Review Of The Sync-One2 AV Synchronisation Measurement from Harkwood Services
03-31-2015 03:00 PM
Pro Tools Expert post followers and anyone with even a cursory interest in ‘things sound for picture’ will know that I am the “In-house Sync Nazi”, and as a dubbing mixer/editor predominately for TV (re-recording mixer if you speak American), I preach accurate AV sync and take no prisoners in the process!
I have on loan in my studio the potential successor to the crown of “the gold standard weapon of choice for the discerning audio post synchronisation police”, previously held by Richard Fairbanks’ SynCheck 3, which has now ceased production. Sync-One2 is the new kid on the block and the has been designed and built from the ground up in Cambridge, England (sorry Massachusetts) by AV consultant and chartered IT professional Jeremy Curtis of Harkwood Services Ltd.
It is a comparable size to Syncheck, and comes to the party dressed in black with an easy to read 16x2 OLED digital display. I instantly found friends with this box as it requires AA batteries, even rechargeables (which I have a plethora of, due to my Nikon flash guns) rather than Syncheck’s 9v PP3. In true Pro Tools Expert style, I tried to break it and not to read the manual. Pressing the on/off button greets you with the unit serial number, but more importantly, a self calibration test to measure background light and noise levels, which helps avoid false readings. A nice reassuring touch.
Just like Syncheck, the sound and light detectors are on the front of the box, Sync-One2 can measure up to ± 2/3 second difference in sound and vision (more than that and you might as well be on another planet). You can either measure the offset in milliseconds, or if you input the frame rate, in frames. I mostly live in the “PAL land” of 25fps - and I pathologically dislike having to divide time by 40ms (the 25fps rate) to get the number of frames, so thumbs up for that one!.
Sync-One2 gives a real time display of the reading and buffers the last 60 readings. So when reading 61 arrives, it throws away reading 1 etc. Readings are displayed relative to the light pulse, so that a positive reading is sound ahead of the picture, and a negative reading is where sound is behind the picture.
The really clever bit and where Sync-One2 scores over SynCheck 2 and is similar to the esteemed SynCheck 3 is that it allows statistical analysis of your readings and can give you average readings and span readings (variation between smallest and largest reading). The span reading is the key for post production AV sync as it shows how much your sync wobbles for each play pass. Is it stable or like a drunk fish on a bike?
A few nerdy bits and bobs that separate the wheat from the chaff show the thought that has gone into this units design.
- You can select to have a speaker distance (if the size of your venue is large and would warrant it) to compensate for the time of arrival due to the slowness of the speed of sound compared to light.
- You can select different video and audio sensitivities for the sensors.
- This box can be a tweaker’s paradise or an auto delight.
- Settings and options are stored in flash memory, but measurements are disposed off when the unit is turned off.
The auto detect of video and audio levels worked fine for me and my distance of just under 2m to my speakers did not justify an audio compensation.
Jeremy has put a lot of work into making sure the detectors are very accurate in this box, the video sensor is able to measure the modulation of LED torches as a pulse! The unit also periodically checks itself for battery level and will tell you if you are low on juice and when you no longer have enough power, it will warn you and then turn itself off.
Using The Sync-One-2
Whilst recording data you get a heartbeat for each correctly measured flash and blip. The display shows the error in mS and in frames and the running average. You can measure thousands of readings, but Sync-One2 stores just the last 60 in its buffer for viewing. At the end of the measurement, you can view the data either one by one or you can view the span (the largest sync wobble variance) and the total average. If someone coughs or turns the lights on erroneously you can delete individual measurements. After a pass it is a breeze to reset the measurements and send the unit back to measurement mode (via its quick auto calibrate of course) to record another run of data.
The Test System
- Pro Tools PC (32Mb) ram running OSX 10.8.5
- Pro Tools HDX 11.3.1
- My video peripheral: AJA IO XT (thunderbolt)
So How Good Was It?
This box is able to measure sync to outstanding levels of accuracy. I ran some simultaneous tests with Syncheck2 so that I could compare its measurements. Syncheck 2 had a flickering light to show that the error was somewhere around the region of 1/16 of a frame (at 25 fps) - the limit of its display resolution. Sync-One2 was able to measure this to 1/100 of a frame and show it varying! This box is both very simple to use, and very accurate indeed.
Whilst using some of the tests files from my Syncheck3 review I noticed some odd results. I started using some of the multi spaced files where the distance between each sync and flash is constantly varying. Sync-One2 was picking up a larger span than I was expecting. Upon investigating the results in the buffer I was picking up a constantly varying pattern , but a predictable pattern. Any test where there is a distinct pattern to the variance should lead one to question what is the cause of this constant pattern, my science degree was not totally wasted. I wonder if the Syncheck test files had been subjected to a software pull up/down to convert from NTSC to PAL
I contacted Jeremy from Harkwood Services and he kindly generated me some test files. Sync-One2 ignores any reading within 10 frames to help avoid any erroneous readings. The test file Jeremy generated (as shown in the video) for me was a DNxHD36 QT multi spaced file.
My AJA IOXT with DNXHD36 QT is completely and utterly rock solid and MOJO like in Pro Tools 11.3.1 as demonstrated in the video. This box is stunningly accurate and very easy to use. “The king is dead, long live the king”.
At slightly under £200 exc vat, which considerably cheaper than its predecessor Syncheck3, if you work with picture and sound, this is, pound for pound, probably the most important box you can buy. What’s more, Jeremy the developer is highly supportive and very proactive.
Don’t have one? Go and buy one now. I am buying one and I am so impressed with Sync-One-2, it gets an Editors Choice award from me.
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