Multicam, Sync Bin, or ? - Which feature am I looking for?

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kayakfishingaddict

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Multicam, Sync Bin, or ? - Which feature am I looking for?

PostWed Oct 30, 2019 2:56 am

Warning: This is a totally newbie question. Sorry for my ignorance here, I've been using Davinci Resolve for about 5 months or so and I'm learning every day about the power of this excellent software.

Overview
I shoot hours of video and audio with a single camera today and I use the onboard captured audio. I'm adding another camera angle shortly and likely a separate audio recording device. I've watched videos and read up on both Multicam (wow!) and Sync Bins (wow!!). That said, I'm not sure if either of those will be able to take my footage and sync everything together over the entire recording session.

Scenario
Here's a typical scenario. I record 4 hours of audio separately from video. At times I turn on camera 1 and record clips, at times I also turn on camera 2 and record clips. When I get home I upload my content and I have something like 20 clips from camera 1, 10 clips from camera 2, and 1 long audio track.

Questions
So my question is what is my next step to get all of this sync'd up and ready for editing? E.g. will it work if I load it all up in a single multicam clip and sync based on audio? Or do I throw it all into a single sync bin? Will that align clips from camera 2 that are hours out from the original sync point where I clapped at the beginning of the recording session?

Or am I supposed to change my process so that I capture clips together, including audio, by turning on both cameras and audio, hitting record on all three, and then stopping all three at nearly the same time, as if I were capturing separate scenes in a movie? That would be very difficult to do in my situation.
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kayakfishingaddict

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Re: Multicam, Sync Bin, or ? - Which feature am I looking f

PostMon Nov 04, 2019 1:46 pm

No one has responded yet as to the proper workflow process. I thought it might help to document what I've tried recently and the fact that it does not work.

I have various clips from two cameras, some where shot simultaneously while other clips were shot with only one camera, or the other camera, on. Unfortunately, DR 16.1.1 does not handle this situation well at all, in fact it does not align the clips at all. What I'm beginning to sense is that DR needs a single clip to run the entirety of the timeline that it can align other clips too. I'm going to try that later today by shooting with an audio capture device continuously running.

It would be truly helpful to have the developers share some details as to what the synchronization algorithm looks for across clips. What hints it uses.

For example, I'd love for it to do a rough sort first using the actual file dates of the clips as the separate cameras are roughly synchronized to the same date/time, then fine tune the alignment for overlapping clips using audio. All of that should be placed on a timeline and then the user could delete the gaps to create a synchronized gapless timeline. That's what I tried to do, however, the synchronization doesn't work.
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Michael_Andreas

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Re: Multicam, Sync Bin, or ? - Which feature am I looking f

PostMon Nov 04, 2019 7:28 pm

I have used audio sync for MultiCam, and I have gotten it to work well if
1. I have a single clip from each camera. I found a utility that would append my continuously sequential GoPro clips together.
2. Audio from each camera is nearly the same. I also generated a slate with a hand clap near the beginning of the take.

You can try applying Angle metadata to all the clips from the same camera after you injest your footage, and checking the appropriate boxes during the MultiCam Clip creation dialog. Maybe that will work, maybe not. Most likely "not" if you stopped and restarted your camera for each take.

One thing you can try is the automatic syncing of just the first clips of each camera with the audio, then select the created MC clip, right-click & Open in Timeline and add the following clips manually by dragging them into the timeline.

One issue I've run into with consumer grade equipment on long recordings is that the separate clocks are not accurate enough to keep the video and audio in sync between recordings and there would be a drift of a few frames over an hour. GoPros tend to run fast, the frame rate is a little high by up to 5 frames/hour.
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Jim Simon

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Re: Multicam, Sync Bin, or ? - Which feature am I looking f

PostMon Nov 04, 2019 7:37 pm

kayakfishingaddict wrote:When I get home I upload my content


Upload means to transfer from a local computer to a remote computer over a network, such as the Internet.

You upload clips to YouTube.

You copy clips to your computer's hard drive.

You import media into Resolve.
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Jim Simon

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Re: Multicam, Sync Bin, or ? - Which feature am I looking f

PostMon Nov 04, 2019 7:38 pm

kayakfishingaddict wrote:am I supposed to change my process so that I capture clips together, including audio, by turning on both cameras and audio, hitting record on all three, and then stopping all three at nearly the same time


That.
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kayakfishingaddict

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Re: Multicam, Sync Bin, or ? - Which feature am I looking f

PostTue Nov 05, 2019 11:38 am

Michael_Andreas wrote:...I have a single clip from each camera. I found a utility that would append my continuously sequential GoPro clips together.


After further experimentation, it does seem that would help the algorithm. Please let me know what utility you use. I've been looking for one that would automatically use the GoPro chaptering filename convention to stitch multiple chapters together.

