Video Generation Audio & Sound

JsonCut provides comprehensive audio capabilities for your videos, including background music, voiceovers, sound effects, and advanced mixing controls. You can layer multiple audio sources and apply professional audio processing techniques.

Background Audio

Add background music that plays throughout your entire video with automatic looping support.

{
  "type": "video",
  "config": {
    "audioFilePath": "/audio/2025-09-14/cmejszvz00000t5afm8qcr6bq/dc4010ef-d0db-43b6-927f-10ddf6761129.mp3",
    "loopAudio": true,
    "outputVolume": 0.8,
    "clips": [
      {
        "duration": 10,
        "layers": [
          {
            "type": "title-background",
            "text": "Looping Background Music",
            "textColor": "#ffffff"
          }
        ]
      }
    ]
  }
}

Background Audio Properties

Property	Type	Description
`audioFilePath`	string	Path to background audio file
`loopAudio`	boolean	Automatically loop audio if shorter than video
`outputVolume`	number	Final output volume (0-1)
`keepSourceAudio`	boolean	Keep original audio from video layers
`clipsAudioVolume`	number	Volume for audio from clips relative to tracks

Audio Tracks

Add multiple audio tracks that can start and stop at specific times, independent of clip structure

{
  "type": "video",
  "config": {
    "width": 1920,
    "height": 1080,
    "audioTracks": [
      {
        "path": "/audio/2025-09-14/cmejszvz00000t5afm8qcr6bq/f70c05ef-d0a1-4e07-8ea2-2a09d2028d24.wav",
        "mixVolume": 1.0,
        "start": 2,
        "cutFrom": 1,
        "cutTo": 10
      },
      {
        "path": "/audio/2025-09-14/cmejszvz00000t5afm8qcr6bq/dc4010ef-d0db-43b6-927f-10ddf6761129.mp3",
        "mixVolume": 0.6,
        "start": 7,
        "cutFrom": 0,
        "cutTo": 9
      }
    ],
    "clipsAudioVolume": 0.5,
    "clips": [
      {
        "duration": 10,
        "layers": [
          {
            "type": "image",
            "path": "/image/2025-09-14/cmejszvz00000t5afm8qcr6bq/ebbb0d92-f4c6-4a07-9124-92b71cd24c50.jpg",
            "resizeMode": "cover"
          }
        ]
      }
    ]
  }
}

Audio Track Properties

Property	Type	Required	Default	Description
`path`	string	✅	-	File path to audio track
`mixVolume`	number	❌	`1`	Relative volume for this track (0-1)
`start`	number	❌	`0`	How many seconds into video to start this audio track
`cutFrom`	number	❌	`0`	Time value to cut source file from (seconds)
`cutTo`	number	❌	-	Time value to cut source file to (seconds)

Clip Audio Layers

Add audio that's tied to specific clips using audio layers. Audio layers will be mixed together, and if cutFrom/cutTo is set, the resulting segment will be slowed/sped-up to fit clip.duration (limited to 0.5x-100x speed).

{
  "type": "video",
  "config": {
    "keepSourceAudio": true,
    "clips": [
      {
        "duration": 4,
        "layers": [
          {
            "type": "video",
            "path": "/video/2025-09-14/cmejszvz00000t5afm8qcr6bq/8d8df335-6655-4160-8066-66510cf08f0d.mp4",
            "cutFrom": 0,
            "cutTo": 4,
            "resizeMode": "cover"
          },
          {
            "type": "audio",
            "path": "/audio/2025-09-14/cmejszvz00000t5afm8qcr6bq/3aee9363-cd80-4d93-8cb6-99d137e16863.mp3",
            "cutFrom": 5,
            "cutTo": 9,
            "mixVolume": 0.8
          }
        ]
      },
      {
        "duration": 3,
        "layers": [
          {
            "type": "fill-color",
            "color": "#D1B43F"
          },
          {
            "type": "audio",
            "path": "/audio/2025-09-14/cmejszvz00000t5afm8qcr6bq/f70c05ef-d0a1-4e07-8ea2-2a09d2028d24.wav",
            "cutFrom": 3,
            "cutTo": 6,
            "mixVolume": 0.7
          }
        ]
      }
    ]
  }
}

Audio Layer Properties

Property	Type	Required	Default	Description
`path`	string	✅	-	Path to audio file
`cutFrom`	number	❌	`0`	Time value to cut from (seconds)
`cutTo`	number	❌	`clip.duration`	Time value to cut to (seconds)
`mixVolume`	number	❌	`1`	Relative volume when mixing (0-1)

Audio Layer Requirements

Audio layers require keepSourceAudio: true to be set in the video configuration to function properly.

