Scene Detection

miketpl wrote on 6/25/2003, 12:54 AM
I am trying out a demo version of Vegas 4. Can anyone tell me how scene detection works? Does it detect scenes only by using the DV timeline or can it create a new clip by detecting changes in the scene? I have tried to capture a VHS tape using a Canopus ADVC100 that converts the signal in to the DV format but without a timeline. All I gotten is a single clip rather than the expected 5.

Comments

whitneyd wrote on 6/25/2003, 1:11 AM
Do a search on my name to find extensive help...................
Grazie wrote on 6/25/2003, 2:58 AM
Hiyah!

V4 and as far as I'm aware all NLE s/w will only capture one large AV>DV conterted file. Analogue, by defination does not come with DV timecode. I don't use the Canopus device, but I do use the Dazzle Hollywood Bridge [DHB]. This DHB only provides a singlestream of DV converted video and audio. thta's it in a nutshell!

As far as I know, and can imagine, I think there are only 2 work-arounds you could employ, I've done both:

1 - Capture complete footage. Put this up on the T/L and do your own scene selection from there.

OR - this is neat!

2 - If you've got an AV in enabled DV cammy, capture to a DV tape. This will provide a timcoded tape. Again you will not be able to make use of the "Scene" detection function - scene detection in V4 relies upon the "Stop/Start" original scene creation while on the shot itself - BUT, now having a timecode you could use the "Advance Capture" batch capture feature and make use of the now timecoded tape - yeah?

There is something else you might consider - and I haven't used it - I understand that Scenealyzer WILL detect "scenes" in the way you wish - I'm not sure it works with a streaming AV>DV - I cna't see how it would control a non-DV device, ie your Canopus to AV VCR! Go to their site and make up your own mind.

However, as I suggested, now having a DV timecoded project on a DV tape I'm presuming Scenealizer could make use of it.

My thoughts are that Scene detection can create a mass of scenes which will become at least for me, unwieldy and makes my work flow messy - yeah? I CAN see the value of scene detection where there are a mass of Stops/Starts - lots of small takes, ie from a fast moving event shoot or planned shoot - but otherwise you need to think long and hard where and why you would need to use scene detection. get back to us and tell us - yer never know there maybe another way of doing this!

You need to recognise that a AV>DV converted stream is regarded as one long lump of video/audio.

So, you have some options. The question I would like you to think about is this - Why are you knocking yourself out attempting to "separate" only 5 scenes? - If I thought you were attempting to manage something like 50 or 100 or over then I could see a reason to look for a way to do this. But only 5? - I'm presuming you're - like me - wanting to "investigate" what this remarkable s/w can do. Believe me, V4 Scene detection works. In my opinion, is it something of value for me? I haven't yet attempted a porject why I need it. I'd rather EITHER do - Advance Capture, batch capture OR get the footage onto the T/L and do my slash and rip there.

Your AV>DV Canopus is still very useful. You could manually start and stop capture approximatley at the 5 points you wish - give it some overun on both sides of the scene for future editing options. - If you don't have a AV in DV cammy BUT you do have DV in enabled cammy, I suppose you could AV>DV from your Canopus, take the DV line out and record that to your DV in Cammy. This will get you your DV Timecoded tape, And again, from there you could do Advnce Capture batch capture, from there. OR again research Scenealyzer.

Mike, could you explain your comment, "....but without a timeline". Am I missing something here?

Hope this helps,

Grazie
jetdv wrote on 6/25/2003, 10:21 AM
Vegas detects scenes based on the Date/Time embedded in the DV stream. Capturing VHS through the ADVC-100 will NOT allow scene detection. You may also want to take a look at the Vegas Tips, Tricks, and Scripts Newsletters.
rmack350 wrote on 6/25/2003, 2:57 PM
Yep. Scene detection is based on "Time of Day" stamp on the DV tape. This means that if you have a DV camera you need to set the time for this to work.

Scenalyzer is supposed to do optical detection. That's what you're asking for but I'm not sure if it can do it on the fly with a video stream.

The idea of dumping your analog to DV tape is a great idea. That way you get time code and many things become possible.

I've had many instances where I needed to recapture clips from a year ago. For this I think that scene detection is vital. However, Vegas Vidcap is a little unwieldy when it comes to renaming all of the clips. I wish you could export a tape log to Word or Excel, make the changes, and then import back into vidcap. Or import into a veg file bin and then recapture that way. Or even make the text file by hand while logging on location and then import for capture.

Rob Mack
Grazie wrote on 6/25/2003, 3:04 PM
Rob, thanks for the recognition! I would be neat if Ed [ jetdv] knew if this could be done with Scenealyzer . . . .

