I use a Sony FX1 HDV camcorder, and I am looking to use a separate digital recorder to record audio for a project. The audio will include talking heads, which will need to be synced to the video in post-production.

I am a newbie at audio issues, and I am wondering, what do I need to do to reduce or eliminate the possibility of the audio going way out of sync in post?

Also, does the sampling frequency affect syncing?

The audio frequency would be best if it was the same as the audio recorded by the camera. Simply because when you put the camera audio and the digital recorder's audio up on the editing software time line. The software may prefer them to be the same.
Once you have done this then the method I use for sync is to find a sharp soundwave peak (or a clap board) that appears on the camera's reference audio track as well as on the main recorded audio. Put a marker on the clips or on the timeline and move the peaks into position together, zoom right in to view a single frame, move them until they are perfect... dependent on your software's capabilities (I use Speed Edit I can get within a frame)
Or you could find a recorder that can record a timecode and feed that timecode from the camera to the audio recorder. This involves capturing the timecodes and matching them.
My above method is easier with less gear needed. However, every time you turn the audio recorder or camera off then you have to go through the whole procedure again. It's best to leave the recorders running, capture everything and just have to match the clips up one time only. They will stay in sync throughout the program.
I usually use this method for multi-camera and multi-track video shoots of concerts. So leaving the recorders running is no problem.

Thanks for the info, I'm going to try recording at 48hz with a clapper board, and see how it goes.

I use a Sony FX1 HDV camcorder, and I am looking to use a separate digital recorder to record audio for a project. The audio will include talking heads, which will need to be synced to the video in post-production.

I am a newbie at audio issues, and I am wondering, what do I need to do to reduce or eliminate the possibility of the audio going way out of sync in post?

Also, does the sampling frequency affect syncing?

The only reliable way to insure sync doesn't drift out over the duration of a shot is for both the camera and the audio recorder to share a common timebase. Since the FX1 doesn't accept genlock, the most practical way is to use an audio recorder such as the Tascam HD-P2 that accepts composite video or blackburst sent from the camera and slaves its clock to it. A slate will establish sync, the common timebase will keep it. Otherwise, a scene may start in sync but after 10 minutes or so some drift may become apparent. (How soon and how bad are extemely variable.)

Steve, thanks for the info. I have a few questions:

1. If a camera has genlock, how do you connect the camera and audio equipment (and with what cables)?

2. With a device such as the Tascam HD-P2, do you connect the camera to the device, send a "blackburst," and then it saves it and you can access the timecode for future recording, or do you have to do it each time?

Genlock normally is via a coax cable with BNC connectors. It does not carry TC.

Steve, thanks for the info. I have a few questions:

1. If a camera has genlock, how do you connect the camera and audio equipment (and with what cables)?

2. With a device such as the Tascam HD-P2, do you connect the camera to the device, send a "blackburst," and then it saves it and you can access the timecode for future recording, or do you have to do it each time?

Rick is right - genlock and blackburst have nothing at all to do with timecode. They deal with the sample clocks in the camera and the recorder.

Genlock is an input on the camera to allow it to accept "house sync" (your FX1 doesn't have one). Broadcast studios where multiple cameras are switched live through a video switcher must have all of the camera synchronized so they all scan the video frame exactly in lock-step, they all start scanning line 1 of each video frame at exactly the same instant. If they don't, there's a momentary jump in the picture and loss of sync when one camera is switched to the other. To insure this, there is a master sync generator that feeds all of the cameras, switchers, and other equipment in the studio with a common clock pulse instead of letting each camera rely on its own internal sync generator.

The same sync issues also apply to recording double system sound. Your camera, and DV in general, uses an audio sample rate of 48,000 samples per second. The sound recorder does too. But 48kHz is a nominal rate - due to tolerances, temperature differences, etc the real rate can be very slightly off that. When you record and playback on the same device it doesn't matter - sound recorded in 1 minute plays back in 1 minute. But when the recording is moved to a different device with a different clock, things change. If, for example, the audio recorder is running at 48,500 samples per second instead of exactly 48,000, when played back on a device that is running exactly on-spec, a recording that was made in exactly one minute will play slightly slow and take a little longer than 1 minute to play back.

Now imagine your camera is really running at 47,500 and the audio recorder at 48,500. You record exactly 1 minute on each and load it into the editor which is running at exactly 48,000. The video will play slightly fast and finish a few seconds less than a minute while the audio will play slightly slow and still have several seconds to go when the video finishes. If they're in sync at the start of the minute, they'll be out of sync at the end. The solution is to once again use a master clock so that BOTH devices use the same timebase and they're running at exactly the same speed. With a camera that has genlock, the house clock controls the camera. The same house clock also has an output signal called "wordclock" which is the standard for controlling audio equipment. So genlock feeds the camera while wordclock from the same clock feeds the audio recorder. That house clock can be either a single physical clock generator hardwired to all the devices on the set or a set of highly accurate battery-powered clocks called "lockit boxes" that can be tuned precisely to each other and then attached to each camera and recorder. The Sound Devices timecode capable recorders actually have the equivalent of a lockit box built in them.

Another way to achieve this lockup is to use blackburst. Blackburst is a continuing signal, the sync pulse embedded in the video that the camera sends to tell a display when a scan line starts. Devices are available that take video blackburst and convert it into wordclock so that when you have one camera and a recorder, the camera can become the "master" replacing the house clock in my above discussion of genlock, wordclock, and audio recorders. The Tascam recorder has such a converter actually built-in so it has an input connector for video sync. (It's not the only recorder with this feature but all the others that have it start at several times the price of the Tascam.) You connect the camera's composite video out to the recorder's video sync input. The camera feeds sync to the recorder continuously as long as you're rolling.

Timecode does NOT control recording or playback speed. All it does is give you a convenient way of aligning the audio and video at a single point in the scene - it's really just a glorified version of a clapper slate and does nothing more than they do. It's the sample clock issue that needs attention if the scenes that are in-sync at their start are to STAY in sync as a shot longer than 5 or 10 minutes plays out.

Hey Steve thanks for clarifying a lot of things for me. I've been going about trying to keep things simple at shoots and genlock is just too much hassle for multi camera shoots of concerts with assorted cameras roaming and panning about. However, in post I have notice drift over our typically 25 minute orchestra compositions. It's usually not significant for a 6 minute pop song and syncing up for every songs edit is usually what happens.
I will definitely experiment with Genlock on some studio shoots where more cabling is convenient.
...but for a quick fix in editing, you could always cut the video tracks and re-sync them to the audio every few minutes of an edit.

