Audio Basics
Bad audio ruins good screencasts. This lesson covers everything you need: normalization, level balancing, music, and fades — the complete screencast audio workflow.
Core Idea
For screencasts, your audio goal is: clear voice at consistent volume, system audio as context, music as background. Everything else is refinement. Get levels right before anything else.
The Screencast Audio Stack
Standard track layout:
A1 [System audio from recording] → -12 to -6 dB
A2 [Microphone / Voiceover] → 0 to -3 dB (dominant)
A3 [Background music] → -18 to -12 dB (subtle)
Rule: Voice always wins. System audio is context. Music is background.
Opening the Audio Mixer
Menu → View → Audio Mixer
OR
Timeline Toolbar → Audio Mixer button (far right)
Audio Mixer shows:
One channel per audio track
Volume fader (drag up/down)
Pan knob (left/right balance)
Mute button [M]
Solo button [S]
VU meter (shows real-time level)
Setting Audio Levels
Target levels for screencasts:
| Track | Type | Target Level |
|---|---|---|
| A1 System audio | Reference audio | -12 dB to -6 dB |
| A2 Microphone | Primary voice | -3 dB to 0 dB |
| A3 Background music | Atmosphere | -18 dB to -12 dB |
In Audio Mixer:
Drag the fader for each track to the target level
Watch the VU meter — peaks should not hit the red zone
Play the timeline → adjust while watching levels move
Normalize Audio (Effect)
Normalization automatically adjusts a clip's peak to a target level:
Select clip → Effects → search "normalize"
→ "Normalize" or "Audio Loudness Normalization"
Settings:
Target: -3 dB (for voice) or -6 dB (for system audio)
Peak normalization: ✅
Apply to all voiceover clips for consistent volume.
Track-level normalize (affects all clips):
Click ⚡ effects icon in A2 track header
→ Add "Normalize" effect
→ All clips on A2 auto-normalized
Audio Fade In / Fade Out
Via mouse (drag):
Hover top-left corner of audio clip → drag red triangle → Fade In
Hover top-right corner → drag red triangle → Fade Out
Via effect:
Select clip → Effects → "Fade In" / "Fade Out" → apply
Set duration in Effect Stack
Standard fade durations for screencasts:
- Voice fade: 10–15 frames
- Music intro fade: 60–90 frames (2–3 seconds)
- Music outro fade: 90–120 frames (3–4 seconds)
Adding Background Music
1. Import music track to Project Bin (MP3, WAV, OGG)
2. Drag to A3 track (bottom audio track)
3. Extend music duration to match video:
If music is shorter than video: Loop or use a different track
If music is longer than video: Trim right edge to match
4. Set A3 volume to -15 dB in Audio Mixer
(Music should be barely audible under voice)
5. Add fade out at the end:
Hover top-right corner → drag triangle to start of fade
Typical: 3-second fade out at end of video
6. Optional: fade in at the beginning
Hover top-left → drag triangle
tip
Use royalty-free music from: YouTube Audio Library, Pixabay Music, ccMixter, or Jamendo. Always check the license before publishing.
Detaching Audio from Video
When you need to edit audio and video independently:
Right-click clip on V1 → Split Audio/Video
→ Audio portion appears on A1, unlinked from video
→ Now trim/move each independently
OR:
Right-click clip → Detach Audio
→ Audio moves to a new track, keeping original link info
Removing Background Noise
Effects → search "noise"
→ "Audio Noise Suppressor"
Settings:
Strength: 0.3–0.5 (start conservative)
Too much → robotic/hollow voice quality
Better option: Use a dedicated noise reduction tool (Audacity, DeepFilterNet)
before importing to Kdenlive.
Audio Sync (Clapping Method)
When recording mic separately from screen audio:
1. Start recording with a loud clap (creates a spike in both tracks)
2. Import both tracks to Kdenlive
3. In Audio Mixer, solo each track and find the clap spike
4. Align both tracks so clap spikes are at the same position
5. Group video+mic together: select both → Ctrl+G
Volume Keyframes
Automate volume changes over time:
1. In Audio Mixer → click the keyframe button on a track
2. Add keyframes at volume change positions
3. Set volume value at each keyframe
Use case: Duck music volume under voice, raise after voice stops
Example:
0:00 Music: -15 dB
0:05 Music: -15 dB (hold)
0:06 Music: -25 dB (voice starts → duck music)
2:30 Music: -25 dB (hold while voice plays)
2:31 Music: -15 dB (voice ends → restore music)
Keyboard Reference
| Action | Shortcut |
|---|---|
| Mute audio track | Click [M] in Audio Mixer |
| Solo audio track | Click [S] in Audio Mixer |
| Toggle track mute | Ctrl+Shift+H (active track) |
| Play with audio | Space |
| JKL transport with audio | J/K/L |
| Open Audio Mixer | Menu → View → Audio Mixer |
Hands-On Practice
1. Open project with screen recording on V1/A1
Import an MP3 music file to Project Bin
2. Open Audio Mixer (Menu → View → Audio Mixer)
Note the A1 VU level during playback
3. Drag A1 fader to -6 dB
4. Select A1 clip → Effects → "Normalize"
Set target to -6 dB → apply
5. Drag music to A3 track
Set A3 fader to -15 dB
Add fade in (top-left drag) and fade out (top-right drag)
6. Play Space → listen to the mix
If voice is unclear: raise A2, lower A1 and A3
7. Add a fade out to the voice (A2) at the end of the video:
Hover top-right of A2 clip → drag 30 frames
8. Ctrl+S → save