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Comment by Jabbles | Hacker News Reader

This is fantastic, but "1080p" can have a dramatic range of qualities. If Inglorious Bastards just fits on the 2GB card and is over 2 hours long then the bitrate will be around 2Mbit/s, which is probably not very good. (cf. ~25Mbit/s for BluRay).

I should also point out that depending on the quality of the encoder, the bitrate is also a bad way of measuring quality. But I believe it is more useful than just saying "1080p".

http://www.wolframalpha.com/input/?i=2+gigabytes+%2F+Inglour...

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Hi - I'm Liz from Raspberry Pi. What you can see in that vid isn't the whole of Inglorious Basterds, but just the trailer (which is why it fits on a small SD card) - we were playing it on a loop. The Raspberry Pi can play back full 25 megabit HDMI; it's part of our mobile phone SoC dividend.

By mobile phone SoC dividend, that's the VideoCore discrete signal processor, right?

From what I can gather Pi has a BCM2763 (as a DSP co-processor to the an ARM, or standalone?) or BCM2835 (combining a DSP and ARM on one chip) ... wikipedia is a bit hazy. (edit: it's the BCM2835 DSP + ARM on a chip, according to the rasberrypi FAQ).

It's got hardware that's dedicated to doing things it's 700MHz ARM chip simply can't, like watching YouTube in fullscreen (obligatory http://xkcd.com/619/). It should be able to do anything a high-end mobile phone can do (except take calls), which is what most people want.

It might be a good deal cooler with a $2 wifi chip (though that might make it harder to manufacture), or a $10 wifi USB adaptor, but I guess you have to draw the line somewhere.

It's a cine clip, so I think it was 24fps. We can decode 30fps, but it's actually quite hard to find content!

Do you have a reference for the technical details of this? Do you know how much power it draws? Are details like MTTF known? Where did you get the H264 decoder from?

Exciting stuff.

I'd be glad to generate some 30fps HD content (nothing fancy, just some CGI loops that will show the smoothness of video playback) in exchange for the ability to purchase the higher-end version sooner.

Well in that case I'm even more impressed. It's a pity the article doesn't mention that. What's the frame rate?

Congrats Liz, great little piece of kit!

Think we are seeing the start of a new uber cheap PC market. Almost zero cost. It will make a big difference in the developing world and I think will be a huge hit (at least amongst the tech geeks) in developed nations.

PS +1 on the comment for wifi in v2

I REALLY want one of these now - how much to get a unit NOW rather than waiting till you hit the $25 price point?

It's not a question of money. They are a UK charity and their 50 alpha boards are out amongst those who can provide the most benefit to the project.

Get in line behind the rest of us. :-)

They're on an alpha unit at the moment IIRC. I'd expect it to cost a lot and to slow down final production for them to start trying to sell at this stage.

Just to nitpick: HDMI is approx 10Gbit/s interface. If you are talking about decoding capabilities, then H.264 profile/level would be more useful metric, ie H.264 High Profile, Level 4 (which I think is what Blu-ray video usually is, or at least close to it).

It's a hardware decoder, right? So it's decoding capabilities are not really representative of it's general performance?

The BCM2835 chipset can decode Level 4.1 H.264 which is an approximately a maximum resolution/fps of 1080p30 at about 60-70mbit/s.

It's far more interesting to know what kind of level [1] the decoder supports. I'd guess it tops out at 4, though one might have hoped for full 1080p60 playback.

[1] http://en.wikipedia.org/wiki/H.264/MPEG-4_AVC#Levels

I think that realistically if you are looking for something like that, you already have your sights set firmly higher than a $25 device... for starters you'd need a decent screen and you'd probably like a nice set of speakers as well. I don't think you'd then go out and get a $25 device to enable the whole setup, but then again, I am not you...

Still, in future versions I'd imagine the SoC would get upgraded appropriately and you'd quite likely get that. And run it off batteries with your roll-out OLED screen that you just stick to any old surface, whack in a nice set of headphones and you're set! Great for camping (hah!)

Damn you beat me too it.

Also its not even actually 1080p that video looks to be running in 2.40:1 (movie aspect ratio) so the height isn't taking up all the screen real-estate.

It is full 1080p, but that clip doesn't have content to the edge of the video frame, so you're seeing black bars at either side (which we are decoding, for what it matters!)

I may totally be missing something but 1080px should be the height. So if you're showing it at a movie resolution you're either at something like 2592x1080 which is actually better then 1080p (but kind of unlikely - very few monitors would support a screen res that high) or you're running at something like 1920x800 which is less then 1080.

Its still pretty slick, not sure what SOC you're using but for that kind of media playback it seems to be something in line with what we're seeing in a bunch of our Connected TVs

Actually if you look at Blu-ray, then in most cases those black bars you see, are encoded in the video. Blu-ray doesn't support other aspect ratios than 16:9 (and 4:3 legacy SD resolutions). So from video decoders point of view it's all 1080p even if some of those lines are just filled with black pixels.

usually videos from actual film are a lower (or higher) aspect ratio that the resolution of the monitor. in the 1080p case most often you get less than the full height since it was recorded that way.

p.s. their platform support decoding full 1080p, that demo just included less height.

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