AVDevToAppMessageType

Message types used by avdevice_dev_to_app_control_message().

Values

ValueMeaning
AV_DEV_TO_APP_NONEMKBETAG('N', 'O', 'N', 'E')

Dummy message.

AV_DEV_TO_APP_CREATE_WINDOW_BUFFERMKBETAG('B', 'C', 'R', 'E')

Create window buffer message.

Device requests to create a window buffer. Exact meaning is device- and application-dependent. Message is sent before rendering first frame and all one-shot initializations should be done here. Application is allowed to ignore preferred window buffer size.

@note: Application is obligated to inform about window buffer size with AV_APP_TO_DEV_WINDOW_SIZE message.

data: AVDeviceRect: preferred size of the window buffer. NULL: no preferred size of the window buffer.

AV_DEV_TO_APP_PREPARE_WINDOW_BUFFERMKBETAG('B', 'P', 'R', 'E')

Prepare window buffer message.

Device requests to prepare a window buffer for rendering. Exact meaning is device- and application-dependent. Message is sent before rendering of each frame.

data: NULL.

AV_DEV_TO_APP_DISPLAY_WINDOW_BUFFERMKBETAG('B', 'D', 'I', 'S')

Display window buffer message.

Device requests to display a window buffer. Message is sent when new frame is ready to be displayed. Usually buffers need to be swapped in handler of this message.

data: NULL.

AV_DEV_TO_APP_DESTROY_WINDOW_BUFFERMKBETAG('B', 'D', 'E', 'S')

Destroy window buffer message.

Device requests to destroy a window buffer. Message is sent when device is about to be destroyed and window buffer is not required anymore.

data: NULL.

AV_DEV_TO_APP_BUFFER_OVERFLOWMKBETAG('B', 'O', 'F', 'L')

Buffer fullness status messages.

Device signals buffer overflow/underflow.

data: NULL.

AV_DEV_TO_APP_BUFFER_UNDERFLOWMKBETAG('B', 'U', 'F', 'L')
AV_DEV_TO_APP_BUFFER_READABLEMKBETAG('B', 'R', 'D', ' ')

Buffer readable/writable.

Device informs that buffer is readable/writable. When possible, device informs how many bytes can be read/write.

@warning Device may not inform when number of bytes than can be read/write changes.

data: int64_t: amount of bytes available to read/write. NULL: amount of bytes available to read/write is not known.

AV_DEV_TO_APP_BUFFER_WRITABLEMKBETAG('B', 'W', 'R', ' ')
AV_DEV_TO_APP_MUTE_STATE_CHANGEDMKBETAG('C', 'M', 'U', 'T')

Mute state change message.

Device informs that mute state has changed.

data: int: 0 for not muted state, non-zero for muted state.

AV_DEV_TO_APP_VOLUME_LEVEL_CHANGEDMKBETAG('C', 'V', 'O', 'L')

Volume level change message.

Device informs that volume level has changed.

data: double: new volume with range of 0.0 - 1.0.

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