Why is my MXF Audio file "Mono" ?!?

EDV

EDV

Well-known member
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Isn't supposed to be "stereo" ?
Input I used was XLR input 2 on Channel 2 ( Shotgun Mic )

From what I know HD will always record 4 channels of audio. The internal Mic on my cam occupies two by default, and the other two channels are for XLR input 1 and XLR input 2. The thing is... this means the camera's internal mic records "stereo" while the XLR inputs record "mono" ? The sound I am getting is great, but in one of my tests it was clearly coming out of one speaker only... so , I wonder if it needs to be converted to "stereo" with left and right channels.
 
A shotgun mic is, by its nature, mono. One shotgun mic = 1 mono channel. To record stereo you need two mics, one connected to input 1, the other to input 2. They also need to be set up in one of several specific physical arrangements with respect to each other - 2-channels is not sufficient by itself to make the recorded signal true stereo.
 
So the audio is recorded as "mono" through the XLR. Does it make sense to convert it to stereo ? Sound Forge takex the MXF file and give you the option of "mono" or "stereo" wav. I tried both and they kind of sound the same, but the "stereo" wav looks different.

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Even if I choose to leave it as "mono" wav, when it comes time to render the .avi , once again, I get the chance to output to "stereo". Any reason to output to "mono" instead? Or am I missing something here?
 
EDV said:
Even if I choose to leave it as "mono" wav, when it comes time to render the .avi , once again, I get the chance to output to "stereo". Any reason to output to "mono" instead? Or am I missing something here?
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What this requires is a fundamental understanding of what, exactly, "mono" and "stereo" are and how they interact.

Mono is a single channel of sound, or playback that comes from one direction/equally from all speakers. You can have a monaural source in a stereo playback system, assuming that source is panned to the center and is thus equally present in left and right playback channels.

Stereo requires two playback channels, but is defined by how those two channels interact. In a stereo image, the two channels have spatial interaction, meaning that they work together to create an image with movement and depth.

If you have only one mic, recorded to both channels, you aren't recording stereo but rather dual mono.

Dialog is a mono source. It is recorded with one mic, though if recorded with several mics on several actors it will likely be multi-tracked, or recorded in multi-mono. When it comes to the final mix, all those recording channels will be panned to the center for monaural playback. Even if it's in a srround mix, the dialog will be strictly in the center channel, unless it is panned for effect to one of the front or rear surround channels (that's rare, and used to indicate an off-camera presence/location).

As another example: if the setup has two actors, each wearing a lav, recorded to separate channels of a 2-channel recorder that generates a "stereo" file, is it stereo? No. It's still dual mono. Why? Because that true stereo requires spatial interaction between the two channels. In this case, the "stereo" (actually dual-mono) file will be split into separate, independent files in post and both panned center.

So handling of these files in post means keeping your dialog files as single-channel and using your NLE's or DAW's audio mixing controls to pan the playback to center. Creating a "stereo" file (which is really just dual mono) is an unnecessary step. Some folks even decide to duplicate the file, drop it into another audio track, and pan it to the other side to get equal playback; this is an ineffective method that not only wastes time and space but also opens up the possibility for phase cancellation if the duplicated track gets offset even by subframes.
 
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Difference between mono and stereo.

Well, as Alex said dialogues are always mono because it's recorded with one mic.

Now, stereo is always with 2 mics or a "stereomic" (which is to make it easy, 2 mics in one....don't think about it...)

Stereo means that if you put a stereo mic somewhere outside (or 2 mics in a certain position that makes stereo, MS, AB, XY, ORF, Blumlein....google it...)
then when the dog barking left, will sound left..the guy screaming right will sound right when you listen back on a stereo setup (just 2 speakers left and right).

As for dialogue it comes from the same "side", it's always mono... If you put it "double" and pan one left and one righ, it's just double mono...
 
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