Synchronised video playback

[Paul Strickland]

Hi there, I'm planning a screening of the 1927 Abel Gance film, Napoleon. For those unfamilier with this silent epic, the final section of 20 minutes is a triptych of 3 4:3 screens. To achieve the full effect of this, I'm planning to have 3 projectors, each showing 1 of the panels, as intended when the film was made. Those nice folks at the BFI have made all of the individual video parts available to achieve this. Although a 4:1 widescreen version is supplied it's not practical to show this without hiring in a much bigger projector, and suffering a significant drop off in quality.

So what I have is 3 1080p 4:3 videos which I need to show using 3 projectors, in sync. My initial thoughts were to have 3 bluray players, somehow manually synced, but this obviously has some risks, especially live with a paying audience. So I'm keen to hear from anyone who has achieved anything similar.

Oh, and the other complication is that I don't have much budget to buy new kit.....

[DB83]

And did those nice people at the BFI also give you permission to play these disks in public to a paying audience ?

[Paul Strickland]

Indeed they did, subject to the usual fees

[video.baba]

Hi there, I'm planning a screening of the 1927 Abel Gance film, Napoleon. For those unfamilier with this silent epic...

I love the way you said 'epic'!!!

My father was much older than me, (a big family), he would love watching all the old movies, the classics. I guess coming home from school, wanting to blast the usual shit from the pop charts was out of the question. Dad was watching TV! I remember coming home from school one day ( a long time ago! ), we had tea (English for Dinner), and a movie started on TV. My God! An ancient black and white SILENT!!!! movie - please kill me! However, got engrossed, movie was amazing. I don't know its name, based on WWI, guy coming back from the War, one leg, rushing on crutches to be back with his wife, I think that was the closing scene. Even as a young teenager, it was 'moving'. They surely don't make them like that anymore.

Sorry. Nothing to do with the OP question but just wanted to comment.

[Paul Strickland]

At five and a half hours, this definitely qualifies as an epic

[video.baba]

Napoleon (1927)

According to IMDB:

4 hr (240 min) (West Germany) 
3 hr 42 min (222 min) (DVD) (Spain) 
5 hr 30 min (330 min) (2000 restoration) (UK) 
3 hr 55 min (235 min) (1981 restored) (USA) 
5 hr 13 min (313 min) (20 fps) (cinémathèque française print) 
5 hr 33 min (333 min) (Blu-Ray digital restoration) (UK)

I don't know why but I really have the feeling I want to check this out.

[smrpix]

Hi there, I'm planning a screening of the 1927 Abel Gance film, Napoleon. For those unfamilier with this silent epic...

I love the way you said 'epic'!!!

My father was much older than me, (a big family), he would love watching all the old movies, the classics. I guess coming home from school, wanting to blast the usual shit from the pop charts was out of the question. Dad was watching TV! I remember coming home from school one day ( a long time ago! ), we had tea (English for Dinner), and a movie started on TV. My God! An ancient black and white SILENT!!!! movie - please kill me! However, got engrossed, movie was amazing. I don't know its name, based on WWI, guy coming back from the War, one leg, rushing on crutches to be back with his wife, I think that was the closing scene. Even as a young teenager, it was 'moving'. They surely don't make them like that anymore.

Sorry. Nothing to do with the OP question but just wanted to comment.

Pretty sure you saw "The Big Parade." Amazing movie -- including an audacious scene where an American soldier is trying to flirt with a French girl and they can't understand each other's language -- and the whole thing is silent!

[johnmeyer]

So what I have is 3 1080p 4:3 videos which I need to show using 3 projectors, in sync. My initial thoughts were to have 3 bluray players, somehow manually synced, but this obviously has some risks, especially live with a paying audience. So I'm keen to hear from anyone who has achieved anything similar.

I won't waste time making ridiculously pointless and unhelpful comments about licensing (what was the point of that?? ).

