Location sound recording for 35mm film shoot/feature questions.

[MT Groove]

I'm gonna be doing the location sound for a 35mm feature. I've done HD shoots but this will be my first 35mm shoot and I got a few questions.

I'll be using Vosgames Boom Recorder Software running on a MacBook Pro, using a MOTU Traveler as the interface. I will also have a Tascam HD-P2 as a backup recorder running simultaneously. I will have access to a Denecke Timecode slate and a Denecke SB2a sync box.

If I understand correctly, the film camera will be running at 24fps but I should roll audio at 30fps. If I record at 48kHz it will need to be pulled down in post. So should I record at 48.048kHz instead? Boom recorder allows file recorded at 48.048 but the MOTU Traveler doesn't support that rate. I emailed Take Vos and he said there's a way to fool the system to run at 48.048 by setting to clock to SMPTE.

What sample rate and frame rate should I really be recording audio at in this case? What should I set the timecode slate to run at? I think I'll be cross jam syncing the slate and the SB2a box and use the SB2a to feed timecode into the Traveler.

Another question is; say in the case I deliver the audio at 48kHz and 30fps. Is it the responsibility of the film transfer house to sync the audio into Avid of FCP files? If so are they gonna pull-down the audio during the telecine process? Or is the audio gonna be sync'd and pulled down during the editing? I'm not sure exactly how this works.

Any advice would be greatly appreciated.

[dr.sound]

MT Groove,
if you don't get your answer here, then go here:
Discussions - rec.arts.movies.production.sound | Google Groups

It's RAMPS where Production Sound Mixers hang out.

[minister]

a long, careful, detailed discussion with all involved in the process so that everyone from production to telecine to picture and audio post know the flow. It looks like you have a good understanding, but that doesn;t mean it is the best solution for the situation.

and as the Doc says, go to R.A.M.P.S .... plenty of good, experienced professionals there... that is where you should get answers (though a few here do good production audio, like Phil Perkins)

[philper]

Originally Posted by MT Groove

I'm gonna be doing the location sound for a 35mm feature. I've done HD shoots but this will be my first 35mm shoot and I got a few questions.

I'll be using Vosgames Boom Recorder Software running on a MacBook Pro, using a MOTU Traveler as the interface. I will also have a Tascam HD-P2 as a backup recorder running simultaneously. I will have access to a Denecke Timecode slate and a Denecke SB2a sync box.

If I understand correctly, the film camera will be running at 24fps but I should roll audio at 30fps. If I record at 48kHz it will need to be pulled down in post. So should I record at 48.048kHz instead? Boom recorder allows file recorded at 48.048 but the MOTU Traveler doesn't support that rate. I emailed Take Vos and he said there's a way to fool the system to run at 48.048 by setting to clock to SMPTE.

What sample rate and frame rate should I really be recording audio at in this case? What should I set the timecode slate to run at? I think I'll be cross jam syncing the slate and the SB2a box and use the SB2a to feed timecode into the Traveler.

Another question is; say in the case I deliver the audio at 48kHz and 30fps. Is it the responsibility of the film transfer house to sync the audio into Avid of FCP files? If so are they gonna pull-down the audio during the telecine process? Or is the audio gonna be sync'd and pulled down during the editing? I'm not sure exactly how this works.

Any advice would be greatly appreciated.

You are on the right track. Neither the Traveler nor the HDP2 have accurate enough clocks for long term sync--you are right to clock them (both) to the SB2. I have done this many times and it works very well. (The HDP2 can clock itself from its TC input, with the Traveler you have to give up an audio input to TC and then tell it to clock itself to that. To get all 8 analog inputs available on the Traveler you have to send it word clock, AES, or SPDIF, not LTC. You COULD send it the SPDIF out of the HDP2, which is being clocked by the SB2's TC, and then could avoid sending the Traveler LTC and get back your 8th analog input. Make sure you read your HDP2 manual about doing 48.048 before you try this.) The TC frame rate should be 30, but the sample rate (48 or 48.048) should be worked out w/ your post folks. If there are no post folks or they don't know how telecine and dailies sync and editorial and audio post will be done, then the default is 30 fr / 48k.

Philip Perkins

[MT Groove]

Thanks for all the replies.

