Does the hmc150 record at 48kHz?

B

becausewemust

Member
I recently got a zoom h4n mic recorder because i love the sound they product to record punk shows. I filmed the first show last night, I am seeing that I can sync it up at start, but somewhere down the line, it gets out of sync.

Maybe the 150 isn't recording at 48kHz like the Zoom is set to?
 
No, the bit rate should not affect whether or not the sound stays in sync, the sample rate however most definately will!

ALWAY record audio at 48k if you desire to later sync it to video. No other sample rate will hold sync (well technically any multiple of 48k, such as 98k, 196k or 24k would work, but you probably would not want to record at those resolutions, especally 24k - no, no).

As to why it is not holding sync with the HMC150 I can not say. How long will it run before it loses sync? You have to be realistic. Even at 48k, you are not likely to be able to hold sync for much more than 10-12 minutes at a time. If you do I will be REAL impressed.

Tom
 
Sample rate should only affect the highest frequencies, not the timing.

The reason your Zoom doesn't hold sync is because audio device manufacturers don't use a standardized clock like camera makers do. You an record DV on six different cameras, both at 48 and 32 kHz, and they will all hold sync with one other over a full hour of tape. But audio devices just don't. Most of them will drift over time. You'll have to adjust for this in post.
 
Unless the clock frequencies are locked via timecode input, you will often see drift between 2 recorders when recording long intervals. My Olympus LS-10 recorder is always out by 8 frames every hour compared to my camcorder.

The GoldWave audio editor is a great and cheap solution to fixing audio timing for computers running Windows, Mac OS-X, and Linux : GoldWave Audio Editor

There is a function in the GoldWave Editor called "TimeWarp" that lets you adjust the timing of an audio track down to 0.0001 sec. So all you have to do is:

1- Line up the START of the two audio tracks in your video editor so that they match.

2- Now line up the END of the audio tracks so they match.

3- Now determine what the timing difference is.

...For example say I get my 8 frames mis-match for an hour long recording on a 24P timeline. 8/24 = 0.3333 seconds.

So I have to change the timing of the external audio by 0.3333 seconds using the GoldWave "TimeWarp" function, then save the re-timed audio file, and now the two audio tracks will match perfectly.

It's easier to do than it sounds, and the results are perfect once you get it down.

I ended up using GoldWave because it was the only audio editor that I tested that was accurate when re-timing audio files. My $400 Sony Sound Forge editor sucks the big one when it comes to re-timing audio.
 
Jim Simon said:
Sample rate should only affect the highest frequencies, not the timing.
Click to expand...


Jim,

I certainly will admit that I could be wrong (Lord knows (and so does my wife) that I have often been), however most audio guys I know seem to believe that using a sample rate of 48k seems to really make a differance in keeping sync, or at least keeping it as long as possible.

Tom
 
I found a loophole around the issue. The h4n has 2 XLR spots, but they are inputs, not outputs. But, it does have a line/phone output jack (headphone jack). So, I took the mini plug in to XLR from my wireless lav and gave it a try, and IT WORKS! So, I hope this will give me the same high quality audio while letting me by-pass having to sync.
 
Does the HMC 150 record a 48kHz?

Does the HMC 150 record a 48kHz?

Yes it records at 48kHz and 16bit................I use a zoom all the time for my audio.......you don't need to use any kind of connection from the Zoom to the HMC. Just always make sure your Zoom is set to 48 / 16 and you will never have any problems sync wise with your HMC video. I have recorded HOURS of continous video with no problems sycning my zoom audio with it.
 
Jim Simon said:
The reason your Zoom doesn't hold sync is because audio device manufacturers don't use a standardized clock like camera makers do. You an record DV on six different cameras, both at 48 and 32 kHz, and they will all hold sync with one other over a full hour of tape. But audio devices just don't. Most of them will drift over time. You'll have to adjust for this in post.
Click to expand...

If you search around (e.g., google "zoom timing drift") you will see that the Zoom recorders are well-known for their extremely bad timing drift (as compared with other devices). I would never use a Zoom for long form recording if I needed to sync it. Many people in narrative film use the Zooms because they have other benefits, and shots are short, so the drift is not so much of an issue. But I have shot longform with many external recorders, high and low quality, and the Zooms are an order of magnitude worse than anything else I've tried. This is not a general issue with "audio equipment"... this is a problem of the Zoom.

Most devices I've used drift about 2 frames per hour. The Zooms drift about 15 frames per hour.
 
You must log in or register to reply here.
Back
Top