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Timecode Sync 50p or 60p video via LTC in Avid or Resolve

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Hi! I am happy to have found this forum!

I have to sync my 50p footage for television to an audio recorder.

timecode can only be provided to the camera Via mini jack audio LTC port.

As the LTC protocol only allows frame rates up to 30p I can only select 25p in the ultrasync one timecode box. The software then has to interpret this timecode and calculate the timecode for my 50p video.

I couldn't do this in avid or davinci resolve, does anyone know a way?

I think tentacle sync studio can do exactly this but I don't own it and it is a rather complicated workflow.

Does anyone know how to do it in an NLE?

especially avid or dr?

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16 hours ago, Sound said:

my 50p footage for television

 

Last time I've checked, television in Germany is 25i

(Or P in an I container.)

 

16 hours ago, Sound said:

provided to the camera Via mini jack audio LTC port.

 

If you do this, does your cam slave to the incoming LTC? If so, you're home free.

 

16 hours ago, Sound said:

I can only select 25p in the ultrasync one timecode box. The software then has to interpret this timecode and calculate the timecode for my 50p video.

 

What software? If you have an LTC in on your cam, the TC in your clips will be metadata that can be read by any NLE.

 

16 hours ago, Sound said:

I couldn't do this in avid or davinci resolve,

 

Why not? Syncing in Resolve and Avid can be done on normal TC, or audio (LTC) if you have put the LTC on an audio channel.
This is pretty standard, RTFM.
 

Now, since you have an Ultrasync, Timecode Systems also has similar software to the Tentacle software, but with way more options, and if you're a novice, more complicated.
(I know, since I wrote that software...)

So, what exactly are you doing, and what does not work?

 

 

 

 

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18 hours ago, Bouke said:

 

Last time I've checked, television in Germany is 25i

(Or P in an I container.)

 

 

Exactly! Bit i am Recording in UHD. And as you know 25i doesnt exist in UHD so I have to Record in 50p.

 

Quote

 

If you do this, does your cam slave to the incoming LTC? If so, you're home free.

It doesnt.

Quote

 

What software? If you have an LTC in on your cam, the TC in your clips will be metadata that can be read by any NLE.

Thats right but its a 25p based Timecode in the Metadata.

Quote

 

Why not? Syncing in Resolve and Avid can be done on normal TC, or audio (LTC) if you have put the LTC on an audio channel.
This is pretty standard, RTFM.

Yes I tried. When I Import Audio in Avid it asks for a Timecode timebase. I can only select 25p as 50p does Not exist. Then i cannot sync 50p Video to Audio with a 25p Timecode timebase.

Quote

Now, since you have an Ultrasync, Timecode Systems also has similar software to the Tentacle software, but with way more options, and if you're a novice, more complicated.
(I know, since I wrote that software...)

So, what exactly are you doing, and what does not work?

 

 

 

 

Just reading out the 25p aux timecode and writing a start timecode of the clip based on the 50p footage in the metadata. Tentacle sync studio can do this, wave agent as well? It's not documented in the manual.

 

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On Avid, you normally assign the LTC to AUX1 (And you sync / subclip whatever) based on that.
If it does not work in 50 (Never tried), switch to 25, sync and switch back.
Does that not work for you?

 

Bouke

 

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1 hour ago, Bouke said:

On Avid, you normally assign the LTC to AUX1 (And you sync / subclip whatever) based on that.
If it does not work in 50 (Never tried), switch to 25, sync and switch back.
Does that not work for you?

 

Bouke

 

How can I switch? 50p is the video framerate not the project framerate. I would have to transcode everything to 50 but then it's hard to go back and takes a lot of time

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6 hours ago, Bouke said:

I ment switch the project rate to 25.

Now, what exactly does not work?

 

 

It doesn't work because avid only compares the frame rate of the video clips (50p) and the audio Timecode base (25p). No matter what the project framerate is set.

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59 minutes ago, Sound said:

avid only compares the frame rate of the video clips (50p) and the audio Timecode base (25p). No matter what the project framerate is set.

 

Hmm. That sucks.
(I don't have 50fps clips here to test, send me one if you like.)
However, my tool is able to:

Scan your video files for normal TC and audio TC

Then scan your BWF files
Then calculate the offset between BWF timestamp / LTC value / normal TC value (for clips that match the video)

Then set a new timestamp on the BWF files so they match the normal video TC.


That 'should' do the trick, but I'm not sure how the app interprets your normal TC.
(Frames could go up to 50 (up and including 49, or be double for two frames)

Please switch to 50 FPS, see if you have a clip with a start TC with a frame number higher than 24.
If so, send me that clip and I'll test it. (I do know that I've build in framerates > 30, but have not tested that many cams...)

 

To send me clips, go here:
https://videotoolshed.wetransfer.com/

 

To toy yourself:
https://www.videotoolshed.com/product/ltc-convert-auxtc/

 

Bouke


 

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Thanks for your help! It doesnt seem to work in 50p but I managed to get it to work in 50i. I didnt manage to import any Video files into Wave Agent. My files now are xavc-s 25p UHD from a Sony a7 III.

 

But I have another big problem. The Mixpre 10 II has a file size limit of 4GB because of the SD card recording. So it always splits audio after some time and creates a new file. in 32bit with 10 tracks 48khz its about 37 minutes. So its very likely to have a video file that has to be synced to multiple audio files, but that doesnt seem to work. Avid and Resolve only sync to the first audio file and ignore the next file. Is there any workaround for that? 

