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Serious Problems With USB and Ethernet On the Raspberry Pi

dannycim Re:Can't get good sound on RPi. Power problems. (202 comments)

Not "sound server" in the sense that you mean.

One of the boards is to be tasked with replacing an aging automatic player in a interactive information booth, the other would replace two loop players in localized FM broadcasts, for the visitors to a tourist centre.

They'd serve sound to the public, not to network clients. But that still makes them servers.

more than 2 years ago
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Serious Problems With USB and Ethernet On the Raspberry Pi

dannycim Can't get good sound on RPi. Power problems. (202 comments)

I bought two Raspberry Pi(es) to use as audio servers and have been disappointed by the sound quality. The on-board audio out's DSP has limited bandwidth so sound is down-sampled to 11 bits. Scratchy. It's not advertised so that was a let-down.

Using a USB AUDIO dongle is no-go either, because of the crappy USB drivers. Stutters non-stop. Here are oscilloscope grabs of two music samples and a 1Khz tone: http://imgur.com/a/rVR99 The flat parts shouldn't be there. The only way to get good sound now is to use rather expensive USB soundboards or the HDMI output, but extracting line-level audio signals from that isn't a simple or cheap proposition.

The power design should be re-thought. If you power your Pi with exactly 5 volts, the voltage drop in the polyfuses causes early failures if you connect peripherals that have medium current demands. If you're lucky your power adapter might supply a bit more than 5 volts (5.25 is nice) and you might not experience too many problems. Me, I've soldered supply wires to test points T1(vcc) and T2(gnd) and bypassed the fuses completely.

I hope they come up with another revision, add a Low-drop-out regulator (+$2) and figure out the USB naggies.

Until then, caveat emptor.

more than 2 years ago
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NASA Shuttle Discovery Set To Buzz Washington, DC

dannycim Back in 1987, over Montreal. (65 comments)

I saw it back in 1987 over Montreal. Not only was it really neat to see the shuttle "in person", it was magnificent to see a 747 flying so low over my town.

If you're there, don't miss it!

more than 2 years ago
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18-Year-Old Student Discovers Comet Break-Up

dannycim Something strange in the article. (68 comments)

FTA: Fragmentation in comets is rarely observed, but can occur when they are closest to the sun and develop spectacular tales of gas, dust and ice particles. The tale originates from the icy core (or nucleus), so when it heats up, vapor from sublimating ices are outgassed into space, dislodging dust and other material.

Shouldn't that be "tails" and "tail", or some different definition of the word "tale" I wasn't previously aware of?

more than 3 years ago
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The Quake Through Eyes of Slashdot Japan

dannycim Re:Engrish (265 comments)

*yours. Glass houses and such.

more than 3 years ago
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Futureproofing Artifacts: Spacewar! 1962 In HTML5

dannycim 50 years later... This is humbling. (175 comments)

You know, after working on my own long term project (25 years between updates), which Spacewar over-shadows by a factor of two, I've realized that code I write now, no matter how trivial, may be read back a long time afterward. And since I'm a very sloppy programmer, this is is embarrassing on a large scale.

Oh well. http://sites.google.com/site/dannychouinard/Home/rdos3-2-coco2-enhanced-dos if you're curious.

more than 3 years ago
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Running ZFS Natively On Linux Slower Than Btrfs

dannycim Re:They Why ZFS? (235 comments)

XFS is extremely prone to data corruption if the system goes down uncleanly for any reason. We may strive for nine nines, but stuff still happens. A power failure on a large XFS volume is almost guaranteed to lead to truncated files and general lost data. Not so on ZFS.

[Citation Needed] as wikipedia would say. XFS is no more prone to data corruption than any other journalled filesystem in the event of unexpected halts.

You should see the fireworks I got on Solaris 10 while I was running a script that did a bunch of zpool commands just as the power went out. Borked everything.

I love ZFS, but I'm not deluded into thinking it's magic.

more than 3 years ago
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Auto Industry's Fastest Processor Is 128Mhz

dannycim Re:Some one who knows.. Post is a LIE (397 comments)

The entertainment packages don't have to live on the other side of the firewall, and they're not necessary to the security of the passengers. The article refers to the automotive module which controls engine functions.

Very different things.

more than 3 years ago
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Auto Industry's Fastest Processor Is 128Mhz

dannycim Luxury! (397 comments)

Luxury. We used to have to get out of the lake at six o'clock in the morning, clean the lake, eat a handful of gravel, work twenty hour day at mill for tuppence a month, come home, and Dad would thrash us to sleep with a broken bottle, if we were lucky!

Meanwhile I'm working on a micro-controller project that runs at 500Hz (not kilo, just hertz).

