Miscellaneous updates:
CocoaConf Chicago early bird pricing ends this weekend. I’ll be there, doing the Core Audio on iOS 5 talk (with MIDI and Audio Unit effects), and a new “Core What?” talk about neat stuff I’ve found over the years in the various C frameworks. A big piece of it will actually center on the CGPDF… stuff in Core Graphics, after all the PDF work I did last fall. Drawing into a PDF and drawing a PDF page into your view are common enough tasks, and the parsing of a PDF is another one of those tasks where the API makes absolutely no damn sense until you understand the problem domain behind it. Beyond that… CFUUID, CF-only collections, other curiosities and oddities.
Oh, and there’s a Fry’s Electronics in Downer’s Grove, about 20 minutes from the conference hotel. I have at least $500 worth of stuff on my shopping list (NAS, FCPX-compatible video card, Rock Band drums or Pro Guitar, out-of-print anime…). So that will add to the fun.
Speaking of CocoaConf, Saul Mora (who recorded our panel at CocoaConf Raleigh) had me on as a guest for NSBrief episode #33, in which we discuss audio theory, Core Audio, and AV Foundation for an hour. Plus, I lay out the plan for the “Reverse Q&A” we’re doing at CocoaConf Chicago, inspired by the Harmonix Reverse Q&A Panel at PAX East 2011. I wondered aloud about the idea of doing this in an earlier blog, and I’m glad we’ll have a chance to give it a shot. Hopefully, this will prove to be a good way to shake up the regular old panel format, and be fun and insightful for audience and speakers alike.
Learning Core Audio continues to work its way through Pearson’s production process. This week we signed off on author bios and cover blurbs. Copy-edit was a few weeks ago… admittedly a bit of a disappointment as I discovered all the third-person sentences had been somewhat mechanically rewritten to second-person (i.e., “we” becomes “you”). Sometimes it works, sometimes it really doesn’t, and I was too tired to fix all the cases of the latter. Still, it would have been nice to have been told about this house style two years ago when we started the damn thing.
Stuff from my CodeMash 2.0.1.2 sessions:
- Precompiler (tutorial) — Developing With iOS 5
- Sample code (4 staged Xcode projects): twitmash-stages.zip
- Session — iOS Networking: Bonjour, iCloud!
- Presentation slides (on slideshare.net)
- iCloud demo sample code: CloudNotes.zip
I’m surprised how fast iOS conference slides go old. I re-used some AV Foundation material that was less than a year old at August’s CocoaConf, some of it already seemed crusty, not the least of which was a performSelectorOnMainThread: call on a slide where any decent 2011 coder would use dispatch_async() and a block. So it’s probably just as well that I did two completely new talks for last weekend’s Voices That Matter: iOS Developers Conference in Boston.
OK, long-time readers — ooh, do I have long-time readers? — know how these posts work: I do links to the slides on Slideshare and code examples on my Dropbox. Those are are at the bottom, so skip there if that’s what you need. Also, I’ve put URLs of the sample code under each of the “Demo” slides.
The AV Foundation talk is completely limited to capture, since my last few talks have gone so deep into the woods on editing (and I’m still unsatisfied with my mess of sample code on that topic that I put together for VTM:iPhone Seattle in the Spring… maybe someday I’ll have time for a do-over). I re-used an earlier “capture to file and playback” example, and the ZXing barcode reader as an example of setting up an AVCaptureVideoDataOutput, so the new thing in this talk was a straightforward face-finder using the new-to-iOS Core Image CIDetector. Apple’s WWDC has a more ambitious example of this API, so go check that out if you want to go deeper.
The Core Audio talk was the one I was most jazzed about, given that Audio Units are far more interesting in iOS 5 with the addition of music, generator, and a dozen effects units. That demo builds up an AUGraph that takes mic input, a file-player looping a drum track, and an AUSampler allowing for MIDI input from a physical keyboard (the Rock Band 3 keyboard, in fact) to play two-second synth sample that I cropped from one of the Soundtrack loops, all mixed by an AUMultichannelMixer and then fed through two effects (distortion and low pass filter) before going out to hardware through AURemoteIO. Oh, and with a simple detail view that lets you adjust the input levels into the mixer and to bypass the effects.
