#core audio

Apple AirTags interface sounds revealed in new iOS 14 leak

A leaker has posted a new video on Twitter that plays the range of interface sounds that will accompany Apple’s widely-expected “AirTags.”

Apple referenced ‘AirTags’ item trackers in an April 2020 support video

https://twitter.com/Soybeys/status/1273580099158159362

William Gallagher for AppleInsider:

More evidence has emerged that Apple’s long-rumored “AirTags” are close to being released has…

It’s time to put Avid Pro Tools 9 through the paces. Does it really work with nearly every IO on the market? Avid claims that as long as there is a Core Audio or ASIO driver – you’re in luck. Just to be sure, we make TJ Martin (with Avid) use a Presonus, Focusrite, RME and a Line 6 interface with Pro Tools 9. We’ll also see anything else that’s new (and of importance) in Pro Tools 9. What does Pro Tools 9 Come with? (1) Pro Tools 9 software DVD (includes bundled software and guides)(1) Pro Tools 9 drivers DVD(1) Audio Loops DVD(1) iLok USB Smart Key (for software authorization)(1) Pro Tools 9 installation guide(1) Intro to Pro Tools 9 guide(1) Software activation card What Avid Says:

Fuel your creativity with a huge collection of over 70 professional sound-processing plug-ins, virtual instruments, and effects, plus a massive library of high-quality audio loops. Whether you want to make music, record audio, crank up new guitar tones, polish sounds, or master mixes, you’ve got a full palette of options at your fingertips to shape ideas from beginning to end. Virtual instruments and audio content :Big Fish Audio 8 GB sound libraryBoom drum machine and sequencerDB-33 tonewheel organ emulator with rotating speaker simulationMini Grand acoustic grand pianoVacuum monophonic vacuum tube synthesizerXpand!2 multitimbral synth and sample workstation

There is a wealth of information out there.  And we know all the stats are posted everywhere so we won't bore you with them.  Find them here:  Pro Tools 9 (Full Version), Pro Tools 9 Crossgrade from LE, and Pro Tools 9 Crossgrade from M-Powered. If you prefer you can go to Avid's Pro Tools site as well to see even more in depth. Video Transcript:

Hey this is Scott Magno, DJ MadFlip, here with UniqueSquared.com. Today we’re going to show you the brand new, recently announced, Pro Tools 9 software. So today we flew in a true professional, this is TJ Martin with Avid and he’s going to show us the new features of Pro Tools 9, one of which I read is that it’s not just going to be compatible with Avid interfaces, but with virtually every interface on the market. So, I went to the warehouse and I took all of these out so we can see exactly how that’s going to work. Here’s TJ.

Thanks Scott, I think we’re up to the challenge so let’s give it a whirl. Ok so, it’s time to start the challenge. So the first IO up is going to be the PreSonus Audio Box. That’s a USB interface, real simplistic here, and it also has a class compliant driver which made it really easy for me so I didn’t even have to install a driver, but, just to prove that it works in Pro Tools, let’s look at it in Pro Tools here.

So, I go up to the setup menu, I’m going to go to IO, and sure enough there it is. That’s the little icon for it, so, let me zoom in, and there it is. So, it is showing up. Now let’s do a quick  recording for you to show that it’s actually recording inside of Pro Tools. We’ll record enable it, now it’s time to hit record and play. It’s already drawing a wave for me, yeah sure enough. Alright, time to hit stop, excellent. So, PreSonus definitely works inside of Pro Tools 9. So now let’s move onto a different interface.

Alright next interface is going to be the Focusright Saffire Pro 24. This is a firewire interface, I’ve installed the drivers already for it. So let’s see how it behaves here, record enable. Got my wave form a little bigger so I can see it better. Record play, it’s already drawing. There’s my fancy E chord. Sure enough, that works as well so on to the next interface.

Alright so, let’s check out an interface by a totally different company now, RME, Called the Fireface 800 and I’m going in with a firewire into my laptop, drivers are installed, record enabled, it’s ready for my guitar. And record, and there’s the waveform being drawn, excellent. Alright so, here’s the UX2 from Line 6. Let’s take a look at this, get record enable going here. So four completely different interfaces here recording in Pro Tools 9, that’s obviously the biggest news.

