GL1 12- & 16-bit Audio Mode Differences

[Ed Baatz]

After reading the brief discussion in the manual, it seems clear enough that there are two separate audio modes with the GL1.

There is the 16-bit audio mode which records the soundtrack at the rate of 48 kHz on 2-channel stereo, and...

There is the 12-bit audio mode which records the soundtrack at the rate of 32 kHz using 2 from 4 channels.

Clear enough. Or is it? I guess (and a guess is the right phrase) that if you want to, you can select the 12-bit audio mode and as you videotape a scene, for example, the built-in mic records two channels of audio. Then, later, you can dub additional soundtracks onto the videotape, laying these tracks down on audiotracks 3 & 4. Then when you later playback the tape you can choose to hear either channels 1 & 2, or channels 3 & 4, or a mix of the two --- which can be varied as desired.

Or, you can select the 16-bit audio mode and record two audio tracks (left and right) and nothing else. No later dubbing allowed?

I have no idea where the 32 kHz and the 48 kHz specs come in or actually mean. Is one better than the other? Is 48 kHz superior to the 32 kHz or vice versa? There must be some difference, otherwise, why bother to differentiate or mention the two different recording "frequencies"?

It seems to me, as someone who is basically and admittedly ignorant, that the 12-bit mode offers more flexibility since you get two channels of stereo audio and then if you later desire you can dub in additional audio, or not. I wonder, why did Canon even bother offering the apparently lame 16-bit mode? Something tells me though that 16-bit audio mode is probably the preferable setting though. Contrary-ism?

So, can some brave soul try and explain the differences between the two modes and hopefully lead me to the proper choice to use. I'm not sure where, exactly, but I seem to remember reading somewhere that the one thing you DON'T ever want to do is mix both 12-bit and 16-bit modes on one physical videotape. I think it might cause problems when later capturing the video into a NLE program?

Isn't it generally preferable to add additional audio and mixing the audio during the editing process and not onto the tape itself via the camcorder in VCR mode...

Any info will be helpful since I am so uninformed. Thanks!

Ed

[Nathan Gifford]

When you are in 4-track (12 bit) mode, you loose some audio resolution. I have never tried mixing both audio modes on the same tape, but I do not think that is allowed.

The second consideration is whether your NLE will support 4-track mode. Most NLEs will not. Some users employ Scenalyzer which, among other thinks, captures 4-track audio.

I frequently use 4-track audio. Without an external mixer, if you want to mix audio from multiple sources you need 4-track. I like to use the XL-1's on board mic with the wireless one I have. I feel it gives the audio more depth.

Happy Holidays,

[Ed Baatz]

Thanks Nathan,

I think I need to find a Basic Audio for Dummies type of book <grin>. I have a definite lack of knowlege in this area. I notice that 32kHz is generally related to analog audio while 44.? is related to CD quality audio and 48kHz is related to digital audio... or something like that.

Maybe someone can suggest a good book (not actually a "dummies" book because they usually stink) for learning the basics of audio - in respect to use with video...

With my GL1, I don't think that I can record audio using the Canon built-in mic and my other mics. It's a matter of one or the other... So for me, generally speaking, I should probably just set the audio mode to 16-bit and fagetabowdit... ;o)

Thanks,
Ed

[Nathan Gifford]

I learn most of what I know on the web. It is amazing what you can find there (or here for that matter).

A really good place to start is Jay Rose's website at http://www.dplay.com.

Hope This Helps,

[Ed Baatz]

Nathan,

I larn most of the little I learn from the various websites and forums like DVinfo (thanks Chris!) and my main complaint is that there isn't enough time to learn all I want to learn. I'm thankful for my cable modem, because if I had to use a 56k there is no way I could wait for each site to pop up. :o) And, then, there are the people like you who share the wisdom and point me in the right direction! The dplay.com website looks like just what I was hoping for...

Now, I'll go over there and read until my head hits the keyboard.

Thanks!

Ed

[Nathan Gifford]

Wish I had a cable modem...(I'm still 56K)

[Don Palomaki]

As noted, 16-bit audio uses a 48 kHz sample rate, which gives usable frequency response past 20 kHz. If you use 12-buit/4-channel mode the usable frequency response is limited to around 15 kHZ - which is adequate for most video. purposes.

Also 16-bit sound provides slightly higher quality beyond the improved frequency response, but again most users will not notice the difference.

But for best results use the 16-bit mode. Use the 12-bit mode only if you need the additional two channels for some purpose.

[Ken Tanaka]

Producing Great Sound for Digital Video
by Jay Rose

http://www.amazon.com/exec/obidos/tg.../-/1578202086/

[Tom Voigt]

Does any camera allow recording 4 audio tracks SIMULTANEOUSLY?

Seems like a very useful feature.

[Nathan Gifford]

Canon XL-1, GL1, XL-1S, GL-2...

Most NLEs do not download the sub channels. A number of people recommend Scenalyzer which does.

[Tom Voigt]

Nathan,

How do you get the 4 inputs into the cam at the same time?

The GL2 manual indicates that you can only record 2 of the channels at a time.........

[Ken Tanaka]

On the XL1s you would typically use the MA-200 which has 4 XLR ports. I'm not sure how you would accomplish this on the GL2 since the MA-300 only has 2, as do the BeachTek and StudioOne XLR adapters.

[Ed Baatz]

With the GL1 (and GL2 I would expect) there are two different "modes" --- a 12-bit mode (at 32 kHz) and a 16-bit mode (at 48 kHz). Neither mode allows videotaping with more than a single stereo soundtrack, or to be more specific, a single left channel and a single right channel.

If you select the 12-bit mode, however, you can LATER dub an addition stereo track (another left and right channel). I have been told in a previous message here, that many NLE programs will not work with a video capture that has this "mode" of audio. A good reason, seemingly, for me to avoid 12-bit mode.

It would be my guess that using a DAT deck or auxiliary recorder of some type would be in order if more than the single left & right channel is desired, or some kind of audio mixer so that you could mix more than the standard two mic setup... or using a more feature rich camcorder --- like the XL1s.

Of course, I am still waiting for my Jay Rose books on audio. Maybe after I get them and study a lot, I will know something for sure about audio.

So much to learn and so little time...

[Tom Voigt]

So you can mix 4 inputs down to 2.

I think it would be supremely useful to have 4 (or 6 or 8) separate inputs recorded at the same time and then decide in post which you are using when and how much.

Of course you can have a separate DAT recorder and sync them up later, but it would be much more straight forward to have multiple inputs on the same piece of tape.

Is there a technical reason why no camera has offered this, even though they can put 4 tracks on a single tape? I am sure that 12 bit sound mic'ed right sounds better than 16 bits mic'ed from somewhere else.

Not to derail the thread, I was just wondering why no one offered it.......

[Tom Voigt]

To follow up on Ken's reply:

I went to B&H website. For the BeachTek DXA-4C Audio Adapter for the Canon XL-1 it says: "Can be used with the Canon MA-100 adapter for 4 discreet balanced XLR inputs at the same time. "

So this is apparently possible on the XL-1's.