2 cameras to record - how to manage the sound?

[Haopengyou]

I want to video a lesson and use it as part of my portfolio to look for a new job. I have a friend who has a pretty good Canon camcorder - I will put that in the back to video me. I have another camcorder that I will put up front, facing backwards to record the students. I have tried this setup before - it does a pretty good job of video, but the audio is not acceptable. I have a wireless microphone that I can wear...but I am not sure how to collect and combine all three - the 2 camcorders and the audio. I can edit the 2 camcorders footage together...that is not the problem..the problem is how to add audio and have it stay in sync with my lips.

[Cornucopia]

In ~descending order of professionalism & accuracy in syncing, the recording methods are:

1. All Gen-locked (blackburst+timecode) fed cameras
2. cameras with identically fed timecode (on audio channel) + identically fed audio (on other audio channels)
3. cameras with identically fed audio (with independent/internal TC track)
4. cameras with identically fed audio (no TC at all)
5. cameras with clean close up audio on some channel, with rest being on-camera ambient audio
6. cameras with on-camera ambient audio

The feeding can be wired or wireless (greater delay w/ wireless).

And in ~descending order of professionalism, accuracy & ease in syncing, the sync/alignment methods are:

1. Plural-eyes app
2. Pro NLE module that converts aux TC (on audio track) to TC track
3. DSLR re-sync
4. Pro NLE module that matches clips to their TC spot in batch
5. Pro DAW module with ADR feature that matches (as-close-as-possible) the waveforms
6. Manual matching of audio waveforms (by zoom-in + mark + snap, if possible)

Since you don't have ALL-genlockable cameras, your best bet is record method #2.

What I would do is this:

1. Make or buy 2 Y-cables, first is Mono Female + Mono Female -> Stereo Male, second is Stereo Female -> Stereo Male + Stereo Male. All are 3.5mm type. 2nd one should be long enough for cam separation distance (or with extenders).
2. Make or buy (at least) 1 3.5mm adapter cable: Stereo Male -> Mono Male
3. Get TC generator app for your phone
4. Plug the Adapter cable Stereo Male into your phone's headphone jack
5. Plug the Apapter cable Mono Male into your 1st Y-cable Mono Female's 1st input
6. Plug the 3.5mm output of your wireless mic into your 1st Y-cable Mono Female's 2nd input
7. Plug the 1st Y-cable's Stereo Male output into the 2nd Y-cable's Stereo Female input
8. Plug the 2 remaining Stereo Male outputs into the external mic jacks of the respective cameras
9. Start TC app running
10. Record
11. Ingest footage
12. Run DSLR re-sync app (with settings that use aux TC) and output/export clips & NLE-of-choice's Project EDL (AAF, XML, etc).
13. Run NLE and load exported EDL - it should ask where the clips are, point in the right direction.
14. DONE! Now, edit as you would like, remembering to at least keep one main audio track with wireless source (probably the BETTER of the 2 cams' audio equipment)

Scott

[smrpix]

As usual, Scott is absolutely correct, but you can simplify it a bit.

Even consumer cameras hold pretty good sync these days. You can feed your wireless mic to one of the cameras and use the other camera to record the room. Then all you need to do in your NLE is sync up the audio/video from both cameras.

Do a couple of tests first.
a) See which camera has a better mic and use that as the room camera. Try it in the actual setting if possible.
b) Make absolutely sure your cameras will hold sync over time (or this all falls apart.) Turn them both on, give a sharp, visible hand clap both cameras can see so you have a sync starting point, leave them both running, go on with your life for an hour or so, come back do another clap, load up your footage, sync it to the claps and see if they match at each end.

You can use a hand clap at the beginning of your actual program to help you find sync as well.

[newpball]

I want to video a lesson and use it as part of my portfolio to look for a new job. I have a friend who has a pretty good Canon camcorder - I will put that in the back to video me. I have another camcorder that I will put up front, facing backwards to record the students. I have tried this setup before - it does a pretty good job of video, but the audio is not acceptable. I have a wireless microphone that I can wear...but I am not sure how to collect and combine all three - the 2 camcorders and the audio. I can edit the 2 camcorders footage together...that is not the problem..the problem is how to add audio and have it stay in sync with my lips.

Hi good friend!

The microphones from consumer/prosumer cameras usually suck big time!

Avoid them like the plague!

Instead get something like this:

Tascam DR-40 4-Track Handheld Digital Audio Recorder:



Use the built-in mics for ambient and hook up two decent microphones in the bottom for close up sound.

[smrpix]

The microphones from consumer/prosumer cameras usually suck big time!

Avoid them like the plague!

