kristink
Posts: 4
Joined: Sat Oct 19, 2013 3:09 am

how to run 2 separate video files to 2 lcd screens from 1 pi

Sat Oct 19, 2013 3:22 am

I want to run two different videos to two separate lcd screens (simultaneously) from one Raspberry Pi. I can only figure out how to run one video to the two screens, but not two separate video files :( Can anyone help or suggest a course of inquiry? Thank you.

karlkiste
Posts: 189
Joined: Tue Jan 22, 2013 8:50 am
Location: berlin, germany

Re: how to run 2 separate video files to 2 lcd screens from

Sat Oct 19, 2013 2:04 pm

My Pi has only a HDMI and a CVBS video output, which can't be enabled at the same time. How do you connect the screens?

kristink
Posts: 4
Joined: Sat Oct 19, 2013 3:09 am

Re: how to run 2 separate video files to 2 lcd screens from

Mon Oct 21, 2013 3:02 am

Hi Karl, If I only wanted to run one video file to the two screens, I was planning to split the cvbs video output to the two screens. I think that would work, but that's not what I need. I need to run two distinct files to two different screens at the same time from one pi and I have no idea how to do it. Anyone have an idea?

Let me know!

Thanks.

ame
Posts: 3172
Joined: Sat Aug 18, 2012 1:21 am
Location: Korea

Re: how to run 2 separate video files to 2 lcd screens from

Mon Oct 21, 2013 4:03 am

The answer is: buy another Pi.

Seriously.

I thought the answer might be to buy a USB->VGA converter, which would add a new VGA video port (so you get HDMI and VGA outputs) but even the cheap ones are about $30, and they depend on drivers being available. The Raspberry Pi is so cheap you really should use one Pi for each display. Here's an article about making a video wall based on that restriction:
http://hackaday.com/2013/07/22/multiple ... ideo-wall/

karlkiste
Posts: 189
Joined: Tue Jan 22, 2013 8:50 am
Location: berlin, germany

Re: how to run 2 separate video files to 2 lcd screens from

Mon Oct 21, 2013 5:16 am

The short answer:
It's impossible.

The bold answer:
Hide the second pi somewhere, it's small enough.

The expensive answer:
Combine the two videos to one, and use a HDMI split-screen machine to separate them again.

The hand-soldered answer:
Combine the two videos, so that one video occupies the odd lines on the CVBS, the other one the even ones. Then split the CVBS using a video amplifier, and build some extra electronics which blanks out all video lines (not the sync) every other half-frame on each output, respectively.

The sensible answer:
If the second screen has a low resolution, like 120x90 or so, it might be possible to use a SPI connection to display a video. This size of video would also be playable without hardware decoding. Using a USB-VGA adapter (thanks for the hint, I almost forgot that ;-) ) even 320x240 or so might be possible.
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ghans
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Location: Germany

Re: how to run 2 separate video files to 2 lcd screens from

Mon Oct 21, 2013 6:30 am

Nice hardware !
What does it do ?

ghans
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karlkiste
Posts: 189
Joined: Tue Jan 22, 2013 8:50 am
Location: berlin, germany

Re: how to run 2 separate video files to 2 lcd screens from

Mon Oct 21, 2013 7:21 am

Nice hardware !
What does it do ?
Thanks ;-)
It's mostly DC/DC converter, you plug in a 12V 2A power supply, and it powers the pi's with 5V "from the backdoor", i.e. through the power pins on P1.

Then, there's a PIC microcontroller which coordinates the videos playing in each pi. The DB9-plug in the front exposes an I2C bus to connect controlling equipment.

jamesh
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
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Re: how to run 2 separate video files to 2 lcd screens from

Mon Oct 21, 2013 7:53 am

kristink wrote:I want to run two different videos to two separate lcd screens (simultaneously) from one Raspberry Pi. I can only figure out how to run one video to the two screens, but not two separate video files :( Can anyone help or suggest a course of inquiry? Thank you.
As other have said - impossible as standard - you can only sensible output to one display device at a time. Also worth remembering that the Pi has the capacity for one 1080p30 decode at a time, not the two you need (assuming 1080p30 is the requirement)

Buy another Pi. By far the easiest approach.
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kristink
Posts: 4
Joined: Sat Oct 19, 2013 3:09 am

Re: how to run 2 separate video files to 2 lcd screens from

Mon Oct 21, 2013 1:25 pm

Thanks so much everyone. So so helpful! I'll try Karl's "sensible" titled route first because the tricky part is that it's for a tiny sculpture with two very small screens and two pis will not fit within it. I might have to do some rebuilding. Thank you again :P This forum is awesome.

kristink
Posts: 4
Joined: Sat Oct 19, 2013 3:09 am

Re: how to run 2 separate video files to 2 lcd screens from

Mon Oct 21, 2013 7:10 pm

Oh dear, :( . I rebuilt the encasing to hold two pis, and now I'm having a very difficult time figuring out how to network them together. I am a beginner. Any suggestions on helpful tutorials on this subject or other resources? (I want them linked because the two video files I want to play are distinct but synchronized and I want ti to be easy for anyone to start it up on their own).

Thank you!
karlkiste wrote:The short answer:
It's impossible.

The bold answer:
Hide the second pi somewhere, it's small enough.

The expensive answer:
Combine the two videos to one, and use a HDMI split-screen machine to separate them again.

The hand-soldered answer:
Combine the two videos, so that one video occupies the odd lines on the CVBS, the other one the even ones. Then split the CVBS using a video amplifier, and build some extra electronics which blanks out all video lines (not the sync) every other half-frame on each output, respectively.

The sensible answer:
If the second screen has a low resolution, like 120x90 or so, it might be possible to use a SPI connection to display a video. This size of video would also be playable without hardware decoding. Using a USB-VGA adapter (thanks for the hint, I almost forgot that ;-) ) even 320x240 or so might be possible.

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