De-Multiplexing Analog Video to Digital Format

What is de multiplexing video? When multiple camera angles are recorded form a CCTV to VHS cassette tape, often times the video will be recorded in a multiplexed formatting. This multiplexed formatting is a rapidly alternated as it plays in a linear fashion from the tape. For forensic video analysis it becomes necessary to examine these camera angles in a linear fashion independently. The De-multiplexing process selects the best frame from each camera view and divides them into their own independent feeds or video clips for examination.

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De-multiplexing equipment is available to the public for purchase, but can be difficult to operate, have compatibility issues and be difficult to find. Typically the De-multiplexing equipment is old and outdated. An advantage to using De-multiplexing services is that we can generate the De-multiplexed video feeds and also create digital video files for analysis and courtroom use.

 

Digital De-Multiplexing Process

Here at Video Forensic Expert, we use DePlex Pro from Ocean Systems to digitally de-multiplex VHS cassette tapes and other types of analog footage used as video evidence. This application is expensive and sometimes difficult to operate, which is why we offer it as an advanced recovery service. In addition, if this type of investigation is going to be used in litigation or a court of law, a qualified forensics technician or forensics expert MUST perform the investigation for it to be considered accurate.

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The De-multiplexing video investigation requires a playable VHS tape with sufficient quality. If the VHS cassette tape doesn’t play back smoothly or picture quality is suffering, the investigation could be unsuccessfully. In order for the investigation to be successful the tools need to be able to identify the various camera angles accurately in order to sift through them to independent video streams. We have VHS playback decks available that have sophisticated tracking functions that will align the VHS cassette tape film against the playback head to optimize the best quality tracking and ultimately the best quality playback to capture from. Below are some examples of the difference in quality between a VHS tape that is tracked well and a VHS tape that is tracked in correctly.

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