| java.lang.Object | |
| ↳ | android.net.rtp.AudioGroup |
An AudioGroup is an audio hub for the speaker, the microphone, and
AudioStreams. Each of these components can be logically turned on
or off by calling setMode(int) or setMode(int).
The AudioGroup will go through these components and process them one by one
within its execution loop. The loop consists of four steps. First, for each
AudioStream not in MODE_SEND_ONLY, decodes its incoming
packets and stores in its buffer. Then, if the microphone is enabled,
processes the recorded audio and stores in its buffer. Third, if the speaker
is enabled, mixes all AudioStream buffers and plays back. Finally, for each
AudioStream not in MODE_RECEIVE_ONLY, mixes all other
buffers and sends back the encoded packets. An AudioGroup does nothing if
there is no AudioStream in it.
Few things must be noticed before using these classes. The performance is
highly related to the system load and the network bandwidth. Usually a
simpler AudioCodec costs fewer CPU cycles but requires more network
bandwidth, and vise versa. Using two AudioStreams at the same time doubles
not only the load but also the bandwidth. The condition varies from one
device to another, and developers should choose the right combination in
order to get the best result.
It is sometimes useful to keep multiple AudioGroups at the same time. For
example, a Voice over IP (VoIP) application might want to put a conference
call on hold in order to make a new call but still allow people in the
conference call talking to each other. This can be done easily using two
AudioGroups, but there are some limitations. Since the speaker and the
microphone are globally shared resources, only one AudioGroup at a time is
allowed to run in a mode other than MODE_ON_HOLD. The others will
be unable to acquire these resources and fail silently.
Using this class requires
RECORD_AUDIO permission. Developers
should set the audio mode to MODE_IN_COMMUNICATION
using setMode(int) and change it back when none of
the AudioGroups is in use.
| Constants | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| int | MODE_ECHO_SUPPRESSION | This mode is similar to MODE_NORMAL except the echo suppression
is enabled. |
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| int | MODE_MUTED | This mode is similar to MODE_NORMAL except the microphone is
disabled. |
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| int | MODE_NORMAL | This mode indicates that the speaker, the microphone, and all
AudioStreams in the group are enabled. |
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| int | MODE_ON_HOLD | This mode is similar to MODE_NORMAL except the speaker and
the microphone are both disabled. |
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| Public Constructors | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Creates an empty AudioGroup.
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| Public Methods | |||||||||||
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Removes every
AudioStream in this group. | |||||||||||
Returns the current mode.
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Returns the
AudioStreams in this group. | |||||||||||
Sends a DTMF digit to every
AudioStream in this group. | |||||||||||
Changes the current mode.
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| Protected Methods | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Invoked when the garbage collector has detected that this instance is no longer reachable.
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[Expand]
Inherited Methods | |||||||||||
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From class
java.lang.Object
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This mode is similar to MODE_NORMAL except the echo suppression
is enabled. It should be only used when the speaker phone is on.
This mode is similar to MODE_NORMAL except the microphone is
disabled.
This mode indicates that the speaker, the microphone, and all
AudioStreams in the group are enabled. First, the packets
received from the streams are decoded and mixed with the audio recorded
from the microphone. Then, the results are played back to the speaker,
encoded and sent back to each stream.
This mode is similar to MODE_NORMAL except the speaker and
the microphone are both disabled.
Sends a DTMF digit to every AudioStream in this group. Currently
only event 0 to 15 are supported.
| IllegalArgumentException | if the event is invalid. |
|---|
Changes the current mode. It must be one of MODE_ON_HOLD,
MODE_MUTED, MODE_NORMAL, and
MODE_ECHO_SUPPRESSION.
| mode | The mode to change to. |
|---|
| IllegalArgumentException | if the mode is invalid. |
|---|
Invoked when the garbage collector has detected that this instance is no longer reachable. The default implementation does nothing, but this method can be overridden to free resources.
Note that objects that override finalize are significantly more expensive than
objects that don't. Finalizers may be run a long time after the object is no longer
reachable, depending on memory pressure, so it's a bad idea to rely on them for cleanup.
Note also that finalizers are run on a single VM-wide finalizer thread,
so doing blocking work in a finalizer is a bad idea. A finalizer is usually only necessary
for a class that has a native peer and needs to call a native method to destroy that peer.
Even then, it's better to provide an explicit close method (and implement
Closeable), and insist that callers manually dispose of instances. This
works well for something like files, but less well for something like a BigInteger
where typical calling code would have to deal with lots of temporaries. Unfortunately,
code that creates lots of temporaries is the worst kind of code from the point of view of
the single finalizer thread.
If you must use finalizers, consider at least providing your own
ReferenceQueue and having your own thread process that queue.
Unlike constructors, finalizers are not automatically chained. You are responsible for
calling super.finalize() yourself.
Uncaught exceptions thrown by finalizers are ignored and do not terminate the finalizer thread. See Effective Java Item 7, "Avoid finalizers" for more.
| Throwable |
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