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Author Topic: GH1 review  (Read 3760 times)
OldRoy
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« on: July 22, 2009, 05:30:40 AM »
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As someone who, many years ago, made a living making video programmes professionally, using analogue "industrial" (for want of a better term) and broadcast equipment and techniques, I have viewed the development of digital video from afar and with some regret that I have never had a chance (or never created an opportunity) to use any of the current hardware and software. My DSLRs lack video and in any case shooting video using a still camera just seems weird to me. What continually surprises me though, is the apparently huge and continuing deficit in terms of audio. Now it was never easy to record sound well on analogue equipment either, so the standards achieved were a good indication of the competence of the programme-maker.

The review notes:
"If you want to really produce good sound you have to record dual system, which means doing the sound with a separate audio recorder and mics and then syncing it up in post. "

"If you want to really produce good sound..." Huh IF? This is an astonishing proviso.

I've seen the en passant reference to timecode-locked audio recording in this context before: the requirement remains the same since I retired from the video game (I was in the hardware R&D/manufacturing business as well as a programme-maker) but I've yet to hear an explanation of how practicable this is today; it ought to be a LOT easier and cheaper than it was - in the mid-80s an integral timecode generator for a broadcast version Umatic cost nearly 1K. I'd appreciate a short description of just how it's done now, if someone can take the trouble. It can be very brief!

On a previous thread on another board someone tried to suggest to me that it was just a case recording wild audio separately and in PP of periodically syncing up and letting it roll. I assume that the contributor had never actually tried this with synch speech. And drop-frame I thought had gone away with the analogue era (standards conversions nightmares resurface) but I'm amused to see it's re-emerged, revived, in the current era. The wonderful thing about standards is that there are such a plethora to choose from, and in that respect it seems nothing has changed in the last 25 years.

Roy
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Chris Sanderson
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« Reply #1 on: July 22, 2009, 07:31:07 AM »
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I often use a 'wild' Edirol mini-recorder to do audio back-up when recording our many-hour video tutorials.
I do this mostly because I use radio-mics recording onto the camera and often there is serious interference (esp. from dreaded iPhones ...) that requires me to have a reasonable backup audio source.

Amazingly, once synched these wild recordings are frame accurate after many, many minutes of recording - there is no apparent slippage in sync.
It seems that modern electronics are very stable indeed in their 'frame-rate'. Synching is now a non-issue.
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Christopher Sanderson
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« Reply #2 on: July 24, 2009, 07:18:10 PM »
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The review says:

"Be aware though that in Motion JPG the camera records at an actual 30 FPS, not 29.97 FPS, which is the industry standard. This seemingly very tiny discrepancy can lead to a loss of audio sync as every thousandth frame is dropped to compensate. This means that audio will build up a delay against video of one frame every thousand frames, which seems like a lot but is only just over 30 seconds worth of footage."

Does this mean that if I try to use second system audio recorded with a device like the Zoom H4n with the GH1's motion jpeg video I will run into sync problems?
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Andy Stauffer
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« Reply #3 on: July 25, 2009, 03:26:05 AM »
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Quote from: aks
The review says:

"Be aware though that in Motion JPG the camera records at an actual 30 FPS, not 29.97 FPS, which is the industry standard. This seemingly very tiny discrepancy can lead to a loss of audio sync as every thousandth frame is dropped to compensate. This means that audio will build up a delay against video of one frame every thousand frames, which seems like a lot but is only just over 30 seconds worth of footage."

Does this mean that if I try to use second system audio recorded with a device like the Zoom H4n with the GH1's motion jpeg video I will run into sync problems?


Hi,

the Zoom H4 has had a history of sync issues so, the 30fps and 29.97 fps may complicate that issue further, unless the H4n is a newer model that has fixed the sync issues.

Cheers John
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michael
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« Reply #4 on: July 25, 2009, 07:39:06 AM »
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This is a murky area.

I would ask though - why shoot Motion JPG? Image quality is not as good as AVCHD, especially in 720/60P mode on the GH1. The oly advantage is not having to transcode, but this is a really minor issue for most people and in some setups isn't even necessary.

Michael
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