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T351 Week 5 - Fall 2014

Editing 102, Audio & Intro to Lighting

Agenda & Announcements:

  • This week in lab we'll cover audio and reflector skills while shooting the Audio / News Exercise - Be sure to come to lab prepared with a hard copy of your paperwork and also have it uploaded to Oncourse before the start of lab! Don't forget to also bring paper releases (or you'll have to get on-camera releases). In this exercise you will interview people on the street and produce a short news story.
  • Next week is lighting. I'm going to show you some advanced interview lighting techniques. In lab you'll get a chance to create an interview/lighting setup. The week after this we won't have lab. The time is dedicated for you to shoot and edit the Interview / Feature story assignment .
  • You should also be designing your Art Video and finalizing ideas for your Final Project. The proposal isn't due for two weeks- but now is a good time to plan.

Agenda - Sound & Intro to lighting w reflectors

  • Loudness & Frequency
  • Types of microphones and their application
  • Signals & metering
  • Examples (music, close up miking, long shot miking, ambience etc)
  • Reflectors
  • Lab assignment:

Introduction

Audio for film and video is more than just recording a good signal. Most soundtracks are multi-layered creations that go far beyond providing us with dialogue from our performers. We hear cues that tell us where they are- outside, inside, what the weather is like, how big the room or environment is, if there is someone sneaking up on them, etc.

When done right the audience doesn't even notice the soundtrack - But even so it's adding an important layer of information.

Audio is an important tool used to motivate edits. (Cutting to the beat in a music video for example.)

Plan time in your production schedule for sound design. Make it an integral part of your planning & production.

Keep it legal! - If you need backgrounds or sound effects for your production you have a few choices. WHatever you do make sure your soundtrack has legal integrity.

  • Production Lab Network Music/Killer Tracks sound effects library - We share this with WTIU.
  • Apple HD/Library/Audio/Loops - Any Apple computer with FCP, Soundtrack Pro, and/or Garage Band installed has some excellent sound effects and loopable components that came with the software.
    • TIP: Open your sounds with Quicktime Player 7 and convert to an AIFF before importing into your project.
  • DIY - You can also record background sounds yourself with the camera or portable audio recorder.

Monitoring - More and more people have surround sound systems and hi-fi audio playback for their TVs. The audio playback most consumers experience at home is likely far better than what you have access to in the Production Lab, either through the iMac's speakers or through the relatively inexpensive headphones that you can check out. Pay extra attention to the sound to ensure it is well-produced. If you want to record and edit strong soundtracks invest in a good pair of headphones.

Audio perspective

Viewers expect sounds from far away to sound more distant and sounds nearby to sound more present. We've been listening to stereo and surround audio for years and are acustomed to taking cues of character positions or locations through the soundtrack. Imagine a long shot in a busy restaurant as our two stars enter and sit down at a table. Over the long shot we'd expect to hear quite a bit of ambient sounds. But then we cut into a closeer two shot, and the audio must sound more intimate. In addition, there's stereo imaging. The audio from the person on the left comes from the left side speaker. But then we cut in to the character with a full screen close up. The sound then comes from the middle.

This is why in dramatic film & TV production, the boom mike is sometimes favored over lavalieres for capturing sound. We can easily vary the distance so the audio perspective matches the camera perspective.

Loudness & Frequency

Loudness can be measured in decibels (dBs) and can be represented visually with VU or digital meters.

Metering & Level Setting:

There are several accepted levels for setting the standard, 1 kHz reference tone or the nominal audio levels: These include –20, -18, and -14. Be sure to check with the broadcaster or production house to see what their norm is. If you are just ooutputting to Youtube or Vimeo you can normalize peak levels up all the way up to 0.

FYI Many broadcast stations (including WTIU) like to have an average dialog level of -20.

AGC

Automatic gain control circuits try to get a consistent level. If it’s soft, it’ll boost the signal. If it’s loud it’ll turn it down. Don’t use it! It’ll bring the noise floor up and reduce your dynamic range.

Frequency is measured in Hertz or cycles per second

  • Hertz = CPS cycles per second
  • Kilohertz (kHz) = 1000 Hertz
  • Human hearing generally ranges from 20 Hz to 20 kHz
  • Concert A = 440 Hz
  • Middle C is 261.63 Hz
  • The human voice ranges from about 100 – 9,000 Hz

Microphones

Microphones convert one form of energy to another: sound waves to electric energy

Microphones can be classified by their electrical characteristics and pickup patterns.

