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Comment by ersii | Hacker News Reader

What kind of video servers are you talking about? For ingesting from a feed/camera in? Streaming out video? Curious.

While these servers can ingest video feeds, they wouldn't (typically) be saving the incoming feeds. These servers play out video over many projectors blended into a single seamless image. If you've watched the past few Olympics opening ceremonies, you most certainly saw the projections.

My recent project, which was relatively small, played back a single video over 4 blended projectors. Each video frame was a 50MB uncompressed TGA file, 30 times a second. On a more complex show, you could be trying to play back multiple video streams simultaneously.

D3 - http://www.d3technologies.com/ and Pandora - http://www.coolux.de/products/pandoras-box-server/

are two of the big players in the industry.

Each video frame was a 50MB uncompressed TGA file, 30 times a second.

Ouch! Not even a PNG?

I'd guess the time to do compression from TGA to PNG may be more than 1/30th of a second. Or at least reliably/consistently so.

Uncompressed TGA is used for two reasons: Quality (this particular image was going on a screen three stories tall) and, as the other commenter mentioned, the time required to decompress images.

I'm not an expert on the exact architecture, but I'm guessing that with uncompressed TGA you just throw the bits at the GPU and they get displayed, while if you have to uncompress images that first gets handled by the CPU (?).

A friend of mine does a lot of programming and installations using Dataton Watchout - where they use 4 or more 4K projectors stitched together into one big image. He's regularly got war stories about problems with the latest batch of SSDs not playing well in RAID0 causing stutters on simultaneous playback of multiple 4K video streams.

Is there an advantage compared to putting each stream on a different drive?

It's possible, and probably advantageous to a point. Eventually you'll hit bottlenecks somewhere, at which point you throw more servers at it.

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