Improve your audio further with the second part of our guide to getting the best sounds from a DSLR or CSC
In Part 1 of this blog, Kristian discussed various ways to get better audio whilst filming on a DSLR or CSC camera.
In Part 2, we are going to go a little deeper into some techniques, gear choices, setup and mixing.
There are several reasons this topic is so important. It’s a given that good audio is such an important part of video production, and while smaller cameras like DSLRs are amazing at capturing amazing quality video (and have pretty much revolutionised filmmaking as we know it) there are limitations to their audio quality and capabilities.
This is partly down to their actual size and partly down to the type of filmmaker they are designed for. But as you develop in your filmmaking, your approach to audio should grow as well, allowing you to accommodate more challenging and complex projects.
Selecting the correct microphone and placement is arguably the most critical first step in getting great audio.
Mono directional mics are generally the best choice when recording someone speaking. They are suited to recording things directly in front of them, rejecting sound from other directions.
Stereo mics are really great for creating a sense of the environment you are filming in, like a busy city or a nature shot in the countryside. A stereo mic can be really great for those more general B-roll shots, or establishing shots when you really want people feel what’s happening in and around the shot.
Built-in camera mics, although sometimes useful for reference audio to sync up with other cameras or external audio recorders, offer audio quality that is generally pretty low. Read in Part 1 where Kristian covers this.
Power. Some mics require power which the majority of small cameras cannot provide without an extra device between the mic and camera. Most video mics have their own battery, but not all.
Use your smartphone
Rode make a great product: the Rode SmartLav. Assuming you have access to a smartphone you can attach the SmartLav to your subject, hit record, pop the phone in their pocket, and you have a very cost effective, good-quality Lav mic recording option. Your subject is also not connected to your camera via a cable so this potentially is a great wireless solution for those on a budget.
Use the Rode SC6 and you can attach two RodeLav mics to the same smartphone and monitor with your headphones at the same time. This is especially great for interviews.
Important note: the RodeLav Mic is specifically designed to work with a smart device and won't necessarily work straight into a camera.
The biggest mistake I often see people make is assuming the best place to put their video mic is on their camera. This seems logical – it's convenient, the cable reaches to the camera easily and the cold shoe mount on the bottom of the mic suggests this is the place it should go. In reality, this mic position is only really good for general sound and ambience. When capturing dialogue, your subject will need to be really close to your camera for it to work.
So once you know what your main audio source is going to be – for example a person you are interviewing – generally you want to get your microphone as close to your subject as possible without it getting in shot.
There are a number of ways you can do this. If the dialogue is coming from a person oncamera then one of the most common methods is using a lavalier mic like the Rode lavalier mic, which attaches to the subject who will be speaking. This can wire directly to your camera or recorder easily via an extension cable – this is cheaper than purchasing a wireless system, but can cause some challenges if your subject is going to be moving.
A lavalier mic worked well when we filmed David Cameron giving a talk. However, they can cause problems if you have more subjects than mics or not enough inputs on your setup – for example, in a Q&A session.
If you have more subjects than mics, a great option is a mono directional video mic on a boom pole. In this case you literally move the mic from one person to the other, depending on who is speaking, which is also useful if your camera and/or subject are moving. This could be from below or above, depending on the shot and environment you're shooting in. It’s important to not let this mic dip into shot, and also to be aware that if you’re holding the mic above your subject, the pole can sometimes cast unwanted shadows you might miss.
There are a number of famous TV shows and films where a boom has dipped into frame – see this shot from the 2006 film Seraphim Falls with Liam Neeson and Pierce Brosnan.
Use your ears
Every space you film in will have its own acoustic properties – some might sound dead, others may be plagued by echoes. The number one tip for finding the best spot to position your subject and mic is to use your ears. Your ears are your most powerful tool when recording sound. Before you even plug in your microphone, stand in the place you are going to record and listen to your source in situ. Listen to their voice; decide if that location is suitable.
