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Is there a way to encode continuous time onto an audio track?

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Peter Holt
Is there a way to encode continuous time onto an audio track?
on Oct 5, 2016 at 6:43:54 am

I do flying videos, where the video is done with an external camera (which runs unattended for the whole flight) and with an mp3 recorder connected to the aircraft audio system (which also runs unattended for the whole flight).

Both devices are started at the same time.

All this works. Here is one example
https://vimeo.com/178217220

However, it would be nice if the two recording devices could be started and stopped as convenient, and then have the two tracks (or fragments of) line up automatically in the video editor (I use Vegas Pro 13). Obviously, audio corresponding to missing video would need to be automatically discarded, and vice versa.

Currently, the only things which I can have lining up automatically on the timeline are subtitles (imported from an SRT file, via Vegasaur). These line up correctly but the imported media events don't line up with anything ? so I still manually slide the stuff along to line it up.

I am sure that in the professional world there is a means of audio recording which is time-keyed, otherwise everybody would need to have the camera running all the time, or they would spend ages lip-syncing afterwards. The clapperboard method is not convenient...


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Richard Crowley
Re: Is there a way to encode continuous time onto an audio track?
on Oct 5, 2016 at 12:38:43 pm

You did not mention what camera(s?) you are using. But there is a timecode generator back available for GoPro...
https://gopro.com/news/getting-syncd-with-timecode-systems

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Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.


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Peter Holt
Re: Is there a way to encode continuous time onto an audio track?
on Oct 5, 2016 at 1:00:23 pm

The camera is a Sony FDR-1000V. This has no usable input except an analog mike input, which is anyway inaccessible when the camera is in the waterproof housing. The camera has wifi but it is crippled functionally to file transfer to IOS/android devices, or uploading to some Sony-owned streaming service. Even bluetooth versions have no such capability over bluetooth.

I chose the Sony for the small frontal area, which makes it more suited to aircraft usage.

It is interesting that a solution does exist. However, it seems that it is limited to recording the audio *in the camera*. Is there an audio recorder which takes Line In and which does the same thing?


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Richard Crowley
Re: Is there a way to encode continuous time onto an audio track?
on Oct 5, 2016 at 1:18:38 pm

The more expensive FDR-X3000 apparently has built-in timecode, but your FDR-1000V is a consumer-targeted, low-budget model.

There appears to be a mic input connector on the bottom (!) of the FDR-1000V. It would be simple enough to make a psuedo-SMPTE TimeCode generator from a postage-stamp size Arduino board. It wouldn't be frame-accurate, but it would get you in the ballpark (within a few seconds) With a couple of those, you could feed one into the camera, and the other into your audio recorder. You would "jam-sync" them together before taking off. Or you could get the more expensive FDR-X3000 or some other camera that natively supports timecode.

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Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.


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Peter Holt
Re: Is there a way to encode continuous time onto an audio track?
on Oct 5, 2016 at 1:27:58 pm

Interesting... I looked at the 3000 but it uses a different waterproof housing so I would have to re-make my whole camera assembly.

Also I have no means of running a wire to the camera. It would have to run over bluetooth. I am not 100% happy about that either because you don't want a piece of equipment, which cannot be turned off by the pilot, radiating anything, on an aircraft which might have to make an instrument landing... That is why I won't use the wifi on the 1000V to start/stop recording.

Is there a standalone timecode recorder which would work with Vegas in the way I originally described?


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Richard Crowley
Re: Is there a way to encode continuous time onto an audio track?
on Oct 5, 2016 at 4:45:38 pm

I don't follow what your proposed workflow is or exactly what is a "standalone timecode recorder"?

BTW: BlueTooth and WiFi both run at 2.4GHz. So I don't understand your reluctance to use WiFI, but willingness to use BlueTooth which operates at exactly the same frequency band?

There is nothing on an aircraft, general or commercial, that operates anywhere near 2.4GHz. Except maybe the flight attendant's MP3 player. It is guaranteed impossible that the 10s of millions of passengers ALL turned off their electronic gadgets each and every time a flight took off and landed. I appreciate extreme safety as much as the next guy, and I don't want to crash anymore than you (or the pilot) does. But all the fru-fru about "turn off all your gadgets" things has been proved to be superstition unsupported by science.

