Introduction: Understanding Audio for Video
Audio is a critical component of video production that often receives less attention than visuals but can make or break a project. High-quality audio enhances storytelling, establishes emotional tone, improves audience engagement, and increases overall production value. Poor audio quality can distract viewers and undermine otherwise excellent visual content. This cheat sheet covers essential concepts, techniques, and best practices for capturing, editing, and delivering professional audio for video productions.
Core Concepts and Technical Standards
Audio Specifications for Video Production
Format | Sample Rate | Bit Depth | Channels | Notes |
---|---|---|---|---|
Broadcast TV | 48 kHz | 24-bit | Stereo/5.1 | Industry standard |
Film | 48 kHz | 24-bit | 5.1/7.1 | Higher dynamic range |
Web/Streaming | 44.1/48 kHz | 16/24-bit | Stereo | Platform dependent |
Social Media | 44.1/48 kHz | 16-bit | Stereo/Mono | Often compressed |
Audio Levels and Metering
Standard | Target Level | Peak Level | Measurement |
---|---|---|---|
Broadcast (ATSC) | -24 LKFS ±2 | -2 dBTP | LUFS/LKFS |
Streaming (e.g., Netflix) | -24 LUFS | -2 dBTP | LUFS |
Web/YouTube | -14 LUFS | -1 dBTP | LUFS |
Theatrical | Variable | -3 dBTP | dB SPL |
Audio File Formats for Video
Format | Use Case | Pros | Cons |
---|---|---|---|
WAV | Production/Editing | Uncompressed, high quality | Large file size |
AIFF | Production/Editing | Uncompressed, high quality | Large file size |
AAC | Delivery | Good compression | Lossy quality |
MP3 | Web/Basic | Widely compatible | Lossy quality |
AC3/E-AC3 | Broadcast/Surround | Surround support | Specific hardware needs |
PCM | Embedded in Video | High quality | Large file size |
Equipment and Setup for Video Audio
Microphone Types and Applications
Mic Type | Polar Pattern | Best For | Challenges |
---|---|---|---|
Lavalier | Omnidirectional | Interviews, dialog | Clothing noise, hiding cable |
Shotgun | Supercardioid | Field recording, boomed dialog | Requires operator, sensitive to handling |
Handheld | Cardioid | Interviews, on-camera presenter | Visible in shot, handling noise |
Boundary/PZM | Hemispherical | Conference rooms, table scenes | Limited placement options |
Stereo | X/Y, M/S, ORTF | Ambience, music recording | More complex setup |
Wireless Systems | Varies | Mobile subjects, clean shots | Battery, RF interference |
Essential Recording Equipment
- Audio Recorder: Zoom H4n/H6, Sound Devices MixPre, Tascam DR series
- Mixer/Interface: For multiple mic inputs and level control
- Headphones: Closed-back for monitoring (Sony MDR-7506, Beyerdynamic DT770)
- Windscreens/Dead Cats: For outdoor recording
- Shock Mounts: Minimize handling noise
- Boom Poles: For positioning shotgun mics above talent
- XLR Cables: Professional balanced connections
- Power Solutions: Batteries, power banks, AC adapters
Camera Audio Connections
Connection | Quality | Use Case |
---|---|---|
XLR Input | Professional | ENG cameras, cinema cameras |
3.5mm Mic Input | Consumer/Prosumer | DSLRs, mirrorless cameras |
Hot Shoe Mounts | Varies | Camera-top mics, wireless receivers |
HDMI Audio | Digital | Monitoring, some external recorders |
Wireless Systems | Professional | Camera receiver to mic transmitter |
Audio Recording Techniques for Video
Dialogue Recording Methods
Method | Equipment | Best For | Setup Notes |
---|---|---|---|
Lavalier | Lav mic, wireless system | Interviews, documentary | Place 6-8″ below chin, hide cable |
Boomed Shotgun | Shotgun mic, boom pole | Film scenes, controlled environments | Position above talent, out of frame |
Camera-Mounted | On-camera mic | Run-and-gun, backup audio | Limited quality, proximity dependent |
Double-System | Field recorder + camera audio | Professional production | Requires sync in post |
Plant Mics | Boundary or hidden mics | Wide shots, multiple subjects | Pre-place in environment |
Room Acoustics and Location Considerations
