Recording - November 2011 - 29

Into the bitstream: Below the display window and next to the codec list is an additional set of three tabs. The first tab shows the output levels of each codec. Most people do not realize that when each codec applies a filter to the sound file, it can actually boost the output level so much that it may clip and distort. As a solution Sonnox gives you what is, in my opinion, one of the most significant features in this plug-in. You now get graphic metering of each codec’s output level and, even more importantly, a clip LED to let you know when it does. Connected to this is a trim tab, which allows you to adjust the codec’s output level downward and avoid clipping in your file. I would wager that until now most of us were probably unaware that this was happening to our files when encoded in other programs. The stats: The next tab offers a statistical listing of how much data compression is being applied. For instance, a 256 MP3 is 1:8, a 128 MP3 is 1:16 and a Lossless AAC is only 1:2. Comparisons and blind taste tests: The last tab allows you to do A/B testing to see which codec truly sounds the best.

If you are auditioning a full multi-track mix, you will need to encode it in real time in Online mode. If you have files that are already mixed down, it may be easier to do this process in the Offline Encode tab. In this mode you drag your file to the central window pane or choose the builtin browser and simply hit Encode; the process is quick and painless. A third option available is Offline Decode, handy for decoding files back to WAV or AIFF for use in your DAW sessions. Batching and tagging There are two things I wish Fraunhofer Pro-Codec did that it does not do. First, you can only ever work with one file at a time, and even though the offline process is lightning fast, a batch process mode to do a whole folder would have been handy.

The Codecs Lossy Formats MP3 – 96 kbps to 320 kbps AAC LC (common Apple AAC file) – 96 kbps to 320 kbps HE-AAC (Super low rate compression used for internet radio) – 16 kbps to 128 kbps HE-AAC V2 (Parametric Stereo) – 18 kbps to 56 kbps Lossless Formats HD-AAC (in my test this was sonically and sizewise similar to iTunes Apple Lossless, but did not show up in iTunes as such) – Core-96 kbps to Core-192 kbps MP3 HD (Lossless MP3 codec only up to 16-bit) – Core-96 kbps to Core-320 kbps With this tab you can seamlessly A/B between two codecs or a codec and the unprocessed signal. An additional mode allows you to make this a blind test, and even gives you a score at the end. I used this to satisfy my own curiosity and see what the audible differences were between MP3 and AAC files at the same bit rate. I did this multiple times on different music styles, and while I swear I can hear a slight mid-high presence shift when A/B’ing, when the plug-in tested me blind I was wrong 50% of the time. Yikes. Grit and grumble: Lastly there is a button that toggles between the codec’s output and the signal that is being cut out. As you would expect, the lower the bit depth, the more is being taken away. For anyone who has played with a noisereduction program where you can audition just the residual noise level, it sounds pretty similar. Encoding and decoding choices Once your codecs have been chosen, analyzed and trimmed, you have two encoding choices, and in each instance you can create five different codecs at one time. Second, when naming your files in the Export Settings section, you can only simply name a file, and then add a suffix, specifically the Codec, Bitrate and Mode. It would have been nice to offer a fullfledged tagger as well. Conclusions Bottom line, Fraunhofer Pro-Codec demystifies the process of MP3 and AAC files and allows us to make completely informed decisions when using said codecs, and it’s really about time someone did this! At $470, this is a pro-level product for mastering engineers and working studios, and not so much made for the casual MP3 creator. Nevertheless, it’s great to finally gain knowledge and control over the lossy-audio encoding process, because knowledge is power... in this case, the power to make better-sounding, more reliably portable song files. Price: $495 More from: Sonnox, www.sonnoxplugins.com
RECORDING NOVEMBER 2011

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Recording - November 2011

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