Questions about GL2's audio at DVinfo.net

David Ho · November 21st, 2003, 04:31 PM

I read on canon's site, the GL2 has two audio channels, 16-bit and a 12-bit. From this, I believe the 12-bit is better for like making a movie, so you can add in sound effects or music in post. Well, my question is, is there an option/button that changes to 12-bit or 16-bit, or is there a default audio channel?

Also, what is the difference between 12-bit, 16-bit, and the three modes provided? Can you use these channels + the modes (normal, voice, wind)?

Aaron Koolen · November 21st, 2003, 04:45 PM

David. The GL2 has two channels, but they aren't the 16/12 bit you're talking about. The 16/12 bit settings are different sample rates that are part of the DV25 standard.

You set the GL2 into either 12bit or 16bit mode via a menu option. If you're operating in 12bit, the DV standard allows you to have 4 channels, but the Gl2 doesn't let you record on them. There are no 3rd and 4th channel inputs.

You almost NEVER want to use 12bit audio due to it's bad dynamic range and aliasing that happens to turn analog into digital 12 bits.

Yes you can use the normal, voice, wind settings with either bit mode, but if you were making a movie you'd be *much* better to just do everything manually and record using external microphone and use other equipment to reduce wind if you can afford it. (Something like a softie for your mic)

So if you're recording in camera for a movie and have 1 or two audio sources (2 actors for instance) then just use 16 bit. If you need more input and can't afford it, go 12 but know that it will probably be awful. Or buy a 4 input -> stereo mixer.

Cheers
Aaron

Don Palomaki · November 21st, 2003, 05:01 PM

The 12-bit mode uses a 32 kHz sample rate. That means somewhat reduced frequency response compared to 16-bit mode. The result is roughly FM broadcast quality audio, and probably a bit better than than standard broadcast TV audio. (The high frequency limit is effectively ~15 kHz.) This works for many applications, but is not optimum for serious sound work, especially music.

The usable dynamic range is about the same as 16-bit mode thanks to a bit of compression in the 12-bit mode and in any case is limited by the noise floor of the camcorder's audio system whether in 12- or 16-bit mode.

If you use 12-bit mode, you will have the option of dubbing sound to the othe two channels later.

But it is better to add additional sound in post production using an NLE system if you can. BTW many moderate priced NLE systems have diffiiculty capturing 4-channel sound.

The bottom line is if you need the ability to dub audio to the other two channels later, give 12-bit mode a test and see if it meets your needs. IF the end product is VHS and viewed on a typical home TV, no one will ever know.

David Ho · November 21st, 2003, 08:24 PM

So I guess, 16-bit is the best option for making the movie regardless of adding music or sound effects in later post, right?

Don Palomaki · November 22nd, 2003, 07:35 AM

YES. 16-bit is the better audio mode with the GL1/2.

November 21st, 2003, 04:31 PM	#1
David Ho Major Player Join Date: Nov 2003 Location: Los Angeles, CA Posts: 354	Questions about GL2's audio I read on canon's site, the GL2 has two audio channels, 16-bit and a 12-bit. From this, I believe the 12-bit is better for like making a movie, so you can add in sound effects or music in post. Well, my question is, is there an option/button that changes to 12-bit or 16-bit, or is there a default audio channel? Also, what is the difference between 12-bit, 16-bit, and the three modes provided? Can you use these channels + the modes (normal, voice, wind)?

November 21st, 2003, 04:45 PM	#2
Aaron Koolen Trustee Join Date: Apr 2002 Location: Auckland, New Zealand Posts: 1,727	David. The GL2 has two channels, but they aren't the 16/12 bit you're talking about. The 16/12 bit settings are different sample rates that are part of the DV25 standard. You set the GL2 into either 12bit or 16bit mode via a menu option. If you're operating in 12bit, the DV standard allows you to have 4 channels, but the Gl2 doesn't let you record on them. There are no 3rd and 4th channel inputs. You almost NEVER want to use 12bit audio due to it's bad dynamic range and aliasing that happens to turn analog into digital 12 bits. Yes you can use the normal, voice, wind settings with either bit mode, but if you were making a movie you'd be much better to just do everything manually and record using external microphone and use other equipment to reduce wind if you can afford it. (Something like a softie for your mic) So if you're recording in camera for a movie and have 1 or two audio sources (2 actors for instance) then just use 16 bit. If you need more input and can't afford it, go 12 but know that it will probably be awful. Or buy a 4 input -> stereo mixer. Cheers Aaron __________________ My Website Meat Free Media

November 21st, 2003, 05:01 PM	#3
Don Palomaki Wrangler Join Date: Sep 2001 Location: Northern VA Posts: 4,487	The 12-bit mode uses a 32 kHz sample rate. That means somewhat reduced frequency response compared to 16-bit mode. The result is roughly FM broadcast quality audio, and probably a bit better than than standard broadcast TV audio. (The high frequency limit is effectively ~15 kHz.) This works for many applications, but is not optimum for serious sound work, especially music. The usable dynamic range is about the same as 16-bit mode thanks to a bit of compression in the 12-bit mode and in any case is limited by the noise floor of the camcorder's audio system whether in 12- or 16-bit mode. If you use 12-bit mode, you will have the option of dubbing sound to the othe two channels later. But it is better to add additional sound in post production using an NLE system if you can. BTW many moderate priced NLE systems have diffiiculty capturing 4-channel sound. The bottom line is if you need the ability to dub audio to the other two channels later, give 12-bit mode a test and see if it meets your needs. IF the end product is VHS and viewed on a typical home TV, no one will ever know. __________________ dpalomaki@dspalomaki.com

November 22nd, 2003, 07:35 AM	#5
Don Palomaki Wrangler Join Date: Sep 2001 Location: Northern VA Posts: 4,487	YES. 16-bit is the better audio mode with the GL1/2. __________________ dpalomaki@dspalomaki.com

November 21st, 2003, 08:24 PM	#4
David Ho Major Player Join Date: Nov 2003 Location: Los Angeles, CA Posts: 354	So I guess, 16-bit is the best option for making the movie regardless of adding music or sound effects in later post, right?