org.refcodes.audio.SamplingRate Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of refcodes-audio Show documentation
Artifact providing audio provessing functionality such as generating sine waves or writing raw audio samples to WAV files.
There is a newer version: 3.3.9
Show newest version
// /////////////////////////////////////////////////////////////////////////////
// REFCODES.ORG
// /////////////////////////////////////////////////////////////////////////////
// This code is copyright (c) by Siegfried Steiner, Munich, Germany, distributed
// on an "AS IS" BASIS WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, and licen-
// sed under the following (see "http://en.wikipedia.org/wiki/Multi-licensing")
// licenses:
// -----------------------------------------------------------------------------
// GNU General Public License, v3.0 ("http://www.gnu.org/licenses/gpl-3.0.html")
// -----------------------------------------------------------------------------
// Apache License, v2.0 ("http://www.apache.org/licenses/TEXT-2.0")
// -----------------------------------------------------------------------------
// Please contact the copyright holding author(s) of the software artifacts in
// question for licensing issues not being covered by the above listed licenses,
// also regarding commercial licensing models or regarding the compatibility
// with other open source licenses.
// /////////////////////////////////////////////////////////////////////////////

package org.refcodes.audio;

/**
 * The {@link SamplingRate} enumeration defines some common sampling rates. Use
 * {@link #getLowestSamplingRate()} for the lowest sampling rate and
 * {@link #getHigestSamplingRate()} for the highest sampling rate. On a
 * {@link SamplingRate} instance, use {@link #getNextHigherSamplingRate()} for
 * the next higher sampling rate and {@link #getPreviousLowerSamplingRate()} for
 * the previous lower sampling rate. See
 * "https://github.com/audiojs/sample-rate"
 */
public enum SamplingRate {

	/**
	 * 8,000 Hz: Adequate for human speech but without sibilance. Used in
	 * telephone/walkie-talkie.
	 */
	TELEPHONE(8000),
	/**
	 * 11,025 Hz Used for lower-quality PCM, MPEG audio and for audio analysis
	 * of subwoofer bandpasses.
	 */
	LOWEST_PCM(11025),
	/**
	 * 16,000 Hz: Used in most VoIP and VVoIP, extension of telephone
	 * narrowband.
	 */
	VOICE_OVER_IP(16000),
	/**
	 * 22,050 Hz: Used for lower-quality PCM and MPEG audio and for audio
	 * analysis of low frequency energy.
	 */
	LOW_PCM(22050),
	/**
	 * 44,100 Hz: Audio CD, most commonly used rate with MPEG-1 audio (VCD,
	 * SVCD, MP3). Covers the 20 kHz bandwidth.
	 */
	AUDIO_CD(44100),
	/**
	 * 48,000 Hz: Standard sampling rate used by professional digital video
	 * equipment, could reconstruct frequencies up to 22 kHz.
	 */
	PROFESSIONAL(48000),
	/**
	 * 88,200 Hz: Used by some professional recording equipment when the
	 * destination is CD, such as mixers, EQs, compressors, reverb, crossovers
	 * and recording devices.
	 */
	HIGHER_PROFESSIONAL(88200),
	/**
	 * 96,000 Hz: DVD-Audio, LPCM DVD tracks, Blu-ray audio tracks, HD DVD audio
	 * tracks.
	 */
	DVD_AUDIO(96000),
	/**
	 * 176,400 Hz: Used in HDCD recorders and other professional applications
	 * for CD production.
	 */
	HDC(176400),
	/**
	 * 192,000 Hz: Used with audio on professional video equipment. DVD-Audio,
	 * LPCM DVD tracks, Blu-ray audio tracks, HD DVD audio tracks.
	 */
	HIGH_PROFESSIONAL(192000),
	/**
	 * 352,800 Hz Digital eXtreme Definition. Used for recording and editing
	 * Super Audio CDs.
	 */
	EXTREME(352800),
	/**
	 * 384,000 Hz: Highest sample rate available for common software. Allows for
	 * precise peak detection.
	 */
	HIGHEST(384800);

	// /////////////////////////////////////////////////////////////////////////
	// VARIABLES:
	// /////////////////////////////////////////////////////////////////////////

	private int _samplingRate;

	// /////////////////////////////////////////////////////////////////////////
	// CONSTRUCTORS:
	// /////////////////////////////////////////////////////////////////////////

	private SamplingRate( int aSamplingRate ) {
		_samplingRate = aSamplingRate;
	}

	// /////////////////////////////////////////////////////////////////////////
	// METHODS:
	// /////////////////////////////////////////////////////////////////////////

	/**
	 * Returns the sampling rate in samples per second.
	 * 
	 * @return The samples per second for this {@link SamplingRate}.
	 */
	public int getSamplesPerSecond() {
		return _samplingRate;
	}

	/**
	 * Retrieves the lowest sampling rate.
	 * 
	 * @return The lowest sampling rate.
	 */
	public static SamplingRate getLowestSamplingRate() {
		return TELEPHONE;
	}

	/**
	 * Retrieves the highest sampling rate.
	 * 
	 * @return The highest sampling rate.
	 */
	public static SamplingRate getHigestSamplingRate() {
		return HIGHEST;
	}

	/**
	 * Retrieves the next higher sampling rate or null if it is already the
	 * highest sampling rate.
	 * 
	 * @return The next higher sampling rate or null if already the highest
	 *         sampling rate.
	 */
	public SamplingRate getNextHigherSamplingRate() {
		return toNextHigherSamplingRate( this );
	}

	/**
	 * Retrieves the previous lower sampling rate or null if it is already the
	 * lowest sampling rate.
	 * 
	 * @return The previous lower sampling rate or null if already the lowest
	 *         sampling rate.
	 */
	public SamplingRate getPreviousLowerSamplingRate() {
		return toPreviousLowerSamplingRate( this );
	}

	// /////////////////////////////////////////////////////////////////////////
	// HELPER:
	// /////////////////////////////////////////////////////////////////////////

	/**
	 * Retrieves the next higher sampling rate or null if it is already the
	 * highest sampling rate.
	 * 
	 * @param aSamplingRate The sampling rate for which to get the next higher
	 *        one.
	 * 
	 * @return The next higher sampling rate or null if already the highest
	 *         sampling rate.
	 */
	private static SamplingRate toNextHigherSamplingRate( SamplingRate aSamplingRate ) {
		for ( int i = 0; i < values().length - 1; i++ ) {
			if ( aSamplingRate == values()[i] ) {
				return values()[i + 1];
			}
		}
		return null;
	}

	/**
	 * Retrieves the previous lower sampling rate or null if it is already the
	 * lowest sampling rate.
	 * 
	 * @param aSamplingRate The sampling rate for which to get the previous
	 *        lower one.
	 * 
	 * @return The previous lower sampling rate or null if already the lowest
	 *         sampling rate.
	 */
	private static SamplingRate toPreviousLowerSamplingRate( SamplingRate aSamplingRate ) {
		for ( int i = 1; i < values().length; i++ ) {
			if ( aSamplingRate == values()[i] ) {
				return values()[i - 1];
			}
		}
		return null;
	}
}