One thing we need to talk about before we go on looking inside the software is the fact that really, the reason that all these different interfaces work inside of Pro Tools is because of Core Audio and ASIO support. So, in the mac world, it’s core audio that’s hidden in the background as your audio entry, and windows it’s ASIO. If you’ve got a driver written for that, you’re straight. Those are the interfaces you can use.

So let’s talk about what else is new, we’ve really given you more. So before you had 48 tracks of audio inside of LE or M power. Now, you’re able to do 96 mono or stereo, you can also do 512 MIDI tracks where before it was 256. What you’re going to do with all that MIDI? I have no idea. 256 busses versus 32 is what it used to be, and now you can capture 32 tracks of audio which before it was only 18. So more is more, that’s what you’ve been given inside of Pro Tools 9.

You’re also getting things like what used to be the music production toolkit 2 or the DV toolkit is now part of it. So what does that mean? Multitrack beat detective was part of the music production 2. You’re now able to slice and dice and quantise audio as if it was MIDI when you use multi beat detective. So that’s pretty cool having that.

Now let’s take a look at what else has been inside Pro Tools, before that, folks don’t even realise when they say things like, “well Pro Tools is pretty blank slate and you’re not starting with much.” But actually, inside of here you’re getting a lot of cool instruments like a grand piano, a B3 organ, and drum machine.

You’ve got the expand 2 which is kind of cool because it’s like your everything box. It’s got every darn sound in it just like you would with like, a Triton, or a Roland work station. You’ve got a virtual analog synthesizer inside of here, and we can also do fun stuff like comping. I can click and drag over a certain section, decide that’s the perfect take of my guitar, send that up to the master track, that makes life easier.

We said the DV toolkit 2 used to be extra, what does that mean? That was for video guys, that was for things like OMF support. OMF is important in video world, but even in audio land. Let’s say you’ve got somebody who’s running, let’s say, Logic and they’re in your band. They’ve started the session and you want to work with the same session. They can export as OMF and you can import that OMF file, and all your tracks are broken up for you in the software. You’ve also got a timeline ruler, so, if you need to do some serious editing inside of video and make an audio event happen at a particular part, boom! You can do it there, and automatic delay compensation has been added.

Automatic delay compensation is something that people have been asking for for some time, and now it’s possible inside of Pro Tools 9, native running on your machine. What you do is go to setup, playback engine, and here it is. There’s something dedicated just in the pulldown menu here. Delay compensation engine, and there’s short or long. Short is an efficient way to do it, but regardless that’s there now.

What happened before was, and often happens in audio land is, if you’ve got all these independent tracks running and you start inserting all these plugins. You’re asking your computer's CPU to do a lot of work. By having automatic delay compensation you don’t have to work about introducing all these new plug ins and creating little delays whether they’re milliseconds or only samples in size. You can have your guitar arriving to the master bus just before, milliseconds before your bassline.

Automatic delay compensation makes up and does a lot of this work for you so you don’t have to think about introducing plug ins and what that means. We also have in there variable pan depth. That was more important to the HD crowd it seemed. If you wanted to emulate the DB difference between a pan. If you go dead center on an SSL, it behaves different from on a Neve. The British engineering society has a different DB difference when you put a pan dead center. So that’s hiding in there, In fact, there’s 73 pages in the “What’s new with Pro Tools” document.

So there’s a ton of new stuff. So, something that is worth pointing out now is that I’ve got my laptop here and my old ilock. They’re much cooler that come in the box now. But that it. It’s beautiful, I could be sitting there, watching dancing with the stars on the couch and editing MIDI at the same time. Whereas before you were always locked down to some sort of interface, so that’s no longer necessary and that helps a lot.

Now, it’s also worth going over the differences in these boxed versions that you can get through UniqueSquared. You’ve got M power Pro Tools 9, and that is the full blown version that you’re getting inside there and that does come with an ilock as well.

But then there’s the cross grades, and that’s really for the folks that are already using LE and using M power, and you want to get into 9. Just make sure you have your ilock, if you’re an M power guy, you’ve already got it, But if you’re using LE, make sure you get one before you get the cross grade or order it at the same time. But really, what you’re getting from Pro Tools 9, as you can see today, is you’re getting more, and it’s more powerful.