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Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.


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Peter Holt
Re: Is there a way to encode continuous time onto an audio track?
on Oct 5, 2016 at 6:02:22 pm

"I don't follow what your proposed workflow is or exactly what is a "standalone timecode recorder"?"

I would like to be able to drop an audio event onto the timeline and have it align with the video, where there is video.

"BTW: BlueTooth and WiFi both run at 2.4GHz. So I don't understand your reluctance to use WiFI, but willingness to use BlueTooth which operates at exactly the same frequency band?"

I don't want to use ither, but there is a huge difference in power.

"There is nothing on an aircraft, general or commercial, that operates anywhere near 2.4GHz. Except maybe the flight attendant's MP3 player. It is guaranteed impossible that the 10s of millions of passengers ALL turned off their electronic gadgets each and every time a flight took off and landed. I appreciate extreme safety as much as the next guy, and I don't want to crash anymore than you (or the pilot) does. But all the fru-fru about "turn off all your gadgets" things has been proved to be superstition unsupported by science."

I don't fly an airliner. They are well shielded, and are built to a high standard when it comes to EMC. Also there are other factors e.g. you can saturate a a circuit whose bandwidth is say only 150MHz, with a 2.4GHz signal.


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Richard Crowley
Re: Is there a way to encode continuous time onto an audio track?
on Oct 5, 2016 at 6:36:18 pm

Does your editing software read SMPTE timecode from an audio channel? If the external camera is running continuously, then you could feed a SMPTE TC stream into the second channel of your audio recorder. You could select the TC time as "run-time" (number of minutes and seconds since you started the camera). Then the audio recording would always know the start point relative to the beginning of the video clip.

If your editing software does NOT read SMPTE TC, then you could make a "voice tag" stream that announces the running time every 5 or 10 seconds. That would at least get you into the ballpark.

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Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.


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Bruce Watson
Re: Is there a way to encode continuous time onto an audio track?
on Oct 5, 2016 at 8:10:34 pm

[Peter Holt] ""I don't follow what your proposed workflow is or exactly what is a "standalone timecode recorder"?"

I would like to be able to drop an audio event onto the timeline and have it align with the video, where there is video."


This requires four things. First, a timecode generator of some kind. The generator has to provide timecode to the video and audio recorders. Second, a video recorder that can record the provided timecode in some way, while it records video. Third, an audio recorder that can record the provided timecode in some way, while it records audio. Forth, an NLE that can read the timecodes recorded by the video and audio recorders, and use these timecodes to line up the video and audio when you drop the video and audio onto your timeline.

You may be able to get around not having specific time code functionality by recording the timecode onto an available audio track. You'd use something like Tentacle Sync maybe (I've never used it, only read about it, and there are undoubtedly competitors as well). As to NLEs that can use audio timecode directly, you'd have to research it.

Can you get away without dealing with timecode? For a few minutes, probably. But your video recorder is going to drift, as will your audio recorder, and there's no telling if they'll drift together or apart, or at what rates. Thus... SMPTE timecode was invented.


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Peter Holt
Re: Is there a way to encode continuous time onto an audio track?
on Oct 6, 2016 at 9:03:04 am

OK, guys, many thanks... looks like I need to go up a learning curve on SMPTE ?

Vegas can use SMPTE, it seems.

Reading up on this, SMPTE involves storing time on every frame of a video and similarly storing time on every sample (?) on an audio track.

But, surely, an mpeg video file already has time embedded in every frame, surely? What does SMPTE add?

I read some web material on SMPTE in audio and it embeds the digital data in the audio, so you need a special player to strip it out, otherwise you can clearly hear it.

Searches on equipment tend to lead to this product every time: http://tascam.com/product/dr-701d/ That does just audio, with masses of features. I don't mind the price if it actually works with Vegas Pro 13... and preferably earlier versions like MSP11 which I have on a laptop I travel with.