- Reflective Surfaces: Glass, hardwood, concrete create echo
- Room Tone: Always record 30+ seconds of ambient noise for each location
- Background Noise: Identify and mitigate HVAC, refrigerators, traffic
- Outdoor Challenges: Wind, traffic, aircraft, natural sounds
- Set Design: Consider acoustic properties of filming locations
- Acoustic Treatment: Portable sound blankets, foam panels for problematic spaces
Recording Levels and Monitoring
- Set levels with -12dB to -20dB average, -6dB peaks
- Always monitor with headphones while recording
- Watch for distortion, background noise, or interference
- Record redundant audio when possible (recorder + camera)
- Use limiters to prevent unexpected peaks
- Check for RF interference when using wireless systems
- Slate or clap at the beginning of takes for sync reference
Audio Syncing and Organizing
Synchronization Methods
Method | How It Works | Pros | Cons |
---|---|---|---|
Slate/Clapboard | Visual/audio cue | Traditional, foolproof | Requires on-set discipline |
Timecode | Electronic sync signal | Frame-accurate | Requires compatible equipment |
Automatic Sync | Software analysis | Fast, convenient | Can fail with poor audio |
Jam Sync | Devices share clock | Set and forget | Drift over time |
PluralEyes | Third-party software | Batch processing | Additional cost |
File Organization for Post-Production
- Use consistent naming conventions:
[Scene]_[Take]_[Audio Source]
- Group files by scene/location
- Back up audio files immediately after shooting
- Keep original files unmodified
- Create proxy/working copies for editing
- Document mic placement and equipment used
- Note any audio issues on set for post-production awareness
Post-Production Audio Workflow
Audio Editing Process
- Import and Organize: Bring files into DAW/NLE
- Sync Audio: Align double-system audio with video
- Dialog Edit: Clean up dialogue, remove unwanted sounds
- Sound Design: Add effects, ambience, and foley
- Music: Add score and/or licensed tracks
- Preliminary Mix: Balance all elements
- Review and Revisions: Get feedback, make adjustments
- Final Mix: Finalize all audio elements
- Mastering: Ensure technical compliance with delivery specifications
- Export: Render final audio according to delivery requirements
Essential Post-Production Tools
Tool Type | Purpose | Popular Software |
---|---|---|
DAW | Audio editing/mixing | Pro Tools, Adobe Audition, Logic Pro |
NLE | Video editing with audio | Premiere Pro, Final Cut, DaVinci Resolve |
Noise Reduction | Clean up audio | iZotope RX, Waves X-Noise |
EQ | Frequency adjustment | Fabfilter Pro-Q, stock DAW EQ |
Compression | Dynamic control | FabFilter Pro-C, Waves C-series |
Reverb | Space simulation | Altiverb, Valhalla Room |
Delivery Tools | Loudness measurement | iZotope Insight, Waves WLM |
Audio Clean-up and Enhancement
Common Audio Problems and Solutions
Problem | Causes | Solution |
---|---|---|
Background Noise | HVAC, electrical, location | Noise reduction, EQ, gating |
Wind Noise | Outdoor recording, movement | High-pass filter, specialized tools |
Plosives | P/B/T sounds into mic | De-plosive filter, EQ dip around 100Hz |
Sibilance | S/SH sounds | De-esser, EQ reduction around 6-8kHz |
Room Echo | Reflective surfaces | Record in treated space, add absorption |
Microphone Handling | Boom movement, adjustments | Shock mounts, editing, replacement |
Clothing Rustle | Lavalier placement | Mounting techniques, moleskin barriers |
Clipping | Input level too high | Re-record if possible, restoration tools |
Hum/Buzz | Electrical interference | Notch filter at 50/60Hz and harmonics |
Dialog Editing Techniques
- Crossfading: Smooth transitions between clips (3-10ms)
- Room Tone: Fill gaps with consistent ambient noise
- Audio Scribble: Use waveform visibility to identify issues
- Alternate Takes: Replace problematic lines from other takes
- ADR: Re-record dialogue in studio when necessary
- Dialogue Isolation: Use EQ, gating to focus on speech
