playback image only on fast forward
Dave
vacation, I shot about 5 (2 hour capacity) tapes. All turned out great,
except one - during playback the display window shows a blue screen unless
the tape is fast-forwarded - then the picture is viewable and very clear
(considering it is being fast forwarded).
When I called Sony, they suggested it was a bad tape, and other folks have
told me I must have changed the record speed - however, I do not see any
setting that allows changing record speed, and the tape was a new Sony HI-8
I bought just for the trip.
Any ideas? Thanks
Steve McDonald
Since your other tapes play back without trouble and the
fast-forward mode reveals that there is a recorded image on the problem
tape, I speculate that the tape-tracking may have been off its precise
position when it was recorded. The tape may have been threaded into an
improper alignment and stayed there while you were shooting. Try
rolling the tape to points throughout its 2-hour length and see if this
persists on the entire tape.
Steve McDonald
DaveC
were taking that video. So you probably only have one of the two
fields recorded. I don't know if there is any NLE that will allow
you to seperate one field from the other. Premiere might but I
haven't used it enough to know about these obscure features, if they
are there? A pro duplicating house may be able to salvage something
out of that tape but it wouldn't be cheap.
Dave
"Dave" <zeon1223@no_spamhotmail.com> wrote in message news:<_tGcnctNH5p...@comcast.com>...
Steve McDonald
There's only one video recording head for Hi-8. Digital8 and DV
are formats with two recording heads, positioned 180 degrees apart on
the rotary assembly.
Steve McDonald
DavesVideo
are formats with two recording heads, positioned 180 degrees apart on
the rotary assembly.>>
I didn't know that and now my explanation for a bad tape of mine doesn't
work any more. I shot a Hi-8 tape and the image was 90% pure static when played
on my Digital8. I was able to salvage it, because one field had only occasional
static. Any clues as to what could of happened here?
DaveC
My Hi8 VCR has 2 rotating heads. My Sony Hi8 camcorder has 4
rotating heads. I believe the the 4 heads in a camcorder function as
2 heads but 4 are needed because the head drum in the camcorder is
only half the normal size of the head drum in the VCR. I don't see
how any camcorder or VCR can function with only 1 rotating video head?
Dave
bigroc...@webtv.net (Steve McDonald) wrote in message news:<1598-3E...@storefull-2113.public.lawson.webtv.net>...
Mike Rehmus
recorded properly and/or the heads are very dirty (the usual cause unless
something has broken)
"Steve McDonald" <bigroc...@webtv.net> wrote in message
news:303-3E15...@storefull-2118.public.lawson.webtv.net...
Steve McDonald
I should have also mentioned that the head drums on 8mm, Hi-8 and
Digital8 camcorders are the same size as are those of the VCRs for those
formats. Some earlier VHS-C camcorders had small head drums and
required two tracking sweeps for each frame.
But, this caused a separation line to appear in the picture when the
tape was played with an adapter on a VCR with a full-size head drum.
So, most of the later VHS-C camcorders were made with full size head
drums.
Steve McDonald
Steve McDonald
I said a Hi-8 recorder has only one recording head. It has other
heads for other purposes. There's 1,800 frames (approx.) per minute
with 1 tracking sweep per frame and the Hi-8 head rpm is therefore
1,800. Digital8 has 5 tracking sweeps per frame, but with 2 recording
heads has to increase the rpm only 2 1/2 times to 4.500. DV uses 10
sweeps per frame and 2 recording heads going at 9,000 rpm.
Steve McDonald
Watty
"DaveC" <dcasp...@email.com> wrote in message
news:79abf7f5.03010...@posting.google.com...
> Sorry Steve, but either you or Sony is wrong. I think Sony is right.
> My Hi8 VCR has 2 rotating heads. My Sony Hi8 camcorder has 4
> rotating heads. I believe the the 4 heads in a camcorder function as
> 2 heads but 4 are needed because the head drum in the camcorder is
> only half the normal size of the head drum in the VCR. I don't see
> how any camcorder or VCR can function with only 1 rotating video head?