Michael_Andreas wrote:Audio from each camera is nearly the same. I also generated a slate with a hand clap near the beginning of the take.


That's a good practice. It's not the cause of my problem in this instance though.

Michael_Andreas wrote:...applying Angle metadata to all the clips....

I've set the angle and the camera on all clips.

Michael_Andreas wrote:Most likely "not" if you stopped and restarted your camera for each take

You're right, it doesn't work well....more on that in a minute.
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kayakfishingaddict

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Re: Multicam, Sync Bin, or ? - Which feature am I looking f

PostTue Nov 05, 2019 11:40 am

Jim Simon wrote:
kayakfishingaddict wrote:When I get home I upload my content


Upload means to transfer from a local computer to a remote computer over a network, such as the Internet.

You upload clips to YouTube.

You copy clips to your computer's hard drive.

You import media into Resolve.


You're correct. I should have specifically stated that "I copied clips to my hard drive."
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kayakfishingaddict

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Re: Multicam, Sync Bin, or ? - Which feature am I looking f

PostTue Nov 05, 2019 12:12 pm

Jim Simon wrote:
kayakfishingaddict wrote:am I supposed to change my process so that I capture clips together, including audio, by turning on both cameras and audio, hitting record on all three, and then stopping all three at nearly the same time


That.


If by "That" you mean "Yes" then I agree, the current software algorithm is not built with my scenario in mind, it's built for what I would term, "manually organized clips that overlap in a simple fashion." That expression is key. Please, let me explain....

Algorithm Discussion
I don't have any specific knowledge of the algorithm used to produce the alignment of clips. However, with the results I've been seeing over the past few days as I play with ~80 clips in DR16, it seems that the DR algorithm wasn't built to take a batch of non-contiguous clips and synchronize them into a single timeline. The algorithm needs assistance to produce that desired outcome.

What you give it should overlap in some manner. In addition, the overlaps need to be simple. For example, if you have GoPro footage where a camera clip is split into two chapters, and you have a second camera clip that spans both chapters, the algorithm won't align the chapters of the first clip end-to-end for you. It will align the first camera's chapter clip with the second camera clip, but the matching stops there. Thus, the suggestion to stitch together chapters of GoPro footage first, is a good one that would tremendously help the algorithm perform the synchronization as a user would expect.

The desired outcome.
To be clear, my desired outcome is for the algorithm to take all of my footage, shot via multiple GoPro cameras, each being turned on and off over time without any prior thinking about synchronizing scenes, and at the press of a button, synchronizing all of that footage together onto a single timeline that allows me to "delete gaps" and then edit the footage and select camera angles as if I was a director.

The algorithm needs assistance to produce that desired outcome.
I'm hopeful that with the following "assistance" the current algorithm will work. I'll test this out today. Here's the workflow I'm going to try:

1. Record with a single audio track on a separate audio recorder that can stay on during the entire filming session. My hypothesis is that this will present the input that the algorithm expects in this scenario, namely a single master clip to align against without any footage gaps for it to deal with.

2. [optional] Pre-stitch GoPro chapters together. If #1 alone doesn't work to fix things, this will certainly help. But I'm hoping that #1 does the trick and that the algorithm will then see chapter 2...n, as clips that align to the single master audio clip.

That may be all that's necessary to create either a single synchbin or multicam clip that could be viewed as the "source" with which to build from.
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Michael_Andreas

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Re: Multicam, Sync Bin, or ? - Which feature am I looking f

PostWed Nov 06, 2019 4:15 am

kayakfishingaddict wrote:
Michael_Andreas wrote:...I have a single clip from each camera. I found a utility that would append my continuously sequential GoPro clips together.


After further experimentation, it does seem that would help the algorithm. Please let me know what utility you use. I've been looking for one that would automatically use the GoPro chaptering filename convention to stitch multiple chapters together.


I have used a program called MP4Joiner to copy all the clips into one continuous file. But it's been some time since I've actually used it. You'll have to try it out for yourself.
_________________________________________________
DR Studio 16.1.1.005 - Win10 Pro 64b - i7-6700K@4GHz - 32GB RAM
- NVIDIA GeForce GTX1070 8GB, "Studio" driver 431.86
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kayakfishingaddict

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Re: Multicam, Sync Bin, or ? - Which feature am I looking f

PostFri Nov 08, 2019 11:46 pm

Ok, so I ran the experiment that I mentioned. Unfortunately, it seems that it almost worked, so I'm going to try to document what I think is a bug in DR16's Multicam synchronization support.

The experiment
I ran two cameras and turned off/on each camera at different times while also recording with a Zoom h1n audio track.

Results
DR16 synchronized all of the footage only where there was a camera continuously on. The moment that both cameras go off, it doesn't matter after that point if you turn one or both back on, the DR16 algorithm seems to quit after that point. In my case, I turned off both cameras. Then waited. Then turned one of them back on and expected it to by synchronized against the continuously running audio track and it wasn't. This seems like a software bug to me.

