Most of the audio I work with starts out as high resolution. Like any other mastering engineer my process has been to take the finished high res masters, reduce them to CD quality and supply those to my clients who pass them on to their digital download aggregator to be encoded for download. MFiT takes that unnecessary step of converting the high res audio to CD quality out of the equation and creates their MFiT tracks directly from the high res source files. And the results sound pretty great. Here’s a more technical description of what I just said direct from Apple:
"Apple’s latest encoding methodology is a two-step process. The first step in the encoding path is to use state-of-the-art, mastering-quality Sample Rate Conversion (SRC) to resample the master file to a sample rate of 44.1kHz.
Because this SRC outputs a 32-bit floating-point file, it can preserve values that might otherwise fall outside of the permitted amplitude range. This critical intermediary step prevents any aliasing or clipping that could otherwise occur in SRC. It is this 32-bit floating file that’s used as the input to the encoder and is one key reason for such stunning results.
Our encoders then use every bit of resolution available, preserving all the dynamic range of a 24-bit source file and eliminating the need for dithering. The advantage of this is twofold. Not only does it obviate the need of adding dither noise, it also lets the encoders work more efficiently as they don’t need to waste resources encoding this unwanted and unnecessary noise."
The full article can be found here.
Every format has limitations that need to be considered by a mastering engineer, whether it's vinyl, CD or compressed audio. Since digital downloads have become the dominant format it makes sense to take the limitations of the format into consideration during the mastering process to avoid problems that can arise from the encoding. Compressed audio isn't perfect but it can sound better than it has in the past.