I posted a technique here:My Video Problems :: View topic - Synchronise external and camera audio tracks. (http://www.mfbb.net/myvideoproblems/myvideoproblems-about25.html) some time ago which might be of some use. No substitute for doing it properly of course, but quite a bit cheaper! :-)
The important thing to remember is that the camera 'clock' has to be the master - even if that is the one that is slightly wrong.
Can save having to sync a long take in small chunks, which I've found can be a bit time comsuming.

Hey Steve thanks for clarifying a lot of things for me. I've been going about trying to keep things simple at shoots and genlock is just too much hassle for multi camera shoots of concerts with assorted cameras roaming and panning about. However, in post I have notice drift over our typically 25 minute orchestra compositions. It's usually not significant for a 6 minute pop song and syncing up for every songs edit is usually what happens.
I will definitely experiment with Genlock on some studio shoots where more cabling is convenient.
...but for a quick fix in editing, you could always cut the video tracks and re-sync them to the audio every few minutes of an edit.

If you have cameras possessing genlock and external timecode inputs, the hard-core way to do it and still have roving, untethered cameras is to use the aforementioned Lockits. No cables required while shooting; they're battery powered and about the size of a cigarette pack, just velcro them to the camera. You have a Lockit box on each camera feeding it blackburst or tri-level sync if you're shooting HD plus one for the audio recorder feeding it wordclock. The Lockits also provide timecode to their hosts. Tuning them all together and jamming them with common TOD timecode before the shoot gives you accuracy across all the devices to within 1 frame per day.

I posted a technique here

Very nice. Maybe repost it here?

I do have a question: If you are working with seconds, do you really need to change the sample rate of the audio clip? I think Vegas lets you work with samples where it would definitely be necessary--and I would think the answer might be more accurate.


No substitute for doing it properly of course, but quite a bit cheaper! :-)

Sure its a subsitute for doing it properly! Its a necessary workaround for low budget people--you've just made the procedure easier to manage. I mean, the information that Mr. House gives is great but not meet the budget ability of the OP.

...Sure its a subsitute for doing it properly! Its a necessary workaround for low budget people--you've just made the procedure easier to manage. I mean, the information that Mr. House gives is great but not meet the budget ability of the OP.

Well, we don't know what the OP's budget is so that may or may not be true. It's certainly true that Lockits aren't cheap - they cost just about as much as the Tascam HD-P2 does, each! Nor are the cameras that can use them cheap - the Canon XH-G1 is the lowest priced one that immediately comes to mind. But in any event, my discussion of Lockits is irrelevant to him since the FX1 lacks the necessary sync and TC I/O to use them anyway. That discussion was addressed more to Don Xaliman's post where he said he worked with multiple cameras in a studio environment - it sounded like his cameras did have genlock inputs. But the importance of syncing the sample rate clocks in the camera and audio recorder still applies to the OP if he wishes to avoid having his audio and video drift out of sync requiring him to fix it in post. When working with a single prosumer camera such as the FX1, the Tascam provides a way of "doing it properly" at a relatively economical budget point. (Very inexpensive, actually, for professional level recorders.) Since the OP apparently hasn't purchased his recorder yet, the ~$1000 Tascam's ability to sync to video versus the inability of such recorders such as the similarly priced Marantz 671, Fostex FR-2, and Edirol R-44, the $600 Fostex FR-2LE, and sub-$500 handhelds like the Zoom may make it a viable option for him that's worth the price difference.

If you will forgive a blatant commercial plug, our product PluralEyes (http://www.singularsoftware.com/autosync) was designed to be an easy, low-cost and automatic solution for exactly this problem. $149 USD.

Bruce

Steve, just to clarify this point, it is correct to say that, if I am using the FX1, and I want to be able to sync up audio and video without physically connecting the camera and the audio recorder, then sending a constant blackburst signal with a composite video cable is not the way to go?

This is a huge shot in the dark, but is there any way to send a blackburst signal from the camera to the audio recorder in a wireless fashion? I figured I'd at least ask.

This is a semi-unrelated question, but how was audio synced to film on motion pictures because NLEs?

This is a huge shot in the dark, but is there any way to send a blackburst signal from the camera to the audio recorder in a wireless fashion? I figured I'd at least ask.

It is POSSIBLE that this may work: Super Small Long Range Wireless Video & Audio Monitoring System Wireless Video Equipment at Markertek.com (http://www.markertek.com/Digital-Video-Production/Video-Cameras-Camcorders/Wireless-Video-Equipment/VC2MS/) This is a case where cheaper may be better--a more expensive system may reclock the input signal which would defeat the porpoise. But if the transmiter spits out exactly what it took in, it could work. Lots of loose ends to sort out.

This is a semi-unrelated question, but how was audio synced to film on motion pictures because NLEs?

Do an google image search for 'film synchronizer'. But you really do it the same way now as before: mark the frame where the clapper hits on the film, mark the frame on the 35mm magnetic film (sound has been transfered from 1/4" to mag film) where the clapper hits and sync 'em up. They, as you edit in the original NLE, keep marking picture and sound at the same place and cut at the same place and you're footage will stay in sync--or not if you didn't lock the camera and audio recorder together (the more things change, the more they stay the same!).

Steve, the old adage Good, Cheap, Fast: pick any two certainly applies here. "Good" is pretty much necessary which only leaves a choice of cheap (manual resync) or fast (hard sync between devices). While I have used and appreciate good equipment, in my personal life, it is a luxury that I need to find subsitutes for.

Steve, just to clarify this point, it is correct to say that, if I am using the FX1, and I want to be able to sync up audio and video without physically connecting the camera and the audio recorder, then sending a constant blackburst signal with a composite video cable is not the way to go?

This is a huge shot in the dark, but is there any way to send a blackburst signal from the camera to the audio recorder in a wireless fashion? I figured I'd at least ask.

This is a semi-unrelated question, but how was audio synced to film on motion pictures because NLEs?

If you are looking at a wireless soloution then why not just send the audio from the sep recordist via a radio mic?

It is possible to do this and still record the sound separate if you wish, that way you have sep sound and a guide on the Fx1 that may be useable as well.
A clapper board will mark and keep sync checked.

