Earlier than we soar into the broad world of audio gear, it is perhaps useful to rapidly go over how audio is definitely recorded. This can enable you to perceive what is going to work finest for you and your setup. In case you’ve jumped forward and need to navigate to the earlier lesson, you may click on right here.
Microphones: Capturing a Wave
Audio recording begins with a microphone, which is a transducer: it takes one kind of power and transforms it into one other kind of power.
So what varieties of power are we speaking about? On the acoustic facet, now we have sound, vibrations or pressured waves that journey via the air. The microphone’s job is to take that and rework it into {an electrical} sign.
For the needs of on-camera sound, I’ll say that there are solely two varieties of microphones to think about: dynamic and condenser. Each varieties basically do the identical factor: they take acoustic power and rework it into electrical power. This electrical sign travels down a cable into one thing known as a preamp.
Preamps: Amplifying the Sign
The preamp’s job is to take {the electrical} sign and amplify it as a result of when it comes out of the microphone, what’s generated by the microphone’s capsule is tiny. This makes the sign just about ineffective, and it must be amplified earlier than the following stage of the method. The subsequent stage is the conversion from analog info, {the electrical} waveform, into digital bits, ones and zeros.
When the sign will get to that time of analog-to-digital conversion, typically you will have some choices primarily based in your digital camera’s system and the audio chips which can be inside it as to how the sign is transformed into digital bits. There are two stuff you’ll have to grasp about that: bit depth and pattern fee.
Pattern Charge
First, let’s discuss pattern fee. Pattern fee is the variety of occasions per second the audio is sampled. With out moving into an enormous technical dialogue, I am simply going to provide the reply right here: 48 kilohertz. That is the reply to the query, “What pattern fee do you select?”
Why 48 kHz? The primary purpose is that it sounds superior! Are there higher-resolution audio codecs accessible on the market? Yup, there’s 96 kHz or 192 kHz. Most individuals can not hear the distinction, particularly contemplating that your video might be consumed totally on a cell system. Somebody who has totally decked-out audio gear and a handled room will most likely watch your video, however general, it is a secure wager that will probably be consumed on cell. If you find yourself out on the earth, there’s noise, and the place there’s noise, it turns into not possible for even a well-trained ear to inform the distinction between 48 kHz and the next pattern fee. So on this case extra shouldn’t be higher—it is simply extra reminiscence.
Audio really would not take up that a lot reminiscence basically, so why not document on the highest fee? The reply is that you just simply need not. Your time can be higher used making an attempt to get a greater signal-to-noise ratio, working in your mic placement strategies, working in your audio processing, and dealing in your audio processing in post-production. Don’t fret about pattern fee—simply stick with 48 kHz. It is what I exploit, and it is what lots of people use. It sounds unbelievable, and you will get wonderful-sounding recordings by sticking with it.
Bit Depth
It is time to get into bit depth. Now do not be confused—that is completely different from bit fee, which is the variety of bits per second. Bit depth is the full variety of bits of knowledge that every one of many samples can maintain. This straight corresponds to the decision of every pattern. Now, decision on this case refers to amplitude decision, which is principally your signal-to-noise ratio: how a lot sign you may document over the noise. 16-bit audio has a most theoretical signal-to-noise ratio of 96 dB, whereas 24-bit audio is 144 dB. These are theoretical maximums as a result of there’s noise that is generated at a number of factors within the audio recording course of, so you may’t really get to these.
It’s possible you’ll be pondering that 144 dB is way louder than 96 dB, and if we had been speaking about sound-to-pressure ratio out in the actual world, you’ll be very proper—144 dB would soften your face. We’re not speaking about loudness ranges right here, although—what we’re speaking about is the quantity of vary you recover from the noise, and that, in contrast to pattern charges, is one thing that you could hear. So when you have the choice to document in 24-bit, go that route.
Audio Codec
The very last thing to speak about is the recording codec, or the audio codec. So you have transformed your audio from analog to digital, you have chosen the popular parameters (48 kHz, 24-bit), and now we have to put it aside. How are we going to put it aside, and what format will we select?
Some cameras do not have an possibility in terms of how the audio is encoded. In case your digital camera information to one thing like AVCHD, H.264, or H.265, it is going to be AAC audio. Is that horrible? No, however it’s a lossy codec, which means it takes info you may really hear and throws it out the window in an effort to make the file measurement smaller. However as we talked about earlier than, audio would not take up that a lot area, so there is not any want to try this. It is a dangerous path to go down as a result of it creates a painful expertise in terms of modifying the audio in post-production.
So when you have the choice to decide on between a lossy codec like AAC and a lossless codec like WAV or AIFF, select the lossless audio. You will have to lookup what your digital camera calls every codec when you have choices: it could be PCM, LPCM, WAV, AIFF, and many others. If it says it is a lossy codec on the wiki, select the opposite one. If you do not have a selection, don’t fret about it, however in terms of getting a brand new digital camera, be sure to have the choice. In case you can, you need to select uncompressed audio—that is going to make post-processing a lot simpler.
Wrapping It Up!
With that, you now know the fundamentals of audio recording. I did discuss some extra technical issues, however do not let that confuse you. The 2 most important takeaways that you just want from this are the overall sign stream that occurs (the microphone, cable, preamp, and analog-to-digital conversion) and the way to decide on a pattern fee (48 kHz), bit fee (24-bit), and codec (uncompressed).
So now that you’ve got an understanding of the audio recording course of, be careful for the following tutorial on this sequence, through which you are going to find out about mic placement and signal-to-noise ratio.