Once again, Apple have released a new OS. Once again, it is named after a giant kitty. Once again, it is not ready for pro users to rush over and expect every little thing to go well. Once again, I find myself scratching my head and wondering how people seem to go through this every time.  The problems I am aware of at present are as follows: 1. Mountain Lion is having trouble with some audio interfaces. I am not at all shocked by this. Initial reports of the newer laptops with USB 3.0 ports expanded to older models with the release of the new OS. Specific to our audience, Native Instruments have been attempting to resolve issues their users are experiencing on both sides of the equation. See Native's support statement below: Native Instruments has conducted compatibility tests with its hardware products under OS X 10.8, connected to USB 2.0 and USB 3.0 ports of both recent and current-generation Mac computers. Some NI products are experiencing a degraded audio signal caused by USB driver issues present in Mac OS X 10.8. The same issues are also present under Mac OS X 10.7.4 on current-generation Macbooks with USB 3.0. If you just can't stand the idea of going over and looking for yourself, the known affected devices are: AUDIO 2 DJ / AUDIO 4 DJ / AUDIO 8 DJAUDIO KONTROL 1GUITAR RIG MOBILEGUITAR RIG SESSIONKORE 1RIG KONTROL 2 / RIG KONTROL 3TRAKTOR AUDIO 2TRAKTOR KONTROL S4 So, while this was initially supposed to have been a USB 3.0 problem, it is becoming clear that the shenanigans extend into the OS as well. Native are busily working on a fix for their users in conjunction with Apple and there are currently Beta drivers available for the fix. Based on what I am reading, there are also some Core Audio issues with some Avid hardware running non-Pro Tools applications. I assume there will be other issues that pop up as people that own the various interfaces make the jump. 2. Gatekeeper and unsigned software and plug-ins are not working out. Gatekeeper is a new security feature for the OS that is, depending on who you ask, either a security measure to protect customers from themselves, or a restriction on third party developers Apple have implemented to force all future software to funnel through the Apple Store. The long and short of it is that unsigned software packages, plug-ins and apps won't install when Gatekeeper is enabled. Fortunately, it can be disabled, and those of us who still think we know what we are doing can proceed onward towards happy, unsecured, apparent oblivion. Native, presumably for the sake of helping their customers in initial encounters with the problem, have also posted a convenient set of instructions for disabling the security measure. Avid have reportedly been working to get their usually lengthy qualification process under control. However, they are also not yet signed for Gatekeeper's purposes. I'm not personally going to make a ruling on the whole Gatekeeper thing. It certainly isn't for me, but I do like purchasing things from the Apple Store, as every time it has gone well, and I can always re-access my downloads in the event I switch computers. As for whether or not it protects my grandma or someone like that from malware, I am unsure. I feel those susceptible to such things will doubtless write checks to and share bank info with foreign princes trying to hide their treasure in times of conspicuously unreported upheaval in their country. I also want to go on record as saying that MY grandma would never do something like that. At the very least, she would call me first. As computer savvy types, it is all of our duty to take the time to discuss important issues like this with our at risk seniors. 3. Make sure you have 8GB of RAM. Otherwise you are shooting your performance in the foot. Much as with Lion, the performance of this OS requires more resources, which will therefore affect all the other things you do. Looks like my i5 at home will receive an upgrade that my aging MBP will not.

It’s time to put Avid Pro Tools 9 through the paces. Does it really work with nearly every IO on the market? Avid claims that as long as there is a Core Audio or ASIO driver – you’re in luck. Just to be sure, we make TJ Martin (with Avid) use a Presonus, Focusrite, RME and a Line 6 interface with Pro Tools 9. We’ll also see anything else that’s new (and of importance) in Pro Tools 9. What does Pro Tools 9 Come with? (1) Pro Tools 9 software DVD (includes bundled software and guides) (1) Pro Tools 9 drivers DVD (1) Audio Loops DVD (1) iLok USB Smart Key (for software authorization) (1) Pro Tools 9 installation guide (1) Intro to Pro Tools 9 guide (1) Software activation card What Avid Says:

Fuel your creativity with a huge collection of over 70 professional sound-processing plug-ins, virtual instruments, and effects, plus a massive library of high-quality audio loops. Whether you want to make music, record audio, crank up new guitar tones, polish sounds, or master mixes, you’ve got a full palette of options at your fingertips to shape ideas from beginning to end. Virtual instruments and audio content : Big Fish Audio 8 GB sound library Boom drum machine and sequencer DB-33 tonewheel organ emulator with rotating speaker simulation Mini Grand acoustic grand piano Vacuum monophonic vacuum tube synthesizer Xpand!2 multitimbral synth and sample workstation