If you are looking at a wireless soloution then why not just send the audio from the sep recordist via a radio mic?

It is possible to do this and still record the sound separate if you wish, that way you have sep sound and a guide on the Fx1 that may be useable as well.
A clapper board will mark and keep sync checked.

Gary, using a plug-in transmitter and recording onto the FX1 directly is fine, but in this setup, is it possible for the boom operator to listen to the recording via headphones? If the plug-in transmitter had a headphone out, that would be ideal, but it seems that the cameraman would have to monitor the sound. I haven't yet found a plug-in transmitter with this feature.

Well, you can run the boom mic through a mixer, have sound guy listen to mixer and send the main output wirelessly to the camera.

Steve, just to clarify this point, it is correct to say that, if I am using the FX1, and I want to be able to sync up audio and video without physically connecting the camera and the audio recorder, then sending a constant blackburst signal with a composite video cable is not the way to go?

This is a huge shot in the dark, but is there any way to send a blackburst signal from the camera to the audio recorder in a wireless fashion? I figured I'd at least ask.

This is a semi-unrelated question, but how was audio synced to film on motion pictures because NLEs?

First of all you have to get clear just what you mean by the word "sync." There's "sync" in the sense that you have an alignment point where a known instant in the sound file, a specific audio sample, can be aligned with the exact frame in the video file that was captured when that sound was recorded. And then there's "sync" in that when you align that known point in the sound with the video frame when it was recorded at the start of a clip and hit "play" the two files STAY in sync for the duration of the shot. A clapper or timecode does the former, video blackburst to slave the sample clocks does the latter.

I'm not aware of a simple system that would send video sync wirelessly. Wireless timecode is no problem but wireless sync is much trickier. That doesn't mean it doesn't exist - Andy mentions a product but I'm not familiar with it in order to say yeah or nay.

Back in the film and analog audio day, extending even into the DAT days, either a sync signal was sent from the camera, or coming from the power mains, or the camera speed was controlled by a crystal oscillator that also sent a signal to the audio tape, or in the case of DAT a linear timecode signal, was recorded on a track that ran parallel to the audio on tape. As the first step of postproduction, the analog or DAT tape was "resolved," ie, re-recorded, onto perforated magnetic filmstock. The tone recorded on the tape or the linear timecode recorded on the DAT controlled the speed of the resolver recording device so that 1 second of recorded audio went onto exactly 24 frames length of magnetic film as indicated by the edge perforations. Then as Andy said, the magnetic perf was physically aligned to the film workprint using a geared "sync block" that locked the two film strips together via their sprocket holes.

The mistaken belief that timecode can both establish sync and maintain sync dates to those days. Timecode on a DAT was recorded as linear timecode, laid down continuously alongside the audio tracks. When the tape was played in telecine, the recorded timecode actually controlled the playback speed during the ingest process. But that's not what happens with modern recordings. A file-based recording, if it has timecode at all, only grabs it as a single point timestamp, the reading of the timecode counter when the first audio sample was recorded. Any later running code is calculated on-the-fly by adding the number of samples played to the starting timestamp. As a result, timecode DOES NOT control playback speed - whether you are copying the audio file as a BWF directly into your NLE or going through a telecine process, the playback speed is 100% dependent on the degree to which the recorder's sample clock at the time the recording was made matches the speed of the playback device's sample clock. A $5000 Sound Devices 744t's sample clock is going to be running at pretty close to spot-on the 48kHz standard. A $400 hand-held Zoom? It's anybody's guess. With some recorder/camera combinations you might get 15 minutes before it becomes noticable. With others, it can be much shorter. Using various compressed recording formats like MP3 or WMA can be a total disaster.

I'm not aware of a simple system that would send video sync wirelessly. Wireless timecode is no problem but wireless sync is much trickier. That doesn't mean it doesn't exist - Andy mentions a product but I'm not familiar with it in order to say yeah or nay.

Isn't this sad? It seems to me that manufacturers are missing a market to solve sync problems in this market. Almost all of these prosumer cameras have no way to sync to each other, or anything else, video or audio.

I can't see any way to solve the video sync problem without genlock inputs or something equivalent, but the audio should be much easier, provided you just need one camera synced. I think that is reasonable, since you can use that camera as your master shot and edit other cameras into that timeline.

I'm not sure how useful sending video sync pulses would be, these cameras have no genlock inputs and it is not the best for audio sync (wordclock or linear timecode would be better). But it would be technically trivial to send vertical sync wirelessly - a $1 sync separator chip would derive the 30Hz pulses which could be sent to any wireless transmitter.

But what I would really like is a box that is small enough to mount on a camera that does just about the opposite of what a lockit does. A box that accepts NTSC video from a camera and outputs linear timecode locked to the video. It should cost no more than $300 or so.

It could be very simple - just input, output, and a reset button to restart the timecode at 01:00:00:00

Any wireless mic transmitter could be plugged into this. Heck, even a $15 hobby FM transmitter module might work, anything that will transmit audio with a 12-15K bandwidth would work.

On the receiving end, anything that locks to linear timecode could be used. Could be the Tascam unit, or something like the Motu UltraLite-mk3 or Traveler-mk3. This would allow multiple audio tracks to be phase locked to the camera, eliminating drift.

Maybe I have just missed it, but I have not been able to find such a box.

-Mike

Almost all of these prosumer cameras have no way to sync to each other, or anything else, video or audio.

Well, you said it right there: prosumer. This is not a function that most prosumer users need.

But what I would really like is a box that is small enough to mount on a camera that does just about the opposite of what a lockit does. A box that accepts NTSC video from a camera and outputs linear timecode locked to the video. It should cost no more than $300 or so.

Ya know, it wouldn't be too hard and I wouldn't be surprised if a company like Horita couldn't slap one together. You could do exactly what you describe with their existing products but it would take several boxes and cost much more than your asking for.

But volume of sales would be a problem: this would be a very small niche. You need the features of a professional but don't want to pay the price. Bad combination.

Oh, another thought: I'm not sure how much R&D companies are going to do for an NTSC based product.

Say, good call on Horita!

I just looked at their site and realized there is pretty close to a bingo with their TG-50 Generator/Inserter. Horita Co., Inc. Affordable Time Code and Video Equipment (http://www.horita.com/)

This is a timecode generator that does window dubs. To do that it MUST lock to the incoming video, so it is synced to the video. And it has a timecode output - if this is, as I assume, linear timecode, and active while in generate/window dub mode - then there it is.

