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5. Videotape, Video Media, and Video Recorders. Objectives. Illustrate the process of cleaning video heads. Identify professional quality videotape formats, as well as other video media types available. Summarize the function of the control track in regulating the playback speed of videotape.
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5 Videotape, Video Media, and Video Recorders
Objectives • Illustrate the process of cleaning video heads. • Identify professional quality videotape formats, as well as other video media types available. • Summarize the function of the control track in regulating the playback speed of videotape. • Recall the purpose of and process for performing a test record. • Explain the role of an RF converter in a television’s use of audio and video signals.
Videotape and Recorder Classification • Video recorder = Deck • Format • Width of tape • Method of placing signal on tape
Recording Medium • Is currently progressing from many formats of tape to various tapeless media • Hard drives • Miniature DVDs • Full-sized DVDs • Flash drives • Even newer technology
Tapeless Advantages • Instant access to any point in recording • No loss of quality when copying • Importing or exporting video to and from computer takes mere seconds
Videotape Construction • Plastic base • Adhesive • Oxide powder • Only place to vary manufacturer cost is to vary quality of adhesive
Videotape Construction (Cont.) • Do not save pennies with cheap tape–it only buys expensive headaches later • When oxide falls off tape, empty spot causes dropout on screen • Discard tape when dropouts start appearing
Video Heads • Found on head drum inside video recorder • At least two heads on all VCRs • Head drum is tilted to record signal in helical scan,also called slant track
Dirty Video Heads • Symptom of dirty heads is many white spots on screen • Consumer calls white spots snow • Professional calls white spots video noise • When given option, always use professional terms–not consumer terms
Causes of Dirty Video Heads • Smoking near VCR • Using poor quality videotape • Pets resting on top of VCR • Fingerprints on videotape • Videotape at end of its useful life
Cleaning Dirty Heads on VHS and S-VHS Decks • Use foam or chamois-tipped swabs dipped in head cleaning solution, denatured alcohol, or wood alcohol • DO NOT USE ISOPROPYL OR RUBBING ALCOHOL! It will leave an oily residue • Do NOT use commercial head cleaning cassettes
Cleaning Dirty Heads on VHS and S-VHS Decks (Cont) • Procedure: • Unplug VCR from power and remove cover from deck • Gently press on top of drum assembly to keep it from spinning • Gently rub swab from side to side on each video head • Replace cover and test VCR
Cleaning Dirty Heads on Digital Video Decks • Artifacts appear when heads are dirty • Use professional name-brand head cleaning cassettes • Follow instructions on head cleaning cassette carefully, otherwise you can damage heads permanently • Do not attempt to clean heads manually
Upward Compatibility • Many tapes are upwardly compatible • Ability of lower-end tapes to play in upper-end decks but upper-end tapes will not play in lower-end decks
Videotape Widths on Reels and Cassettes • 2” tape used on quadruplex (quad), recorders • 1” tape • ½” tape • 6mm
Analog Videotape Formats • VHS • VHS-C • Super VHS (S-VHS),also called Y/C • Betacam • Betacam SP
Digital Videotape Formats • Digital Betacam (Digi-Beta) • Beta SX • Mini-DV • DVCPRO • DVCPRO50 • DVCPRO100 • DVCam • Digital S
Other Digital Recording Media • DVD • P2 • Hard drives • Solid-state memory
VTR Interchange • All VHS tapes can be played on all VHS decks as long as recording system is identical • This makes mass dubbing cost-effective
Control Track • Causes VHS decks to know which speed to run in playback mode • SP • LP • EP • When automatic control track is insufficient, tracking lines appear on screen and operator must use tracking controlto fix
Digital Video Recorder • Does not require videotape • Can record standard video as well as hi-def • Records on: • Hard drives • Solid-state memory • Rapidly becoming professional studio recorder of choice
Inputs and Outputs • Connectors on decks for cables to attach • Input sends signal into deck from a source • Output takes signal out of deck to elsewhere
Before Recording Begins • Label recording medium with identifying info: • Title of program • Director • Scenes to be recorded • Date
Test Record • Record at least one minute • Rewind and playback • Check audio level and quality • Check video level and quality • Adjust as necessary and redo test record until it is satisfactory
Heads and Tails • Always shoot head, which includes countdown and slate • 15 seconds • Always shoot tail for at least 10 seconds
Audio Level on Video Recorder • Analog: keep between –3 dB to +3 dB • Digital: Keep near –20 dB
Radio Frequency • Video recorders create pure video and audio • Many televisions must receive signal on a “channel” • Channel = radio frequency (RF) • Many VCRs have built-in RF converterto do this task
Television Types • Receiver • Monitor • Monitor/receiver • Most modern consumer digital television sets are equipped with multiple inputs making them monitor/receivers
Career Page • The Society of Broadcast Engineers • Helps keep all types of broadcast engineers at top level of their knowledge and skills • http://www.sbe.org/
Review Question What are possible causes of white spots appearing on screen when playing back VHS tape? Smoking near machine; poor quality tape; old tape; pet resting on top of warm machine leaving dander and hair; fingerprints
Review Question How do you get rid of video noise? Clean video heads
Review Question You have determined video heads are dirty. How would you go about cleaning them? Unplug VCR, remove cover Gently press on top of drum assembly Using tipped swabs dipped in head cleaning solution–not rubbing alcohol Gently rub swab from side to side on each video head Replace cover and test VCR
Review Question List technological advancements developed since the days of VHS and Betacam. Hard drive; miniature DVDs; full-sized DVDs; flash drives; etc.