There is a wealth of information out there.  And we know all the stats are posted everywhere so we won't bore you with them.  Find them here:  Pro Tools 9 (Full Version), Pro Tools 9 Crossgrade from LE, and Pro Tools 9 Crossgrade from M-Powered. If you prefer you can go to Avid's Pro Tools site as well to see even more in depth. Video Transcript:

Hey this is Scott Magno, DJ MadFlip, here with UniqueSquared.com. Today we’re going to show you the brand new, recently announced, Pro Tools 9 software. So today we flew in a true professional, this is TJ Martin with Avid and he’s going to show us the new features of Pro Tools 9, one of which I read is that it’s not just going to be compatible with Avid interfaces, but with virtually every interface on the market. So, I went to the warehouse and I took all of these out so we can see exactly how that’s going to work. Here’s TJ.

Thanks Scott, I think we’re up to the challenge so let’s give it a whirl. Ok so, it’s time to start the challenge. So the first IO up is going to be the PreSonus Audio Box. That’s a USB interface, real simplistic here, and it also has a class compliant driver which made it really easy for me so I didn’t even have to install a driver, but, just to prove that it works in Pro Tools, let’s look at it in Pro Tools here.

So, I go up to the setup menu, I’m going to go to IO, and sure enough there it is. That’s the little icon for it, so, let me zoom in, and there it is. So, it is showing up. Now let’s do a quick  recording for you to show that it’s actually recording inside of Pro Tools. We’ll record enable it, now it’s time to hit record and play. It’s already drawing a wave for me, yeah sure enough. Alright, time to hit stop, excellent. So, PreSonus definitely works inside of Pro Tools 9. So now let’s move onto a different interface.

Alright next interface is going to be the Focusright Saffire Pro 24. This is a firewire interface, I’ve installed the drivers already for it. So let’s see how it behaves here, record enable. Got my wave form a little bigger so I can see it better. Record play, it’s already drawing. There’s my fancy E chord. Sure enough, that works as well so on to the next interface.

Alright so, let’s check out an interface by a totally different company now, RME, Called the Fireface 800 and I’m going in with a firewire into my laptop, drivers are installed, record enabled, it’s ready for my guitar. And record, and there’s the waveform being drawn, excellent. Alright so, here’s the UX2 from Line 6. Let’s take a look at this, get record enable going here. So four completely different interfaces here recording in Pro Tools 9, that’s obviously the biggest news.

One thing we need to talk about before we go on looking inside the software is the fact that really, the reason that all these different interfaces work inside of Pro Tools is because of Core Audio and ASIO support. So, in the mac world, it’s core audio that’s hidden in the background as your audio entry, and windows it’s ASIO. If you’ve got a driver written for that, you’re straight. Those are the interfaces you can use.

So let’s talk about what else is new, we’ve really given you more. So before you had 48 tracks of audio inside of LE or M power. Now, you’re able to do 96 mono or stereo, you can also do 512 MIDI tracks where before it was 256. What you’re going to do with all that MIDI? I have no idea. 256 busses versus 32 is what it used to be, and now you can capture 32 tracks of audio which before it was only 18. So more is more, that’s what you’ve been given inside of Pro Tools 9.

You’re also getting things like what used to be the music production toolkit 2 or the DV toolkit is now part of it. So what does that mean? Multitrack beat detective was part of the music production 2. You’re now able to slice and dice and quantise audio as if it was MIDI when you use multi beat detective. So that’s pretty cool having that.

Now let’s take a look at what else has been inside Pro Tools, before that, folks don’t even realise when they say things like, “well Pro Tools is pretty blank slate and you’re not starting with much.” But actually, inside of here you’re getting a lot of cool instruments like a grand piano, a B3 organ, and drum machine.

You’ve got the expand 2 which is kind of cool because it’s like your everything box. It’s got every darn sound in it just like you would with like, a Triton, or a Roland work station. You’ve got a virtual analog synthesizer inside of here, and we can also do fun stuff like comping. I can click and drag over a certain section, decide that’s the perfect take of my guitar, send that up to the master track, that makes life easier.