Runs off 9V, so easily portable.

List $399, probably street price a bit lower, so it is pretty close to the $300 mark I suggested. As a bonus, it will work as a window dub generator. ;-)

Now just feed that timecode into any really cheap wireless setup and you are good to go.

I might just remove the circuit board from that box and put it, along with the board from a wireless setup, into a more suitable one.

-Mike

Say, good call on Horita!

I just looked at their site and realized there is pretty close to a bingo with their TG-50 Generator/Inserter. Horita Co., Inc. Affordable Time Code and Video Equipment (http://www.horita.com/)

This is a timecode generator that does window dubs. To do that it MUST lock to the incoming video, so it is synced to the video. And it has a timecode output - if this is, as I assume, linear timecode, and active while in generate/window dub mode - then there it is.

Runs off 9V, so easily portable.

List $399, probably street price a bit lower, so it is pretty close to the $300 mark I suggested. As a bonus, it will work as a window dub generator. ;-)

Now just feed that timecode into any really cheap wireless setup and you are good to go.

I might just remove the circuit board from that box and put it, along with the board from a wireless setup, into a more suitable one.

-Mike

I think you're making the common error of confusing timecode with sample clock sync. Sending timecode to a file-based audio recorder does not prevent sync 'drift.' File-based recorders do not record LTC nor do they sync their sample clocks to incoming timecode. The only thing such a recorder uses any timecode that is fed to it for is to timestamp the timecode reading associated with the first audio sample into the file header. That's it - timecode does NOT control the speed of either recording or playback. Wordclock does, The key is you need some means of generating wordclock that is in sync with the video sync burst. There are two ways - either a common clock feeds video sync to the camera through genlock AND also feeds wordlock to the audio recorder; OR the camera acts as the master and its video output goes through a box that outputs wordclock slaved to the camera's video sync. The Tascam (and the Sound Devices 788T (but not the 702T or 744T) and the Nagra VI) does that in the recorder, don't know off the top of my head about Deva or Cantar. The only way to prevent 'drift' is that the camera video sync and the audio sample clock must derive from the same master timebase, regardless of how you arrange it. Tiemcode's clock rate is just not high enough to accomplish that.

I am not confused about word clock vs smpte.

The Motu units sync their word clock to SMPTE:

MOTU.com - Clock, sync and MIDI (http://www.motu.com/products/motuaudio/traveler-mk3/clock.html)

"Direct Digital Synthesis™ clock

The Traveler-mk3 is equipped with Direct Digital Synthesis™ (DDS), a DSP-driven phase lock engine and very high frequency digital clock source that produces imperceptibly low jitter characteristics (well below the overall noise floor), even when the Traveler-mk3 is resolved to an external clock source via either word clock or SMPTE time code. "

These are not recorders, 'resolved and 'phase lock' mean just that.

The Tascam HD-P2

TASCAM (http://www.tascam.com/products/hd-p2;9,11,52,16.html)

HD-P2 Synchronization features:

SMPTE/LTC timecode input on locking XLR balanced jack

Timestamps Broadcast WAVE recordings from SMPTE input

Chase locks to incoming SMPTE timecode

Video clock input resolves to house clock

Tri-level sync support for HDTV applications

Includes Frame Lock, Lock and Release and flexible Freewheel settings for unpredictable timecode sources

Pull-up and Pull-down sample rates included for video format compatibility

I am less sure about this one, but 'Video clock input resolves to house clock' sure suggests this.

And 'chase lock' (not just 'chase' ) has a pretty specific meaning to me. 'Lock' being shorthand for 'phase lock'. You can chase without lock, you can lock without chasing.

The sound Devices units (except Sound Devices 788T), and others, make no such claims.

If I am wrong, there is some pretty deceptive advertising going on here...

Tiemcode's clock rate is just not high enough to accomplish that.

That is why phase locked loops were invented.

Linear time code has an included, derivable 4800Hz clock included. Hook that to a phase locked loop with a divide by ten counter in the loop, and you get 48000Hz.

Wordclock...

All that is required is that the vertical sync pulse have less than 1/48000 of jitter for this to work. Since any modern camera is operating off a much higher frequency clock, from which this is derived, that is pretty well guaranteed.

If the audio is recorded phase locked to the camera, there will be no drift. Both the camera and a digital audio recorder are really frame oriented devices.

48000 = 1 audio frame, one second.

1 second of video = 30 frames, or 48000 audio clocks, 48000/30 = 1600 audio clocks per frame.

Feed a video file into your nle, it counts 30 frames and says, that is one second.

Feed an audio file in, it counts 48000 samples and calls it one second.

So there should be no drift, provided both were originally synced to the same clock - the cameras, in this case.

Most file-based audio recorders just time stamp. The specfic devices I mentioned at least claim to also phase lock to incoming linear time code.

... I just looked at the Sound Devices 788T manual. It actually does NOT claim to lock to external linear time code. It only locks to word clock or video (which of course would also solve this problem). This surprises me, though.

-Mike

Well, you can run the boom mic through a mixer, have sound guy listen to mixer and send the main output wirelessly to the camera.

Thanks I was just about to say that as this is the most common application of sep sound.

I have a sign 44 mixer that can record direct to a sony D50 but I can also send a radio link back to the camera as well if required.

I...
... I just looked at the Sound Devices 788T manual. It actually does NOT claim to lock to external linear time code. It only locks to word clock or video (which of course would also solve this problem). This surprises me, though.

-Mike

Yep - perhaps I was unclear - I was trying to say that the SD788T and the Nagra VI share the Tascam's ability to lock their sample clock to incoming video sync but the other SD recorders do not. As for the sample clock chasing LTC, I exchanged emails with the good folks at Sound Devices a couple of years ago about that exact issue. I asked whether their "T-series" recorder's sample clocks would lock to incoming LTC and their response was that they did not. They specifically said the internal timecode counter chases external LTC but the audio sample clock does not, the reason being that it was impossible to derive a sufficiently stable clock from the LTC. It's my understanding that when external timecode is present, the system jams its value into the timecode count register in lieu of the internal clock's count but it never actually influences the internal clock oscillator frequency. It's not actually controlling the clock but instead it merely sets its value by continuously jamming into the register. In pocket watch terms, it's like continually twisting the crown to manually keep the hands showing the same time as the clock on the wall without opening up the watch to adjust the rate it ticks.