I also see a lot of stuff about timecode generators. Why is this a separate function, when everything containing a microprocessor has (or can have) a real time clock for about $1? (I am an electronics hardware/software designer). Presumably the DR-701D contains all that and you just feed in Line In. I have a line level audio signal connection from the aircraft intercom.


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Peter Holt
Re: Is there a way to encode continuous time onto an audio track?
on Oct 6, 2016 at 9:38:59 am

Reading some more, it looks like the key issue is that you need split-second sync between the sound recorder clock (which generates the timecode) and the camera clock.

And this is hard to achieve. One could easily achieve it over say a 10 hour project (fairly cheap quartz crystal oscillator tolerance is say 5ppm, which is c. 0.1 sec over 10 hours) but how do you sync the two to start with?

That is presumably why the DR-701 takes the video signal from the camera, extracts the time from that, and uses *that* to generate the timecode recorded onto the audio. Then nobody needs to sync anything.

But clearly this won't work with a remotely mounted camera to which there is no access before the recording session.

The best one will be able to do is to set two two clocks as accurately as possible.

Does this make sense?


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Richard Crowley
Re: Is there a way to encode continuous time onto an audio track?
on Oct 6, 2016 at 10:21:38 am

Yes. I would think that you could do a "clap sync" when you start the camera and establish the audio recorder time code when the camera starts. Then you could start/stop the audio recorder which would continue to count the time code even when not recording.

As I said in the other (concurrent) response, the accuracy of professional SMPTE TC systems is much better than 5PPM because we are talking about frame-accuracy, which is 30x better than simple "wall-clock" time accuracy. And even at that, the cameras and audio recorders are typically jam-synced every 4 hours (or more frequently).

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Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.


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Richard Crowley
Re: Is there a way to encode continuous time onto an audio track?
on Oct 6, 2016 at 10:16:31 am
Last Edited By Richard Crowley on Oct 6, 2016 at 10:26:55 am

Reading up on this, SMPTE involves storing time on every frame of a video and similarly storing time on every sample (?) on an audio track.
Yes, SMPTE TC identifies each frame with a unique number. No. it does NOT sub-divide into every audio sample. A simple example would be 30 fields per second and 48000 audio samples per second. That would come out to one SMPTE value for each 1600 audio samples. Note that audio for video is essentially universally sampled at 48000 (48K) samples/sec. Virtually all video editing software uses 48K audio sample rate. If you import (for example) 44.1K audio track, it will need to be trans-coded up to 48K, either explicitly by the user, or in many cases, automatically by the NLE software.

But, surely, an mpeg video file already has time embedded in every frame, surely? What does SMPTE add?
No, there is no built-in TC. Of course implicitly, if you know the time when the clip started, you can derive the TC for each frame. Note, however that it is rare that a video camera or audio recorder are exactly precise. All gear drifts. Even professional gear that cost as much as your car. But professional operation uses expensive temperature-compensated crystal oscillators for each camera and audio recorder to maintain sync at least over a few hours. Even the most expensive and stable gear is typically "jam-synced" together at least every 4 hours (at meal breaks, for example).

And the same with audio. If the starting time is known, then you can derive the time from the starting point and the number of samples. In fact, this is the standard for audio recording. A "WAV" (or "AIFF") file is a subset of the RIFF standard which stores different kinds of information in identified "chunks". For example a WAV file contains a block that identifies itself as a RIFF/WAV file, the number of tracks/channels, the number of bits per sample, and the number of samples per second. A super-set of WAV is called BWF (Broadcast Wave Format) and BWF uses extra chunks to store the starting SMPTE TC. But for recorders that do NOT record audio into BWF, a compromise is to simply record the running SMPTE TC onto a dedicated audio track. SMPTE TC was originally designed to be recorded as an audio signal onto one of the audio tracks of an analog video recorder.

