Dan Gruner Posted November 1, 2009 Share Posted November 1, 2009 I am not an expert in video, hence the question. I have done some searching but have failed to find a complete answer to my questions. Basically I need to sync audio recorded on a standalone multitrack HDD recorder (Alesis HD24XR) with video recorded on a camcorder. I have looked into using SMPTE but unsure how to implement it. The typical camcorders I get to use can't generate or chase timecode and it may be the best option to record on n external DVD/HDD recorder if I need to. If I brought an external LTC SMPTE generator and fed this to a track on the HD24 and camcorder (the camcorder's internal mic will not be used), will I then be able to easily line up the audio and video in an editing program like Sony Vegas Pro? Would I need to use timecode embedded into the video signal on the cameera instead? How would all this work? In addition what would be very useful for rehearsals especially, would be the facility for the camera or external DVD/HDD playback controls to directly control the HD24 and play back mutitrack audio with the video all in sync - both jumping to places, rewinding, fast-forwarding etc. This way I can play rehearsal footage through a projector for the artists and multitrack audio back through the desk for soundcheck purposes. I have seen other equipment including a remote for the HD24 that can sync to video - they have a BNC composite video input on. Is this to do with SMTPE or something different? I don't assume its as simple as taking a video feed from the video recorder and telling the HD24 to start/stop playback/record with the video? Any help and advice, including pointers to resources would be much appreciated. I don't mind spending money either if I have to. Dan Link to comment Share on other sites More sharing options...
Shez Posted November 1, 2009 Share Posted November 1, 2009 Having been here a few times... Recording timecode to both devices won't help all that much. What you would ideally do is have both devices locked to a common clock that actually controls the speed at which they run - that way you will always have sample accurate sync. That's possible on the HD24 but not on any domestic cameras. What I have done successfully in the past is to just let the camera and the HD24 run on their own clocks and lined them up in the edit afterwards - this is easy enough to do visually and/or audibly. Just send a track of audio from the HD24 to the camera to eliminate the time it takes for sounds to reach the camera's mic. Over an hour or so of recording, there was no significant drift - modern clocks are pretty accurate. Make very sure you set the HD24 to 48K - the one time I left mine at 44k1 caused me no end of trouble as it actually samples at 44,117Hz... Link to comment Share on other sites More sharing options...
Johnparrack Posted November 2, 2009 Share Posted November 2, 2009 Having been here a few times... Recording timecode to both devices won't help all that much. What you would ideally do is have both devices locked to a common clock that actually controls the speed at which they run - that way you will always have sample accurate sync. That's possible on the HD24 but not on any domestic cameras. What I have done successfully in the past is to just let the camera and the HD24 run on their own clocks and lined them up in the edit afterwards - this is easy enough to do visually and/or audibly. Just send a track of audio from the HD24 to the camera to eliminate the time it takes for sounds to reach the camera's mic. Over an hour or so of recording, there was no significant drift - modern clocks are pretty accurate. Make very sure you set the HD24 to 48K - the one time I left mine at 44k1 caused me no end of trouble as it actually samples at 44,117Hz... MMM...I believe correct me if I'm wrong...video always runs at 25frames per second or 50 fields (assuming PAL).(no control of speed me thinks!!)..if you are going to accurately jam sync audio and video devices via timecode, they also need to both be frame locked..therefore a black and burst input (or reference) to both devices. in the instance of one or neither being able to take genlock, then trying to start each device with the same timecode will be close, but will over time drift quite a bit in editing terms...as you say..most NLE's are easy to line up if you have the material that is easy to spot lip sync on...but personally...frame lock and timecode jam are best...especially in a multi camera rig/edit/shoot. Makes the editors life a lot easier and in the end cheaper for your client. hth..john Link to comment Share on other sites More sharing options...
smalljoshua Posted November 2, 2009 Share Posted November 2, 2009 How about a simple snap board? Sync the close of the board to the sound in Edit. Josh Link to comment Share on other sites More sharing options...
