See, slowing audio properly requires a lot of CPU power. On a desktop Mac, there’s plenty of power to spare these days. Unfortunately—this is not the case in the mobile world. Because Capo is both graphics- and audio-intensive, it eats up a lot of CPU power.

When version 1.0 released, Capo was eating up about 80% CPU while playing audio in the foreground (i.e. with graphics visible) on a 3rd Generation iPod touch, and maybe 75-80% on an iPhone 4. The CPU/RAM improvements on the iPhone 4 were offset by the increase in pixel density pushing the GPU a little harder. C’est la vie.

If I wanted to do anything else with the app, I’d have to fit it into approximately 20% of leftover CPU.

Capo’s effects are both graphics and CPU-hungry, so I had my work cut out for me to add them in the next version. This was especially challenging, because I wanted to keep the live-updating spectrums in the effects control backgrounds as I have on the desktop version. Go big or go home, right?

Luckily for me, there were optimizations added to the slowing engine I use, as well as some further optimization work on my part. That 20% margin increased a little bit more, so I was able to shoehorn an initial implementation of the effects UI into the mix.

The initial approach simply sucked—it caused various skips in the audio, and the graphics were very choppy. It was especially noticeable when you’d scroll the effects controls while they were enabled.

The first culprit was my effects implementations. I built my own Equalizer, but it was taking about 15% of the app’s runtime according to Instruments. I had to take care of this, and re-wrote the tight loop using NEON intrinsics. That took it down to 1.5-2%—sweet!

I also had to re-write my FFT-based vocal reduction to use the Accelerate version of FFT rather than the implementation I previously used. I don’t recall the specifics, but I think the result was approximately 10x faster—the performance optimization team at Apple really kicked ass with their FFT implementation!!

Unfortunately, there was still about 30% of runtime being allocated to my live-updating spectrum drawing. I initially implemented the spectrum drawing using Core Animation and Quartz. That had to be thrown out, and I instead re-built the live spectrum views using OpenGL ES 2. A few custom shaders and other black magic made short work of that—reducing the runtime to about half of what it was before—15-18%. It cost me the prettier anti-aliased curves, but the speed boost was worth it.

In the end, I’m proud of what I shipped today. I know that the progress isn’t as quick as I’d hoped on the iOS side of Capo, but I think I truly nailed this effects implementation. Because of this extended effort, Capo will continue to be the best tool for learning your music by ear on your iPhone, iPod, or iPad.

I can’t wait to find out what else I can shoehorn into that “last 20%” in the future…

Subscribe to the podcast directly, or via iTunes.

Now Apple’s gone and called Capo out as an example of great design and technology use in the 2011 Apple Design Awards! I’m pretty excited about that, and I think you should be too.

As the years have gone by, Apple has moved away from having categories for the Apple Design Awards—even dropping the Mac category completely in 2010. Being a “pro apps” developer on the Mac that serves fairly niche markets, I felt that my chances of winning a Design Award (again!) had eroded to almost nothing over the past 5 years.

Games, social networking apps, productivity, and other mass-appeal products typically win the top honors from Apple. That’s because they do a great job of spreading the technology adoption message far and wide: to users and developers alike.

But this year, a highly specialized musical learning tool has made the cut and beat out some other amazing apps on the Mac App Store. As a musician, an indie developer, an audio nerd, a DSP enthusiast, and performance optimization fanatic, this is a very exciting event. It sends some very welcome motivational messages to my corner of the market.

Learning to play music on real instruments is still cool! Researching and adopting cutting-edge technology will get you noticed! Sweating the details of your app’s performance isn’t a waste of time! Doing it independently is still possible!

So, to celebrate my excitement about this win, and to speed up the adoption of Capo on the Mac and iOS, I’ve put both the Mac and iOS versions of Capo on sale. Up until June 30th, you can buy either (or both!) product(s) for 20% off.

 

If you’re a musician that doesn’t already own a copy of Capo, then you need to jump on this sale quickly! You’ll probably need a few extra bucks to cover the extra picks, strings and sticks you’re going to wear through with all the playing you’ll be doing…

If you didn’t already catch the news, Capo won an Apple Design Award, and I’m still coming down from that high.

But even if I took that out of the equation, the week still rocked hard for me.

I went into WWDC 2011 expecting to hear all the fancy new user-facing Lion features, and attend sessions about trivial things such as the full-screen and multitouch advancements. After the kickoff sessions, my attitude changed completely. I felt that I had to attend a good deal of sessions—even with videos (allegedly) around the corner!

Apple has given developers a great deal of new goodies to make our code go faster, less error-prone, and easier to maintain. With Apple in such a strong position right now, it would be very easy for them to sit back and add features to an already quite solid foundation. I’m so very glad that they’ve not taken that route.

It seems that Apple is never quite done perfecting their products, and the developer tools and APIs come across as a very important Apple product in itself. It’s not only the foundation of their own software, but also the software which is used by third parties to extend their platform further.

I don’t think I’ve ever been more excited to be writing software for Apple’s platforms, and I can’t wait to dive into the exciting projects that I am working on. I’d also like to thank Apple for putting on a great show this year, as usual. You guys work very hard on this stuff, and it really shows!

Subscribe to the podcast directly, or via iTunes.