I think you are correct regarding the Tascam - page 21 of the manual claims the audio clock chases external timecode's embedded clock when present. Of course with consumer cameras like the OP's FX1, getting the darned LTC out of the camera and over to the recorder in the first place is a major stumbling block.

They specifically said the internal timecode counter chases external LTC but the audio sample clock does not, the reason being that it was impossible to derive a sufficiently stable clock from the LTC.

I think it is a shame they left this out. I can uderstand their reasoning in terms of following something like an old analog deck, but that is not the only scenario anymore.

It looks to me like we have fairly inexpensive solution to the lock/drift problem in the in the TG-50.

The video output of the camera is locked to its master clock, and hence to all video and audio it deals with directly.

The Horita. because it is also doing a window dub, MUST be locked to roughly twice the horizontal frequency accuracy in order to do that. And so will be the timecode it outputs.

Now that timecode clock is 4800 Hz but it's actually locked to a much higher freqency. But timecode is limited to about 11Khz bandwidth (by its spec). That is still less than the audio bandwidth it may be transmitted over, so that is not limiting its accuracy any more than the inherent bandwidth of the timecode clock (which must be at least 9600 to pass thatclock accurately per Nyquest).

So, worst case, we are looking at a lock inaccuracy of about 1/9600 or about 0.104 milliseconds. For frame accurate lock to video,you only need about 1/60 or 16 ms.

I call that good enough. The only thing you may not want to do is split a stereo track with one track on the camera and one on the remote recorder. But no one with any sense is going to do that!

Of course there is no way to get the absolute code, there will be an offset. But it will be a consistent offset - set once and everything else will fall into place and remain in sync.

Of course you also need a recorder that locks its clock to the timecode clock like the Tascam.

But the basic problem I was looking at - that few of these cameras have actual timecode outputs or sync of any kind - seems to have a solution. If I want to record a 2 hour concert to a multitrack and have a master shot that is in sync, here is a way to do it without having to use a camera with genlock. Before this thread I was pretty much convinced I would have to build this myself, or use a (big, not portable) Motu Midi Timepiece.

-Mike

I'm looking at the Horita info and don't see how they can help the issue. Neither the WG-50 nor TG-50 output wordclock. You can feed them composite video and they'll read and output the embedded timecode but unless you're using a recorder like the Tascam that can lock its sample clock to incoming timecode we haven't gained anything. And with a recorder like the Tascam, the Horita becomes superfluous since the recorder will clock directly to the video anyway. True, it solves the issue of getting timecode out of a camera that does not have a timecode output but with most file-based recorders timecode is only a glorified slate anyway.

I'm looking at the Horita info and don't see how they can help the issue. Neither the WG-50 nor TG-50 output wordclock. You can feed them composite video and they'll read and output the embedded timecode but unless you're using a recorder like the Tascam that can lock its sample clock to incoming timecode we haven't gained anything. And with a recorder like the Tascam, the Horita becomes superfluous since the recorder will clock directly to the video anyway. True, it solves the issue of getting timecode out of a camera that does not have a timecode output but with most file-based recorders timecode is only a glorified slate anyway.

What is gained is that the Horita sends timecode, which is specifically designed to be sent over any audio path. The Horita is small, and a small cheap wireless transmitter could be attached to it. So it can be pretty portable.

I suppose you could wirelessly transmit the video output from the camera, but that would require a video transmitter - more expensive than something to transmit audio, and not as likey to be in an average kit. Lots of people probably have less-than-great old wireless systems around that they used before they got something good...but would work fine for this purpose.

Work clock is not, like time code, really designed to be sent over an audio path. So while I suppose you might find some device to translate video to word clock, and maybe manage to send it over an audio link, it woud be a hack at best. Also, timecode readers are usually designed to handle transmission errors gracefully. Word clock inputs - not so much.

With timecode, even though the exact timecode will have offset, at least there *some* there and the Tascam can use it to stamp the file.

Also, the device on the remote end may be something else than a Tascam, it could be a computer, perhaps a laptop. With my tiny JLCooper’s PPS-2 timecode to midi timecode converter, I could (loosely, but sometimes good enough) lock anything that will lock to midi timecode (almost any audio/midi production program), with this small box instead of a larger piece of rackmount gear. Timecode/midi timecode is very flexible stuff, you can use it to control lighting, smoke machines, etc. I have a tendency to push the technical edges a bit on productions...

So it's about smallest, most portable, most flexible, easily wireless, cheapest. The cheapest way to do something I don't expect to have to do very often, but which could be very useful from time to time.

Does this make better sense now? Its really about the wireless option. Cheaper than a whole lockit system.

Even the window dub feature might be useful for cueing purposes in certain situations. Sent to any cheap video monitor you get a timecode display almost for free.

-Mike

I am too looking for a small and inexpensive device that can convert Blackburst to wordclock. My SD702 accepts only wordclock. I do not want to invest in an expensive (and mostly complex) device like the Aardvark since most of the times the audio stays in sync anyway. If Tascam can build such a device in a recorder that is far cheaper than my SD702 it should be possible to have one for say $500.

The PluralEyes software that automatically syncs audio sounds great but I think it will only work to synchronize startpoints and not hold sync for a prolonged time. Some sort of automatical slate therefore (am I right?).

Anyway not to complain though. I used to work with a Uher 4200 taperecorder with a built in sync module that could sync perfotape to the flashoutput of my 8mm filmcamera!

What is gained is that the Horita sends timecode, which is specifically designed to be sent over any audio path. The Horita is small, and a small cheap wireless transmitter could be attached to it. So it can be pretty portable.

I suppose you could wirelessly transmit the video output from the camera, but that would require a video transmitter - more expensive than something to transmit audio, and not as likey to be in an average kit. Lots of people probably have less-than-great old wireless systems around that they used before they got something good...but would work fine for this purpose.

Work clock is not, like time code, really designed to be sent over an audio path. So while I suppose you might find some device to translate video to word clock, and maybe manage to send it over an audio link, it woud be a hack at best. Also, timecode readers are usually designed to handle transmission errors gracefully. Word clock inputs - not so much.

With timecode, even though the exact timecode will have offset, at least there *some* there and the Tascam can use it to stamp the file.

