Encoding Settings¶

Control video quality, format, and compression

Fluvie provides extensive control over the final video encoding through the EncodingConfig class.

Table of Contents¶

Overview
RenderQuality Presets
Custom Settings
Output Formats
Debug Options
Examples

Overview¶

Encoding settings control how FFmpeg encodes your final video:

final settings = EncodingConfig(
  quality: RenderQuality.high,
  outputFormat: OutputFormat.mp4,
  audioCodec: AudioCodec.aac,
);

await RenderService.execute(
  composition: video,
  outputPath: 'output.mp4',
  settings: settings,
  tester: tester,
);

RenderQuality Presets¶

Available Presets¶

Preset	CRF	Preset	Use Case
`preview`	28	`ultrafast`	Quick previews, testing
`standard`	23	`medium`	General use, good balance
`high`	18	`slow`	Final output, best quality
`lossless`	0	`veryslow`	Archival, no quality loss

Using Presets¶

// Quick preview
EncodingConfig(quality: RenderQuality.preview)

// Standard output
EncodingConfig(quality: RenderQuality.standard)

// High quality final
EncodingConfig(quality: RenderQuality.high)

// Lossless (very large files)
EncodingConfig(quality: RenderQuality.lossless)

Preset Details¶

Preview Quality¶

CRF: 28 (lower quality)
Preset: ultrafast
Use: Testing, iteration
File size: Small
Speed: Very fast

Standard Quality¶

CRF: 23 (good quality)
Preset: medium
Use: General distribution
File size: Moderate
Speed: Moderate

High Quality¶

CRF: 18 (excellent quality)
Preset: slow
Use: Final exports
File size: Larger
Speed: Slow

Lossless¶

CRF: 0 (perfect quality)
Preset: veryslow
Use: Archival, further editing
File size: Very large
Speed: Very slow

Custom Settings¶

CRF (Constant Rate Factor)¶

CRF controls quality. Lower = better quality, larger files.

EncodingConfig(
  crf: 20,  // Custom CRF (0-51 for H.264)
)

CRF Range	Quality	File Size
0-17	Visually lossless	Large
18-23	High quality	Moderate
24-28	Good quality	Smaller
29+	Lower quality	Small

FFmpeg Preset¶

Controls encoding speed vs compression efficiency:

EncodingConfig(
  preset: 'slow',  // Better compression, slower
)

Preset	Speed	Compression
`ultrafast`	Fastest	Lowest
`superfast`	Very fast	Low
`veryfast`	Fast	Below average
`faster`	Fast	Average
`fast`	Medium-fast	Above average
`medium`	Medium	Good
`slow`	Slow	Better
`slower`	Very slow	Very good
`veryslow`	Slowest	Best

Video Codec¶

EncodingConfig(
  videoCodec: VideoCodec.h264,  // Most compatible
  // or
  videoCodec: VideoCodec.h265,  // Better compression
  // or
  videoCodec: VideoCodec.vp9,   // Open format
)

Audio Codec¶

EncodingConfig(
  audioCodec: AudioCodec.aac,   // Most compatible
  // or
  audioCodec: AudioCodec.mp3,   // Universal
  // or
  audioCodec: AudioCodec.opus,  // Best quality per bit
)

Audio Bitrate¶

EncodingConfig(
  audioBitrate: '192k',  // Higher quality audio
)

Bitrate	Quality	Use Case
`96k`	Acceptable	Speech
`128k`	Good	General
`192k`	High	Music
`320k`	Excellent	High-fidelity

Output Formats¶

MP4 (Recommended)¶

Most compatible format:

EncodingConfig(
  outputFormat: OutputFormat.mp4,
  videoCodec: VideoCodec.h264,
  audioCodec: AudioCodec.aac,
)

WebM¶

Open format, good for web:

EncodingConfig(
  outputFormat: OutputFormat.webm,
  videoCodec: VideoCodec.vp9,
  audioCodec: AudioCodec.opus,
)

MOV¶

Apple ecosystem:

EncodingConfig(
  outputFormat: OutputFormat.mov,
  videoCodec: VideoCodec.h264,
  audioCodec: AudioCodec.aac,
)

GIF¶

Animated images (no audio):

EncodingConfig(
  outputFormat: OutputFormat.gif,
)

Frame Format¶

Control how frames are captured before encoding:

EncodingConfig(
  frameFormat: FrameFormat.png,  // Higher quality, slower
  // or
  frameFormat: FrameFormat.rawRgba,  // Faster, more memory
)

Format	Quality	Speed	Memory
PNG	Lossless	Slower	Lower
Raw RGBA	Lossless	Faster	Higher

Debug Options¶

Save Individual Frames¶

EncodingConfig(
  debugOutputFrames: true,
  debugFramesPath: '/tmp/frames/',
)

This saves each frame as a PNG file, useful for: - Debugging visual issues - Creating frame-by-frame animations - Inspecting specific frames

Verbose Logging¶

EncodingConfig(
  verbose: true,  // Print FFmpeg output
)

Examples¶

// Instagram/TikTok optimized
EncodingConfig(
  quality: RenderQuality.high,
  outputFormat: OutputFormat.mp4,
  videoCodec: VideoCodec.h264,
  audioCodec: AudioCodec.aac,
  audioBitrate: '192k',
)

Web Optimized¶

// Smaller file for web streaming
EncodingConfig(
  crf: 25,
  preset: 'fast',
  outputFormat: OutputFormat.mp4,
  audioBitrate: '128k',
)

Archival Quality¶

// Maximum quality preservation
EncodingConfig(
  quality: RenderQuality.lossless,
  outputFormat: OutputFormat.mov,
  frameFormat: FrameFormat.png,
)

Fast Preview¶

// Quick iteration
EncodingConfig(
  quality: RenderQuality.preview,
  outputFormat: OutputFormat.mp4,
)

Custom Fine-Tuned¶

EncodingConfig(
  crf: 20,
  preset: 'slow',
  videoCodec: VideoCodec.h264,
  audioCodec: AudioCodec.aac,
  audioBitrate: '256k',
  outputFormat: OutputFormat.mp4,
  // Extra FFmpeg arguments
  extraArgs: ['-movflags', '+faststart'],
)

File Size Estimation¶

Rough estimates for 1080p video:

Quality	Bitrate	1 min	5 min
Preview (CRF 28)	~2 Mbps	~15 MB	~75 MB
Standard (CRF 23)	~5 Mbps	~38 MB	~188 MB
High (CRF 18)	~10 Mbps	~75 MB	~375 MB
Lossless	~50+ Mbps	~400+ MB	~2+ GB