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Digital Audio Essentials by Bruce Fries, Marty Fries

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Lossless Formats

Lossless formats store digital audio with absolutely no loss of information. Some, such as PCM, store just the raw audio data with no compression, while others, such as FLAC and MLP, use lossless compression techniques to create files about half the size of files that use PCM. Lossless formats are good choices for archival material that may need to be edited or re-encoded at some point in the future.

PCM

PCM (Pulse Code Modulation) is a common method of storing and transmitting uncompressed digital audio. Since it is a generic format, most audio applications can read PCM (just as most word-processing programs can read a plain-text file). PCM is used for audio CDs and digital audio tapes (DATs), and it is a common format for AIFF and WAV files.

PCM audio can have a wide rage of resolutions, sampling rates, and number of channels. Common resolutions are 8, 16, and 24 bits. Common sampling rates are 22.05, 44.1, 48, and 96 kHz. The number of channels can range from mono and stereo to six-channel (5.1) surround sound.

PCM is based on a straight representation of the binary digits (ones and zeros) of each sample value. When PCM audio is transmitted, each “1” is represented by a positive voltage pulse, and each “0” is represented by the absence of a pulse. Figure 9-2 shows how binary data is represented in a PCM signal.

The PCM lossless format

Figure 9-2. The PCM lossless format

APE

APE (commonly called ...

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