I read some web material on SMPTE in audio and it embeds the digital data in the audio, so you need a special player to strip it out, otherwise you can clearly hear it.
Yes. Back before digital video and audio recording, SMPTE TC was recorded as an audio stream on a spare audio track. Obviously, you don't mix the SMPTE TC track into the audio mix. You only use it to identify the location of the clip in the time-line. Of course, that uses up one of the audio tracks and there is no real need for that if the digital video camcorder or audio recorder handles SMPTE TC internally. But amateur gear is NOT designed to handle SMPTE TC as it is considered a professional feature. So it is included only in higher-price pro gear.

Searches on equipment tend to lead to this product every time: http://tascam.com/product/dr-701d/ That does just audio, with masses of features. I don't mind the price if it actually works with Vegas Pro 13... and preferably earlier versions like MSP11 which I have on a laptop I travel with.
Yes, that is an example of a "pro-sumer" audio recorder that incorporates timecode and writes audio tracks into a BWF format file. Similar "low-price" products are the recent Zoom F4 and F8 recorders. Note, however, that ANY recorder can be used if you have a SMPTE TC generator and a spare audio track.

Whether the BWF style, or the dedicated TC track method is compatible with your NLE (non-linear editing) software is something that you will have to research for yourself. I admit I don't know what "MSP11" means?

I also see a lot of stuff about timecode generators. Why is this a separate function, when everything containing a microprocessor has (or can have) a real time clock for about $1? (I am an electronics hardware/software designer).
Yes, you are correct. Note, however two significant factors:
  • First, the real-time clock in most microcontrollers is not as accurate as most SMPTE TC gear. Of course, that could be remedied by simply substituting a TXCO (Temperature-compensated Crystal Oscillator) in place of (or in addition to) the microcontroller clock.

  • Second, the ability to record the starting TC into the extra chunk in the BWF format is reserved as a "professional" feature for higher-price gear. Most consumer customers don't need frame-accurate TC . And of course you are correct that adding the TC chunk to audio or video recording is essentially trivial here in the 21st century with microcontrollers everywhere, down to and including toothbrushes, etc.


  • Presumably the DR-701D contains all that and you just feed in Line In. I have a line level audio signal connection from the aircraft intercom.
    Yes, there are many discussions and information on recording from aircraft intercom systems. Note that there is often interference from other aircraft systems. A very common problem is background "whine" from generator/alternator power sources on-board. This is typically ignored by users, and masked by ambient noise in the cabin/cockpit. But is is more annoying to people viewing/listening to the recording after the fact.

    Note that a common technique is to take a very small "lav" mic and to simply insert it between the headset ear-cup and the user's ear. That captures the intercom audio without requiring a hard connection into the intercom system. Note also that there are commercial adapter cables which have the special aircraft intercom connector (PJ-055 and PJ-068). One popular source is http://www.mypilotstore.com Users have sometimes (frequently?) resorted to using isolation transformers and/or notch filters to handle the aircraft power noise.

    Indeed, it is trivial to program an Arduino (or equivalent) microcontroller to generate SMPTE TC. But the accuracy will be directly dependent on the accuracy of the microcontroller clock. Even the standard RTC (Real Time Clock) solution typically used for microcontrollers (like DS1307 et.al.) is orders of magnitude LESS accurate than typical TXCO clocks used for SMPTE TC generation. But for an application like yours, frame-accuracy is not really necessary, and the less accurate RTC method would easily get you into the ballpark when syncing audio and video tracks in your NLE.

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    Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.


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    Peter Holt
    Re: Is there a way to encode continuous time onto an audio track?
    on Oct 6, 2016 at 10:56:14 am

    Thanks Richard for a brilliant clarification of all this.

    I just need to check out the Vegas workflow. Some google hits go back 10 years so it looks like it has been in there a long time.

    Re aircraft audio, if you connect into the intercom (a.k.a. "audio panel) - this is usually done by connecting into a spare headset socket - you get the benefit of the radio squelch i.e. total silence unless somebody in the cockpit talks, or ATC talks. That is how this one

    was done. Previously I used the mike in the headset method (I bought a tiny mike and a semi-pro preamp from Sound Professionals in the USA) and that is cumbersome as it keeps falling out when you move about, and it does pick up the same aircraft noise which you hear.

