aving noticed that a majority of copied CD (and even DVD) sold on our (VN) market is of quite a poor acoustic quality. The fact is that they are burned from kind of compressed data, not the original data on genuine disk. This defect is much more apparent with acoustic sound (e.g classical music) than synthesized sound (like tech-no…). It’s quite difficult for one to know since anything compressed at 196 kbps and above can hardly be differentiated without good ears and speakers.

Below is spectrum analyzing of two pieces of sound (from a same CD track), one extracted to the loss-less format flac, one compressed into 128 kbps mp3. Just use the simple sound editor of Audacity, we can see clearly that with the compressed case (image the right): any frequencies above 16 KHz are discarded, compared to the loss-less case (image on the left). We can easily recognize a fake CD, for most of the time, using this simple technique!