I'm going to put on my left brain thunk about the Word and Excel thingy - . . .hmmmm....

Grazie
jetdv wrote on 6/25/2003, 3:22 PM
Scenalyzer DOES include optical scene detection. Can't vouch for how well it works, I've never tried it.
dat5150 wrote on 6/25/2003, 3:27 PM
I bought Scenalyzer and am using it now to capture analog video(before conversion to DV). It works great. The only issue it has is that the optical detection sometimes gets fooled and you wind up with clips of only a few frames that come from one shot. It is a minor nuisance. I give Scenalyzer two thumbs up...highly recommended for analog.
Galeng wrote on 6/25/2003, 5:03 PM
Have also used Scenalyzer and it does a pretty good job. Studio 8 will capture based on scenes rather than time code. I compared the two and they seemed to work about the same. I don't know about going through a av/dv converter though.

Galen
johnmeyer wrote on 6/25/2003, 5:54 PM
Scenalyzer is the way to go for analog scene detection. The freeware version (Scenalyzer) lets you detect scenes in already captured video. The shareware version (SCLive) will do scene detection while you capture. Simply hook up your analog video source to your DV camera, enable pass through (or record to tape), and let SCLive do the rest. It doesn't catch every scene and it can get fooled by someone quickly walking in front of the camera, but it's pretty darn good.

Here's the thread that Whitneyd referred to:

Scene Detection
rmack350 wrote on 6/26/2003, 12:28 AM
What I really dislike is starting a response and then realizing I need to credit someone up the thread but I can't remember who. Just lazy. I could copy my text to the clipboard and then just back up and check...

Anyway, you were spot-on, Grazie.

Rob
kentwolf wrote on 6/26/2003, 12:40 AM
For Scenalyzer to do optical scene detection, that does work...but...

It breaks each scene into a seperate file.

With this file break, I noticed a slight, but repeatable "popping" (audio) sound at the beginning of each clip/scene.

I personally found it best to just "tough it out" and manually cut each scene. Accurate, no popping sound, but it is extremely time consuming...
rmack350 wrote on 6/26/2003, 12:46 AM
Well, the results are in. ScenalyzerLive can do optical scene detection on the fly from analog sources. Should work then with stuff being converted through a camera or through a converter like the ADVC100.

So how easy is it to rename the resulting clips? And can it export or import a text file for batch captures? That would probably make me start using it.

On the text file front, I wish that there was some functionality like Media100. There you can take a tab-delimited log file and import it into a bin as a set of media clips. From there you select the clips you want to aquire and get them. The reason I really really want this is that I work in a Media100 shop. I'd love to take the same logs we use for M100 and use them the batch capture the footage for my own usage. Especially if it would give me a descriptive name or comment field.

The log files have:
REEL NAME
TRACK DATA - "V, A1, A2" Shows which tracks to capture, any combo of video and audio tracks. This may be irrelevant to Vegas
IN TC
OUT TC
DESCRIPTION - could be used for file name and/or comment field
COMMENT - "Good", "NG", "Second Sticks", "Tail Slate", whatever you want to say. Use it for sorting the log entries.

That's all. Pretty simple. We do it in Word and then export as tab delimited.

Rob Mack
Grazie wrote on 6/26/2003, 1:24 AM
Thanks Rob! - I do read peoples' posts very carefully, try and "deconstruct" what they are saying, try and remember [that's the hard part!] what it was like for me when I first started this NLE stuff and then attempt to construct an answer from where that person is, now.

I'm not as technically competent as many, many here. But that has never and will never stop me from trying to have a go! - Yes, a little knowledge is a dangerous thing. And yes, I've made some real "bloopers" here - we all do - even the best. It's the only way I know how to learn. Consequently, I'll keep on feeding back that which I think - IMHO - willl move the debate along.

I feel that scant knowledge is better than no knowledge at all, even if it means I look stupid in suggesting something. Hey, I am that guy who didn't realise the colours on the tv, I use for monitoring, weren't set - at all! - Now, having set the colours as they should be, I've been able to turn a less than average TV into a worthy partner for V4. Where did I learn this vital piece of information? Here! It was something that BillyBoy said that made me think about this.