The process of setting up a .aupreset and getting that into an AUSampler at runtime is quite convoluted. There are lots of screenshots from AULab in the slides, but I might just shoot a screencast and post to YouTube. For now, combine WWDC 2011 session #411 with Technical Note TN2283 and you have as much a fighting chance as I did.
I’ll be doing these talks again at CocoaConf in Raleigh, NC on Dec. 1-2, with a few fix-ups and polishing. The face-finder has a stupid bug where it creates a new CIDetector on each callback from the camera, which is grievously wasteful. For the Core Audio AUGraph, I realized in the AU property docs that the mixer has pre-/post- peak/average meters, so it looks like it would be easy to add level meters to the UI. So those versions of the talks will be a little more polished. Hey, it was a tough crunch getting enough time away from client work to get the sample code done at all.
Speaking of preparation, the other thing notable about these talks is that I was able to do the slides for both talks entirely on the iPad, while on the road, using Keynote, OmniGraffle, and Textastic. Consumption-only device, my ass.
- Capturing Stills, Sounds, and Scenes with AV Foundation
- Core Audio Cranks It Up
One more speaking update: I’ll once again be at CodeMash in Sandusky, OH, January 11-13, 2012.
Daniel Steinberg and I always try to do something different with the “precompiler” tutorial day, but this year, Apple is doing our work for us by making so many changes in the SDKs and tools (Xcode 4 was still NDA this time last year, IIRC). For this year, I’m doing a three-hour introduction to iOS tutorial in the morning, and Daniel is following up with Mac Development for the iOS Developer in the afternoon. It’s a nice reversal of how we did things in 2010, and lets mine serve as a pre-requisite for his.
Also, I’m doing one regular session, iOS Networking: Bonjour, iCloud!, which will be a top-to-bottom tour of iOS networking, from the new and high-level iCloud APIs, all the way down through Foundation and Core Foundation networking, to the nitty gritty of BSD sockets.
There are a number of other iOS related talks — more than I’d been led to believe — and while it’s not quite a full track unto itself, that’s kind of the point of CodeMash, getting people mingling in each other’s stuff. Although I sill reserve the right to scoff at web development as padded-room detention for the pointer-averse.
A few things to keep in mind about CodeMash: it is held at an enormous indoor waterpark resort, the largest in North America. As a presumable consequence, it sells out ridiculously fast: CodeMash 2011 filled up its 700 seats in 3 days. Thanks to the resort’s expansion, there are 300 more registrations available this year, but it’s a safe bet that it’ll fill up fast. Registration begins Monday morning, Oct. 24.
Real life intervenes again (parsing PDF, whee!) and I have to cut short a planned epic iDevBlogADay entry. But I do want to bang out a few quick notes on various topics of interest.
The first is Core Audio in iOS 5, which we can now talk about publicly. If we go through the iOS 4.3 to iOS 5.0 API Differences document, we see that Audio Units accounts for a large number of diffs. This comes from the addition of a suite of units that finally make programming at the unit level a lot more interesting. Whereas we used to get a single effects unit (AUiPodEQ), we now get high and low pass filters, the varispeed unit, a distortion box, and a parametric EQ that lets us play with sliders instead of the “canned” EQ settings like “Bass Booster” and “Spoken Word”. Even more useful, we get the AUFilePlayer, meaning you can now put audio from a file at the front of an AUGraph, instead of the sheer pain of having to decode your own samples and pass them to the AUGraph through a CARingBuffer.
iOS also gets the AUSampler unit introduced in Lion, which provides a MIDI-controlled virtual instrument whose output is pitch-shifted from a source sample. This was shown off at WWDC, although providing the source to the unit by means of an .aupreset is still a dark (undocumented) art. This is the first actual MIDI audio unit in iOS, which makes the presence of Core MIDI more useful on the platform.
Core Audio giveth, but Core Audio also taketh away: iOS 5 removes (not deprecates) VoiceIOFarEndVersionInfo. This struct, and its related constants (specifically kVoiceIOFarEndAUVersion_ThirdParty), were documented as interoperating with a hypothetical “3rd-party device following open FaceTime standards”, something I took note of last May as possibly meaning that FaceTime was still ostensibly being opened up. With the removal of these APIs, I think that closes the book on Apple having any intention to live up to its vow to publish FaceTime as an open standard.
