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Author Topic: Sync Check DCP? Dave Macaulay Film God Posts: 2321 From: Toronto, Canada Registered: Apr 2001 posted 02-28-2012 09:41 PM                     Is there a "sound sync check" DCP available anywhere? This would be like the Dolby SR-D reader setup film with a flash frame and synchronized beep or pop, so that the digital sound delay could be set correctly for different D/A converters. If anyone knows of one, or if anyone can make one, please let me (us?) know. Doremi servers (for example) come set up to have correct sync with the Doremi D-A converter feeding an analog cinema processor. Fully digital processors have a but of latency and the lipsync is close but the sound is slightly late. Sending the AES digital signals to a digital cinema processor like the CP750 gives lipsync that's obviously wrong. Finding reliably synced content has me stumped. I have a few trailers that are "fair" for setting up sound sync, but having a real sync check DCP would be great.  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 02-29-2012 07:08 PM                       This was an idea originally brought to me by Lonny Jennings some time ago. The DCP sync file is easy enough to make but measuring the absolute sync pop is another matter. I'm happy to report that we are working on incorporating it into an existing product. Stay tuned.  |  IP: Logged Dave Macaulay Film God Posts: 2321 From: Toronto, Canada Registered: Apr 2001 posted 02-29-2012 09:18 PM                     As usual, Lonny is several steps ahead of me. I look forward to whatever lets me set sound sync relatively easily. I was with Chuck not long ago, he says hi if I ever talk to you...  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 03-02-2012 01:47 AM                     Making a sync DCP is relatively easy with todays free tools. To actually measure the delay, a very cheap way would be a simpl audio/light sensor connected to a stereo line-in of a laptop or portable audio recorder. One channel with a microphone, the other with a very basic photo-transistor setup. Start Record, beep-flash the sensor, and you will see the delay in waveform view of the recording. If you have a decent digital camera with movie function, you can do the same by just capturing the sync DCP from any 'mean' seat position. Then you just need a basic movie editor that allows you to see picture and audio waveform to analyse the audio shift from a flash frame. - Carsten - Carsten  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 03-02-2012 09:59 AM                       Carsten says, "Making a sync DCP is relatively easy with todays free tools." I just said that two posts back.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 03-02-2012 08:18 PM                     He signed his name twice...perhaps he was just making sure the message go across?  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 03-03-2012 08:15 AM                     quote: Sam D. Chavez I just said that two posts back. No Sam, you didn't mention free tools ;-) Aside from that, Studio Six Digital are currently working on an A/V Sync module for their iPhone tool-suite http://studiosixdigital.com/audiotools/ using the iPhone video recording function. - Carsten - Carsten - Carsten  |  IP: Logged Paul H. Rayton Expert Film Handler Posts: 210 From: Los Angeles, CA , USA Registered: Aug 2003 posted 03-07-2012 04:23 PM                    I'm not sure if this would apply to ALL digital still cameras, but if I were to use mine for such a visual "sync check" comparison (as described by Carsten), there might be an issue because there is a slight latency in my camera's video output, due to image stabilization. So the visual pop might be offset a bit from the audible pop. All we really want and need is a sync "pop" sound of some sort, that is precise and well-defined, and an absolute visual reference -- and have it loop. Then, we can set it to running, go out and listen, see if it's in sync or not, and then dial up (or down) the system. (And then, **hope** that when we get festivals in, with tapes and other video content from all manner of diverse sources, that the "kids" made their movies properly!)  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 03-07-2012 06:00 PM                     There's all sorts of strange gear around, but still even cheap digicams should be able keep video and sound in sync to within one frame or so. And that should be much more accurate than 'guessing' on a loop. If there is an inherent delay in a cameras video processing pipeline, the developers should know this and compensate for it. I'm not talking about live video anyway, but looking at the recording. There are sync check videos with a visual pendulum and the sync pop at the center transition, like a musical metronome. Or more elaborate ones like this with multiple visual sync cues: http://www.youtube.com/watch?v=bCPEidaVzQU They are certainly good to align a system by direct sensing that is way out of sync, but around +/- one or two frames, it gets difficult. Not that it is really THAT important to be precisely on the spot, but if a cheap gizmo can help you, why not use it. You can check your cameras sync capabilties easy with a clapperboard. Or simply two sticks or a clap of your hands. - Carsten  |  IP: Logged Jussi Siponen Film Handler Posts: 75 From: Mikkeli, Itä-Suomi, FINLAND Registered: Jan 2010 posted 03-20-2012 01:32 PM                     Inspired by the BBC sync test video linked by Carsten. I took the sound from the BBC video and adapted the scale for 24fps. This is frame 7 (upper) and frame 12. The "tick" sound occurs half way through frame 12 being visible. BTW, is this the right thing to do -- should it be timed to the "leading edge" of frame 12? If the timing is determined to be correct and I do a QC pass on a real D-Cinema system (in stead of a software DCP player) I can post a download link later this week if there are any takers.  |  IP: Logged Paul H. Rayton Expert Film Handler Posts: 210 From: Los Angeles, CA , USA Registered: Aug 2003 posted 03-20-2012 02:40 PM                    Hi, Jussi -- Yes, great. Please consider this at least one "vote of encouragement" to proceed with your plan. I'd be happy to try it (when you finish it), utilizing my somewhat "antique" Quvis server.  |  IP: Logged Ian Freer Expert Film Handler Posts: 135 From: Wellington, New Zealand Registered: Oct 2003 posted 03-20-2012 04:02 PM                     I have a DCP clip that is almost identical to this that must have come included on some other content I received. I don't recall ingesting in directly, but came as part of something for a film festival so I was ingesting 'everything' to make sure I had the correct versions of DCP's available. I haven't looked at it for a few months but from memory it has the logo of a London, UK post house or something on it. I'll have a look how big it is and see if I can upload it or send it to Brad to put up on the site somewhere. Saves everyone having to re-invent the wheel as it were... Cheers, Ian  |  IP: Logged Jussi Siponen Film Handler Posts: 75 From: Mikkeli, Itä-Suomi, FINLAND Registered: Jan 2010 posted 03-21-2012 01:22 PM                     DropBox is still uploading as I write this. The download link will start to work as soon as the upload is complete (shouldn't take more than 30 minutes): SyncTest DCP (340 MB, runtime 1:30) The delay scale now shows also milliseconds. Re-inventing the wheel is kind of fun, but also potentially embarrassing, given the audience. I hope I didn't mess up somewhere  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 03-22-2012 01:34 PM                     Jussi, this looks very good, thanks!  |  IP: Logged Dave Macaulay Film God Posts: 2321 From: Toronto, Canada Registered: Apr 2001 posted 03-28-2012 08:34 AM                     Thanks a bunch! I haven't run this yet (waiting for projector power) but the DCP did ingest OK into the Doremi server.  |  IP: Logged

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