Okay, this is a plea to those highly competent V4 users out there - please read what you write and truly think if this would make sense to someone who is starting out or from a position a long way from yourselves - yes, I know most do. To try and get inside somone's head through this "forum" medium is mightily difficult. But it can be done - there are some real masters out there who do do this - you know who you are - I wont embarrass them here. They take time to "unravel" what a "postee" is really saying - this takes time, it may take 10 or 20 posts to get to the nub of a problem. If others find this a "pain", then leave the thread and move on to another thread - it's as easy as that. It can be frustrating to read the "same" issue coming up time and time again - this is the cost of having new-blood coming onto our forum - the value is that it is a fresh set of eyes, a fresh approach to V4, a fresh real world experience has come here - be understanding, chances are that person may turn out to be a valuable and valuing V4 operator. And in turn a person that can "give-back" help and in time assistance to others. But, what really gets up my nose, is a Zen-like response to someone who is obviuosly at their whitz-end. Something along the lines of a MS error message. Know what I mean? - Oh let me share this with you all - I had a real "winner" sometime back with MSWord. I did something stupid and up popped a massive, and I mean MASSIVE white screen, with maybe 10pt arial message in the middle saying - "WORD Can not Edit the unkown" - . . . well, I nealry fell off me chair! Scared the daylights out of me! Tales of the Unexpected time! - Real creepy stuff.

Anways back to this - I will still get it wrong - I do rely upon others to pull me back on track. I still have a mental block about interlace and de-interlace, alpha channels and trannies, RGB and Y/C values - but I'll get there - correction I am getting there.

I treat this forum as my online college - where I can learn masses and have and share a bit of fun.

Apologies to those that have taken the time to read this so far - it's been on my back for sometime now. Being told by you, Rob, I was "spot-on" makes my efforts worthwhile - big thanks Robbo!

Now where is that project I was going to finish ?. . . . .

Grazie
Grazie wrote on 6/26/2003, 1:28 AM
Rob! Excellent news! That's some software eh?

Grazie
miketpl wrote on 6/26/2003, 1:42 AM
I am a jaded Studio 8 user who was tired of dealing with the Studio 8 problems with stability. There form was rude and provide little help other than to make there rude comments. I mention this because I am looking for a new product to use and was delighted to receive 12 solid and respectful answers from the Vegas form. This says a lot for the product and the people that use it. I would like to thank Grazie for the time he spent on his response that answer my question and Whitneyd for the link, I tried using search to find the answer but only pulled up sales info, I think I used the wrong search box!

I stated 5 scenes because I did not want to check, but now I have and it’s 112. Studio’s storyboard layout works very well with optical scene detection. You have an album that shows the clips and they are in order, this makes it very easy to do basic editing. However, my VHS camcorder has flying eraser heads and there is no need to trim each clip so I would not take the time with Vegas to create 112 clips, this would make Vegas’s timeline very workable and if it does not crash like Studio then much better.

I will also look into Scenalyzer.

Thanks for all your help.
Grazie wrote on 6/26/2003, 2:13 AM
Hiyah Mike! I wondered where you'd gone to! - Thanks for the acknowledgement. There are many many people eager to assist here. Welcome aboard.

You know what you've done for me? You've made me rethink my own approach to event filming.

Over the past month I've trod a bit of a road to Damascus experience.

I've been booked on 3 occasions to capture 2 weddings, as a 3rd stringer and a a 1st Holy Communion. My best work has been where I've kept the XM2 rock solid and let the action develop in the framing I set - A Scene! Stop the Xm2 reframe, zoom or pan and then and only then hit the red button. The reaction, from my vidpro colleague who booked me, and who also does the editing, was truly, embarrasingly good. Now my point here is that, the way I film dictates the way I edit. Or rather the other way round - my I edit dictates the way I film.

An example: I followed up the last Saturday's wedding job, by on the Sunday, filming a remote controllers club meet at a lake - lots of excellent models etc - but, I did this shoot in mostly the same way. Having had the opportunity to read and then respond to your initial question, I then, yesterday, re-enabled V4's Scene Detection and captured this footage using scene dtection. I too now have something like 120 separate, nicley divided scenes. I'm starting to realise this makes for a better workflow and I'm not all over the place looking for "that" scene or trying to get my head around stupid uneditable zooms and pans. I truth, I really don't need to "edit" anything - the story is all laid out, as it happened. Now, the next big challenge, will be to edit to make something BETTER than just what I filmed. To make a viewable finsihed product where the audience is aware of the edit process AND the edit enhances rather than detracts from the experience - of course editing is a lifelong accumalation of skills and tools learnt by "doing" masses of work. I must learn to crawl before I think I can even walk - forget about running! But hey, it is very tempting with all the features available within V4 just nip up to the Buffet and say . . ."ooohh that would be good! bet that tastes nice! Oh look at that colour!" etc etc

Yes - I've learnt a mass from this YOUR thread - and it's gone way beyond the actiual techie bit of which or what method to use for capture - for me, it has gone to the core of my own "style" of filming - interesting . . . .

Much obliged for this learning experience - I do mean this!

Grazie