We said the DV toolkit 2 used to be extra, what does that mean? That was for video guys, that was for things like OMF support. OMF is important in video world, but even in audio land. Let’s say you’ve got somebody who’s running, let’s say, Logic and they’re in your band. They’ve started the session and you want to work with the same session. They can export as OMF and you can import that OMF file, and all your tracks are broken up for you in the software. You’ve also got a timeline ruler, so, if you need to do some serious editing inside of video and make an audio event happen at a particular part, boom! You can do it there, and automatic delay compensation has been added.

Automatic delay compensation is something that people have been asking for for some time, and now it’s possible inside of Pro Tools 9, native running on your machine. What you do is go to setup, playback engine, and here it is. There’s something dedicated just in the pulldown menu here. Delay compensation engine, and there’s short or long. Short is an efficient way to do it, but regardless that’s there now.

What happened before was, and often happens in audio land is, if you’ve got all these independent tracks running and you start inserting all these plugins. You’re asking your computer's CPU to do a lot of work. By having automatic delay compensation you don’t have to work about introducing all these new plug ins and creating little delays whether they’re milliseconds or only samples in size. You can have your guitar arriving to the master bus just before, milliseconds before your bassline.

Automatic delay compensation makes up and does a lot of this work for you so you don’t have to think about introducing plug ins and what that means. We also have in there variable pan depth. That was more important to the HD crowd it seemed. If you wanted to emulate the DB difference between a pan. If you go dead center on an SSL, it behaves different from on a Neve. The British engineering society has a different DB difference when you put a pan dead center. So that’s hiding in there, In fact, there’s 73 pages in the “What’s new with Pro Tools” document.

So there’s a ton of new stuff. So, something that is worth pointing out now is that I’ve got my laptop here and my old ilock. They’re much cooler that come in the box now. But that it. It’s beautiful, I could be sitting there, watching dancing with the stars on the couch and editing MIDI at the same time. Whereas before you were always locked down to some sort of interface, so that’s no longer necessary and that helps a lot.

Now, it’s also worth going over the differences in these boxed versions that you can get through UniqueSquared. You’ve got M power Pro Tools 9, and that is the full blown version that you’re getting inside there and that does come with an ilock as well.

But then there’s the cross grades, and that’s really for the folks that are already using LE and using M power, and you want to get into 9. Just make sure you have your ilock, if you’re an M power guy, you’ve already got it, But if you’re using LE, make sure you get one before you get the cross grade or order it at the same time. But really, what you’re getting from Pro Tools 9, as you can see today, is you’re getting more, and it’s more powerful.

以前から、iPhoneのCore Audio周りの勉強をしていたのですが、ちょっと歌を歌う機会があってコンコーネ50番という教本を練習しているうちに、「これアプリにしたらいいんじゃない？」と思い立って制作しました。

声楽を勉強されている方、また音大生の必須科目なので、需要あるんじゃないかしら？と思ったのですが、今のところあんまり需要なかったみたい (^ ^;;

このアプリで使っているのは、Core Audioの、Audio Queue Service、Audio Converter Services, Extended Audio Services, Audio Unit Processing Graph Servicesなどです。これらは、永野哲久さんの「iPhone Core Audio　プログラミング」を読んで勉強しました。これ、絶版なので中古で1万円で買いましたけど、本当にそれくらいの価値はあったと思います。永野さん、ありがとう！！

特にキモになるのはAudio Unit Processing Graph Servicesで、iPhone内でマイクとAudioを合成したり、リバーブを入れたり音量調整したりするのに使っています。

音源も自前で準備しました。これは、自宅のMIDI付き電子ピアノをMIDIでMacにつないでLogicで録音しています。50曲あって結構大変でしたが、ピアノからとりあえずMIDIを送って録ってしまえば、多少ずれたり間違えたりしても後で修正できることもあり、3日で録音＆修正しました。これらはm4aでアプリファイルに同梱されています。なので、50曲を搭載したアプリを、いかに100Mbyteに収めるか(100Mを超えるとWiFi環境じゃないとDLできなくなる)という課題もあったのですが、ギリギリのところまで圧縮をかけて何とかなりました。