I don't really need all 8 inputs of the Traveler and can sacrifice 1 input for LTC. The Tascam HD-P2 has the ability to pull-up/down the rate. However I'm not understanding it's user manual very well. It states as follows

-----------------------------------------------------------------
Rate Pull Up/Down
Normally a synchronized audio clock is set to be
precisely 44,100 Hz, 48,000 Hz, and so on. There are
some cases where it is required to run the audio at
pull-up or pull-down rates.
The Rate Pull Up/Down options are:
• Off – Normal use
• 29.97 Up – If and only if the frame rate is 29.97 (DF
or ND), then pull-up the audio clock rate.
• 30.00 Down – If and only if the frame rate is 30.00 (DF
or ND), then pull-down the audio clock rate
------------------------------------------------------------------

I may need to e-mail Tascam to clarify things a bit. Or actually do a little test and compare on my own to verify.

I think I'm able to set the proper sample rate with the Tascam and feed the SPDIF out into the Traveler so they'll be running at the same rate. Then split the SB-2a's output and feed the Tascam and the Traveler. So I guess I can rig the Traveler/Boom Recorder setup to be running at 48048 and receiving a 30fps LTC from the SB-2a. Also, should the slate be running at 30fps non-drop instead of 24?

[philper]

Originally Posted by MT Groove

Thanks for all the replies.

I don't really need all 8 inputs of the Traveler and can sacrifice 1 input for LTC. The Tascam HD-P2 has the ability to pull-up/down the rate. However I'm not understanding it's user manual very well. It states as follows

-----------------------------------------------------------------
Rate Pull Up/Down
Normally a synchronized audio clock is set to be
precisely 44,100 Hz, 48,000 Hz, and so on. There are
some cases where it is required to run the audio at
pull-up or pull-down rates.
The Rate Pull Up/Down options are:
• Off – Normal use
• 29.97 Up – If and only if the frame rate is 29.97 (DF
or ND), then pull-up the audio clock rate.
• 30.00 Down – If and only if the frame rate is 30.00 (DF
or ND), then pull-down the audio clock rate
------------------------------------------------------------------

I may need to e-mail Tascam to clarify things a bit. Or actually do a little test and compare on my own to verify.

I think I'm able to set the proper sample rate with the Tascam and feed the SPDIF out into the Traveler so they'll be running at the same rate. Then split the SB-2a's output and feed the Tascam and the Traveler. So I guess I can rig the Traveler/Boom Recorder setup to be running at 48048 and receiving a 30fps LTC from the SB-2a. Also, should the slate be running at 30fps non-drop instead of 24?

Changing the TC changes the sample rate in that case, a la Fostex. In my tests the 29.97 UP yielded a 30 FPS 48.048 file. You must do tests w/ your own recorder as this kind of thing changed w/ various firmware revs I think. The slate should be @ whatever your audio recorder's frame is. In the US, material going thru normal telecine shot at 24 fps would have its audio recorded at 30 fps. As we have discussed, the sample rate depends on what your editorial people want.

Philip Perkins

[MKaczmarczyk]

Originally Posted by philper

You are on the right track. Neither the Traveler nor the HDP2 have accurate enough clocks for long term sync--you are right to clock them (both) to the SB2. I have done this many times and it works very well. (The HDP2 can clock itself from its TC input, with the Traveler you have to give up an audio input to TC and then tell it to clock itself to that. To get all 8 analog inputs available on the Traveler you have to send it word clock, AES, or SPDIF, not LTC. You COULD send it the SPDIF out of the HDP2, which is being clocked by the SB2's TC, and then could avoid sending the Traveler LTC and get back your 8th analog input. Make sure you read your HDP2 manual about doing 48.048 before you try this.) The TC frame rate should be 30, but the sample rate (48 or 48.048) should be worked out w/ your post folks. If there are no post folks or they don't know how telecine and dailies sync and editorial and audio post will be done, then the default is 30 fr / 48k.

Philip Perkins

could you explain how to send TC from SPDIF? I have motu ultralite and hdp2 and trying boom recorder. I could use 8 channel of my mixer and I'm afraid of TC signal leakage to other channels.

best regards
Mikolaj