Home » Video Production
Category Archives: Video Production
Ok… You’ve assessed the needs of your audience You know your content…you’ve followed your well-planned script which has been whittled down to just the necessary points in the most strategic order possible to teach your topic. You’ve even cleaned up your desktop so that nobody sees extraneous files or folders when you switch applications. What could go wrong?
What could go wrong is what does goes wrong with a majority of the screencasts I see and (unfortunately) hear. You have neglected to put love into the audio portion of your screencast. Sound is the most overlooked attribute in screencasting and video. Bad audio makes your presentations look … well … sound, amateurish and creates an unpleasant situation for viewers.
In some cases this is not your fault or your priority. I get it. 10 teachers in your district just emailed you with the same question about using the snooze feature in Gmail and you decide to make a quick screencast and post it on Youtube so that you don’t have to answer the question an 11th time. In that case you may click away or read on so that you can improve your screencasts for more discerning situations.
Why do I care so much about audio quality?
Let’s answer this question with a few questions:
Why do I care about grammar and punctuation?
Why do I care about being prepared for a presentation?
Why do I care about matching socks?
The answer to all of these is:
Because not paying attention to these things lowers your coolness quotient exponentially.
Why does this happen to screencasters?
Because if you don’t pay attention to a few key points, the properties of sound and the nuances of technology will embarrass you in a way that can only be outdone by brining a drunken spouse to your next staff meeting.
So what are the mistakes that screencasters make?
Choosing the wrong recording software
The first is in choosing the recording software. Many people use free, online applications that do the job but at the cost of compensating sound quality in the interest of space and bandwidth. They don’t do this to be mean. They do this because the higher the audio file encoding settings the more space and bandwidth will be required.
For some of you, these free options are your only option …. so… given the choice between not screencasting or buying a quality screencasting app you should, by all means, just use the tools that are within your budget. You should try different ones. They are not all equal and I have provided a link to some recent comparisons at the bottom of this page.
Not getting close enough to your microphone.
I hear this less now because many people are using the built-in mics on their laptops (mistake 3).
Why is this a problem?
Because the further away a sound source is from a mic the more you hear the sound (and reverberations) of the room. Plus your voice won’t be nearly as loud or as clear. This gets particularly ugly when you add low bitrate encoding to the equation. The kind you get from some free, online screencasting apps. This doesn’t mean that you need to lean over and position your lips right in front of it, that will cause mic pops and distortion. (Save that posture for your after school yoga session). Six inches to a foot and a half is a nice proximity.
Using your built-in computer mic.
These mics just aren’t that good. I don’t want to get into a huge discussion about frequency response, cardioid patterns and transient sensitivity but think of it like this: A quality studio mic (probably overkill for our needs here) costs more than your laptop did. Even when compared to a fully loaded Macbook Pro. I’ve used some mics that were 20,000+ dollars. So based on the fact that your computer does a lot more than just convert soundwaves into electrical energy (that’s what a mic does), it stands to reason that a few corners are being cut in that area.
Picking the wrong room to record in.
Because you already know that close micing is the way to go, the sound of your room ambience is not that important (unless you are trying to recreate John Bonham’s drum parts on “When the Levee Breaks”). But what is important is that you find a quiet place. A room free from noisy vents, outside noises (although I am a sucker for a nearby siren due to my urban upbringing), and free from crowd noises. Again these factors become even more distracting when using low-fi audio files.
Let’s listen to some examples!
First, here is a voice track recorded with lots of room noise using a built-in Chromebook mic and free online screencasting software. Mistakes 1,3 and 4.
Listen for the phasey, swirling, alien sound that is particularly apparent on the words “crowd noise.” This is the result of a combination of a low quality mic and the low bit rate encoding that is part of using free online screencasting software. As for the noise… well that needs no introduction, although it does help to emphasize the swirly sound.
In this example you’ll hear all four mistakes. A mildly noisy room recorded into a free online app from a distance into a built-in microphone. Again…Listen to the swirling aliens that are possessing my voice,
In this example I got closer to the mic. Notice that my voice is clearer and more intimate (don’t be scared) but the aliens are still swirling around me. Mistakes 1.3 and 4 are engaged here.
Now I’m using the same set up but I have added a USB mic into the chain. This is a big improvement, almost bordering on acceptable. Let this be your worst case scenario. The mic has compensated for the lower bandwidth. There is a technical explanation for this I need not frighten you with. I used an Audio-technica AT2020 USB mic for this. I highly recommend this mic for its ratio of quality to pricing.
In this example you can still hear the lower bitrate artifacting but it has been minimized. What? You Can’t hear it? Well you will when you compare it to the following examples.
Now … in the following examples I am using a Macbook Pro with Camtasia. Each example will get a little better. In this one I am using an internal mic. The biggest problem here is that it is picking up way too much room noise in spite of better fidelity on the voice.
This one is closer to perfect. I used the AT Mic again …. big difference. Would have been great if the people in the background could have controlled themselves and been quiet. My fault for making mistake number 4.
And finally… I would like to say that we’ve reached perfection… I would like to, but I can’t. Oh … this is the best one here, but I’m still appalled at the hum that my mic is picking up from my computer’s fan / hard-drive. This could have been avoided in 2 ways:
By suspending a boom overhead… I don’t see a lot of screecasters doing this… a bit overkill for this situation.
By trying to place the mic as far away as possible from the laptop. This is difficult if you need to “click along” with your narration to illustrate steps. This may work if you record your voice-over first then, add the screencast animation after the fact. Perhaps a subject for a future blog post.