Instead, the real focus here is getting all three projectors to start at the same time. To do this I must first assume that the three films are all precisely the same length and sync perfectly (i.e., no missing frames in one film that are not also missing in the two other versions). If not, you need to line them up in your NLE and trim until they match perfectly.

Next, you have to be able to get three players to start at the same time. Since these need to be synced down to the frame, even at 12 fps (or whatever the original frame rate might be) you are going to have problems, because you have to hit the "start" button on all three players within 1/12 of a second of each other.

The only way I can think to make that work would be to combine the three videos together into a single 5760x1080 video file and then somehow feed that to each projector simultaneously and have the projector, or some other device, crop that signal to each projector. As I'm thinking about this, perhaps you could have a master computer playing that widescreen video, and then feed that to three computers that would crop in real time. I think some media players have cropping algorithms built in, but if not, you could easily do the cropping in AVISynth. You can research the SVP project which was designed so people could watch videos that had frame interpolation done in a computer running AVISynth, in real time as the movie is playing.

Finally, I am sure you are aware of Cinerama, which was the original widescreen system (well, maybe not, given this technology). It too used three projectors. You should Google and see if you can come up with how they achieved the synchronization, and how they kept it going after film breaks and splices.

I'm old enough to have actually seen Cinerama in movie theaters, and the other big problem they had was the seam between projectors. Even after you go through the painstaking alignment, you will still get a seam because the original cameras didn't have edges that perfectly aligned, and most cameras have extra area around sprocket holes that is normally masked off during projection. This is yet another reason to consider combining the three movies into one, because you can use all sorts of digital technology to do a little feathering and interpolation at the edges to make that seam invisible.

[DB83]

@johnmeyer

These comments are only ridiculous if the published text on the actual blu ray is also without legal significance.

I was perfectly happy with the OPs response. In fact he was quite polite in his response.

And I am also old enough to recall, and witness, Cinerama. Yet I fail to see the help that even mentioning this does to the topic.

[Paul Strickland]

Thanks for the long post. Gance called the 3 screen technique Polyvision and it is essentially the same process as Cinerama, with many of the same issues you describe. He didn’t just use it for an ultra wide screen effect though, at times the 3 screens have different images, a sort of primitive split screen, as became popular for a while in films like Woodstock.

I’ve been looking at various pc based video players to overcome the sync issue, either running 3 instances on a single pc, or synced across multiple pcs. I’ll have a look at the single file approach you describe, I know vlc has a video wall feature that might be useful.

I’m not worried about trying to feather the images together. The film does appear primitive at times and no amount of fudging will disguise that. In addition the physical screen will not be continuous and seem less, but will be 3 slightly angled panels. It will be a pain to set up, but at least I know what to expect.

[Cornucopia]

NLE trim & sync. Save to intermediate format that works with dedicated multi-channel media player (iirc, doremi is one). Am guessing it uses j2k encoding. Output each stream to its own channel's projector.
Or
Combine to an ultrawide image in intermediate format (in 4+k, i'd expect), store and play from multimedia-optimized pc or dedicated commercial grade settop player device, pass to videowall controller device (matrox, tvone, crestron, extron, etc) to split to the 3 sections.
Or
Look at offerings that work with dig cinema pkgs and do similar playout.

Scott

[johnmeyer]

@johnmeyer

These comments are only ridiculous if the published text on the actual blu ray is also without legal significance.

I was perfectly happy with the OPs response. In fact he was quite polite in his response.

And I am also old enough to recall, and witness, Cinerama. Yet I fail to see the help that even mentioning this does to the topic.

I have two objections to your post:

1. You didn't make any attempt whatsoever to help the OP.

2. You berated him for something that his post in no way suggested he was doing. Heck, try to find a post in any of these forums, or in any forum across the Internet, where you couldn't question the OP's ownership rights, or exhibition rights.

And, if you fail to see the significance of mentioning Cinerama has to the OP, you need only need read his latest reply to see that, once again, you completely and totally fail to understand the topic.

it is essentially the same process as Cinerama, with many of the same issues you describe.