Electrical Characteristics:

Dynamic - Works opposite of a speaker. A wire coil attached to a diaphragm is suspended inside a magnetic field. Sound waves hit the diaphragm making the coil move. This creates a flow of electricity in the coil windings.
Dynamic microphones are typically durable and a good choice for hand held vocals or percussion instruments.

Condenser - (a.k.a. electret or capacitor)- Need batteries or phantom power to operate. A plate or diaphragm moves adjacent to a stationary, charged backplate. The capacitance between the two plates changes as the diaphragm moves modulating an electric current. This current must be boosted by a preamplifier to create a usable signal.

Condenser microphones are more sensitive and create a “hotter” signal. They are a better choice for distant miking and lower level sound sources. Most full range, high-quality studio microphones are condensers.
You must either use batteries or phantom power. Phantom power is 48 volts, which is sent up the microphone cable from the mixer or camera. (Most professional cameras – like the JVCs have phantom power)

Ribbon - A small (extremely delicate) metal ribbon is suspended inside a magnetic field. Sound waves move the ribbon, creating an electrical flow.
Because of their delicate construction, ribbon microphones are not suitable for windy conditions or extremely loud sound sources. They are typically only used for vocal applications. (The RCA mike on Johnny Carson’s desk was a ribbon microphone)

Pickup patterns:

  • Omni (EV635 is the most commonly found dynamic mike. Most lavaliere microphones are condensers and have omni-directional pickup patterns)
  • Cardioid (dynamic cardioids include SM57, SM58 & the RE20. Condenser cardioids include AKGC100, AT4033)
  • Hyper-cardioid (Shotgun microphones- almost all are condensers)
  • Figure eight (All ribbon microphones. The U87 & AKG414 are switchable between Cardioid and figure eight)
  • Other:
    • Boundary or Pressure Zone Microphones (PZM) are flat and designed to be placed on a flat surface. Their pickup pattern resembles half of a sphere.
    • Contact microphones are small and designed to be mounted directly onto a resonating object. (Onto the bridge of a cello or the inside of a guitar) These are used mostly for music.

Applications:

  • Lavaliere - Very popular for film & video. Provide a consistent sound close to the source and are inconspicuous. Wireless versions of these are a must have for professional videographers.
  • Hand held – try to avoid using these unless you’re doing interviews with people on the street (an assistant with a boom would be better). When using, make sure to keep them a consistent distance from the source. Best used on a stand.
  • Stands (floor & desk) obtrusive good for music; desk: obtrusive but an excellent way to hold a microphone (Leno, Letterman)
  • Boom – handheld and floor stand models (typically used with a shotgun mike)
  • Headset – Conspicuous but provide audio monitoring for performers and a consistent sound source. (Used frequently for live sporting events and by singers)
  • Parabolic mount. A large bowl with handles on the outside and a microphone mount on the inside. Place a microphone in the middle and you have a highly directional microphone- more directional and sensitive than a shotgun mike. Commonly used for sporting events and spying, be sure you faithfully listen to the headphone while using. You need to move these continuously to keep them focused.

Signals, cables and connectors

Mic / Line Level - Audio signals are typically either line level or mic level.

Line levels can be +4 dBu or –10 dBv - There are two different levels considered "line level". Professional equipment uses a slightly hotter signal of +4 dBu. Consumer equipment (such as CD players, VCRs, etc) uses -10 dBv. They are cllllllose to being interchangeable, but plugging a +4 output into a -10 dBm input will sound louder and possibly clip or distort. You may need a 12-15 dB pad. Plugging a -10 dBv output from a piece of consumer gear into the +4 input of a mixer will usually work fine, except the signal might be slightly softer.

Balanced vs. Unbalanced - Audio cables are either balanced or unbalanced

Balanced cables have three wires (two conductors & a ground) and are far less prone to electrical interference than unbalanced (2-wire) cables. Long cable runs of unbalanced cables will also cause a loss in high frequencies.