Video Length Considerations

When using keepSourceAudio: true with video layers, the video must be manually cut to match the clip duration if it's longer than the layer duration. Otherwise, compilation issues may occur with subsequent audio tracks. Use detached-audio layers as an alternative if you don't want to manually cut the video.

Audio Speed Adjustment

When cutFrom/cutTo segments are specified, they are automatically sped/slowed to fit the clip duration. This operation is limited to values between 0.5x and 100x speed.

Detached Audio Layers

Audio layers that start relative to each clip's beginning, rather than the global video timeline. This makes it easier to synchronize audio with specific clips without calculating absolute start times across the entire video.

{
  "type": "video",
  "config": {
    "clips": [
      {
        "duration": 4,
        "layers": [
          {
            "type": "title-background",
            "text": "Narrator starts in 1 sec",
            "textColor": "#ffffff"
          },
          {
            "type": "detached-audio",
            "path": "/audio/2025-09-14/cmejszvz00000t5afm8qcr6bq/f70c05ef-d0a1-4e07-8ea2-2a09d2028d24.wav",
            "start": 1,
            "mixVolume": 0.9,
            "cutFrom": 0
          }
        ]
      },
      {
        "duration": 3,
        "layers": [
          {
            "type": "title-background",
            "text": "Music sting starts in 0.5 sec",
            "textColor": "#ffffff"
          },
          {
            "type": "detached-audio",
            "path": "/audio/2025-09-14/cmejszvz00000t5afm8qcr6bq/dc4010ef-d0db-43b6-927f-10ddf6761129.mp3",
            "start": 0.5,
            "mixVolume": 0.6
          }
        ]
      }
    ]
  }
}

Detached Audio Properties

Property	Type	Required	Default	Description
`path`	string	✅	-	Path to audio file
`start`	number	❌	`0`	Start time relative to clip start (seconds)
`mixVolume`	number	❌	`1`	Relative volume when mixing (0-1)
`cutFrom`	number	❌	`0`	Start position in audio file (seconds)
`cutTo`	number	❌	-	End position in audio file (seconds)

Audio Normalization & Ducking

Apply professional audio normalization with ducking effects, perfect for automatically lowering background music when voiceover speaks.

{
  "type": "video",
  "config": {
    "audioFilePath": "/audio/2025-09-15/cmejszvz00000t5afm8qcr6bq/e8af4403-6154-40b7-88a8-4437f677dc81.mp3",
    "audioTracks": [
      {
        "path": "/audio/2025-09-15/cmejszvz00000t5afm8qcr6bq/f53b379f-b711-4732-9266-437e11850171.wav",
        "mixVolume": 1.0,
        "start": 3
      }
    ],
    "audioNorm": {
      "enable": true,
      "gaussSize": 5,
      "maxGain": 30
    },
    "clips": [
      {
        "duration": 10,
        "layers": [
          {
            "type": "title-background",
            "text": "Background Music + Voiceover",
            "textColor": "#ffffff"
          }
        ]
      }
    ]
  }
}

Audio Normalization Properties

Property	Type	Default	Description
`enable`	boolean	`false`	Enable audio normalization
`gaussSize`	number	`5`	Gaussian filter size for smoothing (1-10)
`maxGain`	number	`30`	Maximum gain adjustment in decibels

How Audio Ducking Works

Audio normalization automatically:

Analyzes all audio tracks for volume levels using dynamic range compression
Identifies when multiple tracks overlap in time
Reduces background music volume when voiceover is present
Smoothly transitions volume changes using gaussian filtering
Prevents audio clipping with maxGain limits

Audio Curves in Transitions

Control how audio fades during transitions using audio curves.

{
  "type": "video",
  "config": {
    "keepSourceAudio": true,
    "clips": [
      {
        "duration": 3,
        "layers": [
          {
            "type": "title-background",
            "text": "Default Audio Curves (tri)",
            "textColor": "#ffffff"
          },
          {
            "type": "audio",
            "path": "/audio/2025-09-15/cmejszvz00000t5afm8qcr6bq/e8af4403-6154-40b7-88a8-4437f677dc81.mp3"
          }
        ],
        "transition": {
          "duration": 1,
          "name": "fade",
          "audioOutCurve": "tri",
          "audioInCurve": "tri"
        }
      },
      {
        "duration": 3,
        "layers": [
          {
            "type": "title-background",
            "text": "Exponential Audio Curves (exp)",
            "textColor": "#ffffff"
          },
          {
            "type": "audio",
            "path": "/audio/2025-09-15/cmejszvz00000t5afm8qcr6bq/19043de3-3da1-4793-b2e1-b58ce4ca806a.mp3"
          }
        ]
      }
    ]
  }
}