But Phil… this is great for screencasting. What about video?
Well in making videos, mistake 2 (not getting the mic close enough to your sound source) is the most common. To remedy that, you should use a lavalier (clip on) mic when possible and when not possible, use a shotgun mic. Unless of course you plan on ding ADRs later. What’s an ADR? (you probably won’t be doing them). Here is a nice article comparing mics for video recorders.
All examples back-to-back
Now here are all of the examples back-to-back for your enjoyment and ultimately… your astonishment in experiencing the drastic differences.
And one last thing: Don’t “Go Ahead” yourself into a corner
Didn’t your third grade teacher tell you not to keep using the same word in repetition in a paragraph or essay? Ok, it was your 4th grade teacher. Regardless, check your dialog for this. Often times when we work without a script this can happen. In most tech tutorials I have noticed the the phrase ‘go ahead” is used to the point of giving me hives. I don’t want to embarrass any of my fellow screencasters by posting examples but this can be annoying.
“I’m gonna go ahead and start a new file, then I’m gonna go ahead and enter an avatar. Now I’m going to go ahead and set my background….. go ahead, go ahead go ahead PLEASE!”
It can be that bad in some videos. As a general rule. If you can remove a word from a sentence without changing that sentence’s meaning, leave it out or limit that word to no more than two uses per presentation.
So to sum things up:
Every time you eliminate one of the 4 mistakes above, your audio quality will improve. If nothing else…. Get yourself a good remote mic. When people view your screencasts they might not consciously notice the bad audio, but they will sense that it is not a quality project. Put your best foot forward when you share your valuable knowledge. When you review your next screencast, don’t just check it for visual glitches. Check your sound and give that ugly step child some love.
Below are some links to more information and resources.
First the Mystery
Watch this brief clip. For best results listen on speakers. The flaws are not as obvious on headphones.
What did you hear, Or not hear?
Well… not much. We saw Kim speaking but at best the audio sounded as if it was in a tunnel and at worst … you might not have heard her at all. Very sad … she was saying some deep stuff.
Can you guess what the problem was?
Did you think there was a glitch in the audio export of this clip from editor app, in this case, Final Cut Pro X?
Wrong: That cannot be the case.
Why: Because the audio does not completely drop out in the example. You can still hear the background music! Finished video files do not support multiple audio tracks. There is no way that one layer simply doesn’t get exported from the editing application and the other does (unless of course it’s muted, but that was not the case). It’s all or none for audio in a video file.
If you guessed “phase cancellation:”
Pat yourself on the back, sit back in your chair with your hands behind your head and gloat over your impeccable knowledge of audio production. Post it on social networks, you might even add the triumphant cackle emoji. (Someone needs to make one)
If you did not … read on. This may happen to you.
So what is phase cancellation and how did it mess up Kim’s voice?
Scary, semi-technical definition: Phase cancellation occurs when two identical audio signals combine. When this happens the opposing waveforms “cancel” each other out making the resulting signal sound funny or in-audible.
Here is a brief, simplified, yet still confusing video targeted at budding audio professionals. (Something that video editors need to be). Watch it and then I will give you an explanation of what actually happened.
And…. How to fix it. without re-shooting your video. YES!
Good stuff… but you are probably still scratching your head.
How it Happened
The video was shot using a wireless lavalier mic for close micing. I hope you are doing close micing. See my other post “Audio: The Ugly Stepchild of Screencasting” to find out why. After trouble-shooting the mics I discovered that one of them, the one that was used for the video at the top of the page, had an option on the receiver labeled “Audio Output Selector.” that selector allows for two settings: Balanced or unbalance (dual mono). IT WAS SET TO DUAL MONO! That was it!!!! Dual mono means that the camera was receiving TWO IDENTICAL AUDIO SIGNALS VIA ITS STEREO INPUT.
TWO IDENTICAL AUDIO SIGNALS!!! Guess what….. when TWO IDENTICAL AUDIO SIGNALS are combined. They cancel each other out!! You just read that a few minutes ago.
Problem detected……now what?
The good news is it’s wicked (sorry…I spent numerous years living in Boston) easy to fix phase cancelation. The bad news is, only pro level editing apps offer the feature that you need to fix it.
To simplify: I activated a plug in in FCPX called “Gain.” This plugin has a phase reversal switch. To fix phase cancelation problems you only need to reverse either the left or right channel of the audio signal.
Watch this quick tutorial:
How to fix phase cancellation ing FCPX
How can I avoid this problem?
This problem is not likely to happen if you are only using the mic that is built-in to your camera. These mics are made to be foolproof. They are also, often times, made to be “quality audio proof” (the ugly step child rears his head again) which is why you should always use a “close micing” technique. Particularly if you are doing interviews with people.
Know your Mic
Most auxiliary or wireless mics come with many options. You need to defy all of your instincts and READ THE MANUAL. At least look at the diagrams. Know what all of the buttons do. It’s fun… you get to push buttons. Most of the time, the factory default settings work best. An Audio-Technicha ATW 1701 was used for this shooting. A great sounding mic for the money.
Make a “pre-shoot” check list.
Many of you teach video production at the high school or college level. This means that you may have many inexperienced, yet well-meaning, students shooting video. Once you find the optimal settings for your equipment, make a check list to be gone over prior to shooting. An make sure audio/mic settings are included. Video shoots are often chaotic so this step can really help you avoid problems for both video and audio (its ugly step child).