Dan Gruner Posted November 2, 2009 Author Share Posted November 2, 2009 Having been here a few times... Recording timecode to both devices won't help all that much. What you would ideally do is have both devices locked to a common clock that actually controls the speed at which they run - that way you will always have sample accurate sync. That's possible on the HD24 but not on any domestic cameras. What I have done successfully in the past is to just let the camera and the HD24 run on their own clocks and lined them up in the edit afterwards - this is easy enough to do visually and/or audibly. Just send a track of audio from the HD24 to the camera to eliminate the time it takes for sounds to reach the camera's mic. Over an hour or so of recording, there was no significant drift - modern clocks are pretty accurate. Make very sure you set the HD24 to 48K - the one time I left mine at 44k1 caused me no end of trouble as it actually samples at 44,117Hz... Thanks for the reply. Yea, I have done with with very short video clips, about 30m without problems. However I am starting to do multitrack audio with video more and more now and need a "proper" solution! With regard to sync'ing the clocks of both devices together - this makes perfect sence and wordclock will do that and SMPTE will tell each device where it is on the time line. With regard to getting both the clocks sync'd, cant this be done via video - hence the reason some kit has a video sync input. Would it not be possible to force the HD24 to sync to a composite video stream from the camcorder, by using a BRC or MOTU timepiece to generate ADAT sync from a video signal? My other question relating to the play, fast forward, stop controls etc. I understand I would need to use midi machine control to operate the controls and these could be generated by a sequencer or computer. So I'm looking at Genlock, SMPTE and midi machine control to achieve what I am after. This is getting complicated! Dan Link to comment Share on other sites More sharing options...
Shez Posted November 2, 2009 Share Posted November 2, 2009 MMM...I believe correct me if I'm wrong...video always runs at 25frames per second or 50 fields (assuming PAL).(no control of speed me thinks!!).. Yes, but there's 25.00001 fps and there's 24.9999 fps... No camera runs at exactly 25fps - this is exactly the reason that they need to be synced to a common clock. Link to comment Share on other sites More sharing options...
Johnparrack Posted November 3, 2009 Share Posted November 3, 2009 yes, thats why they are "frame locked"...and yes you can put black and burst or another "Reference" into the video sync input. Basically speaking the with timecode..it runs at 25 fps and so does video..if you lock the audio to a frame then it will be perfectly in sync for the edit with no need for buggering about on the timeline. Also comes in very handy for multiple cameras or playback from for example a audio track on a dat/etc with timecode firing off video clips, lighting cues etc at relevent points where the code matches...but again, all needs to be locked (Genlock/Ref) for it to be accurate. Link to comment Share on other sites More sharing options...
Dan Gruner Posted November 3, 2009 Author Share Posted November 3, 2009 right ok, how can I get any closer to solving my problem? Dan Link to comment Share on other sites More sharing options...
mac.calder Posted November 3, 2009 Share Posted November 3, 2009 Something like the Kramer SG6005 should help - takes your worldclock in from the HD24 and generates blackburst... and voila, you're syched. Run some timcode as well and your editing will be a lot easier. Link to comment Share on other sites More sharing options...
sleepytom Posted November 3, 2009 Share Posted November 3, 2009 well only if you have cameras which support external timecode! that's the key point, if you want an answer to "how do I do this properly?" then the answer is you use cameras which support genlock and external timecode, you pick a device to be the master and you then sync all the cameras to the master timecode. If you don't have cameras which support genlock and timecode then you cannot really sync them to anything, you can bodge common timecode by syncing cameras off the same IR remote but it will drift over time. There are no magic solutions to fix this on cheap cameras, the only way to do proper sync is with professional equipment that allows for common ref sync and external timecode. So how does everyone else do multicamera shoots on the cheap? easy they don't sync the cameras and they rely on the editor to manually align things in the timeline from a clapper board, popped balloon or other strong audiovisual event. Link to comment Share on other sites More sharing options...