There’s lots more to talk about, but I’m already over my allotted blogging time, and work beckons. Perhaps you’d like to hear me speaking about this stuff and demo’ing it? I’m doing an all-new-for-iOS-5 Core Audio talk at two upcoming conferences:
- Voices That Matter: iOS Developers Conference, Nov. 12-13 in Boston, and $150 off with discount code
BSSPKR5. - CocoaConf, Dec. 2-3 in Raleigh, NC, which has early-bird pricing available through Oct. 31.
I’ll also be doing a talk about AV Foundation capture at these conferences. And back on audio, I just heard from my editor that the last three chapters of Core Audio should be in the Rough Cut on Safari Online Books in the next week or so, although I still have some work to do to clean up bits that are broken on Lion (read the sidebar on Audio Components if you’re having a problem creating audio units with the old Component Manager calls) and to clear out forward references to stuff that didn’t end up making the final cut for the book.
I’m a half-day late with my iDevBlogADay post… sorry.
So I was thinking about conference panels recently, something I don’t often attend or participate in. Panels to me seem like something that should work better than they usually do. You have smart, interesting people, but unless they know to “play ball”, to go out of their way to find ways to dig deeper or draw out conflicts and differences between each other, you tend to end up with a lot of head-nodding and personal pet theories that the rest of the panel doesn’t really have a stake in.
It’s not clear that the audience gets a lot out of it either. At Cocoaconf, I was on an iOS developer panel and the first question we got was the hopelessly played out “how do I get my app noticed” one. Ugh. You don’t need a panel for that, we’ve all been griping about that for three damn years now, and if we don’t have good answers yet, we’re never going to. Moreover, I’m not sure that attendees have a good sense of the potential of panels and how they can draw that out.
So here’s a solution. It comes to us by way of the fine folks at Harmonix, makers of Rock Band, Dance Central, the new iOS novelty VidRhythm, the rare iPod nano/Classic game Phase, etc. At their last two panels at PAX, they did a “Reverse Q&A”, which works like this: the panelists either ask big poll-type questions of the room, ask followup questions and get shouted-out responses from the crowd, or they ask “man on the street” style questions to whoever is at the front of the line for the mic. Either way, the topic is then followed up by the panelists and whoever from the crowd happens to be at the front of the line for the mics.
It still seems like a work-in-progress on the Harmonix podcasts, but there is a gem of a great idea here. Anyone who’s working in iOS and attending conferences has something interesting to say, and probably some unique real-world perspectives that wouldn’t necessarily be obvious to the kind of people that get picked for panels. We’re all self-employed hipster indies and authors, so we likely have little if any idea how iOS is playing out in big enterprises, how well or poorly it rubs shoulders with other technologies, etc. So in a Reverse Q&A Panel, I could ask these kinds of questions of whoever is first at the mic: “what do you use iOS for… how’s that working out… what’s missing that you think should be there…”
The responses we would get from the attendees would drive panel discussion, and in a sense, the person at the front of the line for the mic becomes a temporary member of the panel. In this, it’s a lot like the “open chair panel” that I’ve seen pulled off only once (at the Java Mobility conference in Jamuary 2008, where I saw the last gasp of the old world prior to the iPhone SDK announcement a few weeks later).
And I still like the format of both the Reverse Q&A and the Open Chair Panel more than I like straight-up open spaces, which at the end of the day are just chats, and chatting is best done over food and drink, like at the end of Cocoaconf where Bill Dudney, Scott Ruth and I grabbed two guys from Ohio U. that Bill had met and headed down to Ted’s for some bison burgers. That’s chattting. If you’re going to schedule a time and a room, it’s already more formal, and a structure helps set expectations.
I’m inclined to talk up Reverse Q&A as a format to the Cocoaconf and CodeMash organizers… would like to give this a try in the next few months.
And speaking of which, let’s practice. Here are some questions I’d like to ask of Reverse Q&A attendees. Feel free to answer any of them in the comments. I’d like to know what you guys and girls are thinking:
- Do you learn new platforms, languages, and frameworks from books, blogs, official docs, or what? (I want to know so I can figure out whether I should bother writing books anymore… signs point to no)
- What do other platforms do better than iOS?
- What’s the one App Store policy that pisses you off the most?
- Do you sell your own apps, write apps for someone else (employer, contract clients, etc.) or something else? Which of these do you think makes the most sense for you?
- Do you want more or less webapps in your life?
OK, you guys and girls talk for a while…
