Single-Frame Data Capture

Single-frame data capture supports simple video capture. Applications might use this form of data capture to record animated sequences created frame-by-frame or, to capture a single still image, such as a photograph.

This data transfer model typically involves a high data-transfer rate. It is similar to streaming data, except it does not require the continuous transfer of data. The following sequence of operations occurs when a client application requests the transfer of a single video frame:

1. The client allocates the memory for the data buffer.
2. The client sets a pointer to the empty data buffer in a data structure and sends the device driver a pointer to it.
3. When the device driver receives the messages to capture data, it fills the data buffer with information from the frame buffer and updates the data structure.
4. When the device driver has filled a data buffer, it returns control to the client.
5. After the client has finished with the data, it frees the memory used for the data.