Open Core Audio

Here’s a really short CoreAudio (CAF) file I created on the iPod. It has, as is made clear by the info panels, no processing and has been saved uncompressed.

The extension caf is not allowed.
!@#$% (322 KB)
Screen Shot 2017-07-08 at 8.03.33 PM.png
They weren’t fooling around. It’s better digital quality than some of the USB adapters.

I can open it with File > Import, and I can drag it into the Audacity workspace, but I can’t right-click > Open With. Is it correct that FFMpeg is required on Windows? I understand Audacity sits on Apple Core Audio so it’s no stretch that I can open it on a Mac.


As it’s an unusual file-type you’ll have to initially specify what application you want to open it with as default, in order to have it open with a click.

It opens with & without FFmpeg in Audacity 2-1-3 on Windows …
''CAF_Test'' in Audacity 2-1-3 in Windows Vista.png

I remember this. Audacity puts that noise blast at the end. It’s not in the original recording.

If I open the file in the current QuickTime Player, it will let me export as a compressed M4a file, but if I open it in the much older (but still available) QT7, that will allow me to export as a WAV.

Neither the highly compressed M4a nor the WAV (nor the CAF) have that noise blast.


Technology giveth and technology taketh away. You can record an audiobook chapter lying in bed, but it takes an act of congress/parliament to use the work after you do it.

Works for me!


The Core Audio Format is a container for storing audio, developed by Apple Inc. It is compatible with Mac OS X 10.4 and higher; Mac OS X 10.3 needs QuickTime 7 to be installed

That depends on what is inside the container. If it’s 24-bit PCM (as in the file that you uploaded), then FFmpeg is not required. If it contains a compressed audio format, then it may required FFmpeg (depending on what the format is).

That is a load of metadata. An application that fully understands the CAF format (typically an Apple app) will know that it should ignore data at the end of the file. Audacity just sees that the contents are PCM audio data, so reads all of the data including the data at the end, oblivious to the fact that Apple have stuck a load of non-audio data on the end.

What free application can open a .CAF in Windows, convert it to WAV and “know” how to deal with the metadata?

I think you can still get iTunes for Windows and that will let you transfer your presentation to the computer. Oddly, I can’t get iTunes to play the work after it’s transferred.

I wonder how I’m intended to do this? I know I have to fight off tools that are determined to add a rhythm track and it delights in telling me the dominant key of my voice.

Lovely, but can I just have a sound file, please?


If you use an iPod, it is assumed that you have bought into the Apple world.
“The great thing about a Mac is that it integrates seamlessly with all other devices and services - iPods, iPhones, Apple TV, Apple Watch, iTunes, Time Machine, Thunderbold…”

The great thing about a Mac is that it integrates seamlessly with all other devices and services

Seriously, can you picture Windows Media seamlessly integrating with anything else? I bet that phrase never once crossed anyone’s lips.

I don’t think I said iTunes. There’s always the bastard at the family reunion.

I have two impressions of iTunes: iTunes is programmed by the people they get to substitute when the real programmers are on vacation/holiday. iTunes is the division that gets all the Apple newbies while they’re still learning what not to do in the rest of the user environment.

I have Tognazzini’s book on User Interface and I swear iTunes violates something on every page starting with the preface to page one.

And this is the program they picked to interface with the iPod/iPhone.

It gives the impression it’s trying to play my CAF file, but I just can’t find it. I’m not shocked. I lose things all the time…in iTunes.


I’m not kidding about shooting something in bed with the iPod. Given a crowded and carpeted bedroom, my first sound test worked remarkably well. It was the acoustical equivalent of the sun coming up.

“You know? This doesn’t suck.”

Not sucking is a darn good start.


iTunes once was a fairly good media player. It’s the reason there aren’t twelve other players on OSX.

But it became a behemoth with schizoid tendencies. Trying to be a backup utility, a music shop and a sync solution was a bit too much. Still, haven’t found anything better. Songbird is nice, fast, but it crashes once in a blue moon.

Mail is still a lot worse tho…

I got your clip to pass the ACX with a -77.5db NF. I only have my LT to play it back on and it is hard to tell about quality.

  1. Noise Reduction with defaults.
  2. LRO for speech.
  3. Compress at 3 to 1 everything else default.
  4. RMS Normalize to -18.
  5. Normalize to -3.5.

it is hard to tell about quality.

I think I can tell you about quality. I expect hand-holding noises because I was hand-holding it and I’m not shocked about high noise because I don’t remember how far away from the microphone I was.

I’ll do a better mount and test recording in a quiet room that doesn’t feature Wamsutta sheets and bunny slippers.

I was pleased to locate the microphone on the back and clarity makes a significant difference depending on orientation.

I got someone to show me their iPhone and apparently it has two microphones, so it’s a trip to the Genius Bar® and get them to tell me how to tell which one the machine is using for stand-alone recordings.

I know everybody looks down on recording sound that way, but I’m betting the last couple of NPR RadioLab episodes recorded the interstitials and announcements that way. They were not studio recordings like the rest of the show.

“RadioLab is made possible by Zip Recruiter…”

Thanks for the processing.


For $32.00 I can connect any XLR mic to my iPhone. It has a great digital recorder and is used by many professionals for field recording. The NPR streams at 64K when the rest of the world screams “You Can Not Do That” and they sound great! It’s amazing what experience and proper gear can accomplish.

