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Conversions

Paul's Posts — 14 September 2012

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Conversions

My parents always wanted to convert me from an entrepreneur to a guy with a job working for someone else.  My mother, in particular, was terrified I wouldn’t be able to feed my family working for myself.  Moms.

When it comes to streaming audio, however, we have no choice but to agree to be converted or we cannot succeed in our quest to hear music.  Such is the job of the CODEC.

If you remember in our introduction to formats we learned that the two main lossless compression types were FLAC and ALAC.  The “C” in each of these acronyms stands for today’s word, CODEC.  CODEC is a combined word derived from its two functions: to code and decode a signal.  While technical sounding it’s fairly simple to understand.  A CODEC is a program that can convert a signal from one form to another and back again.  Simple.

So when we press play in iTunes we basically connect the track of music on our hard drive to the player and the stream of audio is then sent to our DAC and we hear music.  If we have compressed our music using a lossless method such as FLAC, the computer has no problem storing that file on the hard drive but the player and the DAC do not understand what to do with this file.  If you place the contents of this FLAC file into a player all you get out the other end is noise – not music.

To get music we have to decode the secret sauce back into its original form which, as you’ll remember, is twice the size of the compressed file.  In the comic book days we used a decoder ring to decrypt the code: today we use a program called a CODEC.

CODECs are used for every type of decoding: MP3, OGG, ALAC, APE, FLAC all are converted back to WAV before they can be played by the player – and sent to your DAC.

What’s important here to understand, as our system gets more complex, is that in the local model we’re discussing – where we are depending on the computer’s player to deliver music via USB to our DAC – iTunes has a big job to do getting the sound the way we need before you can hear it.

Tomorrow we will learn why iTunes is not a high-end player and what the aftermarket programs like Bit Perfect, Pure Music and Amarra are doing to fix that and why.

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About Author

Paul McGowan

Paul McGowan is the CEO and co-founder of PS Audio Inc. a Boulder Colorado design and manufacturing company of high-end audio products and services. McGowan has been designing and building high-end products for nearly 40 years. Hobbies include skiing, music, hiking, artisan bread baking, kick boxing and cooking. He lives in Boulder Colorado with his wife Terri and his 4 sons.

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