trystan.org

3D Hipparcos Star Catalog Render

by on May.04, 2012, under Programming

Real-time render of 3dstars (Hipparcos)catalog with proper motion for the upcoming Nightshade 12 release. We begin at a distant orbit about Alcyone in the Pleiades cluster and move outward toward the edge of the galaxy. Then we move back toward Alcyone, never ceasing to orbit that star.

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Mt. St. Helens, exposure stacking

by on Sep.27, 2011, under Photography

9 exposures stacked via HDR plugin for Aperture (Mt. St. Helens, WA).

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Mt. Rainier 9-24-2011

by on Sep.26, 2011, under Photography

These pics were taken at various points around in inside the Paradise park area of to Mt. Rainier up to elevations of around 7000ft (up to the start of the Muir snowfield).

 

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Sky by NSOSG

by on Jul.27, 2011, under Programming

Early render of actual section of night sky from an astronomy visualization project I’m working on. Still lots of tweaking to do but satisfying to get an actual image out of the thing. The data-set is a composition of Hipparcos, Tycho2, and NOMAD star catalog data. This particular scene contained over 6 million stars. Rendering is in real-time at fully interactive frame rates. A larger image is at http://trystan.org/press/wp-content/uploads/2011/07/Screenshot.png.

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Ubuntu Unity vs. Gnome 3, A Developer’s Perspective

by on Jun.02, 2011, under Programming

Ubuntu has been my primary operating system for 3 years running. It has the well deserved reputation of being the most user friendly and ‘desktop’ oriented Linux distribution. However, I recently made the switch to Fedora. I thought I’d add my 2 cents to the barrage of opinions regarding the now heated battle between Ubuntu 11.04, featuring the compiz based Unity desktop, and the Gnome 3 driven Fedora 15.

Why did I switch? After all, I thought Unity was pretty good. It removed the ‘start’ menu concept that has prevailed for the last 2 decades with a search based concept that works quite well. It borrowed the OSX model of focus/context sensitive application menus on the top panel. Good stuff. The bad? Compiz; the sub-system responsible for taking all the 2D GUI stuff and putting it in an OpenGL context so it can be warped, overlayed, blended, etc. Unity is implemented as a Compiz plugin and that’s like building on mud. It’s easy to crash and has a nasty tendency to mess up OpenGL applications. All my OpenSceneGraph apps (including simple demos) stoped worked on the version of compiz released with 11.04. This is nothing new. There has been a history of problems with compiz playing nice. It must be respected for being ‘a first’ for Linux, but it’s not ready for the ‘prime time’ on a development box that must be stable. Additionally, I began to have fairly severe stability problems with the Eclipse IDE (Helios) upon the update to 11.04. It would just randomly crash, usually upon indexing a large C++ project.

Enter Fedora 15 and Gnome 3. Gnome 3 has many of the same features as Unity but does not require Compiz. It uses a completely different OpenGL compositor that, although not as feature rich as Compiz, appears to play nicer with other OpenGL apps and doesn’t totally bork OpenSceneGraph (a must have for my work). As an added bonus, Fedora 15 ships gcc 4.6 whereas Ubuntu 11.04 is still on the 4.5 line. In contrast to Ubuntu 11.04, Eclipse (Helios) has behaved solid thus far.

My takeaway is Fedora is a bit more developer friendly while Ubuntu still may be the better choice for pure desktop users. The base installation of Fedora is sparse by comparison to Ubuntu and users unfamiliar with repositories, package managers and how all that junk ties together may have a harder time getting a fully functional Fedora box together.

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A/D and D/A Conversions

by on Aug.22, 2010, under Music

A point often overlooked by home recording engineers is that for every digital unit in an analog instrument chain an A/D and D/A conversion is being performed. Doing this once or twice with high quality converters is probably not very noticeable, but chaining several digital pedals together is probably not wise. Each pedal will do a full round of conversion and introduce their own ‘flavor’ of signal degradation.

Most home recorders are already converting twice by necessity, getting the sound in and out of the computer. Intuitively, it makes sense to leverage analog processing whenever they’re appropriate to avoid these additional conversions prior to the sound interface. The other option is to record dry and use digital processing ‘in the box’ as there are no additional conversions in this case. There are no shortage of high quality software DSPs.

Most folks, including myself, likely have more pressing problems to address in their home studio. However, A/D conversion is certainly a factor to consider before mindlessly stacking another gadget on the signal chain. Think about where in the chain the gadget is being placed. Could the number of conversions be reduced by rearranging the chain? Could this gadget be placed in a digital loop with the sound interface, thus avoiding another conversion entirely? Most modern rack-mount DSPs do indeed have this capability.

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Guitar Cabinet Simulation

by on Aug.18, 2010, under Music

The amount of ‘color’ imparted to a distorted guitar sound by the speaker cabinet is often understated. Guitar speakers are not high fidelity. Rather they’re designed to roll off high frequencies, typically those over 8khz or so, and usually have poor response to frequencies under 120hz. The high frequency attenuation is particularly important for high gain distorted styles. If absent, listeners will suffer fizz and sizzle.

However cabinets present problems. They’re expensive, heavy, and need to be driven loud to impart the impulse characteristics associated with modern metal and rock. This doesn’t gel with living in a 900 sqft house in a major metropolitan area. Many home recorders and musicians need an alternative.