We’re drifting quite a long way from the original topic of “opening a CAF file”, but out of interest, where’s the 48v phantom power in that set-up?

With all due respect, the quote above was from the third post on this thread and I think I am dead on, as far as staying on topic. To answer your last question:

Dynamic mics do not require phantom power and no one with one day of experience would take a condenser mic into the field to record interviews. Condenser mics are used for controlled environment work and some work off of 12v and 24v phantom as well.

I was commenting about the topic drifting away from the original subject “Open Core Audio” (as in the topic subject line), but as the original subject was answered long ago it’s not important. Rather, I was intrigued by your statement: “For $32.00 I can connect any XLR mic to my iPhone”, as that would have been interesting if true :wink:

Well @Steve, I am not perfect but very seldom do I post on matters I have no experience with as far as giving advice. As far as:

“Audio professionals, listen up. The [Advertising link removed by moderator] ProJive XLR cable is a must-have addition to any audio professional’s world. Take it on the go; it’s the easiest and most straight-forward approach to connecting an XLR microphone or mixer to your iPod, iPad, iPhone, Android, Macbook or any other compatible device. Complete with a standard 1/8-inch (3.5mm) stereo-mini port, you can connect headphones to keep your work to yourself, or output direct to your home stereo, or powered speakers to really crank up the volume. Perfect for musicians, producers, field reporters, news gatherers, live audio engineers, vocal instructors / students, or anyone who wants to improve their device’s audio recording capabilities”.

They are 100% correct and I have one in every glove box for every vehicle I own as well as my other residents and they work FANTASTIC! Now, are you the one who deleted my post in this forum looking for a narrator? if so, could you please give me the link forbidding that type of post. :wink:

I think I’m getting dizzy.

I think we have stunning goal meander.

I think I am dead on, as far as staying on topic

The topic at the top of the thread is how to open a CAF file and make it useful. The target user has an iPhone or iPod and zero dollars for extra equipment. They’re interested in casual voice recording, not formal news gathering.

The problem is not getting your voice into the iPod, it’s getting it back out. That’s been extraordinarily difficult and convoluted and I’m wondering if I’m missing a step somewhere.

That and the file insists on arriving with that metadata hanging out the rear. It’s not hard to fix in any editor, but most capture systems don’t do that.


Maybe but I really don’t see any curves at all going down this road.

I am aware of what the title of the post is. I did not realize you could not make a comment on a different subject the OP posted themselves, within their own thread without someone screaming “Off Topic”. This forum is full of “off topic” post.

I thought you were the one doing the recording. “I’m not kidding about shooting something in bed with the iPod. Given a crowded and carpeted bedroom, my first sound test worked remarkably well. It was the acoustical equivalent of the sun coming up. You know? This doesn’t suck. Not sucking is a darn good start. Koz”

As far as casual or formal news gathering, that has nothing to do with this whatsoever! It was simple a reply back to @steve as he seemed to be intrigued by it and if someone can’t afford $29.00 then maybe we can pass the hat around. I will go first. Send me a PayPal account and I will give the first $5.00.

if someone can’t afford $29.00 then maybe we can pass the hat around.

You may need more than one hat. Remember the target user. I would need between $250 and $300 to recreate everything in that picture.

The only thing they have is the iPhone.

And we’re no closer to resolving the CAF conundrum.


This is a broad statement. “any XLR mic”, that does not specify a particular use case:

This is a specific use case:

“Field recording” covers a lot of scenarios (Field recording - Wikipedia), for example:

Your post was not deleted. It was moved by a moderator to the moderator’s private board to ask for clarification on whether the post should be allowed or not.
It has been decided that the post will not be allowed because we do not allow commercial advertising on the forum, and your post has been deemed to be an advertisement for a commercial engagement.

We do not publish a list detailing what is not allowed on the forum. In my view it would be futile to attempt to do so, as even if we attempted to cover every possible thing that could be posted, there would inevitably be “loopholes” that were not explicitly stated.

It is extremely rare that any of our regular forum contributors make posts that are disallowed, but in such (rare) cases, the post would normally be referred by a moderator to the forum staff board, and if agreed that it should not be allowed, a PM would be sent to the person that posted, to explain why it had been removed. In this case I am explaining to you in this public topic, because you asked in this public topic.

As someone that has used this forum a lot, I would have thought that you would by now have realized that we prefer to try and stick with one subject per forum topic. If that was not clearly evident, I will state that here: We prefer to try to stick with one subject per forum topic.

Nobody “screamed” anything. Let’s just review what I actually did write:
“We’re drifting quite a long way from the original topic of “opening a CAF file”, but out of interest, where’s the 48v phantom power in that set-up?”

They are also very expensive for what they are. I suppose that can be justified because:

  1. This particular type of cable is quite hard to find “ready made”.
  2. They are targeted at Apple customers.
    but nevertheless, $35+ for something that can be made up very easily by combining two $5 adapters is rather expensive (by comparison, a similar cable branded as “LyxPro” is available at about half the price of the “ProJive” version).

If this was a topic about passive XLR to 3.55mm splitters, then it would be appropriate to also mention the limitations of this configuration, such as it not working with phantom powered microphones (yes phantom powered microphones are frequently used for some types of “field recording”), gain being limited by the gain of the iPad / iPhone, it does not provide a balanced XLR input, …

In this post I have only responded to your comments, and not once have I mentioned the actual subject shown in the topic title. As I said before, that is not particularly important in this case because the original question was answered long ago.