QAudioFormat Class
The QAudioFormat class stores audio stream parameter information. 更多...
| 头文件: | #include <QAudioFormat> |
| qmake: | QT += multimedia |
公有类型
| enum | Endian { BigEndian, LittleEndian } |
| enum | SampleType { Unknown, SignedInt, UnSignedInt, Float } |
公有函数
| QAudioFormat() | |
| QAudioFormat(const QAudioFormat &other) | |
| ~QAudioFormat() | |
| QAudioFormat::Endian | byteOrder() const |
| qint32 | bytesForDuration(qint64 duration) const |
| qint32 | bytesForFrames(qint32 frameCount) const |
| int | bytesPerFrame() const |
| int | channelCount() const |
| QString | codec() const |
| qint64 | durationForBytes(qint32 bytes) const |
| qint64 | durationForFrames(qint32 frameCount) const |
| qint32 | framesForBytes(qint32 byteCount) const |
| qint32 | framesForDuration(qint64 duration) const |
| bool | isValid() const |
| int | sampleRate() const |
| int | sampleSize() const |
| QAudioFormat::SampleType | sampleType() const |
| void | setByteOrder(QAudioFormat::Endian byteOrder) |
| void | setChannelCount(int channels) |
| void | setCodec(const QString &codec) |
| void | setSampleRate(int samplerate) |
| void | setSampleSize(int sampleSize) |
| void | setSampleType(QAudioFormat::SampleType sampleType) |
| bool | operator!=(const QAudioFormat &other) const |
| QAudioFormat & | operator=(const QAudioFormat &other) |
| bool | operator==(const QAudioFormat &other) const |
详细描述
The QAudioFormat class stores audio stream parameter information.
An audio format specifies how data in an audio stream is arranged, i.e, how the stream is to be interpreted. The encoding itself is specified by the codec() used for the stream.
In addition to the encoding, QAudioFormat contains other parameters that further specify how the audio sample data is arranged. These are the frequency, the number of channels, the sample size, the sample type, and the byte order. The following table describes these in more detail.
| Parameter | Description |
|---|---|
| Sample Rate | Samples per second of audio data in Hertz. |
| Number of channels | The number of audio channels (typically one for mono or two for stereo) |
| Sample size | How much data is stored in each sample (typically 8 or 16 bits) |
| Sample type | Numerical representation of sample (typically signed integer, unsigned integer or float) |
| Byte order | Byte ordering of sample (typically little endian, big endian) |
This class is typically used in conjunction with QAudioInput or QAudioOutput to allow you to specify the parameters of the audio stream being read or written, or with QAudioBuffer when dealing with samples in memory.
You can obtain audio formats compatible with the audio device used through functions in QAudioDeviceInfo. This class also lets you query available parameter values for a device, so that you can set the parameters yourself. See the QAudioDeviceInfo class description for details. You need to know the format of the audio streams you wish to play or record.
In the common case of interleaved linear PCM data, the codec will be "audio/pcm", and the samples for all channels will be interleaved. One sample for each channel for the same instant in time is referred to as a frame in Qt Multimedia (and other places).
成员类型
enum QAudioFormat::Endian
| Constant | Value | Description |
|---|---|---|
QAudioFormat::BigEndian | QSysInfo::BigEndian | Samples are big endian byte order |
QAudioFormat::LittleEndian | QSysInfo::LittleEndian | Samples are little endian byte order |
enum QAudioFormat::SampleType
| Constant | Value | Description |
|---|---|---|
QAudioFormat::Unknown | 0 | Not Set |
QAudioFormat::SignedInt | 1 | Samples are signed integers |
QAudioFormat::UnSignedInt | 2 | Samples are unsigned intergers |
QAudioFormat::Float | 3 | Samples are floats |
成员函数
QAudioFormat::QAudioFormat()
Construct a new audio format.
Values are initialized as follows:
- sampleRate() = -1
- channelCount() = -1
- sampleSize() = -1
- byteOrder() = QAudioFormat::Endian(QSysInfo::ByteOrder)
- sampleType() = QAudioFormat::Unknown
codec()= ""
QAudioFormat::QAudioFormat(const QAudioFormat &other)
Construct a new audio format using other.
