Out putting wav to DAT to timecoded analog
Out putting wav to DAT to timecoded analog- special effects and filmmaking
I am using a sound and effects track for a 16mm film that I created on a video editing system using the film as video. I know how to do this in theory but was wondering if there is anything anyone can share that I may have missed. I used a keyboard to set tone (one continuous note @ 0). I then inserted a 1 frame beep prior to the first frame of the film to sync the audio to the film. I am playing the wav file and sending it to a DAT recorder at 48K with the DAT reading my tone at -10. I will then send the DAT track to a timecoded analog mag. Am I missing something? Has anyone encountered any problems when synched audio comes from a computer source? I know this is not special effects related but the effects loose all effectiveness when the sounds are off. Thank you for your help
Yes, you might have forgotten one thing. If the video that was cut on the editing system came from a Rank transfer, it used a 3-2 pulldown which slowed it down by .001% to accomodate for the true NTSC (I am assuming you are using NTSC) speed of 29.97 fps. In order to avoid drift when you have your audio synced, you need to speed it back up by .001%. This of course should be done in your audio editing program while still on the computer. Then every thing else should be fine. For a further explanation of syncing and other such concepts, read these two articles:
www.zerocut.com/tech/2_3_audio.html
www.zerocut.com/tech/sync.html
Good luck
Jay
You bring up a good point. For some reason I assumed that the transfer had been recording the 24 fps of 16mm @ 30 fps (29.97). But I thought that I should edit the clips in 24 fps and match the sound accordingly. Is this not the case? Should I be editing at a faster frame rate? Or, should I edit at a drop frame rate based on 24 fps?
Thanks again.
Wow, this gets confusing really quick. Umm, when you say "edit in 24 fps", I assume you are refering to the timecode settings on the computer. They shouldn't make a difference, so long as the speed of the final output is the same as the film. It would best to set them at 24 fps if the film was scanned directly into the computer. You also won't need to correct the timing if you did this. However, if the film was transfered to video (slowling it down), and you edited the audio to the slowed down video, you will need to speed it up regardless of the timecode format (which most likely should be 30 fps, just so it will match the video). If for some reason you don't know if the film ever hit video or not, you might want to try dumping it to DAT both ways, then asking the lab (or whoever) that will be syncing your film which one they want. I hope that made sense.
ps. As far as editing at different framerates goes, it doesn't actually effect the playback speed, just the method used to count it. Hence 1 minute of audio at 30 fps, is the same as 1 minute at 24 fps. The time discrepensy came when color TV was invented and the NTSC board decided to slow video down in order to include color information. For this reason, there is no drop frame rate based on 24 fps.
Jay
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