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TOPIC: LWKS for research - syncronizing larger amounts of video material

Re: LWKS for research - syncronizing larger amounts of video material 6 years ago #43816

  • Hillnhutter
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Hello,
You guys ended up in an interesting discussion. I will leave it by the last Amen and would rather direct focus my the initial question again ...

I found a simple possibility to sync the films from my 6 cameras. I did not manage to sync the films automatically, may be I'm just not capable to use the functions in lightworks, or the video material that comes from my cameras does not contain the necessary information.

What I did:

In an edit, i just added 6 video tracks (and deleted all audio tracks). The material from camera 1 goes to track 1, from cam 2 to track 2, and so on. I sync the cameras by just moving the videos forward and backward on the timeline. To review the video material, I just switch on and of the track I want to see. I do not need to see all videos simultaneous - my laptop doesn't allow me to anyway.
Despite my large files and full HD, each video plays without lagging, and switching between tracks goes quick.

I just have two questions:

1.My cameras split up the film material in 3 data files (each 4 GB). Between the files there are 4 seconds missing. When I place the 3 files in a row in the timeline the second video is 4 sec out of sync, the third 8 sec. I do not manage to move these files for 4 seconds along the timeline. Is there a way to do that, or do I have to insert an empty (black) video clip of 4 sec length?

2. Are there keyboard short cuts to switch on and of tracks? That would help me obviously a lot.

Thank you in advance!

Re: LWKS for research - syncronizing larger amounts of video material 6 years ago #43818

  • fischerb
Hillnhutter wrote:
I found a simple possibility to sync the films from my 6 cameras. I did not manage to sync the films automatically, may be I'm just not capable to use the functions in lightworks, or the video material that comes from my cameras does not contain the necessary information.


did you study the section "Chapter 11: Editing When Playing Multiple Source" in the user manual?
(www.lwks.com/index.php?option=com_docman&task=doc_download&gid=22&Itemid=189)

i don't think, your files will miss any essential information. even if you don't have any useful time code in them, you may use "frame lock" to synchronize your sources.

Hillnhutter wrote:
What I did:

In an edit, i just added 6 video tracks (and deleted all audio tracks). The material from camera 1 goes to track 1, from cam 2 to track 2, and so on. I sync the cameras by just moving the videos forward and backward on the timeline. To review the video material, I just switch on and of the track I want to see.


that looks like a very creative approach
i don't know how good this setup will perform in comparison to usual sync groups.

Hillnhutter wrote:
I just have two questions:

1.My cameras split up the film material in 3 data files (each 4 GB). Between the files there are 4 seconds missing. When I place the 3 files in a row in the timeline the second video is 4 sec out of sync, the third 8 sec. I do not manage to move these files for 4 seconds along the timeline. Is there a way to do that, or do I have to insert an empty (black) video clip of 4 sec length?


the 4GB filesize limitation is typical for old FAT32 filesystems. if your files are part of a "mpeg transport stream" (*.MTS or similar) you can concatenate the parts without this annoying gap using the right tools. for example ffmpeg can do this job (see: ffmpeg.org/trac/ffmpeg/wiki/How%20to%20concatenate%20%28join,%20merge%29%20media%20files ), but there are also some more user friendly tools with graphical user interface available.

having one simple continuous source files makes it much easier to handle the synchronization, but lightworks can also substitute clips by more complex [sub]edits in most cases.

Hillnhutter wrote:
2. Are there keyboard short cuts to switch on and of tracks? That would help me obviously a lot.


yes -- the operation "toggle V[1-6]" -- is usually bound to a shortcut. just use the keybinding reconfiguration dialog to find out your actual keybindings.

i'm not sure if toggling the activity of a video channel will immediately change it's visibility while playing?
Last Edit: 6 years ago by .

Re: LWKS for research - syncronizing larger amounts of video material 6 years ago #43821

  • RWAV
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Agrre with what @fischerb has written, just a few additional comments.

i don't know how good this setup will perform in comparison to usual sync groups.

This should be perfectly good for your situation.

concatenate the parts without this annoying gap using the right tools. for example ffmpeg can do this job

I'd leave them as the size your camera writes - sure you can combine them but then the LW impoert for each file is so much longer and if there is a problem?

Is there a way to do that, or do I have to insert an empty (black) video clip of 4 sec length?