Available Audio Curves

Curve	Description
`tri`	Triangular curve (default)
`exp`	Exponential curve
`linear`	Linear curve

Complete Audio Example

Here's a comprehensive example showcasing multiple audio features:

{
  "type": "video",
  "config": {
    "width": 720,
    "height": 480,
    "fps": 30,
    "audioFilePath": "/audio/2025-09-15/cmejszvz00000t5afm8qcr6bq/e8af4403-6154-40b7-88a8-4437f677dc81.mp3",
    "loopAudio": true,
    "outputVolume": 0.8,
    "clipsAudioVolume": 0.7,
    "keepSourceAudio": true,
    "audioTracks": [
      {
        "path": "/audio/2025-09-15/cmejszvz00000t5afm8qcr6bq/f53b379f-b711-4732-9266-437e11850171.wav",
        "mixVolume": 0.9,
        "start": 2,
        "cutFrom": 0,
        "cutTo": 5
      }
    ],
    "audioNorm": {
      "enable": true,
      "gaussSize": 5,
      "maxGain": 25
    },
    "clips": [
      {
        "duration": 4,
        "layers": [
          {
            "type": "title-background",
            "text": "Background Music",
            "textColor": "#ffffff"
          }
        ],
        "transition": {
          "duration": 0.5,
          "name": "fade"
        }
      },
      {
        "duration": 4,
        "layers": [
          {
            "type": "title-background",
            "text": "Voiceover + Audio Layer",
            "textColor": "#ffffff"
          },
          {
            "type": "audio",
            "path": "/audio/2025-09-15/cmejszvz00000t5afm8qcr6bq/19043de3-3da1-4793-b2e1-b58ce4ca806a.mp3",
            "mixVolume": 0.8
          }
        ],
        "transition": {
          "duration": 0.5,
          "name": "fade"
        }
      },
      {
        "duration": 4,
        "layers": [
          {
            "type": "title-background",
            "text": "Detached Audio",
            "textColor": "#ffffff"
          },
          {
            "type": "detached-audio",
            "path": "/audio/2025-09-15/cmejszvz00000t5afm8qcr6bq/00cd8f87-39bd-4918-8fce-f1f684fa546e.mp3",
            "start": 1,
            "mixVolume": 0.6
          }
        ],
        "transition": {
          "duration": 0.5,
          "name": "fade"
        }
      },
      {
        "duration": 4,
        "layers": [
          {
            "type": "title-background",
            "text": "Audio Normalization",
            "textColor": "#ffffff"
          }
        ]
      }
    ]
  }
}

Audio File Formats

JsonCut supports these audio formats:

Format	Best For	Notes
MP3	Music, voiceovers	Good compression, universal support
WAV	Sound effects, high quality	Uncompressed, larger files
M4A	Voice recordings	Good compression, quality
AAC	Professional audio	Balanced quality and size

Best Practices

Audio Quality Guidelines

Sample Rate: Use 44.1kHz or 48kHz for best compatibility
Bit Depth: 16-bit minimum, 24-bit for professional quality
File Size: Compress appropriately for web delivery
Levels: Avoid clipping, maintain consistent levels

Mixing Tips

Voiceover Priority: Keep voice levels prominent (-12 to -6 dB)
Music Balance: Background music at -18 to -12 dB
Effects Placement: Use sound effects sparingly for impact
Fade Transitions: Apply audio fades at clip boundaries

Performance Optimization

Audio Length: Trim unused portions of audio files
Track Count: Limit simultaneous audio tracks (recommended: max 5)
Normalization: Use sparingly on longer videos
File Formats: Choose appropriate compression levels

Troubleshooting

Common Issues

Audio not playing:

Verify file format is supported
Check file path accuracy
Ensure keepSourceAudio: true for audio layers
Check volume levels are above 0

Audio clipping:

Reduce mixVolume and outputVolume
Use audio normalization to balance levels
Check source audio for clipping

Synchronization problems:

Verify start times for detached audio
Check cutFrom and cutTo values
Ensure clip durations match audio timing

Next Steps

Examples - See complete video examples with professional audio
Layer Types - Learn about audio layer types in detail
Clips & Transitions - Understand how audio works with transitions

Background Audio​

Background Audio Properties​

Audio Tracks​

Audio Track Properties​

Clip Audio Layers​

Audio Layer Properties​

Detached Audio Layers​

Detached Audio Properties​

Audio Normalization & Ducking​

Audio Normalization Properties​

How Audio Ducking Works​

Audio Curves in Transitions​

Available Audio Curves​

Complete Audio Example​

Audio File Formats​

Best Practices​

Audio Quality Guidelines​

Mixing Tips​

Performance Optimization​

Troubleshooting​

Common Issues​

Next Steps​