GH2 Built-in mic or 2.5mm audio input better for post syncing?

V

VMT

Well-known member
I just received the GH2 :grin: and will buy an external audio recorder, Tascam DR-100, for a dual system recording of interviews. I will sync the audio from the DR-100 using PluralEyes.

What's the best way to provide a scratch track for PluralEyes to perform the synchronization analysis? Should I feed audio from the DR-100 to the GH2 2.5mm input jack to get a better scratch track to sync with? Or is the built-in mic
good enough? I don't want to tether the DR-100 to the GH2 or be inconvenienced with an extra audio cable if I don't need it.

Thanks in advance for your response.
 
Last edited:
I'm not sure how PluralEyes works but I'm sure the built in mic would be good enough, the problem with using the mic input without monitoring, is that you may not get audio at all, or horribly distorted.
 
The built-in mic is actually surprisingly good, as built-in dSLR mics go. I've been syncing with a HVX200 just using that.
 
The internal mic will work wonderfully fir tPharoah just told me he knows someone in Pleasant Hill*his. I do it all the time with Pluraleyes and I've never had an issue.
 
I wouldn't waste the money on Pluraleyes, just slate clap & syncing is easy & faster doing it manually.
 
Boncrek said:
What if the situation doesnt allow for clap and syncing?
Click to expand...

good point - I guess from being a sound editor for over 20 years audio sync is just easy for me - when I tried pluraleyes using the camera mic & the boom it didn't do a very good job & took a long time to analyze. I didn't explore it much deeper than that since it was slower than I could do it myself. To the OP I would suggest throwing a video mic on your GH2 to get the best reference audio you can.
 
The built in mic is fine for syncing, a better mic will in fact provide you with a more accurate waveform. This is not an issue if you use a sharp profile reference point like a clap or tapping a glass with a piece of metal like a table knife (very sharp profile, dull knife). The more accurate waveform will generally, depending on how you record the source material and mix it, more closely resemble the outboard audio, particularly at the beginning of the wave slope coming out of a quiet space. You must also calculate the offset, which I'm not sure plural eyes will do anyway. All cams have a slight built in offset. If you are close micing, this is usually not an issue, if you are only using the cam for interviews the offset is going to be small. OTOH, if one of your cams is say 20 feet away and your mics are six feet away you roughly have a 14ms offset. If you have a cam say in a balcony at an event or a distance shot, you can be looking at a whole frame of offset, which looks wrong but sounds right. That is why it is important to have the visual sync as well as the audio sync. If you want really good results, skip the plural eyes and just get quick at reading the wav patterns. Remember to *temporarily* normalize by eye, not by number, the wavs so the shapes are similar. Then after syncing remember to put the audio back to the optimum level.
BTW, if you are doing interviews, not sure the Tascam is what you want, maybe a lav going into an H2, two H1s on booms, etc. Depends on how the interview is set up. Maybe you don't want the Tascam or other Flash recorder in the movie.
 
DrDave said:
The built in mic is fine for syncing, a better mic will in fact provide you with a more accurate waveform. This is not an issue if you use a sharp profile reference point like a clap or tapping a glass with a piece of metal like a table knife (very sharp profile, dull knife). The more accurate waveform will generally, depending on how you record the source material and mix it, more closely resemble the outboard audio, particularly at the beginning of the wave slope coming out of a quiet space. You must also calculate the offset, which I'm not sure plural eyes will do anyway. All cams have a slight built in offset. If you are close micing, this is usually not an issue, if you are only using the cam for interviews the offset is going to be small. OTOH, if one of your cams is say 20 feet away and your mics are six feet away you roughly have a 14ms offset. If you have a cam say in a balcony at an event or a distance shot, you can be looking at a whole frame of offset, which looks wrong but sounds right. That is why it is important to have the visual sync as well as the audio sync. If you want really good results, skip the plural eyes and just get quick at reading the wav patterns. Remember to *temporarily* normalize by eye, not by number, the wavs so the shapes are similar. Then after syncing remember to put the audio back to the optimum level.
BTW, if you are doing interviews, not sure the Tascam is what you want, maybe a lav going into an H2, two H1s on booms, etc. Depends on how the interview is set up. Maybe you don't want the Tascam or other Flash recorder in the movie.
Click to expand...

Thanks for this small writeup. I had heard people mention this problem when syncing particularly when involving far away mics and/or multiple cams as the sound would reach the different cams at different times. Good to know what to do now. Thanks.
 
DrDave said:
BTW, if you are doing interviews, not sure the Tascam is what you want, maybe a lav going into an H2, two H1s on booms, etc. Depends on how the interview is set up. Maybe you don't want the Tascam or other Flash recorder in the movie.
Click to expand...

I will be using either a wireless lav or a shotgun on boom pole, depending on the situation, with the Tascam for interviews. I have used an H2N and found it not to meet my needs (lacks manual dials, headphone output, separate line out).
 
So sounds like the best scenario is to feed the outboard audio into the GH2 when possible and slate for a sharp reference point. But the built-in mic is good enough if the the outboard recorder has to be separated from the camera (such as when not using a wireless and the camera can't be placed close to the subject), under which situation a visual sync might also be necessary.

Thanks for all the informative tips!
 
Last edited:
Do you guys using a separate unit for audio find any drift? When I did that with some older equipment, at times, I had to stretch to fit one or the other.
 
Heartfelt said:
Do you guys using a separate unit for audio find any drift? When I did that with some older equipment, at times, I had to stretch to fit one or the other.
Click to expand...
Depending on the camera, some outboard gear has very little drift. There are, of course, two clocks involved. RME have very good clocks, and I have had good luck with the Fostex and my Canon camcorders. I don't really stretch the audio, as it sounds, well, stretched, I just resync in the gaps.
 
You must log in or register to reply here.
Back
Top