AudioFormat is the class that specifies a particular arrangement of data in a sound stream.
By examing the information stored in the audio format, you can discover how to interpret the bits in the
binary sound data.
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. The AudioFileFormat
class encapsulates an AudioFormat in addition to other,
file-specific information. Similarly, an AudioInputStream
has an
AudioFormat.
The AudioFormat class accommodates a number of common sound-file encoding techniques, including
pulse-code modulation (PCM), mu-law encoding, and a-law encoding. These encoding techniques are predefined,
but service providers can create new encoding types.
The encoding that a specific format uses is named by its encoding field.
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.
An AudioFormat object can include a set of
properties. A property is a pair of key and value: the key
is of type String, the associated property
value is an arbitrary object. Properties specify
additional format specifications, like the bit rate for
compressed formats. Properties are mainly used as a means
to transport additional information of the audio format
to and from the service providers. Therefore, properties
are ignored in the
method.
However, methods which rely on the installed service
providers, like isConversionSupported
may consider
properties, depending on the respective service provider
implementation.
The following table lists some common properties which service providers should use, if applicable:
| Property key | Value type | Description |
|---|---|---|
| "bitrate" | Integer | average bit rate in bits per second |
| "vbr" | Boolean | true, if the file is encoded in variable bit
rate (VBR) |
| "quality" | Integer | encoding/conversion quality, 1..100 |
Vendors of service providers (plugins) are encouraged to seek information about other already established properties in third party plugins, and follow the same conventions.
AudioFormat with the given parameters.
The encoding specifies the convention used to represent the data.
The other parameters are further explained in the class description
.AudioFormat with the given parameters.
The encoding specifies the convention used to represent the data.
The other parameters are further explained in the class description
.AudioFormat with a linear PCM encoding and
the given parameters. The frame size is set to the number of bytes
required to contain one sample from each channel, and the frame rate
is set to the sample rate.
The equals method implements an equivalence relation
on non-null object references:
x, x.equals(x) should return
true.
x and y, x.equals(y)
should return true if and only if
y.equals(x) returns true.
x, y, and z, if
x.equals(y) returns true and
y.equals(z) returns true, then
x.equals(z) should return true.
x and y, multiple invocations of
x.equals(y) consistently return true
or consistently return false, provided no
information used in equals comparisons on the
objects is modified.
x,
x.equals(null) should return false.
The equals method for class Object implements
the most discriminating possible equivalence relation on objects;
that is, for any non-null reference values x and
y, this method returns true if and only
if x and y refer to the same object
(x == y has the value true).
Note that it is generally necessary to override the hashCode method whenever this method is overridden, so as to maintain the general contract for the hashCode method, which states that equal objects must have equal hash codes.
AudioSystem.NOT_SPECIFIED means that any (positive) number of channels is
acceptable.AudioSystem.NOT_SPECIFIED means that any frame rate is
acceptable. AudioSystem.NOT_SPECIFIED is also returned when
the frame rate is not defined for this audio format.AudioSystem.NOT_SPECIFIED means that any frame size is
acceptable. AudioSystem.NOT_SPECIFIED is also returned when
the frame size is not defined for this audio format.If the specified property is not defined for a
particular file format, this method returns
null.
AudioSystem.NOT_SPECIFIED means that any sample rate is
acceptable. AudioSystem.NOT_SPECIFIED is also returned when
the sample rate is not defined for this audio format.AudioSystem.NOT_SPECIFIED means that any sample size is
acceptable. AudioSystem.NOT_SPECIFIED is also returned when
the sample size is not defined for this audio format.java.util.Hashtable.
The general contract of hashCode is:
hashCode method on each of
the two objects must produce the same integer result.
As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the JavaTM programming language.)
AudioSystem.NOT_SPECIFIED,
which any sample rate will match. The frame rates must
similarly be equal, unless the specified format has the frame rate
value AudioSystem.NOT_SPECIFIED. The byte order (big-endian or little-endian)
must match if the sample size is greater than one byte.wait methods.
The awakened thread will not be able to proceed until the current thread relinquishes the lock on this object. The awakened thread will compete in the usual manner with any other threads that might be actively competing to synchronize on this object; for example, the awakened thread enjoys no reliable privilege or disadvantage in being the next thread to lock this object.
This method should only be called by a thread that is the owner of this object's monitor. A thread becomes the owner of the object's monitor in one of three ways:
synchronized statement
that synchronizes on the object.
Class, by executing a
synchronized static method of that class.
Only one thread at a time can own an object's monitor.
wait methods.
The awakened threads will not be able to proceed until the current thread relinquishes the lock on this object. The awakened threads will compete in the usual manner with any other threads that might be actively competing to synchronize on this object; for example, the awakened threads enjoy no reliable privilege or disadvantage in being the next thread to lock this object.
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.
The current thread must own this object's monitor. The thread
releases ownership of this monitor and waits until another thread
notifies threads waiting on this object's monitor to wake up
either through a call to the notify method or the
notifyAll method. The thread then waits until it can
re-obtain ownership of the monitor and resumes execution.
As in the one argument version, interrupts and spurious wakeups are possible, and this method should always be used in a loop:
synchronized (obj) {
while (<condition does not hold>)
obj.wait();
... // Perform action appropriate to condition
}
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.The current thread must own this object's monitor.
This method causes the current thread (call it T) to place itself in the wait set for this object and then to relinquish any and all synchronization claims on this object. Thread T becomes disabled for thread scheduling purposes and lies dormant until one of four things happens:
A thread can also wake up without being notified, interrupted, or timing out, a so-called spurious wakeup. While this will rarely occur in practice, applications must guard against it by testing for the condition that should have caused the thread to be awakened, and continuing to wait if the condition is not satisfied. In other words, waits should always occur in loops, like this one:
synchronized (obj) {
while (<condition does not hold>)
obj.wait(timeout);
... // Perform action appropriate to condition
}
(For more information on this topic, see Section 3.2.3 in Doug Lea's
"Concurrent Programming in Java (Second Edition)" (Addison-Wesley,
2000), or Item 50 in Joshua Bloch's "Effective Java Programming
Language Guide" (Addison-Wesley, 2001).
If the current thread is interrupted by another thread while it is waiting, then an InterruptedException is thrown. This exception is not thrown until the lock status of this object has been restored as described above.
Note that the wait method, as it places the current thread into the wait set for this object, unlocks only this object; any other objects on which the current thread may be synchronized remain locked while the thread waits.
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.
This method is similar to the wait method of one
argument, but it allows finer control over the amount of time to
wait for a notification before giving up. The amount of real time,
measured in nanoseconds, is given by:
1000000*timeout+nanos
In all other respects, this method does the same thing as the method of one argument. In particular, wait(0, 0) means the same thing as wait(0).
The current thread must own this object's monitor. The thread releases ownership of this monitor and waits until either of the following two conditions has occurred:
notify method
or the notifyAll method.
timeout
milliseconds plus nanos nanoseconds arguments, has
elapsed.
The thread then waits until it can re-obtain ownership of the monitor and resumes execution.
As in the one argument version, interrupts and spurious wakeups are possible, and this method should always be used in a loop:
synchronized (obj) {
while (<condition does not hold>)
obj.wait(timeout, nanos);
... // Perform action appropriate to condition
}
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.