50曲あるうちの、1〜3番までが無料で、以下4〜50番を聴けるようにするにはAPP内課金をして頂くという形にしました。試用してもらわないと、どんなものかわからないし、でも無料版と有料版を用意するのもユーザに手間をかけるし、こちらとしてもアプリが２つになって手間がかかるので。

料金をtier4の設定にしたのは、ちょっと強気過ぎたかもしれません。ただ、同様のCDは5,200円するし、価格破壊といえば価格破壊なんだよなー。

あと、CDと違って、演奏中画面上にボールが弾んでテンポを表示します。これはBouncce Metronome Systemという独自技術で、完全に音楽に同期するように作ってあります。手法は秘密。そのほかにも、録音もできるし、シェアもできます。シェアは、動画にしました。最初はSound CloudにUpできるようにしようと考えたのですが、どうもSound CloudのiOS APIが見つからなかったのと、Facebookの場合、音だけをシェアするっていうのが無いので、それなら動画作っちゃえということで、アプリ内で動画を生成する様にしましたYouTubeのShareも搭載したかったのですが、どうもiOS9のUpdate直後だったからか、YouTube APIがエラーを吐きまくるので、今回は断念しました。

This mobile music project came about as a bit of a joke. A colleague who commutes by ferry was talking about how his fellow passengers would get really annoyed by the sounds from other peoples phones, and how it would be funny to set a bunch of phones to start making a lot of noise, that gradually comes together to form a piece of music. It sounded like a fun idea, so I put together an app and some music and tried it out in cafe with some student volunteers just before Christmas.

The Music

The idea with the music was to begin with ringtones and alert sounds, getting people’s attention and probably irritating them a bit. Then these sounds would gradually come together into a piece of music and people would (hopefully) realise the joke and what was going on.

The approach I took was to begin with just a random collection of recognisable iPhone alert sounds, but after a few of them start a call-and-answer type section where a crude 8-bit synth sound would mimic the musical sounds of the alerts, leading up to the synth mimicking three chimes which became the refrain from Jingle Bells. Using a midi arrangement of Jingle Bells I found in the internet’s basement, there then began an 8-bit rendition of the song, which is eventually joined by some ‘real’ software instrument tracks for the rest of the song.

Here is a stereo mix of the audio:

The audio was split into 4 separate tracks, each track was played back on multiple iPhones/iPads for loudness and redundancy (in practice several devices per track were required to get enough volume to be heard above all the chatter and other noise in the cafe). Each device was connected in a local multipeer-to-multipeer network. Any device in the network could send out a ‘play’ signal to start the synchronised playback on all the other devices.

The App

All the networking and playback was done inside a custom app I wrote for the project, making use of iOS’s Multipeer Connectivity and Core Audio frameworks, respectively.

The Multipeer Connectivity is a new framework added in iOS7 (and OS X 10.9) that supports ‘nearby’ networking amongst devices. It can work over infrastructure Wi-Fi networks, peer-to-peer Wi-Fi, and Bluetooth personal area networks, and makes it really simple to find devices, setup connections and send messages and data between connected devices. Further, it is a many-to-many model, rather than a client(s)-server model.

The code to get up and running with a multipeer network is pretty simple. A session object (MCSession) represents the network session and manages connections and communications. Each device in the session, including the local device, is referred to as a peer represented by a Peer ID object (MCPeerID). An Advertiser object (MCNearbyServiceAdvertiser or MCAdvertiserAssistant, the latter providing a standard UI) is used to let other devices know that the local device is able to join sessions of a specified type, and a browser object (MCNearbyServiceBrowser or MCBrowserViewController, the latter again providing a standard UI) is used to find nearby peers to connect with.

In the Nuisance app this is all set up quite simply like this:

