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Why DVD-Video is the Correct Media for Police Video
Playback Compatibility is Essential
The ultimate end of a police in-car video system is the presentation of the video evidence in a courtroom. It is also important to be able to provide copies of the video to the attorneys or even the media. Since the final "consumer" of the video evidence is beyond the police department, wide playback compatibility is essential. The broader consumer market dictates the technologies available for video playback. The only two widely used digital video playback devices are DVD players and personal computers.
Personal Computers for Playback
Personal computers with a Media Player program can play various types of standard video files, but standard video file formats are not well suited for displaying the important metadata information (time, date, officers, triggers, speeds, status of lights, siren, etc.) included in police video. In order to see both the video and the metadata, a proprietary playback program is generally required.
Since video without metadata would not be acceptable as evidence, the courts may need the police department to provide the equipment necessary to fully display this type of evidence. That means the police department will likely need to bring in a computer with the proprietary playback program installed. That computer will also need a projector to display the imagery in court. The police department may need to either bring a projector, or if the courtroom has a projector installed, setup the police computer to work with the courts projector.
Presenting digital police video in court using a personal computer can be a cumbersome and costly proposition. The requirement for metadata also complicates the process of giving copies of the video to the District Attorney's office, defense attorneys, and for public broadcast. If the defense requests a copy of the video, the video may need to be converted into another format, or the defense will need to install a copy of a proprietary playback program.
These requirements may sound feasible, but in practice are very labor and resource intensive, adding cost and potential delays with every court case.
DVD Players for Playback
DVD-Video is the undisputed standard format for digital video. With a DVD-Video disc, the only requirement for playback becomes a $39 DVD player and a standard television that is already in every courtroom. DVD-Video discs support metadata saved in the closed captioning or subtitle layers so this information can be displayed on the television. This text can also be toggled on or off during playback, ensuring that textual information never permanently obscures the video image.
It is also very simple and fast to burn a duplicate copy of the DVD for attorneys, and no special hardware or playback software is required to view the video and the metadata.
DVD-Video is Far Superior to Simple MPEG Files
Nearly all DVD-RAM and server-based in-car video systems record video as rudimentary MPEG files. The DVD-Video file format is based on MPEG-2 video compression but it is "authored" into a more complex file structure than a simple MPEG file. All regular DVD players require DVDs that have been authored in the DVD-Video file format. A DVD-Video disc contains disc navigation information, FF and REW pointers, closed captioning layers, linked yet separate audio tracks, and redundant menu sections. It takes much more sophistication and processing power to author DVD-Video than merely creating MPEG files. This added complexity in the format improves the robustness of the data and removes some processing burden from the playback device. This is why a $39 DVD player is even possible. To play a more rudimentary MPEG file (even if the files are on a DVD-Data disc) a full computer will be required for playback.
| DVD-Video puts the "intelligence" on the disc so the playback device (a DVD player) can be relatively "dumb" and inexpensive. |
To make a playable DVD from basic MPEG files, the video will need to be "authored" with a computer running a DVD-Video authoring program which will fundamentally change the data. The authoring process generally requires the video to be fully decoded and then re-encoded (compressed) again into the DVD-Video format with newly created navigation data inserted. This process generally takes more than twice as long as the length of video being copied. It also means it is no longer the original data.
| Converting simple MPEG video into DVD-Video means the submitted evidence is a manipulated copy of a copy, which could easily be deemed inadmissible in court. |
If at the end of the day it will be required to have a playable DVD as the shared or submitted evidence, then recording and authoring directly to a DVD-Video disc in the car is the obvious and efficient solution.
Starting with DVD-Video Makes Sharing Copies Easy
When your original recording has already been fully authored into the DVD-Video format, it makes the copying process far simpler and dramatically faster. WatchGuard Video provides a program for making copies of entire DVDs or DVDs that contain only specific chapters of interest. This single chapter duplication process does not change the data structure and it can be copied at the maximum speed of the DVD burner. With an 8X DVD drive, a half-hour long traffic stop could be copied in about 2 minutes.
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DVD-Video to DVD-Video |
Un-Authored MPEG to DVD-Video |
Time to Copy
1 Video Hour |
5 Minutes (Files are copied at the maximum speed of the DVD burner) |
Approximately 2- 3 Hours (Requires complete DVD-Video authoring by a PC) |
Recording directly to a DVD-Video disc in the vehicle is the fastest, most efficient and cost effective process for creating, managing, and presenting digital video evidence.
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