Instead get something like this:

Tascam DR-40 4-Track Handheld Digital Audio Recorder:

If you go this route be sure to include it in the sync test I mentioned earlier. My Tascam (dr-05) loses sync by about a frame every 5 minutes in comparison with my consumer and professional cameras (which hold perfect sync with each other) -- very aggravating. (I built presets in Audition to deal with it, but it's a finicky extra step.)

[Cornucopia]

Yes, it's ALWAYS prudent to do a synchronization audio-visual clap at the beginning (and hopefully also ending) of a shoot/clip/take.

BTW, newpball is again grandstanding: microphones from consumer cameras (and even much less from prosumer cams) usually DO NOT "suck big time". The problem they have is in the fact that they don't have acoustic isolation (so there is motor/handling noise, as well as internal emi/rfi susceptibility), and MAINLY, because they are not optimally placed for sound. This is to be expected for any device that deals with Audio plus Video - one of them is given higher priority (almost always Video).

2nd system audio is often a good alternative, but that adds complexity. Certainly extra syncing steps.

My suggestions were based on not adding any appreciable cost to the OPs equipment budget. 2nd system audio WOULD add it.

Just doing the setup the way I suggested avoids relying on the "suckyness" of on-camera audio without adding cost. (Wireless Lav is going to be a pretty good source of sound, assuming quality equipment)

Scott

[newpball]

By the way B&H has a grandstanding sweet deal on the Tascam DR-40, yours for $150 with free shipping and a free license of Sony Sound Forge Pro 11.



http://www.bhphotovideo.com/c/product/1134048-REG/tascam_dr_40br_dr_40_portable_pcm_re...order_xlr.html

[pippas]

If you go this route be sure to include it in the sync test I mentioned earlier. My Tascam (dr-05) loses sync by about a frame every 5 minutes in comparison with my consumer and professional cameras (which hold perfect sync with each other) -- very aggravating. (I built presets in Audition to deal with it, but it's a finicky extra step.)

Although the better quality audio recorders ( and camcorders) tend to hold sync better than the cheaper consumer models, there's still no guarantee of audio sync without genlock.
Each device uses its own crystal oscillator, and all crystals have tolerances... which can, in come cases, even vary with temperature, for example.
In reality these variations are usually minimal with better quality kit.

But it does need to be remembered that even if the audio recorder is 'spot on' and it is the camera oscillator that is slightly adrift, then it is still the recorder audio that needs to be 'stretched' (or squashed) in post. It is always the camera audio that is in sync with the video, and therefore needs to be the 'master' track..

All this can pose a difficult challenge with 2 cameras. It may be difficult to sync 2 camera audios with one external audio track.......

I have tried this using 2 cameras, neither of which had external mic inputs.

So a clapper reference at the beginning and the end of the recording. Stretch or squash the external audio to fit the primary camera audio track, and then hope for the best with the other. (It wasn't too bad in my project)

Best to replace the whole camera audio with the adjusted external audio track before any editing. That way all the 'syncing' has already been done!

Scott's first option is best of course... but tends to be expensive!

[2Bdecided]

I want to video a lesson and use it as part of my portfolio to look for a new job. I have a friend who has a pretty good Canon camcorder - I will put that in the back to video me. I have another camcorder that I will put up front, facing backwards to record the students. I have tried this setup before - it does a pretty good job of video, but the audio is not acceptable. I have a wireless microphone that I can wear...but I am not sure how to collect and combine all three - the 2 camcorders and the audio. I can edit the 2 camcorders footage together...that is not the problem..the problem is how to add audio and have it stay in sync with my lips.

Connect the output from the wireless microphone into the Canon camcorder that's recording you.

Use manual audio recording levels on both camcorders. Do not trust automatic. It will increase the background noise.

If possible, don't attempt to mix the two audio tracks. Cut or fade between them (just like you would video tracks) to include your voice when you are talking, and the students when the students are talking. This will be fine if the students don't talk very much. It will be a problem if the lesson is very interactive because the frequent audio changes will be annoying.

If you really do need to mix the two audio tracks, get the best sync you can, and try to minimise the amount of "you" that's picked up by the camcorder facing the students. Put something physically in the way, or use an external microphone located nearer to (and facing) the students.


If you don't need to mix the audio tracks (you cut/fade between them) then sync is less important - if it's good enough for video cutting, it's good enough for this.

If you DO need to mix the audio tracks, excellent sync is vital.

Cheers,
David.

[newpball]

All this can pose a difficult challenge with 2 cameras. It may be difficult to sync 2 camera audios with one external audio track.......

Who in his right mind would do that?