Review Question What allows VHS machines to know at what speed to play back tapes? Control track
Review Question Describe the process of performing a test recording. Record at least one minute Rewind and play back Check audio/video level and quality Adjust as necessary and redo test record until it is satisfactory
Review Question What do video recorders use to receive audio and visual “channels” from televisions? Radio frequency, or RF, converters
Review Question What are artifacts? Tiny rectangular distortions that appear on the screen when viewing digital tape that has a corrupted signal
Glossary • 1 tape: A reel format videotape available in three formats: Type A, Type B, and Type C. Type C was the most common format. • 1/2 tape: A reel format videotape found only in low-end, industrial equipment. • 2 tape: A reel format videotape used on older machines called quadruplex recorders.
Glossary • artifacts: Tiny, rectangular distortions that appear on the screen in digital video formats when a portion of the digital signal is corrupted. • Betacam: A 1/2 format, broadcast-quality videotape. • Betacam SP: A 1/2 videotape format that used to be the best format for professional television use, but digital video formats are challenging this format in professional markets.
Glossary • Beta SX: A 1/2 videotape that uses digital MPEG compression. • control track: A series of inaudible pulses recorded onto a tape that regulates the speed of the tape in playback. • deck: The common term used for a video recorder/player.
Glossary • Digital Betacam (Digi-Beta): A 1/2 videotape with higher quality than Betacam SP and the capability of recording of digital signals instead of analog signals. • Digital S: A 1/2 digital videotape format that is broadcast quality. Also known as D-9.
Glossary • digital video recorder (DVR): A device that records a digital signal directly onto either a hard drive or a solid-state memory module inside or connected to the DVR unit. • dropout: A tiny white dot seen on the television screen when the medium has fallen off an analog videotape and the video head passes over an “empty spot” on the tape.
Glossary • dubbing: The process of copying a video recording. • DVCam: A 6mm digital format that is proprietary to Sony Corporation. • DVCPRO: A 6mm, metal particle tape used as a professional digital video format. • DVCPRO50: A 6mm digital format with even higher quality than DVCPRO.
Glossary • DVCPRO100: The high definition format of DVCPRO tape. • DVD (Digital Video Disc): An optical disc that can store a very large amount of digital video data, as well as text and/or music. • head: A 15 second “lead-in” recorded at the beginning of every take.
Glossary • helical scan: The pattern in which a video signal is placed onto a videotape. The videotape is wrapped around the video head and, because the head is slanted, the video signal is recorded diagonally on the tape. Also called slant track. • input: A port or connection on a video device through which a signal enters the device, such as the “audio in” port.
Glossary • mini-DV: A metal evaporated tape, 6mm digital video format used by many industrial video producers. • monitor: A television set that can receive only pure video and audio signals. • monitor/receiver: A hybrid television that can receive pure video and audio signals, as well as RF signals.
Glossary • output: A port or connection on a video device through which the signal leaves the deck and travels to another piece of equipment, such as the “video out”. • P2: A static memory card that is proprietary to Panasonic and used in certain high-end cameras.