Also, the device on the remote end may be something else than a Tascam, it could be a computer, perhaps a laptop. With my tiny JLCooper’s PPS-2 timecode to midi timecode converter, I could (loosely, but sometimes good enough) lock anything that will lock to midi timecode (almost any audio/midi production program), with this small box instead of a larger piece of rackmount gear. Timecode/midi timecode is very flexible stuff, you can use it to control lighting, smoke machines, etc. I have a tendency to push the technical edges a bit on productions...

So it's about smallest, most portable, most flexible, easily wireless, cheapest. The cheapest way to do something I don't expect to have to do very often, but which could be very useful from time to time.

Does this make better sense now? Its really about the wireless option. Cheaper than a whole lockit system.

Even the window dub feature might be useful for cueing purposes in certain situations. Sent to any cheap video monitor you get a timecode display almost for free.

-Mike

I understand what you're saying but I'm still concerned about several issues. Firstly, do the majority of the prosumer cameras our posters are using (Sony FX1, Canon XHA1, etc) actually output enbedded timecode in the composite video stream in real time? 2nd, is the Horita extracting and converting video VITC into stable LTC? And the biggy - so we get LTC, what do we do with it? Most of the audio recorders do not slave their audio sample clocks to it. Getting a slate is no problem - the primary issue is getting the camera and the audio recorder clocks to share a common timebase, using the camera as the master and slaving the audio recorder to it. Timecode, smimecode - unless they share a common timebase, after a certain period of time sync will drift. Does generating LTC with the Horita accomplish anything in that regard? Even recording the LTC on a spare audio track in the recorder doesn't do much for us since unlike Avid, 99% of the editing software (Premiere Pro, Vegas, FCP, etc) most DV folks are using doesn't recognise LTC on an audio track or do anything with it if its present (and even if it does, LTC doesn't control the playback rate of a BWF file.)

I understand what you're saying but I'm still concerned about several issues. Firstly, do the majority of the prosumer cameras our posters are using (Sony FX1, Canon XHA1, etc) actually output enbedded timecode in the composite video stream in real time?

Highly unlikely. And completely irrelevent, because I am concerned with the clocks being locked, not the absolute value of the time code.

The horita is locking to the horizontal and vertical timing pulses imbedded in the NTSC video put out by the camera, which are locked to the cameras master clock. It does not know or care about VITC or tri-level sync.

The Horita MUST lock to these in order to insert characters in the video stream to do the window dub, and to generate the 4800Hz clock for the time code it outputs, which must be in sync with the video also. Therefore any timecode it creates will have its clock locked to the video coming in from the camera.

That is the purpose the device is sold for, after all - to create a window dub while generating frame locked linear time code, the sales burb says that pretty clearly. It would be pretty useless if the timecode were not locked to the window dub.

I got lots of window dubs made this way sent to me in the 1980s, to do video sweetening on my analog 24 track. If it were not locked, I would have been screaming loudly. ;-)

2nd, is the Horita extracting and converting video VITC into stable LTC? No. They don't exist for it. A more sophisticated (and expensive) device might be able to do this, if the cameras output VITC. But I doubt they do.

It is creating its own timecode, but with the timecode clock locked to the incoming video clock.

And the biggy - so we get LTC, what do we do with it?

Well, we have time code with an embedded clock that is locked to our master camera. We can feed it to a recorder that will sync to it, convert it to word clock, convert it to midi timecode, convert it to video black burst, anything. Anything we convert it to wil be locked to the same clock as our original camera.


Most of the audio recorders do not slave their audio sample clocks to it.
But some do. Buy one that does. ;-)

Or buy a device that will convert it to wordclock or back to blackburst. Or use a Motu Ultralite, which will lock to it and output locked audio in digital form, which can be fed into any recorder that can record digital audio, or a computer. It will all be locked to the master camera.

Getting a slate is no problem - the primary issue is getting the camera and the audio recorder clocks to share a common timebase, using the camera as the master and slaving the audio recorder to it. Timecode, smimecode - unless they share a common timebase, after a certain period of time sync will drift.

They do. The timecode generated by the Horita had its clock derived from the video sent by the recorder, it is locked to it. So anything you derive from that clock is still locked to the master camera.

Derive the 4800 Hz clock from the timecode. Divide that by 160, you have 30 Hz - video vertical interval. Multiply it by 10, you have 48000 Hz, which just happens to be wordclock.

All still locked to the original source.

Does generating LTC with the Horita accomplish anything in that regard?

Yes, see above.

Even recording the LTC on a spare audio track in the recorder doesn't do much for us since unlike Avid, 99% of the editing software (Premiere Pro, Vegas, FCP, etc) most DV folks are using doesn't recognise LTC on an audio track or do anything with it if its present (and even if it does, LTC doesn't control the playback rate of a BWF file.)

That would be useless, yes. It doesn't matter though if you are moving files recorded to a disk or tape.

What you are missing is the frame oriented nature of both the audio and video. We are just moving blocks of data around.

Lets see what happens one step at a time. (simplifying a bit, ignoring color, etc)

In the camera you record exactly 30 frames on video in one second. You also, in the camera, may record audio - exactly 48000 frames of audio per second. Or 1600 audio frames per field of video. That relationship never changes, because in the camera the clocks that created both were locked together. In the computer, it just plays one frame of video in exactly the same time as 1600 audio samples. It only knows that is 1/30 second because the camera told it so, in the file. It does not know if the camera is telling the truth, if it is really on speed.

What if the camera is wildly off speed from the computer, say running twice as fast as it should? When you import the data, and play it back, it will run the video at half speed, because the file from the camera said it was 30 frames per second video, even though it really wasn't. The audio from the camera will also play back at half speed, because its data said it was 48000 audio, even though it really wasn't.

The absolute speed is wrong for both, but because both were originally recorded syncronized to the same clock, they are still in sync with each other. There are still exactly 1600 audio frames per one video frame. Even if you seperate the audio from the video, save it as a file, and then reload it, they will still be in sync because when the computer reloads the file, it still just sees it as 1600 audio frames to matchup with each video frame.

The exact same thing happens if the audio was recorded to a separate recorder but which was locked to the cameras clock. So imagine the same fast running camera running twice speed. It is really clocking twice as fast as it should be, but it creates a file that says '30 frames = 1 second'. The audio recorder is synced to this clock,which is actually running twice too fast, but it doesn't know this, it still writes a file that says '48000 frames = 1 second'

So when you load the video file into your computer, it sees 30 frames and plays it as one second of video. It loads the audio file and calls 48000 audio frames one second (even though it was actually running twice as fast). So again, both run exactly at half speed in the computer, and are perfectly in sync wth each other.