 

 

On 9/29/2019 at 1:18 PM, Bouke said:

 

Hmm. That sucks.
(I don't have 50fps clips here to test, send me one if you like.)
However, my tool is able to:

Scan your video files for normal TC and audio TC

Then scan your BWF files
Then calculate the offset between BWF timestamp / LTC value / normal TC value (for clips that match the video)

Then set a new timestamp on the BWF files so they match the normal video TC.


That 'should' do the trick, but I'm not sure how the app interprets your normal TC.
(Frames could go up to 50 (up and including 49, or be double for two frames)

Please switch to 50 FPS, see if you have a clip with a start TC with a frame number higher than 24.
If so, send me that clip and I'll test it. (I do know that I've build in framerates > 30, but have not tested that many cams...)

 

To send me clips, go here:
https://videotoolshed.wetransfer.com/

 

To toy yourself:
https://www.videotoolshed.com/product/ltc-convert-auxtc/

 

Bouke


 

 

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3 hours ago, Sound said:

I didnt manage to import any Video files into Wave Agent

I take that as a typo...

 

Easiest workaround, do NOT record poly.

 

Then, for the few files this will be the case:
Autosequence the whole shebang in Avid.
Then ffwd and see if you have spanned clips, if so, export them from Avid as Wave.
(Avid will make RF64 for you, keeping the timestamp.)

Make sure the linking is then done on the new files.

You could (if you are lazy) do an entire day to one clip after the autosequence, and have all video link to that single file.
(I know a sound guy who starts rec in the morning, stops rec while walking back to the car.)

 

hth,
Bouke

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19 hours ago, Constantin said:

it’s not that easy as you can only

 

Well sorry, don't mistake me for a sound guy, I don't know this gear.
(I'm in post / development.)

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Thanks. I just found out mixpre 10 II has Timecode jumps in 25p. So it's unusable for Timecode sync. I wonder why the sound devices guys don't warn their customers.. that can really destroy a production.

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55 minutes ago, Sound said:

Thanks. I just found out mixpre 10 II has Timecode jumps in 25p. So it's unusable for Timecode sync. I wonder why the sound devices guys don't warn their customers.. that can really destroy a production.


how did you find out? It’s a pretty common framerate and someone should have posted about it. I for one have not read about it, but maybe I just missed it. Got any further info?

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I tried to sync it up in Avid. As these files are split automaticall after 37 minutes I tried to sync two audio files to one video file. But the result was one frame with 22 Audio tracks. so the Audio Files were overlapping by one frame. As I asked Soud Devices they told me they already know that there is a lag of one frame after about 15 minutes in 25p. I have opened a new topic in the equipment forum. I cannot believe that they dont warn their customers as this can bring them into serious trouble..

I

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There is really a lot wrong with the lingo used here.
BWF has no timecode, it has a time stamp, a number representing samples.

That can be converted to TC, but the time stamp itself has nothing to do with any video frame rate.
So if there is a bug, it's due to a wrong timestamp on the spanned clips, and that MUST bite EVERY project framerate.

 

As an example, your recorder splits every second, and you start recording at TC 00:00:01:00

The first clip (assuming you're recording @ 48K), then has a timestamp of 48001

The second clip then must have a timestamp of 96001

 

To see how big the offset is in your case, write down the Samples After Midnight of the first clip, and find out the amount of samples in the first clip.
(Using a HEX editor, it's the value after DATA divided by the ByteDepth and Amount of Channels.)
Add those, and that should be the SAM of the new clip.

Now, the new clip has probably a lower SAM, hence the overlap.
But, Avid does not think in video frames when it comes to syncing. Avid uses SAMPLES. (Hence way more accurate.)
 

The fix is easy, if the first clip of a spanned set is accurate. Just autosequence the first clips, then manually butt edit the remaining, then export.
(I could fix the timestamps easily by adding a small option to my BWF toolbox, but I'm swamped in porting all my stuff to 64 bits.)

Bouke

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Hmm. So how can it be possible that the problem only exists in 25p? At least sound devices is saying so. Does it make any difference which framerate I set in the recorder? 

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I have no clue, since I don't have access to the source code of the recorder nor Avid.
Speaking of, Avid has two meanings, for some it means ProTools, for others (me) it means Media Composer.

 

Setting framerate on your recorder affects how to interpret incoming LTC / outgoing LTC, and perhaps a stupid tiny bit of metadata in the BWF files (that can be ignored by MC if you want it.)
Framerate setting 'should' not affect the timestamp of next files in a splitted set.
When you say 'only exists in 25p', is that an Avid (what avid)  project, or a 'I've set my recorder to 25p and then the shit hits the fan'?

Keep in mind, I cannot mind-read. (But I can fix the existing files if needed.)



 

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I connected an external Recorder, Ultrasync one. So I set it to output timecode to the ultrasync one first (25p). After that I set it to take the timecode from the ultrasync (25p). And then i created an Avid Media Composer project, because I need to sync video and audio. Video is fed into my small Sony Alpha camera via Minijack Audio LTC. As Media Composer cannot create an AutoSequence by Aux Timecode and is not able to convert AUX Timecode to Starting timecode of the clip there is no way to create an AutoSequence. The only Option is ClipSync, but that results in 1 Frame files as the timecode overlaps. I can convert Audio Timecode to Clip Starting Timecode in Davinci Resolve - Then export the video file to avid and then do an AutoSequence in Avid. Syncing one Video file with the two audio files in Resolve doesnt work as well and there is no real AutoSequence function in Resolve. Only a Multicam function.  Its a shame. The mixpre 10 II isnt a very cheap recorder, but it only records polywav with 4GB limit and has massive timecode issues.. So all in all its really not usable.

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