Dan Gruner Posted November 4, 2009 Author Share Posted November 4, 2009 The camera is only for reference purposes really and just one camera. I am quite happy to invest in a decent camera with genlock and timecode if necessary. My question earlier with regard to syncing of a composite video stream from an inexpensive camera was in the sence of using this camera as the master sync device and slaving the HD24 of of it. It appears there are several devices that can sync from a video signal (naimly the HD24 BRC). With regard to the editing stage, I gather you can load in 2 sets of media containing timecode (either video or audio) and the program will keep them in sync from a defined startpoint? Dan Link to comment Share on other sites More sharing options...
dbuckley Posted November 5, 2009 Share Posted November 5, 2009 If you are recording video: The whole idea of recording timecode is that the devices don't need to be syncronised to each other; it is the presence of the recorded timecode on multiple things that enable them to be brought together to frame accuracy in post. Either use the HD24 to generate MIDI Timecode, get a MTC to LTC converter and record the audio onto the camcorder(s), or use a standalone generator and record audio onto the camcorders and to the HD24. Or do both together! To play back video and audio synced live, make the video the master, and use a LTC / MTC converter to get MTC into the HD24. The HD24 should chase and lock to the video. However..... this could be fraught with trouble though; do a google for HD24 chase MTC - altogether too many hits for such a simple thing to do... Link to comment Share on other sites More sharing options...
ceecrb1 Posted November 6, 2009 Share Posted November 6, 2009 I just fell across this link..Page 2 has a little more info for what you're looking for.. http://www.videomaker.com/article/2325/ Not too detailed but a start. Link to comment Share on other sites More sharing options...
sleepytom Posted November 7, 2009 Share Posted November 7, 2009 Have you tried simply recording the audio and the video separately and then manually aligning them in vegas? Its actually very easy to do, and if your not using mutliple cameras or doing much in the way of complex editing then I don't really understand why you think you need a better solution? I quite frequently do this in vegas and I never really have much of a problem with it. Generally I find that just lining up the start is good enough even for a hours worth of footage. I use the following procedure..Make a new composition, Import the video to the timelineImport the audio to the timelineAlign the video and audio using the video's audio track waveform as a guide, it helps if someone used a clapper board when shooting but even if no clapper was used its very fast to line them up manually just by looking at the waveforms and listening to the results.Then go to the end of the timeline and check that the sync is OK (its usual to hear a slight phasing as the sync will not be perfect but this doesn't matter) Group the audio and video tracks so they behave as a single clipMute the video audio track.Save the composition. This composition can now be imported into a new timeline for further editing - compositions imported into the timeline behave just like regular media files but with the advantage of being able to go back into them and make any adjustments you might need, this kind of nesting of comps is possibly the most important technique to understand with video editing / compositing as it maintains quality and saves vast amounts of render time. Either use the HD24 to generate MIDI Timecode, get a MTC to LTC converter and record the audio onto the camcorder(s), or use a standalone generator and record audio onto the camcorders and to the HD24. Or do both together! Recording LTC on the audio track of the video won't help you as it won't be seen by vegas as timecode, the video timecode will still be the internally generated timecode from the camera. One option that has not been suggested is to get a separate video recorder with timecode input. Something like the datavideo DN200 is cheaper than buying a new camera and gives you the advantage of direct-to-edit recording / tapeless workflow. This would be my choice of solution if you decide your not happy with doing it manually in vegas. Link to comment Share on other sites More sharing options...
Dan Gruner Posted November 8, 2009 Author Share Posted November 8, 2009 Many thanks for the info. It looks like I'm going to have to seek further support from a video production company with regard to all this, especially my requirement to sync the control of the HD24 to the video recording device and have both playback in sync. Thanks, Dan Link to comment Share on other sites More sharing options...
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