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Audio Formats Introduction
Audio Formats
Every data line has an audio format associated with its data stream. The audio format of a source (playback) data line indicates what kind of data the data line expects to receive for output. For a target (capture) data line, the audio format specifies the kind of the data that can be read from the line. Sound files also have audio formats, of course.
In addition to the encoding, the audio format includes other properties that further specify the exact arrangement of the data. These include the number of channels, sample rate, sample size, byte order, frame rate, and frame size. Sounds may have different numbers of audio channels: one for mono, two for stereo. The sample rate measures how many "snapshots" (samples) of the sound pressure are taken per second, per channel. (If the sound is stereo rather than mono, two samples are actually measured at each instant of time: one for the left channel, and another for the right channel; however, the sample rate still measures the number per channel, so the rate is the same regardless of the number of channels. This is the standard use of the term.) The sample size indicates how many bits are used to store each snapshot; 8 and 16 are typical values. For 16-bit samples (or any other sample size larger than a byte), byte order is important; the bytes in each sample are arranged in either the "little-endian" or "big-endian" style. For encodings like PCM, a frame consists of the set of samples for all channels at a given point in time, and so the size of a frame (in bytes) is always equal to the size of a sample (in bytes) times the number of channels. However, with some other sorts of encodings a frame can contain a bundle of compressed data for a whole series of samples, as well as additional, non-sample data. For such encodings, the sample rate and sample size refer to the data after it is decoded into PCM, and so they are completely different from the frame rate and frame size.
WMA Formats
Windows Media Audio format. A special type of advanced streaming format file for use with audio content encoded with the Windows Media Audio codec. The .wma extension indicates a file format and how the content is encoded.
WAVE Formats
It is not an audio codec. It is the file format. This format was created by Microsoft and IBM, and it has unfortunately become a popular standard. It specifies an arbitrary sampling rate, number of channels and sample size. It also specifies a number of application-specific blocks within the file. It has a plethora of different compression formats.
It is the files with .wav extension. But this files can be converted by different codecs. NCTAudioStudio3 supports the following types of WAV files:
Microsoft PCM, Microsoft ADPCM, DSP, GSM, VOX, A-law U-law, CCUIT G723.1, CCUIT G721, CCUIT G723, CCUIT G726, CCUIT G729 (A)
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