That's probably the easiest way to do it - generate a 'black' tile, mark and park exactly the length you need - put it out of the way in a corner of your screen as a tile, use that every time you need to inrset your space.

yes -- the operation "toggle V[1-6]"

also if you 'chord-click' (hold down right key, tap left key) on a track button it will select just that track and deselect all others.
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Re: LWKS for research - syncronizing larger amounts of video material 6 years ago #43843

  • Hillnhutter
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Hi again,
thank you for the replies. Yes, I got the sync groups working now. Thanks. For the sync groups I need to attach the 4GB files. The method just to fill in 4 sec of empty video seems most simple to me.
But I have a bigger problem now... I need the videos to replay without lagging as I measure the pedestrians walking speed as a frequency. If the video lags, I'm in trouble. I also need to run the videos forward and backwards. It works ok forward, but when I switch to backward (even after having first stopped the video and then started backward), the video stops, or lags.
I have switched of live video editing and concurrent players so only one video window is active. The other window is just updated when I stop the film. It works ok forward, but when I change replay to backwards it does not. The same happens in "my method" with more video tracks.
Obviously my computer does not manage the task.
What could I do? Rendering the mpg4 files to mpg2? I tried re-rendering with eyeframe, which resulted in a 10 times file increase - 600GB for one film session - Ill do 15 of them. What conversion setting could I use? Would it really help?
If it all doesn't work - I just have to review the films without synchronizing... it works, but takes much more time.
Someone here suggested a simple video mixer program as an alternative program. Would that work any better? The files to replay are still large...
Thanks!

Re: LWKS for research - syncronizing larger amounts of video material 6 years ago #43846

  • fischerb
Hillnhutter wrote:
But I have a bigger problem now... I need the videos to replay without lagging as I measure the pedestrians walking speed as a frequency. If the video lags, I'm in trouble. I also need to run the videos forward and backwards. It works ok forward, but when I switch to backward (even after having first stopped the video and then started backward), the video stops, or lags.


if you have to play backwards, transcoding to a more edit friendly format would help a lot!
you could also decrease the resolution. usable 720p mpeg2 iframe only at 50-100 Mbps should not need much more bandwith (=storage) than your 1080p source material. just do some short tests, what resolution and bandwidth you really need, to have enough image quality for your research. preparing the source matrial this way, you should not see any performance problems, even on very weak machines.

Re: LWKS for research - syncronizing larger amounts of video material 6 years ago #43847

  • RWAV
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It works ok forward, but when I change replay to backwards it does not. The same happens in "my method" with more video tracks. Obviously my computer does not manage the task


Both your computer is not up to the task of the required real-time relentless mathematics converted into images and the H264 codec was never intended for this kind of back-forward-back work.

If you can transcode to an SD 16:9 picture at DV50 data rate as an .avi (I think that's possible in LW - about 7.5 MBytes/sec don't know about eyeframe,) you should have adequate resolution and performance, I think. (In a typical multiplexed broadcast transport stream an SD MPEG-2 Video rate is under 1 MByte/sec. Sure that's had some spectacularly brilliant compression work perfumed on it - but if you increase that rate 8 times and take way some of the compression magic - you still should have a pretty good picture for your purposes.
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Re: LWKS for research - syncronizing larger amounts of video material 6 years ago #43851

  • fischerb
RWAV wrote:
If you can transcode to an SD 16:9 picture at DV50 data rate as an .avi (I think that's possible in LW - about 7.5 MBytes/sec don't know about eyeframe,) you should have adequate resolution and performance, I think.


just as a small remark to avoid confusion: RWAV is speaking about "Bytes per second" and i was given values in the more common bandwidth notation of "Bits per second"... so we are roughly saying the same

Re: LWKS for research - syncronizing larger amounts of video material 6 years ago #43855

  • Hillnhutter
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I tried to render from my mpg4 to an SD DV 50 - that did not work, what comes out was just too bad. Tried then SD DV100 - that was ok. But the file size increased by factor 4.5!

I have also a Sony camera (that I use for manual filming) that does AVCHD files with 1440 resolution. Those files work well - forward and backward.
So I tried to render to that format - quality was better then the SD DV100 format and the file size increased just by factor 1.6!!!

What do you think?

I'm not sure if LWKS is the best solution for file conversion. I need it to run over night, so I need to be able to place all files at once and let it go... Any suggestions? Guess Eyeframe does not AVCHD files - at leas I don't see something that looks alike.

