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The most unhinged video wall, made out of Chromebooks

varun.ch

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Re: The most unhinged video wall, made out of Chromebooks

#21

Post by szvsw »

greggman25 wrote: post #9

I worked at Google when Chromebook shipped. They put out a call for decorations for the lobby and I proposed something similar to this but they said "no" :( Maybe because I asked for 40-64 machines :P I would not have tried to sync video though. Instead I'd have made time based animations and use the network the synchronize the clocks. you can see an example here: https://www.youtube.com/watch?v=64TcBiqmVko It's 8 ma…

If you have fixed media (as opposed to realtime dynamically generated or streamed etc) this trick can go a very long way - or even if it is generative, if the time is used to drive the animation. It just requires good clock sync, like you said, which can be non trivial (especially if audio is involved where desync of even 20-30ms becomes very noticeable). But yeah, with NTP/PTP you can get v v far.

Re: The most unhinged video wall, made out of Chromebooks

#23

Post by dividuum »

szvsw wrote: post #20
dividuum wrote: post #16

Earlier quoted context omitted.

I operate a digital signage company based around the Pi. Curious what problems you run into. SD cards?

The deprecation of OMXPlayer has been problematic for one, since I rely on some custom applications which need to be able to have some fairly precise/low latency requirements between when you tell it to start playing vs when the playback actually starts, etc. I haven’t found a suitable mechanism which meets our reqs on a Pi for controlling/playing videos yet since that deprecation. The lack of a regular HDMI output i…

> The deprecation of OMXPlayer has been problematic for one, since I rely on some custom applications which need to be able to have some fairly precise/low latency requirements between when you tell it to start playing vs when the playback actually starts, etc. I haven’t found a suitable mechanism which meets our reqs on a Pi for controlling/playing videos yet since that deprecation.

Yeah. The Pi3 -> Pi4/5 jump was quite a massive change in how things work. I've been writing my own playback engine for 10 years now and that one was quite challenging. Precise playback start is something my software supports: You control everything in Lua and can, for example, preload a video and then start it based on either internal logic or based on an external trigger. Up to the Pi3, my software also supports dynamically adjusting the HDMI clock, so the vsyncs of multiple displays are synchronized. Customers have been using that for almost 10 years for video wall playback.

If you go with the hosted version of the software, provisioning is as simple as extracting a single 60MB zip file to an empty SD card and placing that into the Pi. If needed you can even use the API to preconfigure that ZIP file to include settings like WiFi.

Re: The most unhinged video wall, made out of Chromebooks

#25

Post by cjaackie »

mezzman wrote: post #22

This one from 2013 when the Chromebook Pixel was announced was pretty great too. https://tomsepe.com/portfolio/google-pixeltree/

I remember when someone adapted the Chromebook Pixel display as a standalone monitor [0]. I’m sure it made the rounds here. I was almost tempted to do it myself because, at the time, it was a nice 4:3 screen. I couldn’t , the Chromebook Pixel was too beautiful to hack up.

[0] https://hackaday.com/2015/05/02/excruciating-quest-turns-chr...

Re: The most unhinged video wall, made out of Chromebooks

#26

Post by i-am-gizm0 »

varun_ch wrote: post #7
jojol wrote: post #4

Excellent work, and a great read. What videos did you end up playing on this after your testing was complete? Do you have any recordings to share of this in action?

Thank you! We haven’t figured out what to play on it yet actually - I think the plan is to build out all the tools so that our school can create and upload their own videos (eg. montages of students work - this is in the Design workshop after all) to display on the screen. It could be self-service even after we graduate in June.

I think a very wide game of Pong would be fun!

Re: The most unhinged video wall, made out of Chromebooks

#27

Post by xmprt »

nashashmi wrote: post #6

I wonder if it would have been easier to make just one video and have the computer zoom in to different parts of the video. And then run the video simultaneously through a web browser

The toughest part of this wasn't setting up different videos to play on each screen but rather the "run videos simultaneously through a web browser" part. So even if you could decode and process such a large video on those Chromebooks, it wouldn't help with video sync. That's not to mention the other challenges with installing the software and getting it to autoload on startup.

Re: The most unhinged video wall, made out of Chromebooks

#28

Post by xmprt »

varun_ch wrote: post #7
jojol wrote: post #4

Excellent work, and a great read. What videos did you end up playing on this after your testing was complete? Do you have any recordings to share of this in action?

Thank you! We haven’t figured out what to play on it yet actually - I think the plan is to build out all the tools so that our school can create and upload their own videos (eg. montages of students work - this is in the Design workshop after all) to display on the screen. It could be self-service even after we graduate in June.

If you want to spend more time on this I think one fun idea would be an infinite bouncing DVD logo. Just sync the location of the logo every time it bounces so all devices have a consistent view and then the individual screens can compute whether and how much of the logo to show and at which location.

Re: The most unhinged video wall, made out of Chromebooks

#29

Post by nolist_policy »

szvsw wrote: post #8
varun_ch wrote: post #3

Earlier quoted context omitted.

Thank you! I didn’t get the chance to mention them in the blog post, but yes we checked out the price tags on the commercial solutions :) It’s crazy! I’ve always wondered how much of the cost is hardware vs software… and I would imagine professional digital signage is also designed for reliability longevity and all that.

Reliability is a big part of it - but they are not really all that expensive for what you get IMO, especially in an enterprise context. A BrightSign is effectively a very sandboxed Linux box (you can SSH into them!) which has extremely reliable video and audio output, plus a huge amount of customizability, networking, scripting etc - plus various fleet provisioning/management software that goes with it. In terms of $…

By the way, you can use Chromebooks and -boxes for digital signage (and kiosk) as well if you manage them with Google Cloud.

Re: The most unhinged video wall, made out of Chromebooks

#30

Post by jpeggtulsa »

Me and another developer did this on a 300 seat call center on Windows Embedded thin clients probably 8 years ago now. We used timestamps and a high precision javascript library for synchronization. After everybody went home for the night, it would scroll the name of the business and the stats from the day across all the screens until a couple hours before the first calls, then it would load a queued video or text or even just colored lines similar to the windows screen saver depending on the day.
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