Few things are more frustrating than a great dive with a pro-sumer camera. HDV is simply inadequate due to Inter-frame or I-Frame MPEG recording. And that’s only the beginning. Low-to-no color sampling [4:2:0 vs. 4:2:2], minuscule data rate (25Mbs vs. 100 Mbs), and use of mini-DV tape vs. tapeless workflow add to the nightmare, but most importantly HDV does not meet broadcast standards. HDV I-Frame compression compares groups of frames to determine the compression algorithm. [see below] That’s fine for a ‘talking head’ interview where very little changes frame-to-frame, but ask yourself the logical question. Is any frame of underwater video similar to the one prior? Much less the last 15-frames? Of course not, and so the results are substandard at best. DVCPRO is a professional broadcast format. Most importantly each frame is compressed separately. HDV is doomed to consumer cameras. As broadcast standards get more demanding HDV will be kicked to the curb, left at the dock.
Want to shoot Pro High Definition? - Buy our rugged, balanced, high quality AquaVideo Marine Case for the Panasonic HVX-200 P2 camcorder. This is the first system to provide true production level, 24p 4:2:2 recording in a compact and affordable underwater package. Rated to depths of 50 meters/165 feet, it is easy to set up and easy to use. Did I mention quality??? See our HD PodCast or our store main page hd2o.tv or the clips below in this FLOG. [caption id="attachment_907" align="alignright" width="288" caption="DVCPRO-HD ~ u/w housing for HVX-200 "]
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Buy Our Rig: includes the housing and light kit; ships in a secure plastic bin. $3000.00 studio@hd2o.tv
Optics are designed to provide an extreme wide angle view – for dramatically clearer, more colorful underwater pictures. (The lens I use - Century .75x bayonet specifically for the HVX200 - MSRP $1195) Glass dome port optical system (not acrylic) is optically neutral; corrects for distortions and aberrations and allows true lens-magnified macro and zoom-through without having to change lenses or optical setup. Stainless steel closure clamps, five front and five back, are quick and secure the 1″ acrylic end-plates with spring-loaded locking latches to prevent accidental opening. X-ring seals are highly reliable.
Controls to all major camera functions are on this rig to include; power, record trigger, zoom, focus, iris, mode, user 1, 2, 3, white balance, A/B presets, etc. About 48 lbs dry, this rig is small, self contained, rugged, and extremely agile in the soup. 10.75” diameter allows the camera?s LCD to be open and viewed through the clear backplate without glare. Velcro secures the battery pack for the SuperNova 250w 3400K HID light-kit. We use a 100GB FireStore FS-100 which also fits below the camera mounting plate, or use P2 cards.
Ships in a plastic bin; 16″x18″x24″.
HVX200 Camera, Century .75 lens mount, FireStore FS-100 are NOT included. studio@hd2o.tv
Intra- vs. Inter-frame compression facts :
[Wikipedia] Most compression systems used for acquisition in the digital cinematography world compress footage one frame at a time, as if a video stream is a series of still images. This is called intra-frame compression. Inter frame compression systems can further compress data by examining and eliminating redundancy between frames. This leads to higher compression ratios, but displaying a single frame will usually require the playback system to decompress a number of frames from before & after it. In normal playback this is not a problem, as each successive frame is played in order, so the preceding frames have already been decompressed. In editing, however, it is common to jump around to specific frames and to play footage backwards or at different speeds. Because of the need to decompress extra frames in these situations, inter-frame compression can cause performance problems for editing systems. Inter-frame compression is also disadvantageous because the loss of a single frame (say, due to a flaw writing data to a tape) will typically ruin all the frames until the next keyframe occurs. In the case of the HDV format, for instance, this may result in as many as 6 frames being lost with 720p recording, or 15 with 1080i recording [3]. An inter-frame compressed video stream consists of groups of pictures (GOPs), each of which has only one full frame, and a handful of other frames referring to this frame. If the full frame, called I-frame, is lost due to transmission or media error, none of the P-frames of B-frames (the referenced images) can be displayed. In this case, the whole GOP is lost.
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