define SEVICE_TYPE @"publicnuiscance" - (void)setupMultipeerSession { // Create a Peer ID for the user of this device NSString *displayName = [NSString stringWithFormat:@"%@ on %@", [[NSUserDefaults standardUserDefaults] stringForKey:@"username"], [UIDevice currentDevice].model]; MCPeerID *peerID = [[MCPeerID alloc] initWithDisplayName:displayName]; // Create the session that peers will be invited/join into. // We use no encryption to keep things as fast as possible session = [[MCSession alloc] initWithPeer:peerID securityIdentity:nil encryptionPreference:MCEncryptionNone]; session.delegate = self; // Create the advertiser assistant for managing incoming invitations. // The session name is used as the 'service type' // Note: the service type must be 1–15 characters long and contain only // ASCII lowercase letters, numbers, and hyphens. advertiserAssistant = [[MCAdvertiserAssistant alloc] initWithServiceType:SEVICE_TYPE discoveryInfo:nil session:session]; // Start the assistant to begin advertising availability [advertiserAssistant start]; // Initialize the session browser controller browserViewController = [[MCBrowserViewController alloc] initWithServiceType:SEVICE_TYPE session:session]; browserViewController.delegate = self; browserViewController.minimumNumberOfPeers = kMCSessionMinimumNumberOfPeers; browserViewController.maximumNumberOfPeers = kMCSessionMaximumNumberOfPeers; }

The app UI has a ‘Join Session’ button, which simply presents the MCBrowserViewController’s browsing view:

- (IBAction)joinSession:(id)sender { [self presentViewController:browserViewController animated:YES completion:nil]; }

Sending messages to peers in a session is a simple method call: MCSession’s -sendData:toPeers:withMode:error:. This is how one of the four tracks is assigned to each connected device:

- (IBAction)assignTracksToPeers:(id)sender { NSUInteger i = 0; NSArray *signals = @[setTrack1Signal, setTrack2Signal, setTrack3Signal, setTrack4Signal]; // Interate through each connected peer and assign a track to each. for (MCPeerID *peer in session.connectedPeers) { NSError *sendError = nil; // Sent the signal to this peer [session sendData:signals[i] toPeers:@[peer] withMode:MCSessionSendDataReliable error:&sendError]; // Check the error return to know if there was an issue sending // data to peers. Note if any peers in the 'toPeers' array // argument are not connected sending will fail. if (sendError != nil) //… i++; if (i == 4) i = 0; } }

In this case I’m using the MCSessionSendDataReliable mode to send the data. In this mode “The framework should guarantee delivery of each message, enqueueing and retransmitting data as needed, and ensuring in-order delivery. This message type should be used for application-critical data.” (from the MCSession documentation [LINK]). When using the app, one person will hit the assign tracks button in the UI, causing the above method to run, before the music is started. As it is crucial that each device gets assigned a track, and tracks are distributed evenly, the reliable mode is used.

However, the reliable mode can introduce significant and variable amounts of time for each message to be sent and verified. When it is time to start the music playing, all the devices need to start at the same time, so the play music signal is sent from one device, using the MCSessionSendDataUnreliable mode.

- (IBAction)playMusic:(id)sender { NSError *error = nil; [session sendData:playMusicSignal toPeers:session.connectedPeers withMode:MCSessionSendDataUnreliable error:&error]; // Check the error return to know if there was an issue sending data // to peers. Note any peers in the 'toPeers' array argument are not // connected this will fail. if (error != nil) //… }

In unreliable mode “Messages to peers should be sent immediately without socket-level queueing. If a message cannot be sent immediately, it should be dropped. The order of messages is not guaranteed. This message type should be used for data that ceases to be relevant if delayed, such as real-time gaming data” (from the MCSession documentation [LINK]). For this project, where all the devices are using wifi and on the same ad-hoc network, this ensured that all the devices received the play signal at essentially the same time, ‘essentially’ meaning that there was no perceivable difference in timing between the music coming from different devices spread around the room.

Sending in unreliable mode does introduce the possibility that any particular device in the network may not receive the play signal, and therefore not start the audio playback, but this was countered by having multiple devices for each audio track so that the music would still be complete, if perhaps a little quieter in parts. In practice all the devices received the signal OK, but this was in a reasonably small area, and the devices were never more than around 4 meters apart. Larger distances may introduce problems.

Playback of the audio tracks was done using Audio Units connected in an AUGraph. This approach has the advantage over other, higher level audio APIs of allowing the audio to be pre-buffered into RAM so that there is minimal time between receiving the ‘play’ message and audio playback beginning.

