FleaBit
Posts: 16
Joined: Thu Jan 17, 2013 1:31 pm

How's this thing work?

Sun May 19, 2013 1:33 pm

After fighting memory card brand related issues to get this camera working, once I have it working, I'm stuck. I can type the commands and get a flash of a preview on the screen, but what's actually happening? Is it actually capturing video or jpegs and storing them somewhere? If so, where? Or, are raspivid and raspistill just tools to be used by something else to actually capture it, meaning you have to write code to make something actually capture? Or do those commands capture it. If so, where's the magic storage place (I can't see any directories listed in that area where those commands are)?

I got to this party late, so forgive me. I have exactly 1 day of exposure to it. I've searched a searched but haven't found anything that actually shows you taking stills. Lots of streaming instructions, but I can't find much on stills.

Is there a guide for taking stills, where they are stored, how it all works, or am I completely missing something obvious (which is HIGHLY possible).

Thanks for putting up with my basic questions!

Oh, let's just add a scenario in case that helps- I'd like to capture stills at will.

User avatar
fbutler
Posts: 302
Joined: Thu Mar 15, 2012 4:09 pm
Location: Surrey, England

Re: How's this thing work?

Sun May 19, 2013 1:39 pm

FleaBit wrote:After fighting memory card brand related issues to get this camera working, once I have it working, I'm stuck. I can type the commands and get a flash of a preview on the screen, but what's actually happening? Is it actually capturing video or jpegs and storing them somewhere? If so, where? Or, are raspivid and raspistill just tools to be used by something else to actually capture it, meaning you have to write code to make something actually capture? Or do those commands capture it. If so, where's the magic storage place (I can't see any directories listed in that area where those commands are)?

I got to this party late, so forgive me. I have exactly 1 day of exposure to it. I've searched a searched but haven't found anything that actually shows you taking stills. Lots of streaming instructions, but I can't find much on stills.

Is there a guide for taking stills, where they are stored, how it all works, or am I completely missing something obvious (which is HIGHLY possible).

Thanks for putting up with my basic questions!

Oh, let's just add a scenario in case that helps- I'd like to capture stills at will.
The basic instructions are in this post:
http://www.raspberrypi.org/archives/3890
To see a full list of options for the raspistill program use the command:

Code: Select all

raspistill | less

FleaBit
Posts: 16
Joined: Thu Jan 17, 2013 1:31 pm

Re: How's this thing work?

Sun May 19, 2013 2:07 pm

Thanks, I'd seen all of that and was still missing something. In rereading it, I think I had the lightbulb moment finally. Some days the light comes on quicker than others!

Thanks!

FleaBit
Posts: 16
Joined: Thu Jan 17, 2013 1:31 pm

Re: How's this thing work?

Sun May 19, 2013 8:45 pm

Okay, apparently the lightbulb that came on burned out quickly.

When I type the following in :

Code: Select all

raspistill -o image.jpg
I get the following error message :

"mmal: main: Error opening output file: image.jpg
No output file will be generated"

I'm not sure how I'm capable of taking something so simple and making it so complicated, but apparently I have a talent for it :)

DirkS
Posts: 7547
Joined: Tue Jun 19, 2012 9:46 pm
Location: Essex, UK

Re: How's this thing work?

Sun May 19, 2013 9:00 pm

"mmal: main: Error opening output file: image.jpg
No output file will be generated"
Do you have write permission for the location the file is written to?

Gr.
Dirk.

FleaBit
Posts: 16
Joined: Thu Jan 17, 2013 1:31 pm

Re: How's this thing work?

Sun May 19, 2013 10:47 pm

That's a good question and part of my original question. Where's it writing to?

It's a bone stock, fresh install of the OS, with nothing else done other than installing the camera. I've followed the exact examples in the documentation and that's the errors I'm running into. I'm surprised I'm the only one to see it, since I've modified nothing.

DirkS
Posts: 7547
Joined: Tue Jun 19, 2012 9:46 pm
Location: Essex, UK

Re: How's this thing work?

Sun May 19, 2013 11:10 pm

That's a good question and part of my original question. Where's it writing to?
Current working directory. If you've just logged in with user Pi that will be /home/pi and if you issue the raspistill command from there it should not give any permission problems.

Gr.
Dirk.

FleaBit
Posts: 16
Joined: Thu Jan 17, 2013 1:31 pm

Re: How's this thing work?

Mon May 20, 2013 12:18 am

I did that and got the same error. I chmod'ed it and now it all seems to work fine.

Thanks for the help. Hopefully my questioning on this part is over, as it looks like I have taken several photos and confirmed their location and quality.

Thanks for the help, I appreciate it!

GardenSteamer
Posts: 1
Joined: Wed Aug 22, 2012 3:44 pm

Re: How's this thing work?

Mon May 20, 2013 4:36 am

I had the same problem and solved it with

sudo raspistill -o image.jpg

User avatar
fbutler
Posts: 302
Joined: Thu Mar 15, 2012 4:09 pm
Location: Surrey, England

Re: How's this thing work?

Mon May 20, 2013 7:17 am

GardenSteamer wrote:I had the same problem and solved it with

sudo raspistill -o image.jpg
You shouldn't need to run the camera commands as root. It looks like there are permission errors due to where you are in the directory structure when you run the command. You must have write permissions to the directory where you are creating the image.jpg file.

Pshock13
Posts: 1
Joined: Mon Feb 03, 2014 11:13 am

Re: How's this thing work?

Tue Aug 11, 2015 3:58 am

fbutler wrote:You must have write permissions to the directory where you are creating the image.jpg file.
I'm have trouble writing to '/mnt/picam' a directory that I created. As in ...

Code: Select all

raspistill -o /mnt/picam/test.jpg
I get this error

Code: Select all

mmal: main: Error opening output file: /mnt/picam/test.jpg~
No output file will be generated
How do I go about checking the permissions of /mnt/picam?
how do i change the permissions?
and how do I know what permissions to change them to?

JimmyN
Posts: 1109
Joined: Wed Mar 18, 2015 7:05 pm
Location: Virginia, USA

Re: How's this thing work?

Tue Aug 11, 2015 3:25 pm

You should have created a new thread for your question rather than adding to an old one. But since you're here....

You created a mount point /mnt/picam. The permissions and ownership for /picam will be determined by the mount command you used when mounting the drive to /mnt/picam. What type of filesystem is the mounted drive using? If it's FAT32 or NTFS they don't supply any credentials so ownership and permissions have to be specified in the mount command. If not specified the default would be root as the owner of everything in /picam.
If it's an ext* filesystem you can use the "chown" command on the mounted drive (/picam) if you need to change the ownership.

You can see the ownership and permissions for the mounted drive by using:

Code: Select all

ls -l /mnt
If ls -l shows something like

Code: Select all

drwxr-xr-x 2 root root 4096 Jan  9  2015 picam
then the mounted drives files (picam) belong to root and you'll need to use 'sudo' to write to it. If it looks more like

Code: Select all

drwxr-xr-x 2 pi pi 4096 Jan  9  2015 picam
then the files belong to 'pi' and you're all set.

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