Resolving questions I don't understand it.

[Vespasian]

Okay this might sound lame to the pros but I just don't understand how you transfer sound to video tape. I was wondering if some people with experiance can share how they do it.

So far though:

I understand that you take your film and telecine it to get it on video. I was also wondering about negative film. How is that transfered to video? So you got your film on video that was shot in crystal sync or pilitone, and you have a cassette tape that was crystal synced or pilitoned with your audio on it, and a video tape with your film on it. You have to have a resolver right, and the only one I know of is TFG micro resolver, but how does that thing work? How exactly do you put the sound on the video? I know there are different methods, and I would like to know them all but whatever anyone can tell me would be great. I have done a lot of research on this subject and nobody seems to go into detail. Thank you ahead of time.

[rollemfilm]

here is the idea in a nut shell: you need to have a camera that runs at a perfect speed. standard in the USA is 24fps. now, you also have to have an audio recorder that runs at a perfect speed. some cameras can not be modified for a perfect crystal speed. so, many of these cameras can be set up to send a signal of it's running speed. these cameras can utilize what the Film Group calls a "digital to pilotone converter"...this converts PC/shutter rates to a 60 hz tone to be recorded on one track of the recorder. now, if you have a camera that "will" run at a perfect speed, there is no need to record the speed of the camera on the audio track. but, you do need to keep the audio running at a perfect speed. so, you use a modified recorder that records it's own 60 hz tone. the resolver will slave the recorders speed to a perfect steady speed to sync with the cameras pictures. when you transfer to video via a Rank scanner, the speed of the film is slowed down by one tenth of one percent. therefore, you need to
resolve the audio via 59.94 hz instead of 60 hz. if you were going to edit on film, you need not make this speed adjustment. same goes for a standard telecine transfer. if you use a DAT recorder or a MD recorder, you need not make a pilotone recording unless you are recording the speed of your camera. Nagra recorders are offten built with an internal pilotone and resolver. the only thing that can help your recording more is timecode. that is for another posting....hope this helps some.

[Actor]

Suppose for the moment that your camera is crystal sync but your sound recorder is not. This means that your sound recorder is a cassette recorder or reel-to-reel recorder such as a Nagra or Uher. It is nearly impossible to make reel-to-reel recorders crystal accurate, i.e., they gain or lose less than 1/24 second in 11 minutes. The way a reel-to-reel recorder works in that the tape passes between the capstan and an idler pulley. The capstan pulls the tape off the free wheeling feed reel by friction alone.

Now it would seem that the solution to making a Nagra crystal accurate would be just a matter of powering the capstan with a crystal motor, but that is not enough. The problem is two fold. First, the tape can slip and second, the tape can stretch. Either of these means the tape will not play back with crystal accuracy.

Nagra's solution to this is to record a 60 Hz tone on a separate track of the tape. The tone is generated by a device called an SLO. I?m not certain what SLO stands for but my guess is Synchronizing Local Oscillator.

It is in playing back the sound that the resolver comes into play. The resolver has two inputs: one for the signal from the SLO and the other for the signal from the Nagra's sync track. The resolver detects any difference in the two signal's phase. If the two are not in phase (thus not of the same frequency) then the resolver either speeds up or slows down the Nagra to bring the two into phase.

Now suppose that instead of having a crystal sync camera we have one that generates a Pilotone which is recorded on the Nagra's synce track instead of the SLO signal. The Pilotone is generated by the camera's motor and will be 60 Hz if the camera is operating at 24fps, or proportionally higher or lower if the camera is fast or slow. This system basically adopts the worldview that the camera is always correct and it is the rest of the universe (including the Nagra) that is speeding up or slowing down. This is a manifestation of the relativity principle, that reality depends upon the viewer's POV. During playback the resolver (again comparing the sync track to the SLO signal) cannot tell whether variations in the sync signal came from variations in the Nagra's speed or the camera's speed or a combination of both.

As for how negative film gets transferred to video, the NTSC system uses 0 volts to represent total black and 1 volt to represent complete white. The transfer system simply reverses this, making 0 represent white and 1 volt represent black. This is done with both the luminance and color signals. Which is done is determined simply by throwing a switch. Some cameras and editors can do this as well.

<font color="#a62a2a" size="1">[ November 12, 2002 04:53 AM: Message edited by: Actor ]</font>

<font color="#a62a2a" size="1">[ November 12, 2002 05:09 AM: Message edited by: Actor ]</font>

<font color="#a62a2a" size="1">[ November 25, 2002 03:46 AM: Message edited by: Actor ]</font>

[Vespasian]

Actor thank you for the wonderful explination. I pretty much knew that the resolver was used for playing back audio at perfect sync, but are you saying that a crystal synced cassette deck like The Film Groups WM-D6C crystal synced recorder is not going to record and play back at crystal sync speed without a resolver? Or will it?

[rollemfilm]

the pro-walkman is already quartz locked from the factory. it will run as steady as any analog tape can. but, with the 60hz tone and resolver it will eliminate any fluxuations that have occured.

