The Times’ Malachy Browne explains:
The Times’s video unit, where I am a producer focused on visual and open data investigations, turned to a relatively new technique: investigative video reporting, or so-called video forensics, pioneered and developed by a small community of human rights groups and niche social journalism outlets over the last decade. Its greatest value is in documenting hard-to-reach places like war zones, but the tools can be used wherever there’s an abundance of visual evidence. (In May, a Times video debunked Syria and Russia’s claims about a chemical weapons attack; in June, another video identified 24 men, including members of the Turkish president’s security detail, who attacked protesters outside the Turkish ambassador’s Washington residence.)
The approach makes use of every available piece of data in a given set of video files: the videos themselves and every pixel we see in the images, but also the audio tracks and the metadata — timestamps, geolocation information — embedded in the files. The files can come from social media uploads or submissions from witnesses themselves (most cellphone videos log the hour, minute and second they were recorded in file data).
The behind-the-scenes essay explained the process:
For our video investigation on the Mandalay Bay shooting, published over the weekend, I gathered and annotated dozens of videos and audio clips recorded at various locations — inside the festival, at the hotel itself and on Las Vegas Boulevard and Giles Street, where the police responded and concertgoers fled. And I searched social platforms and downloaded clips that were verified by wire services, ending up with well over an hour of footage and two hours of police scanner and fire scanner audio.
The bursts of gunfire, 12 in all, served as scaffolding for the timeline. And by analyzing and lining up the audio waveforms of 30 videos filmed by concertgoers, the Las Vegas police and bystanders, my colleague Barbara Marcolini and I reconstructed as closely as possible the complete 10 minutes of the assault.
Traditional reporting and information-rich visuals and graphics provided additional clarity and precision. The journalists C. J. Chivers, Thomas Gibbons-Neff and David Botti — all former Marines — vetted audio of the gunfire. Mr. Botti and Jon Huang, a journalist in The Times’s graphics unit, helped me count the number of bullets. Video and graphics editors Drew Jordan, Chris Cirillo and Nicole Fineman layered visuals over raw material to explain the evidence. And throughout the investigation, Times reporters in Las Vegas — Jennifer Medina, Julie Turkewitz, Adam Goldman, Mitch Smith and others — relayed information from on the ground.
Our investigation uncovered several key pieces of information. Perhaps most crucially, we were able to approximate the very second the first bullet was fired.