BMPCC4K - does not detect LTC timecode

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MarcusWolschon

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BMPCC4K - does not detect LTC timecode

PostWed Dec 05, 2018 5:00 pm

I'm experimenting with LTC timecode.
Coming from GH5 and the BMPCC, I never had the luxury of a camera (or audio recorder) that did support LTC natively.

For testing purposes I have a cellphone generate an LTC timecode in the proper frame rate.
(On stage we will have a proper 19" time base later but I need to verify that this is working to justify the expense.)
A special cable removes any DC (plug in power) from the microphone input and brings the headphone signal down to mic level on one stereo channel while allowing a regular microphone on the other stereo channel. So we still have regular sound to sync if the timecode idea fails.

In the camera and with a variable resistor on the cable I can tune it down to -10dB or 0dB mic level
or see about -32dB line level on the camera display.

(I'm afraid to give my expensive camera a 2Vpp or 3Vpp signal into the 1/8" TRS input designed for 1V line or the lower mic level without anything in the user manual stating that this is supported.)

Never did the camera indicate the [EXT] icon to show that a timecode has been detected.
Resolve on the other hand instantly detected the timecode
and when I manually changed the timecode in the clip properties and then used "Update timecode from audio - LTC" it worked instantly.

The manual only says "The microphone input also accepts SMPTE compliant
LTC timecode from an external source." but does not give any details.
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Kristian Lam

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Re: BMPCC4K - does not detect LTC timecode

PostFri Dec 07, 2018 12:05 am

Hi,

I would first ensure you send line level output, if possible, from your setup and then either ensure the 3.5mm setting in the Pocket Cinema Camera 4K's audio page is set to 'Line' OR that no 3.5mm audio input is selected.

See if the camera picks up the timecode. For Pocket Cinema Camera 4K, timecode does not have to be written to an audio track. The camera will still pick it up and write a proper timecode metadata.
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Jamie LeJeune

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Re: BMPCC4K - does not detect LTC timecode

PostFri Dec 07, 2018 3:54 am

Thank you for the info Kristian!

I'm still waiting for my Pocket 4K pre-order to ship, so I haven't been able to test it myself yet. I am curious to know, is the Pocket 4K able to take LTC pulse as line input through the 3.5mm jack, and also record a mono audio channel through the miniXLR at the same time?
Last edited by Jamie LeJeune on Fri Dec 07, 2018 4:58 am, edited 1 time in total.
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Kristian Lam

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Re: BMPCC4K - does not detect LTC timecode

PostFri Dec 07, 2018 4:50 am

Jamie LeJeune wrote:Thank you for the info Kristian!

I'm still waiting for my Pocket 4K pre-order to ship, so I haven't been able to test it myself yet. I am curious ti know, is the Pocket 4K be able to take LTC pulse as line input through the 3.5mm jack, and also record a mono audio channel through the miniXLR at the same time?


Hey Jamie,

Yes, this will work.
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Jamie LeJeune

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Re: BMPCC4K - does not detect LTC timecode

PostFri Dec 07, 2018 4:58 am

Great to know! Thanks! Thanks
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MarcusWolschon

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Re: BMPCC4K - does not detect LTC timecode

PostFri Dec 07, 2018 5:41 am

Kristian Lam wrote:Hi,

I would first ensure you send line level output, if possible, from your setup


It's not posible with the setup I have at this moment.
Since you wrote "if possible", what to do in the "else" case?

Kristian Lam wrote:and then either ensure the 3.5mm setting in the Pocket Cinema Camera 4K's audio page is set to 'Line' OR that no 3.5mm audio input is selected.


Since the levels for left and right channel on the TRS socket are ganged,
does this mean it's not possible to record a mic level regular microphone on the other stereo channel
at the same time?
So external audio can only be recorded in Stereo if one of the microphones sends a Line level signal
and only Mono (using the Mini XLR) otherwise?

Kristian Lam wrote:See if the camera picks up the timecode. For Pocket Cinema Camera 4K, timecode does not have to be written to an audio track. The camera will still pick it up and write a proper timecode metadata.
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Denny Smith

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Re: BMPCC4K - does not detect LTC timecode

PostFri Dec 07, 2018 5:46 pm

Deleted :mrgreen:
Last edited by Denny Smith on Sat Dec 08, 2018 6:26 am, edited 1 time in total.
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MarcusWolschon

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Re: BMPCC4K - does not detect LTC timecode

PostFri Dec 07, 2018 5:58 pm

Denny Smith wrote: The camera only has two audio channels, so you can not have a stereo audio and LTC input at the same time.
Cheers


Above a Blackmagic employee wrote "For Pocket Cinema Camera 4K, timecode does not have to be written to an audio track. The camera will still pick it up and write a proper timecode metadata."


Sorry if it would have been obvious for people who work with LTC that it would have to be line level.
For people new to this, it would have been nice if this was mentioned in the manual.
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Denny Smith

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Re: BMPCC4K - does not detect LTC timecode

PostFri Dec 07, 2018 7:37 pm

Deleted. :geek:
Last edited by Denny Smith on Sat Dec 08, 2018 6:26 am, edited 1 time in total.
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Kristian Lam

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Re: BMPCC4K - does not detect LTC timecode

PostSat Dec 08, 2018 3:23 am

MarcusWolschon wrote:
It's not posible with the setup I have at this moment.
Since you wrote "if possible", what to do in the "else" case?


I spoke too soon. Doubled checked the setup (with Tentacle Sync) and it will also work with mic input levels.

(I'm afraid to give my expensive camera a 2Vpp or 3Vpp signal into the 1/8" TRS input designed for 1V line or the lower mic level without anything in the user manual stating that this is supported.)


We can also tolerate a 3Vpp signal into the 3.5mm so you may want to play around with that to see if it's a level issue.
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Gavin_c_clark

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Re: BMPCC4K - does not detect LTC timecode

PostTue Dec 11, 2018 7:19 pm

Just been testing this out. Using a tentacle sync e, the camera picks up and locks on with mic level set on the tentacle and the 3.5 mm input but couldn’t get it to pick up at line level on both?

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