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Sample Type and Width
The sample type defines the format of a single sampling value; the width
of a sample defines the number of bits required to represent the value on
a storage medium. Both are of course dependent. Typical values are:
- Telephone Recording: ALAW (World) or ULAW (US), 8 bits
Be aware that sometimes the bit order may be reversed. Decompresses ALAW
roughly correspond to 13 bits linear PCM; decompressed ULAW 14 bits PCM.
- PCM (linear), usually 16 bits, either
- Signed (values from -32768 to +32767) or
- Unsigned (values from 0 to 65535)
- ADPCM, 8 bits
ADPCM is a form of sound compression that has a
good compromise between good sound quality and
fast encoding/decoding time. It is used for
telephone sound compression and places were full
fidelity is not as important. When uncompressed
it has roughly the precision of 16-bit PCM
audio. Popular version of ADPCM include G.726,
MS ADPCM, and IMA ADPCM. (from the sox man page)
- GSM
GSM is a standard used for telephone sound compression in European countries and it is gaining
popularity because of its quality. It usually
is CPU intensive to work with GSM audio data.
(from the sox man page)
If you use more than 1 byte per sample, you also have to define the
machine format:
- Big Endian (Motorola Processors): most significant byte first (10)
- Small Endian (Intel Processors): least significant byte first (01)
Next: Number of Channels, Interleave
Up: Technical Specifications
Previous: Sampling Rate
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BITS Projekt-Account
2004-06-01