- Clip Gain: Adjust levels before applying effects
- Batch Processing: Apply consistent treatment to similar audio
EQ for Video Dialog
Frequency Range | Effect on Dialog | Typical Adjustment |
---|---|---|
Below 80 Hz | Rumble, handling noise | High-pass filter |
100-250 Hz | Fullness, muddiness | Cut to reduce room resonances |
250-500 Hz | Body, warmth | Gentle sculpting as needed |
500-1 kHz | Clarity, presence | Small boosts for intelligibility |
1-3 kHz | Articulation | Key range for speech intelligibility |
3-6 kHz | Presence, sibilance | Careful control to avoid harshness |
6-10 kHz | Brightness, air | Subtle enhancement for clarity |
Above 10 kHz | Air, detail | Very subtle adjustment |
Sound Design and Music
Layering Audio Elements
Layer | Purpose | Priority |
---|---|---|
Dialog | Primary communication | Highest – always audible |
Primary SFX | Story-critical sounds | High – support narrative |
Secondary SFX | Environmental, contextual | Medium – enhance realism |
Ambience | Establish space/location | Medium – creates environment |
Music | Emotional tone, pacing | Varies based on scene |
Foley | Movement sounds, tactile | Support primary action |
Music Placement and Mixing
- Music should enhance emotion without competing with dialogue
- Use volume automation to duck music during dialogue
- Consider frequency masking between music and speech
- Use stems (separate elements) when available for more control
- Instrumental sections for dialogue-heavy scenes
- Bridge scenes and transitions with musical themes
- Clear music rights and licensing before final delivery
Sound Effects and Foley
- Use sound libraries for efficiency (Soundsnap, Epidemic Sound, etc.)
- Record custom effects for unique sounds
- Layer multiple sounds for complex effects
- Pan effects to match screen position
- Create perspective with reverb and volume
- Consider the emotional impact of sound choices
- Use foley for clothing movement, footsteps, and handling sounds
Mixing for Different Platforms
Surround Sound Mixing
Channel | Content | Placement |
---|---|---|
Center (C) | Dialogue, anchored sounds | Front center |
Left/Right (L/R) | Music, ambient sounds, panned effects | Front left/right |
Left/Right Surround (Ls/Rs) | Ambience, environmental effects | Side/rear left/right |
LFE (.1) | Low-frequency effects, rumble | Non-directional |
Height channels (Atmos) | Overhead sounds, immersive elements | Above listener |
Platform-Specific Considerations
Platform | Audio Considerations | Special Requirements |
---|---|---|
Cinema | Full dynamic range, surround sound | 5.1/7.1/Atmos mixing |
Broadcast TV | Compressed dynamic range, loudness standards | -24 LKFS, dialog at -27 LKFS |
Streaming | Platform-specific requirements | Check current specs |
Social Media | Heavily compressed, often mobile listening | Mono compatibility, high clarity |
YouTube | Easily audible dialog, limited dynamic range | -14 LUFS target |
Mobile/Tablets | Limited speakers, headphone listening | Check mono compatibility |
Loudness Standards and Management
- LUFS (LKFS): Loudness Units relative to Full Scale
- True Peak: Actual peak level including intersample peaks
- Dynamic Range: Difference between loudest and quietest parts
- Dialog Normalization: Calibrating levels based on speech
- Downmixing: Converting surround to stereo/mono compatibility
- Limiters: Preventing digital overs while maximizing loudness
- Loudness Meters: Tools to measure and ensure compliance
Delivery and Quality Control
Final Delivery Formats
Delivery Type | Format | Notes |
---|---|---|
Master File | WAV, AIFF | Uncompressed, for archiving |
Broadcast Master | WAV + metadata | Specific loudness requirements |
OTT Streaming | Various | Platform-specific requirements |
DVD/Blu-ray | AC3, DTS | Compressed surround formats |
Web Video | AAC, MP3 | Compressed stereo |
Separate Stems | Multiple WAVs | Dialog, music, effects as separate files |
Quality Control Checklist
- ✓ Dialogue intelligible throughout