Think about the acoustics of the environment you're recording in. Try to keep your subject away from large reflective surfaces or echoey corners and corridors. If the shot is perfect but you are struggling with a harsh unpleasant sound, or you are getting early reflections, you can deaden the space by hanging easily accessible items like duvets and blankets out of shot on lighting stands and tripods or duct-taping them to walls. If you have a hard echoey floor that is causing problems, another trick is to place a rug or duvet on the floor below the subject (providing it is out of shot, or works with the shot).
In this shoot at Vodafone HQ, the big black draped fabric had the dual purpose of creating a backdrop and helping to deaden the sound in a very large room.
If you only have a small space to film in, then try and get your subject nearer to a wall that is more broken up with items. In a shoot with actor Brian Cox we had him sit near a bookshelf. When flat walls are broken up by shelves, books, furniture and the like, they help diffuse and disperse the sound in multiple directions and at different times, reducing any early reflections back into your mic. This may not work for the look of every shot but it's worth considering when possible.
Filming your talent in front of a wall that’s broken up with items can help reduce any early reflections back into your microphone.
Some microphones have a fixed polar pattern and there are other microphones that have variable polar patterns. The most important thing is to understand what the different patterns do, so that you can select the best mic for you in each situation.
There are many different variances on polar patterns depending on the manufacturer and mic, but below is a chart that will help get you started.
Think of a polar pattern as your field of view from an audio perspective.
Omni-directional literally means picking up sound equally from all directions. Sounds that are closer to the microphone will still be louder than those further away, but the mic is not rejecting sound from any particular direction.
Bi-directional (also known as figure of eight) mics record sound to the front and rear of the capsule, rejecting sound from either side.
Cardioid microphones capture most of the sound in front of the capsule within around 120 degrees.
Ultra-Cardioid, often referred to as shotgun microphones, have a very narrow field that they capture from. This can be useful for capturing specific sounds in noisy environments, though the mic still does need to be as close to your subject as possible.
Monitoring and metering
As discussed in Part 1, good monitoring is really important. Closed back headphones are most commonly used, as they isolate your ears from other sounds and enable you to focus on what your microphone is picking up. In some very noisy situations with a lot of background noise, I have found that I’ve needed to go a step further and use in-ear style isolating monitors, the kind more commonly associated with live musicians, which help isolate your ears even further to hear what you’re really capturing.
Most cameras have on-screen audio meters these days during filming, which is great as this has not always been the case. Many early DSLRs with video capability had no on-screen meters or even a headphone output for monitoring.
A good basic guide would be keep yourself in the yellow and try and stay out the red. You don’t want your audio to peak, as digital distortion sounds nasty and is very hard to fix later.
You also don’t want your audio to be too quiet. I’ve heard some say they record fairly quietly in camera and then turn it up whilst editing, but it's not that simple.
Line and mic preamps have a certain noise floor. You generally get a small mini jack connector as opposed to the larger much more robust XLR inputs you get on bigger cameras.
Getting your signal up to at least -12DB will ensure your recorded audio is louder than the quieter hiss or background noise the built-in preamp in your camera makes in standalone.
Again, use your ears. If it sounds good, it probably is good.
There are a variety of additional devices you can purchase to expand your camera’s audio features. The benefits depend on which one you get – most include professional XLR inputs, phantom power for mics that require it, more inputs and more professional audio metering and monitoring.
These devices can add a lot of great features, but also add a level of complexity to your camera rig. They sometimes require their own power, and often still are summing down this audio to the same stereo two-channel internal audio recording in-camera.
In the early days of DSLR filming, external recorders were pretty much essential for professional-sounding audio, as these cameras just didn’t have the audio features that we are used to today.
With external recorders, you are adding a process to your workflow by recording separately and then having to sync up with your footage in post.
The benefits to using an external recorder, depending on the unit you get, include: professional audio connectivity, many more professional settings and the ability to record your audio at a greater distance from your camera.