    I have sent this thread to Tascam and maybe they will confirm this should work... it needs to generate its own independent timecode.

    I am amazed mp4 video doesn't store the time in each frame! All the players such as VLC must be faking it, by counting frames. That is something to which I will have no solution, but then I don't need timing to better than a second or two. However, when I have loaded video and audio from separate sources (I use the $100 Tascam mp3 recorder) onto the timeline, there is zero evident offset after a 7hr flight, so it is good enough despite the camera spending time at -25C, etc.


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    Peter Holt
    Re: Is there a way to encode continuous time onto an audio track?
    on Oct 6, 2016 at 10:57:45 am

    Sorry, above video is the wrong one, but I can't edit this post. This is the right one


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    Richard Crowley
    Re: Is there a way to encode continuous time onto an audio track?
    on Oct 6, 2016 at 11:18:53 am
    Last Edited By Richard Crowley on Oct 6, 2016 at 11:20:59 am

    Well, you aren't exactly doing "lip-sync" so you probably don't notice any significant drift. However, if you were doing something requiring precise picture/sound sync, you could expect several frames of drift after even 10 minutes at room temperature.

    HOWEVER as even inexpensive, mass-produced consumer gear inevitably gets better from more accurate crystal manufacture, that is going up to 20 or 30 minutes with less than 1 frame of drift.

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    Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.


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    Richard Crowley
    Re: Is there a way to encode continuous time onto an audio track?
    on Oct 6, 2016 at 11:43:39 am

    Searches on equipment tend to lead to this product every time: http://tascam.com/product/dr-701d/ That does just audio, with masses of features. I don't mind the price if it actually works with Vegas Pro 13... and preferably earlier versions like MSP11 which I have on a laptop I travel with.

    I just minutes ago read this characterization in another forum:

    "And the DR-701D TC drifts like a ship with out a rudder. So except when it's constantly jammed with HDMI TC it is not going to stay in sync."

    Ref: http://www.dvxuser.com/V6/showthread.php?349657-Recorder-v-Mixer&p=19866612...

    ---------------------------------------------------------------------------------
    Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.


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    Peter Holt
    Re: Is there a way to encode continuous time onto an audio track?
    on Oct 6, 2016 at 1:08:43 pm

    Interesting... it must depend on what they are doing with it. It can't possibly be bad enough for what I want : )

    The DR701 also has a terrible battery life. External power (USB, or their battery pack) is really necessary for most things. OTOH the little $100 recorders can do 50-100hrs of recording on 2xAA.

    I can see some people, if mono is OK, will be recording a timecode on one of the two audio channels, from a timecode generator. Then you can use any cheap sound recorder.

    There is a lot of stuff online on this. One could read it for days.


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    Peter Holt
    Re: Is there a way to encode continuous time onto an audio track?
    on Oct 7, 2016 at 1:49:00 pm

    I have one more Q if I may:

    Does video have no timecode in it at all? Not even on the first frame?

    Because if it doesn't, there is little point in timecoding the audio. One needs to timecode the video also.

    But I am sure I am wrong, because the HDMI-derived timecoding of audio which this does
    http://tascam.com/product/dr-701d/overview/
    could not work. There must be a timecode coming out of the HDMI data. Doesn't this timecode also get recorded in the mp4 file, in the camera?


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    Richard Crowley
    Re: Is there a way to encode continuous time onto an audio track?
    on Oct 7, 2016 at 3:35:24 pm
    Last Edited By Richard Crowley on Oct 7, 2016 at 3:41:03 pm

    Does video have no timecode in it at all? Not even on the first frame?
    Professional cameras do. But it doesn't sound like that is what you are using.
    Note that if you can set the time/date on the camera, and the video file has a proper time/date stamp, that gives you a rough time reference when the video started (assuming you set the camera properly).

