise your debug level and focus on the zmc process to find why the capture is failing.

supwin · Post by **supwin** » Mon Dec 14, 2009 12:17 pm

cordel wrote:
[Restarting capture daemon for Camera1, shared memory not valid]
Is not the same as a "Can''t shmget"

Shared Memory Not Valid usually means that the initial capture failed which results in no image to put into shared memory which in turn means that there is nothing in shared memory to retrieve.

You need to raise your debug level and focus on the zmc process to find why the capture is failing.

what should I do?
sorry I don't understand what your mean.

please explain to me a little bit more.

thank you mr.cordel

Post by **cordel** » Mon Dec 14, 2009 6:52 pm

Using logs and debug is noted here.