GStreamer Pre-Record Element

Product Description

The pre-record is a GStreamer element that records buffers continuously into a temporal FIFO (at buffering state) and lets them pass through otherwise. Pre-record is ideal to keep track of events right before a trigger occurs, you can set pre-record to buffering until the trigger occurs and then leave buffering to start pushing the recorded buffers and the new data downstream. For example, using pre-record in a car's video capture system along with an accelerometer allows the history right before an accident to be captured. Using pre-record with motion detection allows the changing scene to be included in the video allowing the sensitivity of the motion detection to be turned down and thus avoiding false MD triggers.

Configuration

The pre-record FIFO size can be configured according to your needs (it is specified in milliseconds). When buffering pre-record doesn't pass any buffer downstream. After the FIFO is filled the oldest data is released as new data is added. When you want to start recording, you can trigger the GStreamer pre-record element, changing the buffering property. Once triggered, the element will pass the data in the FIFO downstream (to be saved to a file for example) while adding any new data to the back of the FIFO buffer so no data is lost. Eventually, the downstream elements will drain the FIFO such that the GStreamer pre-record element simply passes received buffers downstream as they are received. Once the GStreamer pipeline is taken out of the PLAY state, the GStreamer pre-record element resets and will again go into buffering mode of operation.

Platforms Supported