Some external recorders like the Tascam DR-70D are multitrack recorders and mixers combined, which give you the ability to mix and record more than the standard two channels that most small cameras can do by themselves. You could, for example, have a lav mic, a shotgun mic on a boom and a stereo mic all recording at the same time with one camera. You then have the ability to adjust the balance between these sources in post-production.
The majority of smaller cameras these days by default record audio at 24bit 48khz internally, which is pretty good. Some slightly older cameras like the Canon EOS 5D Mark III record at 16bit 48khz, while some new cameras such as the GH5 can record up to 96khz.
But what do all these numbers mean?
Let’s give those numbers some context. 16-bit 44.1khz is the standard for compact disks, established back in the 1980s. 24bit 48khz has been the standard for digital video delivery for some time now.
44.1khz means 44,100 samples per second. So 48khz means 48,000 samples per second, and so on. More samples = more information.
Higher bit rate gives you more headroom for peaks, so I would recommend recording at 24bit 48khz even if you are going to compress down a lot later for various platforms.
So now you’ve got your shots with great audio, it's time for the edit and mix. Just like with the capturing process, there are endless techniques and tools we can use to mix the audio for our videos, but here are a few fundamentals to get you started.
The first tools to get your head around are: volume/automation, panning and equalisation/filtering.
First take one or two passes playing through your video and focus on getting your balance. Pull down anything that jumps out too much and bring up anything you're struggling to hear. It’s good to do this first whilst your ears are fresh and you’ve still got a good perspective. Your first gut feeling towards the levels is normally correct. The longer you are mixing/editing, the more you lose perspective; your ears can become fatigued, and adjust to the mix even if the balance isn’t correct.
Once you’ve got a good balance between all of your audio sources, you can then go through your project and automate any problem areas. In a lot of editing software people do this with the pen tool, literally drawing the audio level up or down when needed.
Most video software has the ability to automate the audio using the audio track mixer, and with the right setting you can ride the fader at the right moments like a conventional audio mixer. Your edit software will remember these moves.
When to automate
There are lots of creative ways to use automation with your audio, but the most key and obvious way to use this tool is to add some final further fine-tuning to your mix. There may be a moment when something momentarily gets too loud or too quiet, and you want to fix it without changing your whole mix. Automation allows you to make quick tweaks to address these kinds of issues.
Another use is to adjust the balance between your music and dialogue. It’s useful to have the ability to quickly turn music down whilst there is dialogue and then turn it back up again.
Panning is great way of spreading your audio across the stereo field. It’s an ideal space in which to be creative here, but a solid place to start is to make space for things like dialogue in the centre while panning things like music (which is generally stereo) and sound effects left and right. This will stop all your audio competing for the same space.
Often it's great to try and make your stereo sound field reflect what's happening on screen in the edit. For example, if in the right-hand side of your shot there is a car with its engine running, get a recording of a car running and pan it to the right. Panning things around to match your shot can really add great depth and a sense of space to your video.
As you get more confident with automation, you can also automate panning in the mixer, so that sounds follow things that are moving on screen.
Equalisation / filtering
Equalisation can be confusing, but essentially is just a tool to boost or cut frequencies that shape your sound. If something is sounding too boomy and bassy then you can cut some low frequencies. If something is sounding too muffled and unclear, you can boost some higher frequencies to make it cut through more, and so on.
Without going into too much depth, my best tip once again is use your ears, if it sounds good it most likely is good.
My next advice is: Filter. Adding a high-pass filter to most sources other than music can really help clean up a mix. It can really help cancel out unwanted low-frequency noises like traffic in the background, the low hum of an air con unit, etc. You will be amazed how much this tightens up your sound.
For dialogue, you are safe cutting below 100Hz, but as with anything use your ears and decide what sounds best.
If you have any questions about audio you’d like to see answered in the blog, feel free to ask us on Twitter.
About the Photographer
Ross Gill is co-founder, audio specialist, producer and director at Global Fire Creative. Ross works in studio, live and broadcast audio production, specialising as in areas such as music production, sound design, foley, mixing and mastering.