Bug Scenario - in case the developers read these messages
When you film with a GoPro and multiple cameras in my scenario. Your main camera films continuously while you turn the second one on to capture some action from another angle. Thus, your second camera, by design, is off most of the time. So, let's say it's off and your main camera's battery runs out. For a period of time you have a gap where neither camera is on while you change the battery. Although you're still recording audio with your zoom h1n. DR fails to sync footage after the battery change.
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Michael_Andreas

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Re: Multicam, Sync Bin, or ? - Which feature am I looking f

PostSat Nov 09, 2019 5:26 am

Here's an idea. Record some random footage with your GoPro longer than the audio channel, then replace the GoPro's audio track with the external recorder. To make this work, make sure the GoPro has a large memory card and power your GoPro from a USB battery bank. Sync the video you just created with your other video, then briefly select that footage to get the audio you want, then switch video only to your real cameras.
_________________________________________________
DR Studio 16.1.1.005 - Win10 Pro 64b - i7-6700K@4GHz - 32GB RAM
- NVIDIA GeForce GTX1070 8GB, "Studio" driver 431.86
- C: Drive 250 GB SSD - Project/Cache Drive 1 TB SSD
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kayakfishingaddict

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Re: Multicam, Sync Bin, or ? - Which feature am I looking f

PostSat Nov 09, 2019 6:13 am

Michael_Andreas wrote:Here's an idea. Record some random footage with your GoPro longer than the audio channel, then replace the GoPro's audio track with the external recorder. To make this work, make sure the GoPro has a large memory card and power your GoPro from a USB battery bank. Sync the video you just created with your other video, then briefly select that footage to get the audio you want, then switch video only to your real cameras.


Hmmm, I believe I understand your thinking. I think you're stating, that one possible hack/work around would be to change the long running audio clip into a long running video clip. Since DR seems to trigger off of the video for multicam, this would fool DR into synching the entire off/on session as if it were truly a single multicam session. Then, just ignore the long running video.

I gave that a try by simply converting the audio to video by adding an image and converting it to .mp4. Unfortunately I get the same results. The last camera 1 clip does not sync although the audio does match up near the end of the hacked .mp4 clip. I think this just means that my assumption of DR triggering off of the video is incorrect, although there's still a bug in the software.
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Michael_Andreas

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Re: Multicam, Sync Bin, or ? - Which feature am I looking f

PostSat Nov 09, 2019 6:19 am

I've never been able to get more than one set of concurrent clips to sync. Had to sync the camera restarts manually, but it's been awhile since I made a multicam. So I guess it was not fixed in version 16.

If I do it again, I'm going to see if free-running timecode works better, even though I'll probably have to manually sync it anyway but at least it should be within a couple of seconds if I carefully set my camera clocks.
_________________________________________________
DR Studio 16.1.1.005 - Win10 Pro 64b - i7-6700K@4GHz - 32GB RAM
- NVIDIA GeForce GTX1070 8GB, "Studio" driver 431.86
- C: Drive 250 GB SSD - Project/Cache Drive 1 TB SSD
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kayakfishingaddict

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Re: Multicam, Sync Bin, or ? - Which feature am I looking f

PostSat Nov 09, 2019 6:28 am

kayakfishingaddict wrote:
Michael_Andreas wrote:Here's an idea. Record some random footage with your GoPro longer than the audio channel, then replace the GoPro's audio track with the external recorder. To make this work, make sure the GoPro has a large memory card and power your GoPro from a USB battery bank. Sync the video you just created with your other video, then briefly select that footage to get the audio you want, then switch video only to your real cameras.


Hmmm, I believe I understand your thinking. I think you're stating, that one possible hack/work around would be to change the long running audio clip into a long running video clip. Since DR seems to trigger off of the video for multicam, this would fool DR into synching the entire off/on session as if it were truly a single multicam session. Then, just ignore the long running video.

I gave that a try by simply converting the audio to video by adding an image and converting it to .mp4. Unfortunately I get the same results. The last camera 1 clip does not sync although the audio does match up near the end of the hacked .mp4 clip. I think this just means that my assumption of DR triggering off of the video is incorrect, although there's still a bug in the software.


Ok, that didn't work, but just to ensure that DR would sync the clip I next chopped the audio file inside of DR and rendered that out. I then imported that rendered audio and created a new multicam clip with the video that wouldn't sync and that audio and it worked. Of course this does not produce the desired outcome as I now have two overlapping but not synchronized multicam clips when the desired outcome is just one. What it does prove, at least to me, is that (1) DR can synchronize the clip to the audio, and (2) it just refuses to do that in the same multicam clip. That to me is clearly a bug.

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