>
all the way around the drum.).
Since *ALL* helical VCRs only wrap around part of the drum (usually
half), more than one head is *ALWAYS* needed.
Even fancy VHS decks with 6 heads only use two for Video during normal
playback (Others may be used as "flying" erase for edit or for helical
Audio tracks laid between the video, or for better puase or extended
recording).
Old Analog Tranverse head drum recording usually has 2" tape and at
least 4 heads in use normally.
Since 1976 when I started repair & service of Reel to Reel Video I have
never seen a single head VCR.
--
Watty is EI9FEB
There are more stupid answers than stupid questions. ;-)
Reverse copy and type to send me email (Plain text only)
newsg...@typecopy.net
DaveC
and camcorders work. My Sony EV-S900 Hi8 VCR manual says it's Video
recording system has a rotary two-head helical scanning system. It
is my understanding that the heads in the Hi8 system record both audio
and video from the same head. One head is used for one field and the
other head is used for the second field of the NTSC interlaced field
system. So there are 2 heads mounted on the head drum, 180 degrees
from each other. Each head is used 50% of the time. During it's
50% duty cycle, that head is recording everything there is to record
on the the tape (video, audio, housekeep information). There are no
heads used for other purposes in the Hi8 system. If you can point me
to any official information to the contrary I would be happy to
consider it.
Dave
bigroc...@webtv.net (Steve McDonald) wrote in message news:<23549-3E1...@storefull-2114.public.lawson.webtv.net>...
Steve McDonald
Your understanding has mixed several characteristics of different
recording systems into one mythical format. In 8mm and Hi-8 recording,
the Hi-Fi audio track is laid down by a separate audio head, positioned
just before the video head. The audio track is lower frequency and goes
deeper into the recording layer than the video signal. There is no
audio track between the video tracks. On VHS and Beta recorders, a
linear audio head lays down a monaural track (non-helical) on the edge
of the tape. On non-stereo VHS and Beta VCRs, this is the only audio
track. 8mm and Hi-8 do not have this linear audio track. Even monaural
8mm audio is Hi-Fi and is laid under the video signal. Hi-Fi stereo VHS
and Beta use this same audio-under-video recording system for the stereo
signal. 8mm and Hi-8 recorders do not have video heads that are 180
degrees apart on the drum-----that feature is found on Digital8 and DV
recorders. Please study the specifications and mechanics of these
formats
before trying to continue this pointless thread.
Steve McDonald
Steve McDonald
I must retract one main point I made previously, about only one
recording head on an 8mm/Hi-8 VTR (Video 8) and also about one minor
element of my description. Other posters had some incomplete or
partially incorrect information on this thread about this complex
subject, but I made the most outstanding errors. The webpage in the link
below contains information that explains the correct details. Scroll
way down to get to the part that discusses Video 8, specifically. I
studied this page thoroughly and learned quite a bit. Many other
formats are also explained.
There actually is what is technically a pair of longitudinal or
linear audio-type tracks on Video 8 recordings, but they are used for
operational data and not audio. There is no separate control track for
Video 8, as four pulse tones within the helically-recorded signal
provide tracking control information. Hi-Fi audio is laid down by the
two helical recording heads in the multiplex of frequencies that include
video luminence and chrominence segments.
An interesting feature is the way PCM digital audio is recorded or
later dubbed on the tape. In PCM-capable Video 8 VTRs, the degrees of
tape-wrap around the head drum is increased from the standard 180, to
221. The PCM recording is then laid down as an extension of the ends of
the standard helical tracks, in an area where it can be later erased and
re-recorded (dubbed) without erasing or interfering with the video or
analog audio recording. If a Video 8 tape that has PCM audio recorded
on it is played on a VTR that has analog audio only, its playback heads
never contact the digital audio track extensions and ignore them.
http://www.rcc.ryerson.ca/rta/tvtech/the_book/chapter12/main.html
This next link is for a page that has more specific details about
DV recording.
http://www.video.com.mx/articulos/DigitalVideoRecordingandDataFormats.htm
Steve McDonald