[MovieStuff]

<BLOCKQUOTE><font size=2 face="Verdana, Helvetica, sans-serif">quote:</font><table border="0" width="90%" bgcolor="#333333" cellspacing="1" cellpadding="0"><tr><td width="100%"><table border="0" width="100%" cellspacing="0" cellpadding="2" bgcolor="#FF9900"><tr><td width="100%" bgcolor="#DDDDDD"><font size=2 face="Verdana, Helvetica, sans-serif">Originally posted by Vespasian:
are you saying that a crystal synced cassette deck like The Film Groups WM-D6C crystal synced recorder is not going to record and play back at crystal sync speed without a resolver? </font></td></tr></table></td></tr></table></BLOCKQUOTE>

Analog decks designed for film work come in two versions. A basic Nagra doesn't really work any differently than a multi-track recorder in that it will record the location audio on one track and a synch reference on another track. There is nothing "crystal" about its running speed; it is merely a really steady analog recorder. However, the fact that it records a synch reference on an open track means that the sound can be resolved later on to match the film. Think of the Nagra as "punching" invisible sprocket holes in the tape as it goes along.

Then there are self resolving Nagras. They record just like the other Nagras do but have the added ability to play back the audio so that the synch reference pulses are kept in step with a reference signal generated by the on-board crystal oscilator. Since the same crystal was used to generate the pulses to begin with, and since cyrstal generated pulses are (for all practical purposes) perfectly steady, the playback will be perfectly steady as well.

But self resolving Nagras can also use a different synch reference during playback, such as a 60 cycle line signal. In either case, the tape will speed up and slow down to match the rate of the incoming synch signal. This is called "resolving".

[MovieStuff]

Here is another way to see it:

Imagine that you have four musicians and one of them is the drummer but none can show up at the recording studio at the same time. If the drummer records first on a multi-track recorder, then all the other musicians can play their written sheet music to the beat of the drummer after the fact, even if each musician can hear ONLY the drummer and not the other musicians. That is because they are resolving their performance to match the rate established by the drummer. Likewise, the Nagra has multi-tracks, one of which records the "drum beat" established by either an on board crystal or a synch signal generated by the camera. This drum beat can be used later to line up other sound components of the audio mix, just like the musicians playing one at a time.

[Vespasian]

Okay Moviestuff I kinda understand what you are saying. WOuld you say that the WM-D6C crystal sync redorder modified by TFG is a self resoving recorder? Would I have to hook the WM-D6C to any other hardware like a resolver unit when playing it back to get it on the computer to use it with frames captured by the workprinter?

Thank you Moviestuff, and would also like to thank you for making and producing the cine mates and workprinters. I think it's people like you who are the beating heart of the low budget film community. You make things cheaper and easier for all of us to make films. I can't wait until I can afford the workprinter. I am looking forward to using it.

[MovieStuff]

<BLOCKQUOTE><font size=2 face="Verdana, Helvetica, sans-serif">quote:</font><table border="0" width="90%" bgcolor="#333333" cellspacing="1" cellpadding="0"><tr><td width="100%"><table border="0" width="100%" cellspacing="0" cellpadding="2" bgcolor="#FF9900"><tr><td width="100%" bgcolor="#DDDDDD"><font size=2 face="Verdana, Helvetica, sans-serif">Originally posted by Vespasian:
WOuld you say that the WM-D6C crystal sync redorder modified by TFG is a self resoving recorder?</font></td></tr></table></td></tr></table></BLOCKQUOTE>

I really don't know if it's self resolving or not. But now that you understand the concept and the differences, I'm sure that the Film Group could fill you in on the specs.

<BLOCKQUOTE><font size=2 face="Verdana, Helvetica, sans-serif">quote:</font><table border="0" width="90%" bgcolor="#333333" cellspacing="1" cellpadding="0"><tr><td width="100%"><table border="0" width="100%" cellspacing="0" cellpadding="2" bgcolor="#FF9900"><tr><td width="100%" bgcolor="#DDDDDD"><font size=2 face="Verdana, Helvetica, sans-serif">Originally posted by Vespasian:

Thank you Moviestuff, and would also like to thank you for making and producing the cine mates and workprinters. I think it's people like you who are the beating heart of the low budget film community. You make things cheaper and easier for all of us to make films.</font></td></tr></table></td></tr></table></BLOCKQUOTE>

Oh, man! Don't you know? I'm "anti-super 8"! (an old and silly story)

Anyway, I appreciate the compliments. Super 8 is how I got started a long time ago and I think it is a great medium for doing some serious work, not because it's easy to use like video or 16mm but, rather, because it's damned hard. 16mm is so easy to shoot it's ridiculous. I mean, seriously, with the image processing available on a Rank, you'd have to be a total moron to not get a decent image off of 16mm. Shooting super 8 means better planning, tighter shooting and careful lighting. When I see something good in 16mm, I think,"So what?" When I see something good in super 8 I think,"Now that took some skill." Super 8 teaches you disipline in ways that no other medium can match. I mentioned in another thread about how Kodak wants more people to continue shooting 16mm. For that to happen, people need to keep shooting super 8 and that's all there is to it. I sincerely believe that when super 8 goes, more and more beginning film makers will start out in video and stay there. That will be the beginning of the end of film production as the digital cancer eats its way up the different formats over time. First super 8, then 16mm then 35mm then IMAX! Ahhhhh! Turn it off, turn it offffffff! [img]graemlins/cry.gif[/img]