    There must be a timecode coming out of the HDMI data.
    No. That Tascam page is talking about "genlock" (locking the RATE of the video camera frame clock with the rate of the audio recorder sample clock. That is a different matter than timecode which is the actual hour minute second frame serial number of each frame. Here is part of a tutorial from B&H:

    Editors should be aware of a few issues when transferring video to another deck, device, or NLE computer system. The time code will not transfer if you connect via analog video, composite RCA, S-video (Y/C), component, or HDMI interfaces. Time code is carried through iEEE1394 (DV), RS-422 protocol, or through a camcorder that incorporates a separate time-code channel, typically with a BNC connector. Time code is crucial, especially if you want to do a "batch capture" with your NLE. Batch capturing is the process of capturing selected clips from a recorded-on-source tape, based on a log or shot list created by the user.


    https://www.bhphotovideo.com/find/newsLetter/Time-Code.jsp



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    Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.


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    Richard Crowley
    Micro-Tutorial: TIMECODE and GENLOCK
    on Oct 7, 2016 at 4:06:07 pm

    Timecode and Genlock are two different and independent functions, very frequently used together, and often confused.

    TIMECODE is a method of indexing each frame of video (and a frame's worth "block" of samples of audio). The timecode includes hours, minutes, seconds, and frame numbers. This MAY be the actual time-of-day ("wall clock" time), or it may be some other arbitrary number as decided by the production workflow.

    GENLOCK is a method of "locking" the frame-rate of the camera with other cameras and/or audio recorders. It cancels "drift" where unlocked gear runs at slightly different speeds because of normal variations in manufacturing tolerances. It sets one "master" reference which everyone else agrees to use (instead of their own internal clock). The "master" may not be any more accurate than each piece of gear, but the point is that they all run at the same RATE.

    Back in the days of analog video, all studio cameras were required to be GENLOCKed together so that they could be seamlessly switched/dissolved etc. in the production switcher. Modern digital gear tends to use "frame-buffering" where digital video coming from unlocked cameras is artificially "synced" together. This DOES cause a slight latency, and for that reason some higher-end digital gear still supports genlock.

    Note that modern designs have started to exploit GPS where BOTH the time (TIMECODE) and the rate (GENLOCK) can be locked together by using the wireless signals from the GPS constellation of 32 satellites. (Or the alternatives like the Russian GLONASS or the proposed systems from the EU (Gallileo), China, Japan and India.)

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    Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.


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    Peter Holt
    Re: Micro-Tutorial: TIMECODE and GENLOCK
    on Oct 7, 2016 at 5:13:01 pm

    OK; thank you Richard, again.

    This comes down to whether my FDR-1000V camera actually records any kind of timecode.

    The spec suggests it does if the higher rate format, X-AVC-S, 50mbits/sec (at 50FPS 1080P), is selected. It isn't clear whether this records a timecode into the file, or just burns it into the video like the old Hi-8 camcorders used to do (which would be stupid). But in any case in that format I get just 5hrs of recording at most, which is not enough unless I turn it on and off.

    The other way would be to burn a fake SMPTE timecode into the mp4 file afterwards, with some bit of software. That obviously won't be the exact time; it will at best be the file date/time incremented by 20ms for every frame encountered. And it will have to assume the recording was continuous. But this defeats the point of timecoding... which (in my case) is having *discontinuous* video and still having the audio clips synced.


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    Peter Holt
    Re: Micro-Tutorial: TIMECODE and GENLOCK
    on Oct 7, 2016 at 6:02:31 pm

    "That Tascam page is talking about "genlock" (locking the RATE of the video camera frame clock with the rate of the audio recorder sample clock. "

    How does that enable the sync of audio clips with video clips, if the camera video has no timecode on it?

    Or does that process assume the video does actually have timecode on it, but the DR701 doesn't use it and just uses the frame rate from the HDMI signal? I guess the latter may have been their only option since a DSLR is probably not outputting the video anywhere, so the only way to get any timing info from it is by looking at the HDMI and that doesn't contain the timecode either, but obviously you can count the frames... and it probably extracts the date/time of the start of each clip from HDMI as well.

