d@alice.UucP (Dan Rosenberg) (03/07/86)
> I have a slight video problem that I need a quickie fix for: > I am, along with six other students, producing a video tape on various > subjects in physics. Several scenes MUST be in slow motion. All video was shot > on a 1/2" VHS deck (Panasonic PV-8000) then dubbed up to 3/4" U-matic format. > The scenes that had to be in slow motion were then dubbed up using the frame by > frame "slow" advance feature of the PV-8000. In viewing the 3/4" tape, and the > 3/4" composite master, we were quite pleased. Cheap, crisp, clear slow motion > video. I suppose I left out one important fact: The video was insert edited on the 3/4" tape, which was (of course) blacked to a standard (N)ever (T)wice (S)ame (C)olor video. Playing the 3/4" tape caused almost zero flutter of the image, only the dubbing caused trouble. Fix: We noticed terrible video dubbing with the rest of the "mess" (i.e., switcher, sync gen, and such) on. For some reason the 3/4" editor likes to pay attention to its video input while playing. We have a patch panel set up that defaults VDA 1 (Program) to VTR 1 (deck we dub from). Simply disconnecting the cable behind the VTR cleared things up. This occurrence caused some consternation, because there is a switch to select Sync input, and a separate sync input. If one disrupts sync to the switcher ("Un-Genlocking" it, turning off sync generator) the 3/4" VTR's image is disrupted. Why would the VTR care about video in during playback (esp if sync switch is set to "Normal", which means, I suppose, from tape control track, and nothing connected to sync in)? This switch also has "internal" (VTR's own sync), and "external" (from TBC, or whatever): what should this be set to? Can't trust these durn manuals any more! Result: We got 10 great dubs onto 1/2", and they play back rather well even on the oldest VTRs. Rather amazing that we went from 1/2" to 3/4" to 3/4" down to 1/2" and got video that was QUITE good. Strange, people used to say (and still do) that 1/2" is S**T, and 4 generation was terrible... Again, posting this through a friend. Any mail to be directed to: ...!ihnp4!charm!kalucki Thanks All: John Kalucki (Physics Research @ Bell Labs, MH, NJ) A quite silly student at: Governor Livingston Reg. H.S. Bell Labs won't even admit that CE's exist, never mind have opinions, or even worse (horrors) minds...
brown@nicmad.UUCP (03/10/86)
In article <5085@alice.uUCp> d@alice.UucP (Dan Rosenberg) writes: >> I have a slight video problem that I need a quickie fix for: >> I am, along with six other students, producing a video tape on various >> subjects in physics. Several scenes MUST be in slow motion. All video was shot >> on a 1/2" VHS deck (Panasonic PV-8000) then dubbed up to 3/4" U-matic format. >> The scenes that had to be in slow motion were then dubbed up using the frame by >> frame "slow" advance feature of the PV-8000. In viewing the 3/4" tape, and the >> 3/4" composite master, we were quite pleased. Cheap, crisp, clear slow motion >> video. > > I suppose I left out one important fact: The video was insert edited >on the 3/4" tape, which was (of course) blacked to a standard (N)ever (T)wice >(S)ame (C)olor video. Playing the 3/4" tape caused almost zero flutter of the >image, only the dubbing caused trouble. > Fix: We noticed terrible video dubbing with the rest of the "mess" >(i.e., switcher, sync gen, and such) on. For some reason the 3/4" editor >likes to pay attention to its video input while playing. We have a patch >panel set up that defaults VDA 1 (Program) to VTR 1 (deck we dub from). >Simply disconnecting the cable behind the VTR cleared things up. This >occurrence caused some consternation, because there is a switch to select >Sync input, and a separate sync input. > If one disrupts sync to the switcher ("Un-Genlocking" it, turning >off sync generator) the 3/4" VTR's image is disrupted. Why would the VTR >care about video in during playback (esp if sync switch is set to "Normal", >which means, I suppose, from tape control track, and nothing connected to >sync in)? This switch also has "internal" (VTR's own sync), and "external" >(from TBC, or whatever): what should this be set to? Can't trust these >durn manuals any more! Oh boy, this does change the outlook of things. If I understand what you are saying, the output of the video switcher is fed into the 3/4" VCR as well as the output of the 3/4" VCR being sent to the switcher and the VCR sync switch is in NORMAL. You have video feedback. When the VCR switch is in NORMAL, it does NOT look at internal sync only. If there is incoming video, it will strip off the sync and use it. But, because the incoming signal is the same signal, trouble can result. Especially when the special effects portion is reached. A little different sync timing exists (covered in earlier discussions) which causes the VCR to go a little wild. I have done the same type of thing. Because of all of my connections, I have ended up feeding the ouput of the 3/4" into the 3/4" VCR. I now supply external sync to the 3/4" VCR and flip the switch to EXTERNAL. This keeps the incoming video, which is the same out going video, from causing problems. Since you have a video switcher, I would suggest feeding the gen-lock signal to the VCR and set the switch to EXTERNAL. Then you can keep the input signal connected. Also, for best recording results, it is best to supply external sync and set the 3/4" VCR to EXTERNAL. Why, because the recorder will then use the external sync to record the control track. If the incoming video had a glitch in the vertical sync area, the recorder could lose sync and garbage the recording for about 2 seconds. I know, I have had that problem for a few years, until I found out why my external generated sync wasn't working. The external sync to the 3/4" VCR will have to be supplied to any VCR player as well. If the player cannot except external sync (consumer VCRs), then then the 3/4" recorder will HAVE to be set to NORMAL. Try recording a consumer VCR with the 3/4" VCR set to external and see what happens. If external sync is used, all devices in the chain MUST have the same external sync. For all of you 3/4" VCR users, the Sony NORMAL/EXTERNAL video sync switch has the following priorities: (At least on my unit) NORMAL: No incoming video, no incoming sync; use internal sync Incoming video, no incoming sync; use sync from incoming video Incoming video, incoming sync; use sync from incoming video EXTERNAL: No incoming video, no incoming sync; use internal sync Incoming video, no incoming sync; use sync from incoming video Incoming video, incoming sync; use incoming sync As can see from the above, the normal operation of the switch means that if it is in the NORMAL position and incoming video is there, it will use that for sync. If the switch is in EXTERNAL and external sync is there, it will use that. Otherwise the sync will be derived from the next level down in the priority table. The priority table is: 1. External Start of EXTERNAL priority 2. Incoming Video Start of NORMAL priority 3. Internal I hope that the above information has helped the original poster, as well as anyone else using 3/4" video equipment. -- ihnp4------\ harvard-\ \ Mr. Video seismo!uwvax!nicmad!brown topaz-/ / decvax------/