The audio was handled by a single ‘AudioPlayer’ class. In its -init method the Audio Units and the Graph are set up like this:

// create the empty audio units graph // audioUnitsGraph is an AUGraph instance variable NewAUGraph(&audioUnitsGraph); // make a ComponentDescription structure to fetch audio units AudioComponentDescription componentDescription; componentDescription.componentManufacturer = kAudioUnitManufacturer_Apple; componentDescription.componentFlags = 0; componentDescription.componentFlagsMask = 0; // add the nodes in reverse signal order: // output < file playback // add an ouput node componentDescription.componentType = kAudioUnitType_Output; componentDescription.componentSubType = kAudioUnitSubType_RemoteIO; AUNode outputNode; MWLogOSStatus(AUGraphAddNode(audioUnitsGraph, &componentDescription, &outputNode)); // add a file playback node for the loop & connect it to the Output Node componentDescription.componentType = kAudioUnitType_Generator; componentDescription.componentSubType = kAudioUnitSubType_AudioFilePlayer; AUNode filePlaybackNode; MWLogOSStatus(AUGraphAddNode(audioUnitsGraph, &componentDescription, &filePlaybackNode)); MWLogOSStatus(AUGraphConnectNodeInput(audioUnitsGraph, filePlaybackNode, 0, outputNode, 0)); // Open the graph: Instantiates every Audio Unit in the graph. MWLogOSStatus(AUGraphOpen(audioUnitsGraph)); // Initialize the graph: Initializes the graph and the connected Audio Units MWLogOSStatus(AUGraphInitialize(audioUnitsGraph)); // initialize the instance-variable pointer to the file player unit MWLogOSStatus(AUGraphNodeInfo(audioUnitsGraph, filePlaybackNode, NULL, &filePlayerUnit)); // Start the graph running: Begins audio rendering through the graph. MWLogOSStatus(AUGraphStart(audioUnitsGraph));

Each device running the app gets assigned one of the music tracks. When this happens, the AudioPlayer instance preloads the relevant audio file like this:

// Open the music file (needs closed again when we are finished with it) MWLogOSStatus(AudioFileOpenURL(audioFileURL, kAudioFileReadPermission, 0, &musicFileID)); // Pass the file ID to the file player unit MWLogOSStatus(AudioUnitSetProperty(filePlayerUnit, kAudioUnitProperty_ScheduledFileIDs, kAudioUnitScope_Global, 0, &musicFileID, sizeof(musicFileID))); // Set play region info - play whole file, don't loop. ScheduledAudioFileRegion playRegion; playRegion.mTimeStamp.mFlags = kAudioTimeStampSampleTimeValid; playRegion.mTimeStamp.mSampleTime = 0; playRegion.mCompletionProc = NULL; playRegion.mCompletionProcUserData = NULL; playRegion.mAudioFile = musicFileID; playRegion.mLoopCount = 0; // 0 = do not loop playRegion.mStartFrame = 0; playRegion.mFramesToPlay = UINT_MAX; MWLogOSStatus(AudioUnitSetProperty(filePlayerUnit, kAudioUnitProperty_ScheduledFileRegion, kAudioUnitScope_Global, 0, &playRegion, sizeof(playRegion))); // Prime the unit // From Technical Q&A QA1786 // https://developer.apple.com/library/ios/qa/qa1786/_index.html : // "Note: When this call is made the audio unit begins reading the audio // files and will not return until the number of frames specified by the // property value have been read" // From kAudioUnitProperty_ScheduledFilePrime comments in // AudioUnitProperties.h // "The number of frames to read from disk before returning, or 0 to // specify use of a default value" UInt32 primeFrames = 0; MWLogOSStatus(AudioUnitSetProperty(filePlayerUnit, kAudioUnitProperty_ScheduledFilePrime, kAudioUnitScope_Global, 0, &primeFrames, sizeof(primeFrames)));

And finally, when the device receives the play signal over the network, playback is started like this:

// Set the start time of the file player unit to be the next render cycle AudioTimeStamp startTime; startTime.mFlags = kAudioTimeStampSampleTimeValid; startTime.mSampleTime = -1; // -1 = next render cycle MWLogOSStatus(AudioUnitSetProperty(filePlayerUnit, kAudioUnitProperty_ScheduleStartTimeStamp, kAudioUnitScope_Global, 0, &startTime, sizeof(startTime)));

Tasty Pixel and Audanika have something new coming that'll probably be the biggest step forward for iOS music making since Core MIDI: Audio Bus. Soon you'll be able to send the audio you generate in one app to another, live.

(via iosmusician.com)

If they can get this working it could be a hugely powerful enhancement for all iOS audio and music apps...