Mastering for iTunes

Mastered For iTunes is a standard for digital files for online music within the iTunes store. All our studios and engineers are accredited by Apple to produce Mastered for iTunes masters. Mastered for iTunes files are higher resolution than CD quality, and are encoded with the Apple AAC encoder, the end result being the .m4a file. These files are higher quality than most other online music stores.

Over recent years, digital and online formats has increased just as the demand for digital music sales has. There are over 16 billion downloads of AAC encoded music out there, so it make sense to create masters specifically for the iTunes digital format.

What is the AAC encoder?

This is the iTunes encoder, it is the format in which the audio is compressed and encoded. Because it is encoded from a higher resolution source file the resulting file will sound better than the average MP3. The Mastering for iTunes encoding gives you the convenience of portable digital audio whilst still retaining the higher quality than MP3, but not quite as high as your CD quality.

Hi resolution?

During the recording process, you may notice that your engineer is recording at 96/24 resolution, some even go as far as 192/24. They do this as this resolution captures more samples, therefore the quality of the audio is higher. Engineers will do this because we believe that using higher resolution in the beginning and throughout the recording and mixing process, we will achieve higher resolution and a superior listening quality in the final product.

What sample rate to master for iTunes?

If you are planning to get your tracks Mastered for iTunes make sure your tracks are recorded at 96Khz and 24bit .WAV files.

Mastering the tracks at this sample rate allows for the higher quality audio when mastering for iTunes. As the audio is compressed and decoded during the MFIT process, it is essential that as much detail is retained as possible otherwise you could be making your music sound less crisp. This is why we love mastering for itunes from files that are at least at 96/24. To get the best quality masters, the resolution in the MFIT process needs to be as high as possible.

Downsampling and dithering

To create masters at industry standards, such as CD and AAC, we need to downsample from these high resolution files, such as 96k or 192k.
This is the process know as ‘Sample Rate Conversion’. Downsampling allows the files to change from a 96k file to a CD size file, 44.1k, for example.

Dithering on the other hand, this changes the bit depth. So for CD quality it is 16bit, but an engineer may record at 24bit. So to create the right files, we need to dither these files down in size.

Apple encoding process

Apple encodes using a two step process. Firstly the audio goes through sample rate conversion, creating a 44.1k version of the audio. This is the standard for CD quality, and also the first step in creating the mastered for iTunes master copy.

The second step in the process is preserving the dynamic range of the 24 bit file. This is why it is important to record and send mixes at this bit depth. The encoders use every bit of dynamic range possible to eliminate the need for dither.

As mastering engineers, we know how transparent you want your record to sound.


If you’ve recorded a whole project in 44.1/16, leave it that way and save MFiT for next time! We won’t achieve anything from upsampling that music, no extra data is added purely because that data wasn’t there in the first place. But if you’ve recorded at 24bit then Mastering for iTunes will still make your record sound great, so leave the files as they are.