One alternative is to simply record via the line out on a pre-amp…this sucks big time. You can compensate a bit with high and low cuts on an EQ but it will sound very thin and fizzy. Leaving the power amp in the chain and brining the signal back down to line level through a load box and speaker simulator is better. Many of these units feature adjustable high cut and voicing controls. Additionally, you retain the color of the power amp section. But the results are usually still disappointing. There’s something missing, speaker impulse response.

The sound heard on most rock and metal recordings of guitar is the result of miking a speaker cabinet. Without a cabinet in the chain, it’s virtually impossible to reproduce certain dynamics captured by the microphone. Enter speaker impulse samples. Thanks to Prof. Fourier, it is possible to tease apart the speaker impulse data for all possible tones given any guitar speaker. These impulse ‘deconvolutions’ may then be convolved with any digital audio track to replace the otherwise missing impulse dynamics. Several ‘convolution reverb’ plug-ins are available for the task.

With well captured data from a good cabinet and microphone, the results are amazing compared against the unprocessed track. Many free guitar speaker impulse deconvolutions can be found via Google. At least one free convolution engine exists for Linux platforms, jconv, and can be integrated with Ardour via the Jack protocol. I highly recommend anyone recording guitars direct-to-console check these tools out.

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Song Demo 1

by on Aug.09, 2010, under Music

Here’s a song created using the Ubuntu Studio tool chain discussed in previous posts. The drums are programmed using Hydrogen but the guitar and bass are real instruments. Both were recorded ‘direct to console’ with the bass going through a Sansamp NYC. The guitar chain is Engl 530 -> VHT 2/90/2 -> Palmer ADIG-LB (load box).

Untitled_demo1.mp3

This was after spending about a month’s worth of solid weekends learning the tools and reading some advice from professional metal producers/engineers. In the field of sound engineering, I’m still very green.

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Gear Research Syndrome

by on Aug.01, 2010, under Music

I’ve been reading a series of informative and entertaining articles on home recording by Brandon Drury. The articles say less about what ‘to do’ and more about what ‘not to do’. This is not a criticism, rather it’s very appropriate for this craft. One particular pitfall illustrated, under which I’ve self diagnosed, is Gear Research Syndrome. Countless hours studying details of amplifier design, tube characteristics and other issues that have much less impact on an overall mix than many non-gear related issues.

Symptoms of the disorder include attention on manufacturing differences between Russian KT88 tubes and various knock-offs at opposed to important factors such as the instrument, skill, and the physical recording and monitoring environment.

Cognitive behavioral therapy is indicated in any instance of this disorder. The individual must be trained to recognize the excessive research behavior and reduce the amount of gear research. The additional attention redirected to more important issues will result in sound improvement and reinforce the behavioral change.

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Sweetening Metal Drum Tracks

by on Jul.19, 2010, under Music

Contemporary metal drum tracks sound pretty far from natural, they usually sound more like heavy grade pyrotechnics. When one first sits down to reproduce this sound it can be fairly daunting. Whether mic’ing a drum set or using software samples, raw drums are going to sound thin compared to what ends up on modern metal albums or in concert acts that mic the set and apply processing on a per channel basis. I’ve found a couple tricks that seem to work well for getting closer to the ‘over the top’ punch and smack adored by metal fans. My experimentation has all been performed on Hydrogen with LADSPA effects.

The Kick
Metal mixes will often synchronize the kick attack, a bass guitar attack, and a staccato attack on guitar simultaneously for a super non-syncopated punch effect. The kick is often on top of all this in the mix and that takes a ‘big’ kick that’s ‘perceived’ as ‘deep’. There are a couple do’s and don’ts here.

First, chorus works miracles on kicks. Apply it to the kick and only to the kick. Play with the settings until you achieve the desired size of balls. I’ve successfully used a multi-voice chorus LADSPA plugin to this end. The A-B difference is extreme. Mixing the chorused signal with the dry signal will help preserve the kick punch/attack. A 50/50 mix has worked well for me.

Next, I think it’s generally good to avoid reverb on a kick as it can kill the attack. I’ve heard it used effectively on older ’80s metal but it seems uncommon in modern metal, where the ‘fist in the face’ punch takes precedence. If it is used then the wet signal should be mixed with the dry as to preserve attack.

Snare
The snare seems much more variable, even amongst a sample of closely related metal bands. Tuning can vary quite a bit as can the level with respect to the overall mix. However, I’ve found that the careful application of plate reverb can effectively spice up a snare hit, specifically in sampled kits. I’ve used a LADSPA plate reverb that includes some filtering allowing for adjustment of sonic characteristics as well. A formerly ‘stock’ sounding snare blast now possesses an almost ‘gunshot’ like quality. And that’s what we metal folks like; the drums that sound like the 4th of July.

Cymbals and Hats
Thus far it’s my experience that cymbals sounds good relatively unprocessed. Some EQ may be in order depending on the situation, but I don’t see much point in toying with the natural resonance with reverb or anything else per say.

Toms
Toms are still a bit of a mystery to me. I’m not particularly happy with results I’ve achieved thus far. The toms seem to lack in pitch characteristics and sound ‘flat’. I’ve experimented with reverbs, which didn’t provide good results. Perhaps something to broaden the frequencies like pitch shifting would help. It’s also possible that I simply have poor tom samples. Anyone who would like to chime in is certainly welcome!

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