Another month brings with it another set of improvements for Radioshift. We’ve just released version 1.1.3, which fixes several distinct bugs related to timed recording, as well as issues with playback of RealAudio stations. We’re also taking advantage of improved listings for the BBC, provided by our partners at RadioTime, Inc.

Radioshift 1.1.3 is a free update for all licensed owners of Radioshift, so all existing users should simply click to download. If you haven’t experienced the best way to listen to and record radio on your Mac, check out Radioshift now with a free trial.

In his post announcing Pulsar, Paul mentioned that it was our first public exposure of our new technology called AHKit2. I’m going to talk a bit about what it is, why it’s here, and what it will do for you.

Introduction
AudioHijackKit is the full name of one of our internal frameworks, and it’s called AHKit for short. AHKit is the high-level audio processing framework that drives Audio Hijack Pro, Airfoil, and Nicecast.

Despite the name, the framework is not only for “hijacking”, the term we use to describe grabbing the audio out of any application on your system. AHKit also provides facilities for grabbing audio from input devices, applying audio effects, showing level meters, recording to a file, and some support functions like timed actions. Pretty much every feature you see in Audio Hijack Pro’s session view corresponds directly to a feature in AHKit.

Why a new version?
AudioHijackKit still works just fine but it was starting to get a little limited. The main problem was that it has a very linear idea of audio processing. It processes audio with a pipeline: audio goes in one end and comes out the other, used or altered by each stage in the pipeline. For example, Airfoil’s pipeline looks something like this:

Audio Source -> License Enforcer -> Effects
-> Speakers -> Output Meter

Audio starts off with the license enforcer, which is the module that overlays noise after 10 minutes if you haven’t unlocked the full version with a license key. From there, it next goes to the audio effects, where the audio is adjusted by the equalizer and other controls. After going through the effects, the resulting audio then goes out to the local and remote speakers. Finally, it goes to the output meter, which is that little moving levels bar at the bottom of the Airfoil window.

An astute reader might now wonder: why does the audio have to pass through the speakers before going to the meter? Can’t it just go straight to both? That’s due to the linear nature of the pipeline. We could switch the order around, to go to the meters and then the speakers, but that doesn’t really make any more sense. Ultimately, AHKit requires that the audio flow in a straight line, and it can’t just go out of one module and go into two others at the same time.

Now compare this with the graph from Pulsar. This is taken directly from a comment in Pulsar’s source code:

Streamer
/ \
SpecMeters Enforcer
\
Volume Control
\
Device Output

This follows a much more logical path. Audio comes in from the internet through the streamer. From there it goes straight to our meters. It also goes straight from the streamer to the license enforcer, from there through the volume control to the output, which plays it out your speakers.

Of course this could have been done with the old-style pipeline too, by putting the meters inline with the rest and having them output the audio that they receive. But the idea is that this is much cleaner and simpler, and for more complex cases it opens up far greater possibilities.

Effects
Audio Hijack Pro offers a huge, powerful, and intimidating effects tab for every session. Using that effects tab you can mix in audio from multiple sources, apply effects to pieces of them, and pretty much just run your own mixing board. It’s a lot more flexible than this AHKit pipeline I’ve been discussing, so how does that work? It ends up doing something like this:

Input -> Effects -> Output
| ^
v |
Effects Patch

To AHKit the effects appear as a single monolithic module, and that module then implements all of these fancy patches and routing and such inside itself.

When we started building AHKit2, we thought about the effects system and we wondered why we needed two different systems at all. Why not just integrate everything together into one? So that’s exactly what we did. AHKit2 provides functionality similar to the Audio Hijack Pro effects tab, although even more powerful and flexible, and uses that functionality as the basis for everything.

In AHKit, there is a sort of artificial partition between effects and the rest of the processing stream. Effects actually belong to a separate framework called sw4fx, which in turn loads every effect from an external plugin. The plugin architecture used by sw4fx is rather difficult to work with, so we only rarely build new ones. If we need to add effects processing to an application (for example, to add a balance control) and that application doesn’t already use sw4fx, it’s a bunch of trouble to add sw4fx, hook everything up, get the plugins installed in the right place, and get it all up and running.