- ✓ No dropouts or digital artifacts
- ✓ Consistent levels between scenes
- ✓ Meets loudness specifications for platform
- ✓ No unauthorized music or effects
- ✓ Correct channel configuration
- ✓ Sync maintained throughout
- ✓ All required deliverables included
- ✓ Metadata correctly embedded
- ✓ Correct file formats and specifications
Export Settings by Platform
Platform | File Format | Sample Rate | Bit Depth | Target Loudness | Peak Limit |
---|---|---|---|---|---|
YouTube | AAC/MP4 | 48 kHz | 16-bit | -14 LUFS | -1 dBTP |
Vimeo | AAC/MP4 | 48 kHz | 16-bit | -16 LUFS | -1 dBTP |
Broadcast | WAV/AIFF | 48 kHz | 24-bit | -24 LKFS | -2 dBTP |
Netflix | Various | 48 kHz | 24-bit | -24 LUFS | -2 dBTP |
Theatrical | Various | 48 kHz | 24-bit | Variable | -3 dBTP |
AAC | 44.1/48 kHz | 16-bit | -14 LUFS | -1 dBTP | |
TikTok | AAC | 44.1/48 kHz | 16-bit | -14 LUFS | -1 dBTP |
Common Problems and Solutions
Troubleshooting Audio Issues
Issue | Possible Causes | Solutions |
---|---|---|
Out of Sync | Mismatched frame rates, editing errors | Resync, check timeline settings |
Inconsistent Levels | Poor mixing, different recording setups | Level automation, compression |
Unintelligible Dialogue | Background noise, poor recording | EQ enhancement, ADR if necessary |
Distortion | Clipping, over-processing | Re-record, restoration tools |
Phase Issues | Misaligned mics, stereo problems | Phase alignment, mono check |
Excessive Background Noise | Poor location, equipment issues | Noise reduction, ADR |
Music Drowning Dialogue | Poor mixing decisions | Automation, frequency carving |
Poor Transitions | Editing issues, level jumps | Crossfades, consistent ambience |
When to Use ADR (Automated Dialogue Replacement)
- Location audio is unusable due to noise/interference
- Performance is good but technical quality is poor
- Script changes after shooting
- Heavy accents need to be moderated
- Dialogue needs to be heard over unavoidable environmental noise
- For voiceovers and narration
Best Practices and Tips
On-Set Audio Practices
- Scout locations for acoustic properties before shooting
- Always record room tone at each location
- Use redundant audio recording when possible
- Monitor audio with headphones during every take
- Document equipment, settings, and any issues
- Communicate with the team about audio needs
- Control the environment whenever possible
- Have backup equipment ready
Post-Production Efficiency
- Use templates for common workflows
- Create keyboard shortcuts for frequent operations
- Use track presets for dialogue, music, effects
- Apply batch processing for similar audio clips
- Create submixes/groups for easier control
- Save complex signal chains as presets
- Label and color-code tracks consistently
- Save incremental versions of your project
Client Communication
- Set clear expectations about audio quality
- Educate on the importance of good production audio
- Establish review and approval process for audio
- Discuss music licensing early in production
- Create reference mixes for client review
- Document feedback systematically
- Consider accessibility needs (subtitles, described audio)
Resources for Further Learning
Books and Publications
- “Modern Recording Techniques” by David Miles Huber
- “The Location Sound Bible” by Ric Viers
- “Dialogue Editing for Motion Pictures” by John Purcell
- “The Sound Effects Bible” by Ric Viers
- “Audio Post Production for Film and Television” by Mark Cross
Online Resources
- Pro Tools Expert (tutorials and articles)
- Sound on Sound magazine
- Film Sound theory (FilmSound.org)
- LinkedIn Learning courses on audio post-production
- “Tonebenders” podcast
- Curtis Judd YouTube channel (video audio techniques)
- Location Sound Recordist groups on social media
- A Sound Effect blog
Software Tutorials
- LinkedIn Learning / Lynda.com
- Groove3
- YouTube channels specific to your DAW/NLE
- Manufacturer websites for specific plugins
- Specialized forums for audio post-production