We here at TUAW have expressed our love of VisualHub, Techspansion's great video encoding app, time and again. But what if those crazy folks at Techspansion decided to take the video part out of VisualHub? The resulting app would be very much like AudialHub, an audio converter that takes many UI and functionality cues from VisualHub.

Read on for our full review.

Update: I mistakenly quoted the special VisualHub cross-upgrade promotional price as the full price for AudialHub. This error has been corrected.

Main Window

When you first download AudialHub ($14.41 $18.81 for the full version, the free demo will convert the first minute of any compatible audio files) you are prompted to download some open source audio libraries which AudialHub uses to work its magic. The 3.6 meg download is installed very quickly, and then you're good to go.

Here is the main user interface for AudialHub:

Very streamlined. As you can see in this screenshot, I have two audio files waiting to be converted. The first is an MP3 while the second is an AAC file that I purchased from the iTunes Store. You'll notice the red 'X' and the Runtime listing of 'DRM' on the iTunes store track. As you might expect, AudialHub cannot convert any audio formats that are protected with DRM since that would likely not be legal. It would be nice if AudialHub wouldn't even allow you to add DRMed tracks to its conversion queue, but since the app has to determine if the file is DRMed or not the red X is a good solution.

What it can do

AudialHub will convert a wide variety of file formats to and fro, including:

• AAC
• MP3
• WMA (Windows Media)
• 3G (for various cellphones)
• Ogg Vorbis (the format of choice for a number of Hippies 2.0)
• AIFF
• WAV
• Apple Lossless
• FLAC

You can also use AudialHub to burn either an Audio Disc or MP3 CD.

Many of you are thinking, 'Can't iTunes convert audio files for free?' It can but with a few limitations. iTunes only supports encoding in the following formats:

• AAC
• AIFF
• Apple Lossless
• MP3
• WAV

If this list covers all the formats you're interested in you might think that AudialHub would be money wasted, but then that might not be the case.

The real advantage that AudialHub has over iTunes is that it has been designed from the ground up as a batch converter. If you have a large number of audio files to convert from one format to another, AudialHub has you covered. Better yet if you want to convert all those files and then upload them all to a server AudialHub is your app. Why? One word: workflows.

The 'When done' menu, my favorite feature of VisualHub, is included in AudialHub:

This seemingly innocuous menu has saved me more than a few dollars of electricity over the years (and isn't being green the new black?). When AudialHub is done doing its thing you can have it quit itself, automatically put your Mac to sleep, add the converted files to iTunes, or open the folder in which the files were saved. Powerusers can even have AudialHub run a script when it is finished encoding. This enables you to create workflows that take those newly encoded files and do any number of things (upload them to a directory, post them to your blog, email them to a distribution list, and so on). The possibilities are endless.

Not only can you take the files AudialHub creates and have a script interact with them, you can even have AudialHub combine them all into one big file. This could come in handy should you want to create an extra long MP3 from a number of different MP3s for an exercise soundtrack (just to name one possible application of this feature off the top of my head).

Another big advantage AudialHub has over iTunes is previewing your files. You don't actually have to convert your whole file in order to hear what it will sound like. Simply click the preview icon and this window pops up:

Click play and you'll hear what the final file will sound like, provided you check the 'Play including Compression' box. Change some settings and hit 'Generate Preview' to make sure the sound is still up to snuff. You can even set how much of the file you want to preview (by default it starts 5 seconds into the file and plays for 10 seconds, looped).

Why spend time working when you can mess with settings?

Speaking of settings, AudialHub offers you a slew of settings to fiddle with. The application is set to automatically determine the best settings for the file itself, but if you're a control freak you can delve into the 'Advanced Settings' and get exactly what you want.

The first Advanced Setting tab is called 'Audio:'

Settings of note available here are:

• 'Fit each file into:' This lets you set an upper limit to the size of the resultant file. Very handy for you podcasters out there.
• 'Normalize' This is also handy for podcasters out there who push out audio tracks with a number of different people talking at the same time but not in the same place. The volume levels are usually way off between participants (one person has their mic volume cranked all the way up, another person likes to whisper). Normalizing will try to get all the audio to be around the same volume.

'One-offs' are next:

As you can see these settings were designed for working with only one file in mind, but you can apply them to a batch if you like. You can trim some audio off the front and the end of a file, set the tags of the file, or check out what the tags are currently set to.

'Info' gives you, as you might guess, information about the currently selected file:

You can also set a number of different options in Advanced Settings and then save that configuration for use on another copy of AudialHub, or for use later.

Buy one copy of AudialHub, get infinite copies for free

As I said, AudialHub is all about batch processing of files. But what happens when you have 53 MP3s you want to change into AACs and 14 WMAs that you need to be MP3s? AudialHub has you covered with Queues.

Command-N creates a new AudialHub 'Queue,' which is just another copy of the application. This allows you to run any number of copies of AudialHub concurrently so you can convert large numbers of files from one type to another. This also allows you to convert a number of different files and have each Queue fire off a different script (one queue might be simply converting files, while another is converting files and then uploading them to the web, and so on).

It worked for Ford, it'll work for you.

You say your computer is scattered with MP3s that need to be converted to something else? Or you spend all day creating countless audio files and you want to convert them as you go, rather than creating a batch of them? AudialHub has a mode that's just for you.

Under the Conversion menu sits 'Start Assembly Line,' as seen below:

Once you start the Assembly Line, as I did above, AudialHub patiently waits for you to drag files into the main window or onto the Dock icon. Once a file has been added to the Assembly Line it immediately starts converting according to whatever settings were entered (in the above screenshot any file added to AudialHub would be converted to an MP3). Combine this with Queues and you can have several Assembly Lines running at the same time for each audio format AudialHub supports.

The $18.81 question

All of these features are great, but are they worth $18.81? If you have lots of audio files that need to be converted into other formats then the answer is clearly 'Yes.' Without a doubt, AudialHub will save you countless hours, and allow you to do things with your files that you probably thought about doing before, but didn't get around to doing because implementing them would have taken too much time. AudialHub offers up a number of very good features in a UI that is clear to use, and with documentation that is actually fun to read (seriously, even if you don't buy this app make sure you read the included documentation).

If the fact that iTunes can actually convert audio files into other formats came as news to you, AudialHub is not an app for you. Likewise if you convert an AAC into a MP3 once every few months there is no compelling reason for you to part with your hard earned cash. Just use iTunes for your occasional converting needs and you'll be fine.

AudialHub is a well thought out application that is targeted at a very specific group of users. It's safe to say that those users are very happy that AudialHub is on the scene, and will recoup the $18.81 investment in no time flat.