If you keep the code tight and hand-craft it, 128Mhz is blindingly fast.

more than 3 years ago
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Sophos Researcher Suggests Password 'Free' to Spur Wi-Fi Encryption

dannycim Re:He has no clue what he's talking about... (332 comments)

Idiots like this give the IT security field a bad name as being made up of charlatans and snake-oil sales men.

Sadly, in my experience, it mostly is made up of charlatans, snake-oil salesmen and incompetents. Good security people are really rare.

more than 3 years ago
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Sophos Researcher Suggests Password 'Free' to Spur Wi-Fi Encryption

dannycim Here's how I'd do it. (332 comments)

1. Bring laptop with extra WiFi dongle into a public area.
2. Connect to Free WiFi spot using internal nic.
3. Act as an Access Point on second nic with a cooler sounding SSID.
4. NAT traffic to first WiFi net and grab everything of interest.
5. ???
6. Profit!!!1!!ONE!

more than 3 years ago
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The State of Linux IO Scheduling For the Desktop?

dannycim Easy problem to understand, hard to fix. (472 comments)

The problem is this: Let's say you do an action that reads 5 blocks on the disk. While the system is idle it has nothing else to do so your 5 blocks are read immediately, super fast.

While the system is doing some other I/O intensive job, it might be doing 500 block reads at the same time. Everything goes in the same queue, so your task is only %1 of the requests that have to be done in a set time. Result: Your task takes 100 times longer.

This is the problem that all the scheduler are trying to solve: trying to be fair so that every task gets a reasonable share of priority, while keeping performance at an optimum level.

For example, some O/S researchers have tried to implemented multiple-tiered system where every I/O is tagged with flags that indicate if the call came from an interactive user action, or was generated by non-interactive jobs (daemons, lower-level layers, etc...) and then give higher priority to the user requests. Two problems with that approach is it can be very hard to differentiate the two and that any heavy user task may prevent system tasks to work in a timely fashion and the user tasks may depend on the system tasks to complete their jobs in order to proceed; vicious circles and race conditions.

I'm glad I'm not trying to code a kernel scheduler, they're very hard problems and figuring one out that can be fair for all types of uses is nigh impossible.

The great thing about the open source O/Ss is that everything's done in the open, there's intense discussions going on about in the field, and there's multiple solutions being worked on and tested.

To me, Linux has always felt like it gave much higher priority to I/O than the "user experience". It's something I've come to expect. If I copy gigabytes from a disk set to another I gladly accept that my web browser's going to be sluggish for a time, all the while feeling content that at least it's going to be done so efficiently that it's going to last for the shortest amount of time possible.

Other O/Ss that I won't name may "feel" better, but have nowhere near the same I/O throughput that Linux has.

more than 3 years ago
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Meg Whitman Campaign Shows How Not To Use Twitter

dannycim Re:Dear god, please let it be fuwa fuwa time! (147 comments)

You do know Mio-chan is fictional, right?
Though the seiyuu's are not :)

Dreams... Crushed... Will to live... fading... Tell me it ain't true!

Then again, I'd be pretty surprised if it were the seiyuus playing the instruments in K-ON!

about 4 years ago
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Meg Whitman Campaign Shows How Not To Use Twitter

dannycim Dear god, please let it be fuwa fuwa time! (147 comments)

When I read the description I was all like "Oh please oh please oh please oh please let it be the one I think it is!"

Mio Akiyama has nothing on that bass player, that's an excellent rendition of Fuwa Fuwa time.

about 4 years ago
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Survey Shows How Stupid People Are With Passwords

dannycim Re:What about logging in over public WiFi? (427 comments)

Sharing a password with your wife, assuming you trust her, not that big of a deal.

It's a big deal and not a good idea. When your security is broken for whatever reason (trojan, key logger, intrusion, etc...) you don't want to have the extra trouble that a tiny possibility of a doubt exists that maybe, just maybe, your wife did it.

about 4 years ago
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Google Releases New Image Format Called WebP

dannycim Re:x264 WebP JPG (378 comments)

That'll teach me to post before coffee.

about 4 years ago
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Google Releases New Image Format Called WebP

dannycim Re:x264 WebP JPG (378 comments)

Originally the title read x264 > WebP > JPG but my less-thans got gobbled up. Also, sed 's/the//'

about 4 years ago
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Google Releases New Image Format Called WebP

dannycim x264 WebP JPG (378 comments)

The guy at the englishhard.com makes a strong argument for x264 with a proper comparison with non-compressed images upfront. Google has a bad history of not being able to admit they're not the best at everything, and in this case, for my money, they sure aren't.

about 4 years ago

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