The FrameQueueSink is the preferred sink when the application's task requires processing all frames in a video stream.
The sink is created by calling FrameQueueSink::create, and requires a reference to an instance of a class derived from FrameQueueSinkListener. The listener's methods are called when an image becomes available for processing, or when the sink's state changes.
The sink internally manages two queues of FrameQueueBuffers:
When the FrameQueueSink receives an image from the device, it takes a buffer from the input queue, copies the image data into it, and places it at the end of the output queue. If the input queue is empty when the sink receives an image, the image will be dropped. Information about the number of frames copied or dropped by the sink can be queried by calling getFrameCountInfo.
To avoid frames being dropped by the sink, the application has to ensure that there are buffers available in the input queue at any time. It is therefore imperative to re-queue buffers that have been extracted from the output queue after they have been processed.
The FrameQueueSinkListener::sinkConnected method is called when the sink image format has been decided during the call to Grabber::startLive or Grabber::prepareLive. It can be used to allocate buffers in the correct format and enqueue them before the first images are received from the video capture device.
The FrameQueueSinkListener::framesQueued method is called each time after a frame has been filled with image data and copied to the output queue. If one more frame is added to the output queue during the execution of the callback, the callback is called again immediately.
When the actual streaming begins:
When Grabber::stopLive is called
Header File: tisudshl.h
Introduced in version 3.5
This function creates a number of buffers and puts them into the input queue.
Creates a new FrameQueueSink.
Fetches the FrameCountInfo from the sink.
Returns the current count of FrameQueueBuffer objects in the input queue.
Retrieves the FrameTypeInfo of the current connection.
Returns the current count of FrameQueueBuffer objects in the output queue.
Returns true when Grabber::stopLive was called. The sink is required to halt operation and return from any callbacks as soon as possible.
Returns if the sink is currently connected.
Fetches all FrameQueueBuffer instances from the input queue and returns them.
Fetches all currently available FrameQueueBuffer instances from the output queue and returns them.
Fetches a single FrameQueueBuffer from the output queue and returns it.
Frame count information from the sink.
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