The computer plays both audio and video with its own clock. It believes whatever is in the file, that is all it has to go on. 1600 audio per 1 frame video.

When dealing with files and frames, pure digital data, ony the original clock rates they were recorded at must match. That is all that matters. The computer is always playing back both with its single clock.

If you have a Tascam, you can feed it the linear timecode directly.

With one of the Sound devices units, you would need to convert it to word clock. A (small, inexpensive) Motu Ultralight could do that, and function as a mixer and preamp as well.

All should sync up with no drift.

If you consider something like the Motu as just 'the other side of the chain', and add in the cost of a really cheap wireless link, I am pretty sure you are still well under the cost of a lockit system, and the Motu adds many other useful functions (preamps, mixer, computer interface).

I don't know what you would do with this, but here is what I would do:

Buy not the ultralight, but the next one up, the Travelor. Now I could use this with my favorite multutrack audio recording software on a laptop to record a whole band, multimiced just like in the studio, locked to camera. Live, portably, inexpensively, and in sync. I could even run lighting and effects for the band through midi at the same time. ;-)

-Mike

I am too looking for a small and inexpensive device that can convert Blackburst to wordclock. My SD702 accepts only wordclock. I do not want to invest in an expensive (and mostly complex) device like the Aardvark since most of the times the audio stays in sync anyway. If Tascam can build such a device in a recorder that is far cheaper than my SD702 it should be possible to have one for say $500.

The PluralEyes software that automatically syncs audio sounds great but I think it will only work to synchronize startpoints and not hold sync for a prolonged time. Some sort of automatical slate therefore (am I right?).

Anyway not to complain though. I used to work with a Uher 4200 taperecorder with a built in sync module that could sync perfotape to the flashoutput of my 8mm filmcamera!

If you don't mind a wired connection, all you need is a simple wordclock generator that will lock to video. Now, why can't I find a cheap one?...

This might work:

MOTU | MIDI Timepiece AV (USB/Serial) MIDI Interface | 1156 (http://www.bhphotovideo.com/c/product/176659-REG/MOTU_1156_MIDI_Timepiece_AV_USB_Serial_.html)

$ 499.95

Makes sure it does this function in standalone mode though.



-Mike

Wired to the camera is not that much of a problem, but wired to 220V is not that nice ;-)

Ok...

If you are using Sony cameras I can give you a tip that will solve your issues.

It's called TTL and it's from Fisher Robotics.

It was designed to function with Canon cameras also but unfortunately, it seems that XH-A1 has troubles with it. I know... I have one!

What this thing does is convert the embedded LANC TC signal from Sony and Canon LANC terminals to LTC. It works like a breeze... On Sony cameras! Not so on Canon. Strangely, it works perfectly on my old Canon XM2 (the US GL2), but not on my newer XH-A1.

I have it working on a Sony though and it slaves my Tascam HD-P2 with no hassles at all.

If you care, talk with Fisher himself. I'm almost certain that if many XH-A1 users insisted with him he probably would have solved this Canon issue long time ago.

Hope that helps

Mario - It probably runs on 5 volts internally. Renove the bulky transformer, replace with a battery.

Another device that might be found more cheaply on the used market: The ProTools Video Slave Driver (circa early 1990's). Its sole function was to create WordClock locked to incoming video. And yes, it was also AC powered and rack-mounted but not very large or heavy. Sorry if this device has been mentioned before, I didn't read the whole thread.
It could be helpful for someone setting up a DIY locked audio solution for minimal cash. I still have mine but none of the other gear from that now antique system.

Ok...

If you are using Sony cameras I can give you a tip that will solve your issues.

It's called TTL and it's from Fisher Robotics.

It was designed to function with Canon cameras also but unfortunately, it seems that XH-A1 has troubles with it. I know... I have one!

What this thing does is convert the embedded LANC TC signal from Sony and Canon LANC terminals to LTC. It works like a breeze... On Sony cameras! Not so on Canon. Strangely, it works perfectly on my old Canon XM2 (the US GL2), but not on my newer XH-A1.

I have it working on a Sony though and it slaves my Tascam HD-P2 with no hassles at all.

If you care, talk with Fisher himself. I'm almost certain that if many XH-A1 users insisted with him he probably would have solved this Canon issue long time ago.

Hope that helps

VERY COOL!!, to bad more sub $1000 recorders dont have BNC Word Clock/Video Ref In.

Here is a link to the specs.

http://www.fisher-robotics.com/PDFs/TIMETOOLLv1Flyer.pdf

VERY COOL!!, to bad more sub $1000 recorders dont have BNC Word Clock/Video Ref In.


It's not the lack on sub $1000 cameras that bothers me, it's the lack of any kind of sync above that price point. You literally have to go to the very top of the line - if even there - too get any kind of sync at all.

They put really crummy audio sections into these cameras, with the excuse that if you want good audio you are going to go double system anyway. But then make it very hard to do so.

The lack of any kind of sync input means if you want to switch cameras live, you have to put a TBC literally on every input to the switcher, a very expensive proposition. All for the lack of simple backburst sync, something the very first 'consumer' camera I ever used had, back in the video stone age of black and white cameras.

I hear the excuse that the markets are not big enough, but really, this is useful to anyone who is using multiple cameras recording anything longer than 30 minutes or so, or who has to switch live.

I see people doing video for churches here wanting to do this. I see people from corporate environments wanting to do this. These are small markets?

The main market for $5000 cameras is grandma, to make nice videos of her grandchildren? Maybe I am wrong, but that just seems unbelievable to me.

Or why not come into the 21st century and just automatically lock sync to GPS (now appearing even in cheap consumer gear) or use some other kind of wireless sync? These cameras have so many frills yet are so lacking in some basics. They can put complicated auto everything in, but to get a simple switch to manual mode I have to spend much *more* money? Just to be able to change a lens, I have to spend thousands more? It costs so very much more to put a lens mount on a video camera than a still camera?

This market looks so irrational to me.

Very frustrating.