Re: LWKS for research - syncronizing larger amounts of video material 6 years ago #43857

  • fischerb
Hillnhutter wrote:
I'm not sure if LWKS is the best solution for file conversion. I need it to run over night, so I need to be able to place all files at once and let it go... Any suggestions? Guess Eyeframe does not AVCHD files - at leas I don't see something that looks alike.


no - lightworks is not the right tool to do file conversions or transcoding. i would use plain ffmpeg for such a job. this gives you a maximum of control over any relevant transcoding option. but there may be some useful tools around to manage all this settings through a more comfortable gui.

simply try the following options or something similar:
 ffmpeg -i inputfile 
 -vcodec mpeg2video # the target format
 -intra             # use the i-frame only variant
 -b 50m             # the bandwidth
 -an                # no sound
 -s hd720           # the resolution
 output.mpg

Re: LWKS for research - syncronizing larger amounts of video material 6 years ago #43858

  • Hillnhutter
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Hmm, I think I'm too much of a nerd in this terms. I do not really understand what you posted. I think I need a GUI. ... ore a "nerd explanation" of what you just posted.
I could do the specification of the export from LWKS - pressing on buttons and see what happens... but I don't really know what LWKS did or what the AVCHD file really is

Re: LWKS for research - syncronizing larger amounts of video material 6 years ago #43861

  • Hillnhutter
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Well I found a converter that suits my needs (and capabilities ). That does a MPG2 file from my MPG4 files with an increase of file size by factor 1.5. That seems fine. It seems reasonable quick as well. Hope it keeps running over night.
Thank you guys for you help!

Re: LWKS for research - syncronizing larger amounts of video material 6 years ago #43865

  • fischerb
Hillnhutter wrote:
Hmm, I think I'm too much of a nerd in this terms. I do not really understand what you posted. I think I need a GUI. ... ore a "nerd explanation" of what you just posted.


sorry! -- sometimes it's very hard to find the right starting point to explain solutions in a more useful way...

ffmpeg (www.ffmpeg.org) is a very simple command line program. there are lots of applications using this tool in the background, making it easier to access it's possibilities. eyeframe converter, a tool used by a lot of people here in the forum, is just one of them. but there is an important drawback with all this helpers/simplification: you don't see/control anymore what's really going on behind the surface! that can be very important -- for example: if you can choose only the target format "mpeg2" but not the very important additional option "-iframe" (that stands for the "i-frame only" variant of mpeg2) you will get again a result, that does not work very well when you want to play it backwards. the same counts for a manually choosen bandwidth. that's why i strongly suggest to do it the hard way and use the command line (or a very powerfull and complex gui-wrapper). i know, it may look a little bit strange and uncomfortable first, but it will give you a lot of power back in your hands, when you get used to it.

sure, it would be much easier, if lightworks itself would give us better external transcoding possibilities, so that i could give you just a line of ffmpeg options and you only had to copy and paste it somewhere in little text-box... -- but i don't think, we will see such an simple transcoding helper in lightworks in the near future...

Re: LWKS for research - syncronizing larger amounts of video material 6 years ago #43872

  • khaver
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fischerb, you can edit and add ffmbc command lines in eyeframe. In the codecs options dialog box select a preset and click the button on the right. Edit the command line and either save to a new preset or overwrite the existing one (not a good idea). If you save to a new file, you will have to close and re-open eyeframe for your new preset to be available.
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Re: LWKS for research - syncronizing larger amounts of video material 6 years ago #43878

  • fischerb
khaver wrote:
fischerb, you can edit and add ffmbc command lines in eyeframe.


ohh! that's fine to know!

as you may know, i'm working nearly exclusive on linux workstations, where EFC is not available.
i even don't miss it so much. there are so many other ways to the same job, and i prefer more unix like batch processing.

khaver wrote:
In the codecs options dialog box select a preset and click the button on the right. Edit the command line and either save to a new preset or overwrite the existing one (not a good idea).


that's exactly the behavior i always suggest to include in lightworks itself!

everything would be so easy, if the developers of lightworks would make it possible. it would work on any platform, it could be much more efficient (by using direct pipes instead of huge temporary files), and the user community could concentrate a little bit more on the real thing: instead of only making pointless propaganda about the wonderful value of this very accessory, they could finally search for the most adequate ffmpeg options and share them with colleagues here in the forum. for new users like Hillnhutter it would be a lot of help to just copy and past the right recipe, while others could extensive customize the transcoding/export themself.

but -- thanks khaver! -- i hope you know, this sarcasm has nothing to do with your very competent and illuminating role in this forum...
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Re: LWKS for research - syncronizing larger amounts of video material 6 years ago #43881

  • donkpow
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@fischerb,

I don't understand what you want. Either you want an import transcoder with a complete and complex set of tools like ffmbc and ffmpeg or you want a push button solution where lwks sets all the parameters for imports.

It's not like there are that many options for editable formats. Using this thread as a platform to force your agenda is not a pleasant read. In this case, all solutions are at hand for a problem that revolves around transcoding time and storage space. What is your advice on this occasion? Either you have a solution to reduce transcoding time and storage space or you don't.
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