The National Transportation Safety Board has completed its initial review of a digital video recorder system recovered from the duck boat that capsized on a lake in Missouri earlier this month, killing 17 people. In a statement issued on Friday, the NTSB said: "Recording media including an SD card and a removable hard drive from the vehicle's digital video recorder camera system were recovered by divers before the duck boat was salvaged."The device captured feeds of video and audio from five angles, according to the NTSB. Four cameras were outward-facing and one was pointed inward. The agency noted the sound quality throughout the recording "varies widely," making it difficult to understand exactly what people are saying sometimes.Once retrieved, the contents were sent to a lab in Washington, D.C., but the NTSB stressed it has not validated the recordings against local time and cannot yet offer an analysis of the information. "As such, no conclusions regarding the cause of the accident should be made from this preliminary information," the statement said. The Ride The Ducks Branson boat was overturned by rough waves as a violent storm passed over Table Rock Lake on July 19. Seventeen of the 31 passengers and crew members aboard the vessel died. The preliminary report indicates the boat's captain conducted a safety briefing that included "the location of emergency exits as well as the location of the life jackets" at 18:50 — approximately 10 minutes before "whitecaps rapidly appeared on the water and winds increased."Three minutes later the captain made an call over a handheld radio, unintelligible on the recording. Within seconds, a bilge alarm went off and the captain appeared to shut it off. The captain then made a second unintelligible call over a handheld radio. In the final minutes of the recording, "Water occasionally splashes inside the vehicle's passenger compartment," according to the report. The video cuts out at 19:08:27 — just over 35 minutes after the duck boat left the terminal facility. At the time it was still on the surface of the water. NTSB officials said investigators plan to begin verifying the collected data "and developing a detailed transcript of the sequence of events." Here is a linkto the full timeline of the video. Copyright 2018 NPR. To see more, visit http://www.npr.org/.