The cables that connect your home stereo equipment together (with RCA connectors on the ends) are unbalanced lines. They only have two wires, a conductor and a ground. The cables with XLR connectors on the ends (like mike cables) are balanced. They have three wires- two conductors and a ground- that’s why they have three pins or plugs on the connectors.

Balanced lines are less likely to pick up hum and distortion than unbalanced lines. You can use them on long cable runs without audio degradation. Unbalanced lines are likely to pick up radio interference and lose high frequencies on long cable runs.

Running cables - Don't run cables adjacent to AC power cords. Keep them separated as much as possible and cross them at 90 at intersections.

Know how to properly wrap cables! You need to know this in order to work professionally- really. Ask me in lab if you need a refresher.

Wireless microphones - Diversity vs. Non-Diversity - Diversity receivers have two antennas.

Compressors - Used to reduce the dynamic range (loudness). Digital audio has a great deal of dynamic range (signal to noise). Unfortunately we often need to reduce the amount of dynamic range to make the audio signal more suitable for analog tape, TV broadcast or for radio transmission.

Compressors let you select a threshold level. Sounds louder than the threshold are compressed by an amount that you can specify. You can also set the attack and delay of the compression.

Audio that has been compressed can have a higher nominal level than non-compressed audio. Reducing the overall dynamic range creates less variation in the dynamic range. In other words, the differences between the loudest and softest parts are reduced. With a more consistent audio level, the overall signal gain can be increased.

Limiters - They reduce the dynamic range (like compressors), but can totally limit the signal, not just reduce it.

Expanders - The opposite of a compressor. Sounds above a set threshold are expanded, or the gain is increased.

Foley - Named after Jack Foley, the term is used to define the process used to re-create sound effects during the post-production phase.

ADR (Automated Dialog Replacement) - The process of replacing dialog and sounds in post-production.

Jim's Audio Production Tips:

  • In general, lavaliere (wired & wireless) and shotgun microphones are the most usfeul mics in video/film field production. These are the mic you'll commonly use for interviews and capturing dramatic scenes. Desktop (stand-mounted) and handheld microphones can also be useful- mainly when you have folks at a table or podium- or when someone needs to hold a microphone.
  • Get some good headphones! - I like having a few good pairs - totally enclosed and bud-type (noise-cancelling is a nice feature)
  • Faithfully monitor your audio with headphones while shooting and make sure your levels are in the proper range. Listen to both tracks for drop-outs, popped Ps or Ts, and any other distortion. Record a little and play it back. If you are in a noisy environment, go to somewhere where you can hear it.
  • When shooting interviews you can use one track for your subject and the other for either your interviewer or NAT sound from the camera.
  • Never use AGC unless you have no other option (shooting breaking news, covering a fire, etc.). An alternate method is to set one channel 6dB below the other.
  • When shooting B-roll or any video, always record audio- even if you don't think you need it.
  • DSLR/film shooters: When you're shooting sound with a separate audio recorder always slate or clap to establish a synch reference. If you need to synch audio tracks in post PluralEyes by Singular software might be useful.
  • On location, always record some ambient audio with the same microphone you are recording your interview with. (Often called room tone.) This can be layered into the soundtrack during post. If you need to add some dialog to a scene, you’ll have a background bed to lay under it.
  • When scouting shooting locations listen. Is it quiet enough? (vehicle noise, construction, etc.) You need to make sure to not record unwanted sounds or copyrighted music in the background.
  • Are you taping a person in the field and also recording voice overs? If so, use the same microphone in the same manner. This way the audio will match.

Audio Questions to Ponder- How would you deal with the following:

  • How would you record an on-camera reporter? (In the field? Behind a desk?)
  • An interviewer and a guest?
  • Three people having a roundtable discussion at a table?
  • A dramatic scene in a house with lots of action & movement?
  • Imagine you've recorded an awesome interview downtown. You used a wireless lav on your talent on channel 1 and the camera mic (picking up street noise) on channel 2. How will you edit these clips into your sequence?

There is no single "right" way to do any of them. What you choose depends upon your level of skill and available equipmen and time.

FYI The Production Lab has the following tools which might be useful:

  • Mic stands (& C stands)
  • microphones
  • field mixers
  • field recorders
  • slates

Lab this week:

You will carry out the Audio / News Exercise. Be sure to bring two copies of your paperwork. You'll also need to get either on-camera releases, or use paper releases (found on the website.)

 



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