Page 284 - The ROV Manual - A User Guide for Remotely Operated Vehicles 2nd edition

The standard analog tapes of old have given way to various digital storage mediums including digital videotapes (e.g., miniDV, DVCPRO, DVCAM, etc.), DVD (defined as a digital video disc, digital versatile disc, or just a DVD), and DVR (digital video recorder). The original optical disc for recording consumer video was the video CD (VCD) introduced in 1993 using the MPEG-1 (Motion Picture Experts Group) digital compression format. The follow on to the VCD was the DVD’s introduction in 1996 integrating the MPEG-2 compression format.
Today, the most widely used format for exchanging digital video is the DVR, which records digi- tal video to a hard drive, flash drive, or some other digital media capture. DVRs record and play in the current industry standard compression formats including MPEG-4, MPEG-2.mpg, MPEG-2.TS, VOB (Video Object), H.264, and ISO images video (with AC3 and MP3 used for audio track format- ting). However, the typical DVD is encoded and plays in MPEG-2 format, which is generally a digitalization of analog data with standard compression.
Videos are recorded on capture devices in various capacities/speeds based upon the desired image playback quality requirement and degree of digital capture space. The three consumer-grade recording speeds are standard play (SP), high-quality (HQ), and long play (LP) (the actual acro- nyms will vary with manufacturer). The various recording speeds allow for differing picture resolu- tions based upon the image quality preferred. The standard DVD has a 4.7 Gb capacity with the nominal video length per DVD of 2 hours; therefore, the SP will record at 2.35 Gb/h. LP records at a considerably lower data rate (,1 Gb/h), allowing for 10 1 hours of video on the same DVD; however, the quality of the video is of a much lower resolution than it is in the SP mode. The same happens with an HQ mode only in the opposite direction whereby the DVD is full after only 1 hour. A summary is as follows:
LP: “Long play” mode whereby a longer video length per unit storage capacity (e.g., 10 hours per DVD) with substantially lower video resolution (e.g., 0.6 Gb/h of data capture in this mode) SP: “Standard play” mode with typical length and quality to nominal quality (e.g., 2.35 Gb/h in this mode)
HQ: “High quality” mode whereby the image resolution is enhanced through speeding of the data rate for higher image resolution (e.g., 4.7 Gb/h in this mode).
10.5 Video compression
This section is also termed “how to get 10 pounds of stuff into a 5 pound bag” (i.e., any data that is nonrandom can be compressed).
As stated above, the introduction of the VCD corresponded to the promulgation of the MPEG-1 standard in the early 1990s. The stated purpose was to play back the audio
video combination on a standard compact disc (used extensively in the music industry at that time) with a bit rate of 1.416 Mbps (1.15 Mbps of which would be video). The mathematical compression algorithm for the process of digitizing analog video into digital format is termed a “codec” (for compression/ decompression). In the early days of codec development, chaos ensued with many organizations touting the “best codec” in attempts to win general acceptance by industry. Chaos gave way to industry standards with the formation of the Motion Picture Experts Group (MPEG). The early MPEG-1 standard allowed for proprietary compression/decompression algorithms, thus fragmenting
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