    I trid to phone Tascam UK (Teac) but there is just an answering machine on their tech line # they gave me! And they don't return calls.

    I think every DSLR records in .mov (all those I have used did, including my Pentax K3) and that is Quicktime and that contains SMPTE as default, as far as I can find out.

    So that is probably how all this hangs together.

    But unless the camera itself is adding SMPTE to the video, none of this audio stuff will be of any use.


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    Richard Crowley
    Re: Micro-Tutorial: TIMECODE and GENLOCK
    on Oct 7, 2016 at 7:01:09 pm

    How does that enable the sync of audio clips with video clips, if the camera video has no timecode on it?
    The Tascam recorder derives the RATE from the HDMI video (amateur "genlock"). Some recorders even start/stop automatically when the camera is started/stopped. Dunno whether that Tascam DR701 does or not?

    But since there is no timecode via HDMI, it is left to the user to work that out. This is typically done with a clapstick/slate where you can slate the scene/angle/take, etc. on the board (and announce it verbally for the audio) and then snap the sticks together to establish simultaneous video and audio sync point. That has been the tradition for 100 years, and it continues to be almost universal to this day. Of course, that is impractical for you, but then you have a very "far out" application there.

    I have to wonder, if you are starting/stopping the camera (remotely) why can't you simply start/stop the audio recorder at the same time? Maybe I'm still not understanding your operation.

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    Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.


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    Peter Holt
    Re: Micro-Tutorial: TIMECODE and GENLOCK
    on Oct 8, 2016 at 2:58:16 pm

    No; a perfectly good point.

    It is however difficult to do that accurately, because the remote control of the camera is over wifi (using a clumsy phone app) while the recorder I currently use (a low end Tascam one) needs two button presses.

    The simplest thing would be to control the camera on/off as required (if only to get the required 7+ hours out of its X-AVCS mode in which the timecode appears available, but which runs for a max of 5 hours) while run the recorder unattended.

    I will investigate the camera timecode options further and report on any progress.


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    Richard Crowley
    Re: Micro-Tutorial: TIMECODE and GENLOCK
    on Oct 13, 2016 at 5:51:27 am

    Doesn't the camera write a separate video file each time you start it? What does the date stamp on the file say?

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    Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.


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    Peter Holt
    Re: Micro-Tutorial: TIMECODE and GENLOCK
    on Oct 13, 2016 at 9:00:54 am

    Yes; if you stop the camera and restart it, it will close the current file and open a fresh one, whose date stamp is the time it was started.

    It then continues to write into that file, until 4GB is reached, and then it closes that one and immediately starts another one whose date stamp is the time *that* one was started.

    IOW, what you would expect.


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    Richard Crowley
    Re: Micro-Tutorial: TIMECODE and GENLOCK
    on Oct 13, 2016 at 11:25:32 am

    So, with knowledge of the starting time of the first "take", you effectively have rough "time code" for each clip. Doesn't that get you what you are looking for? You aren't needing genlock/lip-sync for your application, you just need some rough way of correlating a video clip with an audio clip. So even a tolerance of 1 or 2 minutes would be perfectly adequate to match up video and audio files.

    ---------------------------------------------------------------------------------
    Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.


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    Trevor Asquerthian
    Re: Micro-Tutorial: TIMECODE and GENLOCK
    on Jan 17, 2017 at 11:26:55 pm

    Assuming:
    a. that you have video that does not record a TC track (but does record a date/time stamp for file)
    b. that your audio is continuously recorded
    c. that the video stop/starts


    Best thing is to get the video TC track to match the date/time stamp

    https://www.videotoolshed.com/product/qtchange/ --- does this, I think


    Then to string out videos so that there is black where there was no recording (Avid does this with 'autosequence' - other NLEs you have to do it manually, although you may be able to do it by stringing all clips in one timeline, exporting an EDL or XML and copying the source timecode to the record timecode)

    Then add the audio (continuous recording) to this. Timecode or date/time stamps may help get you close.

    Now slide all the video (or the audio) to get sync... should be reasonably consistent across a few hours, likely to drift a bit as nothing is locked.



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