In AHKit2, in contrast, everything is a “node”, which is an Objective-C class with a pretty simple interface. Creating new effects is as simple as creating a new node subclass. Any AHKit2-using application can use any AHKit2 node with ease. This should make it much easier for us to extend our software in the future, which in turn means that you get to see more great new features from us.

The Future
AHKit2 got its public debut as part of Pulsar, which serves as a good testbed for the basic functionality. We’re learning how it works out in the real world and, yes, we’re finding some new bugs.

Pulsar uses only a small portion of AudioHijackKit2′s capabilities, but we have big plans. Imagine setting up a graph like this:

Microphone iChat
/ / \ / \
Level Meters / \ / \
/ \ / MP3 Recorder
MP3 Recorder Net Streamer

This gives you a nice interview-recording setup, with each side of the conversation going into a separate file, and the whole thing being mixed together and sent out to a remote computer over the network in real time.

AHKit2 doesn’t have all of these features yet, but the foundation is there. And while we can’t make any specific promises at this point, we hope that it will enable some great new features in our applications in the months and years to come.

We’ve posted another update to RAOperationQueue, this time to fix a mach port leak. Download RAOperationQueue 1.0.2 here.

This bug was due to incorrectly using mach_port_deallocate to destroy our mach port. This function only works on certain mach ports, and for ours it’s required to use mach_port_mod_refs instead. This update just switches out the one for the other.

The severity of the leak depends on your usage of the code. It leaks one mach port per RAOperationQueue and one per RAWaitableSelectorOperation. Other RAOperations will not leak. Regardless of your usage, this is still a recommended update for everyone.

For more info on what RAOperationQueue is and why you might want to use it, see RAOperationQueue, an open-source replacement for NSOperationQueue.

Rogue Amoeba isn’t exhibiting in a booth this year at Macworld, but I’m out here for it nonetheless. I sat down with Dan Moren of Macworld, along with Mac community man-about-town John Moltz and raconteur John Gruber, for a very special Macworld podcast. We talked about the keynote, the show floor, and everything else under Moscone’s high ceilings.

So check out this very special Macworld podcast. If you have half as fun listening to the show as we had making it, well then, we’ll have had twice as much fun making the show as you’ll have listening.

We shipped Radioshift Touch 1.0.0 exactly three weeks ago, and after a couple hiccups (including Apple inadvertently removing Radioshift Touch from the App Store not once but twice), we’ve got a 1.0.1 update available for everyone! This update addresses several small but important issues, including:

Restarting
If you were playing audio when you quit Radioshift Touch, it will automatically load that same stream on your next launch. This is great for when you receive a phone call or need to quickly drop out of the application for something. As soon as you relaunch, you’ll be listening to your music again.

Taps
In our 1.0.0, we were requiring too many taps to load a stream, including showing an Stream Info page that didn’t provide a whole lot. With 1.0.1, tapping a stream from search results now immediately starts it playing.

Artwork
We’re now receiving and displaying higher quality artwork where available, from our partners at RadioTime, who provide the data for Radioshift Touch.

Bitrate
We had a lot of requests to show the bitrate of the stream you’re receiving, so this is now included on the Now Playing screen. These bitrates changes with our SmartStream feature, so you may notice different bitrates for the same station, depending on your connection.

Minutia
We’ve fixed several bugs, including an issue where Favorites would no longer be sortable, improved stability on bad streams, turned off auto-correct on the search field (so you can easily search for call letters like KBBL), and more.

So if you’re already using Radioshift Touch, be sure to update through the App Store. If you haven’t used Radioshift Touch yet, you can get listening to great live content on the iPhone, with thousands of internet radio streams at your fingertips, right now. Check out Radioshift Touch by visiting the Radioshift Touch webpage and purchase it right through the iPhone App Store.