Basic Photography Course

Figure 13-6.Basic videotape track system.

Most videotape recorders put at least four separate

tracks on the tape: the video track that contains the
picture information, two audio tracks that contain all

sound information, and a control track that controls the
videotape and rotation speed of the video heads
(fig. 13-6).

VIDEO TRACK.

-When video signals are

recorded in the normal NTSC composite configuration,
one pass of the head records a complete field of video
information (Y+C). The next pass of the head, (or, if you
have a two-head machine, the second head) lays down
the second field right next to it, completing a single

video frame. Two fields make up a single frame. The
two heads must "`write" sixty tracks (thirty frames) for
each second of NTSC video. In the four-head VTR, one
pair of heads records at normal tape speed and the other
pair records at a slower speed.

AUDIO TRACK.

-The audio tracks record the

audio signal. They are usually recorded by fixed
recording heads that are near the edge of the tape and
run along the length of the videotape. Because of the
demand for stereo audio and for keeping certain sounds

separate even in monophonic sound, all VTR systems

provide at least two audio tracks.

CONTROL TRACK.

-The control track contains

evenly spaced blips or spikes, called the sync pulse, that
mark each complete television frame. These pulses
synchronize the tape speed and the rotation speed of the
recording heads. This allows the tape to be played on a
similar machine without picture breakups. Because the
control track marks each frame of recorded video, it also
aids in videotape editing.

Hi8 Track System

Because space is so limited in 8mm videotape, these

systems squeeze the automatically generated time code
and other data between the video and audio portion of a
single-slanted track The time code has been developed
to provide a precise editing reference by recording the

exact frame address onto the tape. The 8mm time code
is digitally recorded by units of hour, minute, second,

and frame by the video heads. The 8mm time code is

used only for 8mm format and is not compatible with
other recording formats.

The Hi8 VTR splits each slanted track into audio

frequency modulation (AFM) and video information. It
also uses a pulse code modulation (PCM) audio track

The audio technology used in an Hi8 VTR is superior to
video home system (VHS). The video/AFM audio track

and the PCM audio track are separated by the time-code

data (fig. 13-7).

VIDEO MONITOR

For viewing purposes, you must playback the

recording either to the transmitter or directly to a
receiver (TV set or monitor). At the receiver, the video
and audio signals are separated and processed by
separate circuitry. This circuitry changes the video and
audio signals back to sound that you can hear and
pictures that you can see. The sound is reproduced at the
loudspeaker, and the picture is reproduced on the face
of the cathode-ray picture tube.

A primary part of the monitor system is the

cathode-ray tube. A type of cathode-ray tube is used in

Figure 13-7.Hi8 VTR tracks.

13-8

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DOFMaster for Windows On-line Depth of Field Calculator DOFMaster for Mobile Devices On-line Depth of Field Table Hyperfocal Distance Chart Articles FAQ Recommended Books Support Contact Links Home As an Amazon Associate I earn from qualifying purchases.	contents <- previous page next page -> Figure 13-6.Basic videotape track system. Most videotape recorders put at least four separate tracks on the tape: the video track that contains the picture information, two audio tracks that contain all sound information, and a control track that controls the videotape and rotation speed of the video heads (fig. 13-6). VIDEO TRACK. -When video signals are recorded in the normal NTSC composite configuration, one pass of the head records a complete field of video information (Y+C). The next pass of the head, (or, if you have a two-head machine, the second head) lays down the second field right next to it, completing a single video frame. Two fields make up a single frame. The two heads must "`write" sixty tracks (thirty frames) for each second of NTSC video. In the four-head VTR, one pair of heads records at normal tape speed and the other pair records at a slower speed. AUDIO TRACK. -The audio tracks record the audio signal. They are usually recorded by fixed recording heads that are near the edge of the tape and run along the length of the videotape. Because of the demand for stereo audio and for keeping certain sounds separate even in monophonic sound, all VTR systems provide at least two audio tracks. CONTROL TRACK. -The control track contains evenly spaced blips or spikes, called the sync pulse, that mark each complete television frame. These pulses synchronize the tape speed and the rotation speed of the recording heads. This allows the tape to be played on a similar machine without picture breakups. Because the control track marks each frame of recorded video, it also aids in videotape editing. Hi8 Track System Because space is so limited in 8mm videotape, these systems squeeze the automatically generated time code and other data between the video and audio portion of a single-slanted track The time code has been developed to provide a precise editing reference by recording the exact frame address onto the tape. The 8mm time code is digitally recorded by units of hour, minute, second, and frame by the video heads. The 8mm time code is used only for 8mm format and is not compatible with other recording formats. The Hi8 VTR splits each slanted track into audio frequency modulation (AFM) and video information. It also uses a pulse code modulation (PCM) audio track The audio technology used in an Hi8 VTR is superior to video home system (VHS). The video/AFM audio track and the PCM audio track are separated by the time-code data (fig. 13-7). VIDEO MONITOR For viewing purposes, you must playback the recording either to the transmitter or directly to a receiver (TV set or monitor). At the receiver, the video and audio signals are separated and processed by separate circuitry. This circuitry changes the video and audio signals back to sound that you can hear and pictures that you can see. The sound is reproduced at the loudspeaker, and the picture is reproduced on the face of the cathode-ray picture tube. A primary part of the monitor system is the cathode-ray tube. A type of cathode-ray tube is used in Figure 13-7.Hi8 VTR tracks. 13-8 contents Basic Photography Course <- previous page next page ->	As an Amazon Associate I earn from qualifying purchases.
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