So, you've now made two separate posts, neither of which did one thing to help this person. However, given your past posts in other threads, I will not be surprised at all if you don't make another one.

[DB83]

^^Well funny you berate me for establishing/confirming that the OP was doing something legal. Sure there are forum rules about that. Yet conveniently bi-pass all the other OT replies.

As for actual help in achieving the OP's goal one might have to consider how these separate sequences are stored on the disk. Are they seamless branching or, as I suspect, just extras. If the latter then the default will be the multi-view which makes separate projection even more complicated.

[smrpix]

Rather than consumer Blu Ray players, OP may want to look into media players such as those made by brightsign which are often used in art exhibitions and public ads, that can be networked and synchronized. (I don't have enough hands-on experience to give more specific advice.) They are available for rental.

[johnmeyer]

NLE trim & sync. Save to intermediate format that works with dedicated multi-channel media player (iirc, doremi is one). Am guessing it uses j2k encoding. Output each stream to its own channel's projector.
Or
Combine to an ultrawide image in intermediate format (in 4+k, i'd expect), store and play from multimedia-optimized pc or dedicated commercial grade settop player device, pass to videowall controller device (matrox, tvone, crestron, extron, etc) to split to the 3 sections.
Or
Look at offerings that work with dig cinema pkgs and do similar playout.

Scott

Scott,

That is really useful stuff.

I looked at some of the Doremi servers, but they look like they are simply media servers, for people who still want to store their movie collection on drives instead of discs, and then access them with a "point-n-shoot" interface. (I assume this is a dying breed, given streaming.)

However, I didn't quite see how you could get it to start the three video streams at exactly the same time. Of the two challenges (the other being feathering the edges), this is the key thing for making it work.

[Paul Strickland]

Hi there, lots of good stuff for me to play with. A question. Does anyone have any experience with something called SyncPlay. It's primarily meant for people to watch the same video at the same time across the web, but with a bit of tweaking, I might be able to achieve the result that I'm trying for.

[Cornucopia]

"Syncplay is not designed to have millisecond-level precision as this is not necessary for users to have a shared viewing experience." - I think this FAQ response right there is reason enough NOT to use it for this/your purpose.

Scott

[Paul Strickland]

Thanks Scott, I've spoken to the developers who pointed out the limitations. I'm having a play with it at the moment, to see how good / bad it is for syncing. They gave me some config tips to try and minimise latency etc.

It's also worth restating the nature of the video material. It's silent, so there is no dialog or sound effects that would look horrible if out of sync. Given the financial outlay (nil) it's worth a look, and I may have other uses for it as well.

I've also found something similar which is designed for proper sync, but it's a bit techie. Setting up for SyncPlay may be useful experience if I go down other routes

[Paul Strickland]

Hi all, I've been working away on this, so I thought I'd bring you up to speed with progress so far.

VLC has a open multiple files option, but it seems to be broken at the mo. I've seen it working (sort of) on an older version. Spoke to the devlopers, but they seem to think it was more aimed at subtitles and adding audio. Dead end, I think

Running trials with Mplayer, using the -udp-master/slave functions. Works OK and you can see it re-syncing the videos when they get out of sync. Good, but not quite good enough. The drifting sync may be hardware related. I've asked their user group for any tips, as there are a lot of options that I have no idea about.

As MPV is apparently a fork of Mplayer, I thought that the -udp stuff may be there, but I can find no reference to it. Works well with Syncplay, though.

The ultra wode intermediate file approach intrigued me, but I can't find an editor or util that will allow me to create a file 5760 pixels wide. The big editing boys (Premiere, Vegas) are talking about 8k capabilities, but I don't have budget for that sort of money. I could shrink it down to 4096, but I don't want to lose the resolution.

Had a play with something called VVVV, but it defeated me...

Any further thoughts would be much appreciated.