If you record the sound separately you would obviously not use one single track, after all this is not the sixties anymore! And obviously you would not use the audio from your camera microphones either (except perhaps for synching or fallback if someone messes up). Just use one audio interface source!

Just take the video from your cameras and the audio from your external microphones through a single audio interface (or multiple if you want fallback) this will prevent all kind of phase distortions due to bad synching.

Simple, effective, high quality and professional!

The reason not to use the microphones of the cameras is not only the questionable quality of the microphones but also camera/lens/zoom noise, inflexibility of microphone positioning, bitdepth, sampling frequency and encoding limitations.

For live recording in 2015 there is really no reason not to record 24bit/96Khz minimum.

Synching will be just fine. Unless you are running some scientific video recording a microsecond difference here and there between the sound and video will not make a big difference. And with integral recordings it is a total non issue. Clap your hands (that's free by the way, no need for $100+ digital clapboards) in the beginning and at the end and sync and timestretch the sound if you need to.

[pippas]

All this can pose a difficult challenge with 2 cameras. It may be difficult to sync 2 camera audios with one external audio track.......

Who in his right mind would do that? .......

Anyone trying to match up a remotely recorded audio track with the video from two cameras?.......

No need to record a single track... you might want to retain some camera audio as ambience in the final mix...
But .... if syncing the remote audio is required, then you have to select one video source or the other to sync to.

With decent kit, it's not going to be much of a problem in reality... unless the video 'take' is very long......

[smrpix]

All this can pose a difficult challenge with 2 cameras. It may be difficult to sync 2 camera audios with one external audio track.......

Who in his right mind would do that?

If you record the sound separately you would obviously not use one single track, after all this is not the sixties anymore! And obviously you would not use the audio from your camera microphones either (except perhaps for synching or fallback if someone messes up). Just use one audio interface source!

Just take the video from your cameras and the audio from your external microphones through a single audio interface (or multiple if you want fallback) this will prevent all kind of phase distortions due to bad synching.

Simple, effective, high quality and professional!

The reason not to use the microphones of the cameras is not only the questionable quality of the microphones but also camera/lens/zoom noise, inflexibility of microphone positioning, bitdepth, sampling frequency and encoding limitations.

For live recording in 2015 there is really no reason not to record 24bit/96Khz minimum.

This is utter, unrealistic hogwash. In 2015 there are plenty of good reasons -- economic, technical and practical -- to use a variety of techniques including allowing each camera to run independently.

[Haopengyou]

Thanks! I will have to spend some time this weekend to understand your technology. I appreciate the ideas you have shared and look forward to learning. I had one thought as I was reading your suggestions that might make this all much simpler. My tablet does a pretty good job as a camcorder in the light levels in my classroom. Is there some way I can connect the camcorder in the back directly to my notebook, have the tablet in the front send the video via wifi directly to the notebook in the back, and have two wifi microphones also connected to the computer? It will probably require the purchase of an audio mixer - that is on my list of things to buy anyway So the result is that the camcorder is connected to the notebook by cable, the droid tablet camera is connected to the notebook by wifi, and the two wireless mics are also connected to the notebook - hopefully all recording in sync with each other.

[smrpix]

I can connect the camcorder in the back directly to my notebook, have the tablet in the front send the video via wifi directly to the notebook in the back, and have two wifi microphones also connected to the computer... So the result is that the camcorder is connected to the notebook by cable, the droid tablet camera is connected to the notebook by wifi, and the two wireless mics are also connected to the notebook - hopefully all recording in sync with each other.

If it stays in sync it's a miracle. If the whole thing doesn't simply choke on the bandwidth and input demands consider yourself really, really lucky.

[newpball]

My tablet does a pretty good job as a camcorder in the light levels in my classroom. Is there some way I can connect the camcorder in the back directly to my notebook, have the tablet in the front send the video via wifi directly to the notebook in the back, and have two wifi microphones also connected to the computer? It will probably require the purchase of an audio mixer - that is on my list of things to buy anyway So the result is that the camcorder is connected to the notebook by cable, the droid tablet camera is connected to the notebook by wifi, and the two wireless mics are also connected to the notebook - hopefully all recording in sync with each other.

Please tell me you are kidding.

You seriously want to consider this idiotic setup for a portfolio for a new job?

Sound is very important in video. People tend to tolerate sub par video with good sound much better than good video with sub par sound.

Buy/rent/borrow a digital sound recorder with at least one good clip microphone. Record the teacher with the clip, use another mic if you have students asking questions and also record ambient (in stereo). Use the two cameras for video only (use the sound only for sync). Put it together with an NLE and render with a good delivery codec.