I hope Scarlet and maybe the Chinese start giving some of these companys ulcers soon, to match mine. ;-)

-Mike

You make some good points, though what I meant by sub $1000 recorders was not camera's. I meant flash based audio recorders. With the TTL device you could use any Sony cam with a LANC out and then run a BNC cable to a flash recorder such as the Tascam HD-P2 and maintain sync, sorry for the confusion.

Ben

You make some good points, though what I meant by sub $1000 recorders was not camera's. I meant flash based audio recorders. With the TTL device you could use any Sony cam with a LANC out and then run a BNC cable to a flash recorder such as the Tascam HD-P2 and maintain sync, sorry for the confusion.

Ben

Oops, I guess my general frustration level caused me to misread your post. Sorry....

It is too bad about the inexpensive flash recorders, but here at least I can understand these are not really built for the video market.

You make some good points, though what I meant by sub $1000 recorders was not camera's. I meant flash based audio recorders. With the TTL device you could use any Sony cam with a LANC out and then run a BNC cable to a flash recorder such as the Tascam HD-P2 and maintain sync, sorry for the confusion.

Ben

That's exactly right Ben. And for what it matters, I think that Tascam's recorder is THE bang for the buck concerning flash based recorders. So why do you need any others? ;-)

Oops, I guess my general frustration level caused me to misread your post. Sorry....

It is too bad about the inexpensive flash recorders, but here at least I can understand these are not really built for the video market.

I think one of the reasons the Sound Devices 702T and 744T do not slave to video blackburst or incoming LTC is that their clock/timecode generators are actually made by Ambient and are essentially the same as on-board Lockit boxes in their own right. In fact, if you're using a Lockit on the camera, you can tune the two together just as if they were two Lockits and get to within 1 frame per day accuracy. I'm thinking they just didn't think many folks with $5000 prosumer cameras would be attempting much double system sound while people using full-blown pro cameras would either be using house clock or Lockits.

I'm thinking they just didn't think many folks with $5000 prosumer cameras would be attempting much double system sound while people using full-blown pro cameras would either be using house clock or Lockits.

Well, I generally agree in practical terms, and in their market. Their clocks are good enough even without extraordinary measures to stay in sync for close to an hour (with first class cameras), and just how often do you need to do takes on a movie set or in ENG that are over an hour long?

But I do see in some of the forums the pros asking each other about interfacing to some of these less expensive cameras being used for things like webisodes and reality shows, where these cameras do not necessarily have such accurate clocks. A use maybe not anticipated when Sound Devices designed their stuff.

The reason we spend the big bucks on stuff at that level is that it is robust, reliable, and flexible in ways that lesser gear that might work fine in the audio sense is not, and because we want to never, ever have tell a producer or director 'Sorry, my gear cannot do that'.

In that regard, my own personal feeling is that such a top of the line recorder should be able to sync in any format that has ever been in general use in the industry. That would include not only all the various kinds of SMPTE, but things like 'pilot tone' and 60 Hz as well. And a pro deck should be able to chase lock on set. It's not just about the 1 in 10000 chance you might need this to use in the normal, old fashioned way, but also because having such extra capabilities sometimes allows you to solve problems in creative ways.

I've done crazy things using capabilities that were used in weird ways - like syncing an analog 24 track to a non timecode dat machine with LTC on track 2, to be able to record 20 more takes of a vocal sequentially, using different offsets. Not exactly a 'normal' use of timecode, especially in a music production! It got us through though, and that was all that mattered in the end. I couldn't have done that without the 'extra' ability of my syncronizer to do offsets, something not normally required to lock two decks together for a music production.

If I were making my living doing sound for picture, I'd buy Sound Devices top of the line recorder without the slightest hesitation. But I would also have to buy one of the Tascam units to cover the hole the in the SD capabilities, and I should not have to do that.

But that is just me, considered a fanatic by some. ;-)

-Mike

It's got me thinking.
I have not noticed much sync drift in my concert recordings but a bit does appear on the +15 min compositions. So in my quest to better use the equipment I have, it struck me that since I often record separate audio on a Tascam DA-38 8 track digital tape recorder that the simple act of hooking a cable between my Canon XH-A1 composite out and the word sync in, on my Tascam deck, I will accomplish much better sync. Assuming that the length won't vary by the time I capture the audio into the computer, mix it in Wavelab and place the mixed wave file into my video edit timeline.
At least it will be an improvement over the machines all going on their own clock.
Thanks for the insight.

That's exactly right Ben. And for what it matters, I think that Tascam's recorder is THE bang for the buck concerning flash based recorders. So why do you need any others? ;-)

Thats a good point, I have heard a lot of good things about it. I just kinda wish the Edirol R-4 had it. Its 4 channels and the one I have been looking at.

For what its worth The Marantz PMD620 keeps great sync with video, when using 48khz WAV files. I have kept sync up to an hour many times.

Ben

It's got me thinking.
I have not noticed much sync drift in my concert recordings but a bit does appear on the +15 min compositions. So in my quest to better use the equipment I have, it struck me that since I often record separate audio on a Tascam DA-38 8 track digital tape recorder that the simple act of hooking a cable between my Canon XH-A1 composite out and the word sync in, on my Tascam deck, I will accomplish much better sync. Assuming that the length won't vary by the time I capture the audio into the computer, mix it in Wavelab and place the mixed wave file into my video edit timeline.
At least it will be an improvement over the machines all going on their own clock.
Thanks for the insight.

Ah, I hope you read the rest of this thread and understand you cannot just plug a video output into a word clock input wthout a converter in between.

I think these had a video sync card option though (blackburst), do you have that?

-Mike

I think these had a video sync card option though (blackburst), do you have that?

-Mike
----------------------
That option is not available on my model, the DA-88 and 98 model had that option.
I re-read the post in this topic and am now clear that if I ever need right on sync, then more gear can be acquired. As for now, editing the video and synchronizing the audio from the post mix, one composition at a time has been fairly forgiving and the drift very small, much smaller than the - "within a half of a frame" - offset that often appears in lining the clips up on the frame based timeline of NLE's.
... is the audience really listening ???.

I just found two cheap Video Slave Drivers from Protools (these convert blackburst from the composite output of the camera to wordclock that can be fed to my SD702 recorder).

They are rackmount 220V devices, but I will try to convert them in a new housing with battery feed. If, or rather when ;)) I succeed I will have one spare for another dvinfo user.

Good find Mario!
Of course the US version was 120v.
Another note, they could do 44.1k or 48k sample rate, but nothing higher than that.