#390959 - 02/29/00 06:17 PM
Music for post/ sample rate questions...
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Doug_dup4
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Registered: 12/09/01
Posts: 1
Loc: Pottstown,PA,UNITED STATES
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I have a couple questions about sync issues in post production. I have to write some music for a film that is being telecined.
1. I'll get the video on a tape that's been recorded at 29.97 fps. As I understand it, telecined video is recorded at 30fps. Because of the difference, does that mean that I have to reduce the sample rate of my music by 1%? Is this what's called 'pulldown?' I just started composing in ProTools, and in the export options, you can choose a custom sample rate - is this how I should convert, or isn't the quality that good?
2. The music samples I use are all 24bit, 48 khz, so would the adjusted sample rate for the entire session be 47.952khz, and dithered to 16 bit?
3. I've been thinking about buying an Aurora Fuse video capture board (I read Roger's comments about the AV option, but I can't afford it right now). By digitizing the video, can I avoid having to rent a timecode dat to properly sync the music to picture? IOW, by sample rate converting and dithering the music file within ProTools, I can send in the AIFF file and the post editor can 'pull up' at that stage?
Thanks for your time!
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#390960 - 03/01/00 10:02 PM
Re: Music for post/ sample rate questions...
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Roger Nichols
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Registered: 12/13/99
Posts: 1249
Loc: Miami, Florida
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Doug
OK, here goes.
Is the film going to be shown as a film or as a tv show? If all of your music is going back to film, then there MAY be sample rate conversion necessary. Pay close attention, I am having brain frost just thinking about this.
1) If the audio will be laid back with digital audio dubbers right to film, then you do nothing... everything will work out fine at 48kHz.
2) If the audio MUST be laid back to the video tape, and then transferred to the film, then you should sample rate convert UP 1% to 48.048kHz so that when they slow it down to 48kHz to sync back into the video tape your audio will be played back at 48kHz (1% flat), but in the transfer to film it will go back up 1% putting it right back where you started.
If you use the sample rate conversion in Pro Tools "Bounce to Disk" page DO NOT USE THE TWEEK-HEAD SETTING.... It sucks. Just use BEST.
If you read this ten times quickly it makes more sense.
If the show was shot on film, transferred to video tape and will stay in video form for final viewing on tv, then you should stay at 48kHz, which is what digital audio for 29.97 video uses. You need to do nothing.
If you are using 24 bit you will have to dither to 16 bits for the final mix. Pro Tools dithering is fine.
Video...
Have them burn in time code on the tape, or better yet, have them give you a QuickTime file with "vis-code" (time code burned in). You can then import the QuickTime movie into Pro Tools without the AV option. This is plenty good enough to get the hits in the right place.
The other way to do it is the way I did it 15 years ago. Get a VHS video tape with time code burned in and SMPTE (VITC time code on the video track if you have a USD or Video Slave Driver or SMPTE on one channel of the audio if you have a SMPTE Slave Driver)
You can still frame to see the exact time code for music hits, and then work on the music without the video running. If you want to see the music with the video, just play back the VHS with the ProTools as slave.
Thanks
Roger
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