QAudioFormat::~QAudioFormat()
Destroy this audio format.
QAudioFormat::Endian QAudioFormat::byteOrder() const
Returns the current byteOrder value.
参见 setByteOrder().
qint32 QAudioFormat::bytesForDuration(qint64 duration) const
Returns the number of bytes required for this audio format for duration microseconds.
Returns 0 if this format is not valid.
Note that some rounding may occur if duration is not an exact fraction of the sampleRate().
参见 durationForBytes().
qint32 QAudioFormat::bytesForFrames(qint32 frameCount) const
Returns the number of bytes required for frameCount frames of this format.
Returns 0 if this format is not valid.
参见 bytesForDuration().
int QAudioFormat::bytesPerFrame() const
Returns the number of bytes required to represent one frame (a sample in each channel) in this format.
Returns 0 if this format is invalid.
int QAudioFormat::channelCount() const
Returns the current channel count value.
参见 setChannelCount().
QString QAudioFormat::codec() const
Returns the current codec identifier.
参见 setCodec() and QAudioDeviceInfo::supportedCodecs().
qint64 QAudioFormat::durationForBytes(qint32 bytes) const
Returns the number of microseconds represented by bytes in this format.
Returns 0 if this format is not valid.
Note that some rounding may occur if bytes is not an exact multiple of the number of bytes per frame.
参见 bytesForDuration().
qint64 QAudioFormat::durationForFrames(qint32 frameCount) const
Return the number of microseconds represented by frameCount frames in this format.
qint32 QAudioFormat::framesForBytes(qint32 byteCount) const
Returns the number of frames represented by byteCount in this format.
Note that some rounding may occur if byteCount is not an exact multiple of the number of bytes per frame.
Each frame has one sample per channel.
参见 framesForDuration().
qint32 QAudioFormat::framesForDuration(qint64 duration) const
Returns the number of frames required to represent duration microseconds in this format.
Note that some rounding may occur if duration is not an exact fraction of the sampleRate().
bool QAudioFormat::isValid() const
Returns true if all of the parameters are valid.
int QAudioFormat::sampleRate() const
Returns the current sample rate in Hertz.
参见 setSampleRate().
int QAudioFormat::sampleSize() const
Returns the current sample size value, in bits.
参见 setSampleSize() and bytesPerFrame().
QAudioFormat::SampleType QAudioFormat::sampleType() const
Returns the current SampleType value.
参见 setSampleType().
void QAudioFormat::setByteOrder(QAudioFormat::Endian byteOrder)
Sets the byteOrder to byteOrder.
参见 byteOrder().
void QAudioFormat::setChannelCount(int channels)
Sets the channel count to channels.
参见 channelCount().
void QAudioFormat::setCodec(const QString &codec)
Sets the codec to codec.
The parameter to this function should be one of the types reported by the QAudioDeviceInfo::supportedCodecs() function for the audio device you are working with.
参见 codec() and QAudioDeviceInfo::supportedCodecs().
void QAudioFormat::setSampleRate(int samplerate)
Sets the sample rate to samplerate Hertz.
参见 sampleRate().
void QAudioFormat::setSampleSize(int sampleSize)
Sets the sample size to the sampleSize specified, in bits.
This is typically 8 or 16, but some systems may support higher sample sizes.
参见 sampleSize().
void QAudioFormat::setSampleType(QAudioFormat::SampleType sampleType)
Sets the sampleType to sampleType.
参见 sampleType().
bool QAudioFormat::operator!=(const QAudioFormat &other) const
Returns true if this QAudioFormat is not equal to the other QAudioFormat; otherwise returns false.
All elements of QAudioFormat are used for the comparison.
QAudioFormat &QAudioFormat::operator=(const QAudioFormat &other)
Assigns other to this QAudioFormat implementation.
bool QAudioFormat::operator==(const QAudioFormat &other) const
Returns true if this QAudioFormat is equal to the other QAudioFormat; otherwise returns false.
All elements of QAudioFormat are used for the comparison.