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Old 09-28-2007, 01:35 PM   #1
Registered: Sep 2003
Distribution: Debian
Posts: 69

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4 port video capture card using the bttv module - use Composite0-3 at once


I am trying to use my own software that I have created in Adobe Flash to work capture cards to create a flash video surveillance system. This means I need the functionality of Linux to interact with these video cards (norm, tuner, composite etc...) instead of using xawtv.

This is my seutup:

Linux kubuntu kernel 2.6
pci 4 port generic video capture card. it has one conexant chip and works with the bttv mod

When I do a dmesg | grep it outputs:
[58.069712] bttv: driver version 0.9.16 loaded
[58.069724] bttv: using 8 buffers with 2080k (520 pages) each for capture
[58.069732] bttv: Host bridge needs ETBF enabled.
[58.069846] bttv: Bt8xx card found (0).
[58.069950] bttv0: Bt878 (rev 17) at 0000:00:10.0, irq: 9, latency: 132, mmio: 0xf0005000
[58.069978] bttv0: using: GrandTec Multi Capture Card (Bt878) [card=77,insmod option]
[58.069997] bttv0: enabling ETBF (430FX/VP3 compatibilty)
[58.070037] bttv0: gpio: en=00000000, out=00000000 in=00f36fff [init]
[65.427986] bttv0: using tuner=-1
[65.428001] bttv0: i2c: checking for TDA9875 @ 0xb0... <6>NET: Registered protocol family 10
[71.858946] bttv0: i2c: checking for TDA7432 @ 0x8a... <7>eth0: no IPv6 routers present
[78.257237] bttv0: i2c: checking for TDA9887 @ 0x86... not found
[84.656088] bttv0: registered device video0
[84.656460] bttv0: registered device vbi0

Looking at other peoples setups I see that they have a bttv1, bttv2 etc which I believe represents capture cards or a capture card with multiple chips. In my /dev/ i only have video0, this is because the card I have only has one chip but four ports.

With the bttv mod:
modprobe bttv card=77 pll=1 no_overlay=1

v4lctl norm NTSC

I then open up my flash software and select the card 77 that shows up as a camera option and I have video capture composite0. I can change the composite input with this command
v4lctl setinput composte1

This works great but I still only have one input.

So how can I get all four inputs to work at once?

Old 09-28-2007, 05:50 PM   #2
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Registered: Dec 2005
Location: Massachusetts, USA
Distribution: Ubuntu 10.04 and CentOS 5.5
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Originally Posted by waffe View Post
This works great but I still only have one input.
So how can I get all four inputs to work at once?
I think you should have a separate instance of the software for each input. Maybe you could have four child processes off of the main process.
Old 09-28-2007, 06:26 PM   #3
Registered: Sep 2003
Distribution: Debian
Posts: 69

Original Poster
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I have been down that train of thought a little bit but I am quite sure that if I made a new instance of the software for each camera the only camera that would work would be that last one I turned on.

I have been told that one chip on the capture card can except four channels of input all at once - what I expect to see on my software end is still only one camera to select (/dev/video0) but that one camera will be divided into four quadrants each with one of the ports being captured.

Old 10-29-2007, 04:00 PM   #4
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Registered: Jul 2007
Posts: 5

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Hi Waffe,

I think I have a similar card and have similar problems to you! (see my original post "Sky 104" 4 channel bttv capture card)

I've installed the card in a windows box to see what happens.

If you are only viewing 1 input it captures it perfectly. If you increase the number of inputs you are viewing the frame rate rapidly gets worse.

I believe the software is cycling through the 4 inputs one by one, so all the images are full frame size, but if you are viewing all 4 the windows software only manages about 1fps per screen. (it spends more time swapping input than actually capturing a frame)

I hope this helps you with your software.

Old 04-20-2008, 07:36 AM   #5
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Registered: Apr 2008
Location: Melbourne, Florida
Distribution: Ubuntu 12.04, Fedora 17
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I recently purchased a $3.00 4/port card from ebay which was also made in Taiwan. There was no information provided for this card in a Linux environment and it took me awhile to get it working. My assumption was that Linux would see video0, video1, vide02, etc. Not true. Linux sees one device with multiple channels, i.e., video0,0; video0,1; video0,2; video0,3. In other words device:channel. See http://www.usefulramblings.orgsidbar for a more detailed explanation on how to get this working with Zoneminder.

Last edited by squeel; 04-20-2008 at 07:41 AM. Reason: typo corrections.


bt878, bttv, capture, conexant, video

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