The Backend Class

Required Functions

• bool supportsOSD()
• bool supportsFourcc( quint32 )
• bool supportsSubtitles()
• bool supportsVideo()
• QStringList availableMimeTypes()

Function Documentation

bool supportsFourcc( quint32 fourcc )

Tells whether the FOURCC (four character code) is supported for the VideoDataOutput interface. If you return true, you have to be able to return VideoFrame objects accordingly from VideoDataOutput.

Parameters

fourcc

A four character code defining a video frame format.

Returns

true if your VideoDataOutput can output video frames in the requested format.

false if the video frames can not be converted into the requested format.

QStringList availableMimeTypes()

Lists the MIME types the backend can read and decode.

QSet<int> <device/codec/effect/...>Indexes()

Returns a set of indexes that identify the devices/codecs/effects/... the backend supports. This list needs to be compiled from looking at available hardware and virtual devices/plugins/... . The implementation should use cached information, but you need to invalidate the cache whenever the hardware configuration changes or new virtual devices come available/new plugins are installed/... .

Returns

The indexes of the available devices/codecs/effects/...

See also

QString <device/codec/effect/...>Name( int index )

QString <device/codec/effect/...>Description( int index )

QString <device/codec/effect/...>Name( int index )

Returns the name of the given device/codec/effect/...

Parameters

index

The index of one device/codec/effect/... this is one index out of QSet<int> <device/codec/effect/...>Indexes()

Returns

A translated user visible string to name the device.

See also

QSet<int> <device/codec/effect/...>Indexes()

QString <device/codec/effect/...>Description( int index )

QString <device/codec/effect/...>Description( int index )

Returns the description of the given device/codec/effect/...

Parameters

index

The index of one device/codec/effect/... this is one index out of QSet<int> <device/codec/effect/...>Indexes()

Returns

A translated user visible string to describe the device.

See also

QSet<int> <device/codec/effect/...>Indexes()

QString <device/codec/effect/...>Name( int index )

qint32 audioCaptureDeviceVideoIndex( int index )

Parameters

index

The index of the device. This is one of the indexes the backend returned via QSet<int> <device/codec/effect/...>Indexes()

Returns

An index of a video capture device that is associated with the given audio capture device. For example a webcam might have both a video and an audio capture device, and in order give the user a hint that the audio and video capture devices belong together this index is used.

If there is no associated video capture device return -1.

qint32 videoCaptureDeviceAudioIndex( int index )

Parameters

index

The index of the device. This is one of the indexes the backend returned via QSet<int> <device/codec/effect/...>Indexes()

Returns

An index of a audio capture device that is associated with the given video capture device. For example a webcam might have both a audio and an video capture device, and in order give the user a hint that the video and audio capture devices belong together this index is used.

If there is no associated audio capture device return -1.