QAudioDeviceInfo Class Reference
[QtMultimedia module]

Detailed Description

The QAudioDeviceInfo class provides an interface to query audio devices and their functionality.

QAudioDeviceInfo lets you query for audio devices--such as sound cards and USB headsets--that are currently available on the system. The audio devices available are dependent on the platform or audio plugins installed.

You can also query each device for the formats it supports. A format in this context is a set consisting of a specific byte order, channel, codec, frequency, sample rate, and sample type. A format is represented by the QAudioFormat class.

The values supported by the the device for each of these parameters can be fetched with supportedByteOrders(), supportedChannels(), supportedCodecs(), supportedFrequencies(), supportedSampleSizes(), and supportedSampleTypes(). The combinations supported are dependent on the platform, audio plugins installed and the audio device capabilities. If you need a specific format, you can check if the device supports it with isFormatSupported(), or fetch a supported format that is as close as possible to the format with nearestFormat(). For instance:

         QAudioFormat format;
         format.setFrequency(44100);
         ...
         format.setSampleType(QAudioFormat::SignedInt);

         QAudioDeviceInfo info(QAudioDeviceInfo::defaultOutputDevice());

         if (!info.isFormatSupported(format))
             format = info.nearestFormat(format);

A QAudioDeviceInfo is used by Qt to construct classes that communicate with the device--such as QAudioInput, and QAudioOutput. The static functions defaultInputDevice(), defaultOutputDevice(), and availableDevices() let you get a list of all available devices. Devices are fetch according to the value of mode this is specified by the QAudio::Mode enum. The QAudioDeviceInfo returned are only valid for the QAudio::Mode.

For instance:

 foreach(const QAudioDeviceInfo &deviceInfo, QAudioDeviceInfo::availableDevices(QAudio::AudioOutput))
     qDebug() << "Device name: " << deviceInfo.deviceName();

In this code sample, we loop through all devices that are able to output sound, i.e., play an audio stream in a supported format. For each device we find, we simply print the deviceName().

See also QAudioOutput and QAudioInput.

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