There are over 250 million iOS devices in the world today connected to Apple’s vast iTunes ecommerce system. Considering the ubiquity of such a digital audio-ready footprint, there’s a fairly strong chance that just about any commercially-released music title will, at some point, be heard on an iPod, iPhone, or iPad. The resulting market of music consumers who want their content with them to enjoy on-the-go, at home or anywhere dictates that professional mastering engineers should plan and monitor the output of their efforts to provide the very best listening experience possible on iOS devices.
During the first quarter of 2012, Apple implemented their new high-resolution encoding process for creating AAC's. (An AAC is what you download from iTunes, and is the iTunes version of an mp3, both being data-compressed audio files.) In order to take full advantage of the improved quality of this new encoding, Apple has released a set of guidelines and tools to assist mastering professionals in delivering optimized source files for this new high-resolution encoding and ecommerce process, allowing the mastering engineer to audition the changes that take place during AAC encoding prior to committing your mix to processing. Apples’s goal is to build awareness of best practices that will help to ensure that consumers have a great listening experience on their mobile hardware. When these guidelines are followed, the music is considered to be "Mastered for iTunes". DES Mastering supports Apple's efforts and has the full set of tools and the knowledge to prepare finished masters for release into the iTunes environment with the best possible quality.
It All Starts with Tracking and Mixing in High-Resolution
If you have been following our blog, you know that I have emphasized over and over the importance of tracking, mixing and mastering in high-resolution, meaning 24 bit, and preferably 96k, but at the very least at 48k/24 bit. Apple is now requesting that their music partners submit their source files at 96k/24 bit as the ideal in order to take full advantage of their new encoding process.
As we have pointed out in previous posts, this does not mean that you should sample rate convert your 44.1k/16 bit files to 96k/24 bit. This will do nothing for you. Even if you use the best mastering-quality SRC, the resulting 96k file will sound exactly like the 44.1k file, and from most commercially available SRC's the 96k file will actually sound worse than the original 44.1k file due to artifacts and distortions created during the sample rate conversion.
So once again, here are the important points:
If possible, track and mix at 96k/24 bit. At the very least track and mix at 48k/24 bit.
If you are mixing 'in the box', do not perform any sample rate conversion. The mix files should be the same sample rate that the project was tracked at. Again, upsampling a 44.1k or 48k mix to 96k will gain nothing, and will potentially lose quality.
Do as little processing to the overall mix as absolutely possible, and preferably none. This means little or no eq, compression or limiting applied to the stereo master buss. This doesn't mean that you should not eq or compress individual tracks as you see fit - just try to leave the stereo buss clean of any processing.
Leave headroom in your mix. if you are doing a proper 24 bit mix, there is no reason for the hottest peaks in your mix to exceed -3dBfs, and ideally they will sit at -6dBfs.
For more detailed info on this see Mixing in Preparation for Mastering Part 1 and Part 2.
Have a professional master your project. Whether you use DES Mastering or not, you should have a mastering professional finish your project. You may have the best mix engineer in the world, but that does not qualify him as a mastering engineer. It is a completely different skill set, and a completely different way of using seemingly familiar tools. Your project should be mastered in a proper mastering room, not a control room, by a mastering engineer, and preferably one who knows how to create the best possible mastered files for downloadable formats.
Have a professional master your project. Whether you use DES Mastering or not, you should have a mastering professional finish your project. You may have the best mix engineer in the world, but that does not qualify him as a mastering engineer. It is a completely different skill set, and a completely different way of using seemingly familiar tools. Your project should be mastered in a proper mastering room, not a control room, by a mastering engineer, and preferably one who knows how to create the best possible mastered files for downloadable formats.
The Best Encode Begins with DES and soundBlade
Encoding for any lossy format such as AAC or mp3 benefits from the highest quality source file possible. This is because the end result of the encoding process is a data compressed file that affects the audio quality. To achieve the best encoded result, it is important to start with the highest quality sound possible, such as that derived by DES Mastering using the Sonic soundBlade mastering system. The Sonic Studio Engine (SSE) used in the soundBlade system enables key processing to deliver pristine sound that is free of artifacts that can be caused by other lesser audio engines. Just because a manufacturer works "Pro" into the name of their product does not make it a mastering-quality platform. When Apple creates an AAC from a soundBlade master it will yield the most desirable output suitable for publishing on the vast iTunes ecommerce platform.
Remastering for iTunes
If you have a back-catalog of music that is already available in the iTunes Store, or that has not yet been released on iTunes, you might consider having DES properly re-master your project for iTunes delivery. This would require you to have your original mix files, and those will hopefully be 24 bit and 48k or above. If you submit your remastered music to Apple, they will perform a series of tests, and if they determine that the proper guidelines have been followed and that there is an improvement over your previous release, this will earn you the "Mastered for iTunes" badge.
If you mastered with DES at any time over the past 3 years, we more than likely still have your project in our archive, and if you delivered mixes in high-resolution, then it will be a relatively simple process to create mastered high-res files as Apple is now requesting; it would not require a complete remastering. Contact us for details.
