Audio Codecs

Frame supports a wide range of audio codecs for different quality requirements and compatibility needs. This guide explains the differences between lossy and lossless codecs, use cases, and optimal settings.

Lossy vs Lossless

Lossy Codecs
Lossless Codecs

Lossy Audio Codecs

Lossy codecs achieve smaller file sizes by discarding audio information that is less perceptible to human hearing.

Characteristics

Smaller file sizes: 10-20x smaller than lossless
Perceptual quality: Optimized for human hearing
Irreversible: Cannot recover original quality
Suitable for distribution: Final playback, streaming, sharing

Supported Lossy Codecs

AAC - Modern, efficient codec
MP3 - Universal compatibility
Opus - Best quality/size ratio for web
AC3 - Surround sound, home theater
Vorbis - Older open-source codec

When to Use Lossy

Final distribution and playback
Streaming audio/video
Portable device playback
Web delivery
When storage space matters

Supported Audio Codecs

AAC (Advanced Audio Coding)

Modern successor to MP3 with better quality at the same bitrate.Codec ID: aac

Use Cases

General-purpose audio encoding
Mobile device playback
Streaming video/audio
Modern applications (2010+)
Apple ecosystem compatibility

Quality Settings

Recommended Bitrates:

64 kbps - Minimum for speech/podcasts (mono)
96 kbps - Low quality music (stereo)
128 kbps - Standard quality music (most use cases)
192 kbps - High quality music
256 kbps - Very high quality
320 kbps - Maximum quality (near-transparent)

Channel Configurations

Mono (mono): 1 channel - Speech, podcasts
Stereo (stereo): 2 channels - Music, most video
Original (original): Preserve source channels - Surround sound passthrough

Container Compatibility

Works with: MP4, M4A, MOV, MKV

Example Configuration

{
  "audioCodec": "aac",
  "audioBitrate": "128",
  "audioChannels": "stereo"
}

AAC provides better quality than MP3 at the same bitrate. For modern applications, AAC at 128 kbps is equivalent to MP3 at 160-192 kbps.

MP3 (MPEG Audio Layer 3)

The most universally compatible audio codec, supported on virtually every device.Codec ID: mp3

Use Cases

Maximum device compatibility
Legacy device support
Standalone audio files
When guaranteed playback is critical
DJ software and music libraries

Quality Settings

Recommended Bitrates:

64 kbps - Very low quality (avoid)
128 kbps - Acceptable quality
192 kbps - Good quality (recommended minimum)
256 kbps - High quality
320 kbps - Maximum quality

MP3 at 128 kbps is noticeably lower quality than AAC at 128 kbps. Use 192 kbps or higher for music.

Channel Configurations

Mono - Single channel
Stereo - Standard two-channel
Joint Stereo - Optimized stereo encoding (automatic)

Container Compatibility

Works with: MP3 (standalone), MP4, AVI, MKV

Example Configuration

{
  "audioCodec": "mp3",
  "audioBitrate": "192",
  "audioChannels": "stereo"
}

Opus

Modern, highly efficient codec optimized for internet streaming and VoIP.Codec ID: libopus

Use Cases

Web video (WebM container)
VoIP and video conferencing
Low-latency streaming
Real-time communication
Bandwidth-constrained scenarios

Quality Settings

Recommended Bitrates:

32 kbps - VoIP, speech (mono)
64 kbps - Good quality speech/music
96 kbps - Transparent music (recommended)
128 kbps - Very high quality
192 kbps - Maximum quality (overkill for most uses)

Characteristics

Best quality/bitrate ratio: Superior to AAC and MP3
Low latency: Ideal for real-time applications
Adaptive bitrate: Works well at any bitrate
Limited compatibility: Primarily web browsers and modern apps

Container Compatibility

Primary: WEBM (also supports: OGG, MKV)

Example Configuration

{
  "audioCodec": "libopus",
  "audioBitrate": "96",
  "audioChannels": "stereo"
}

Opus at 96 kbps often matches or exceeds AAC at 128 kbps in quality. It’s the codec of choice for the “Web Share” preset.

FLAC (Free Lossless Audio Codec)

Open-source lossless codec that preserves perfect audio quality.Codec ID: flac

Use Cases

Music archival and preservation
Audiophile listening
Audio mastering workflows
Source files for lossy conversions
High-fidelity music collections

Characteristics

Compression: Typically 40-60% of original size
Quality: Bit-perfect, lossless
No quality settings: Automatically optimal
Fast decoding: Low CPU usage for playback
Metadata support: Rich tagging capabilities

File Size Expectations

For CD-quality audio (44.1 kHz, 16-bit stereo):

Uncompressed WAV: ~10 MB per minute
FLAC: ~5-6 MB per minute
AAC 320 kbps: ~2.4 MB per minute
AAC 128 kbps: ~1 MB per minute

Container Compatibility

Primary: FLAC (standalone), also: MKV, OGG

Example Configuration

{
  "audioCodec": "flac",
  "audioChannels": "original"
}

FLAC is the “Audio FLAC (Lossless)” preset in Frame. It preserves perfect quality while reducing file size by approximately 50%.

ALAC (Apple Lossless Audio Codec)

Apple’s proprietary lossless codec, optimized for the Apple ecosystem.Codec ID: alac

Use Cases

Apple device audio libraries
iTunes/Music app integration
iOS/macOS audio playback
Lossless within Apple ecosystem

Characteristics

Compression: Similar to FLAC (~40-60%)
Quality: Bit-perfect, lossless
Apple integration: Native support in Apple apps
Limited compatibility: Primarily Apple devices

FLAC vs ALAC

Feature	FLAC	ALAC
Compression	Slightly better	Slightly worse
Compatibility	Universal (except Apple)	Apple ecosystem
Open source	Yes	No (Apple proprietary)
Metadata	Vorbis comments	iTunes tags

Container Compatibility

Primary: M4A (also supports: MOV, MP4)

Example Configuration

{
  "audioCodec": "alac",
  "container": "m4a",
  "audioChannels": "original"
}

Use ALAC for Apple device libraries, FLAC for everything else. Frame provides the “Audio ALAC (Apple)” preset for M4A files.

PCM / WAV (Uncompressed)

Completely uncompressed audio - the largest files but universally compatible.Codec ID: pcm_s16le

Use Cases

Professional audio editing
Audio production and mastering
Maximum compatibility requirements
CD authoring (44.1 kHz, 16-bit)
When file size is not a concern

Characteristics

No compression: Largest file sizes
Zero processing: No encoding/decoding overhead
Universal compatibility: Every audio application supports WAV
Professional standard: Common in audio production

File Sizes

CD quality (44.1 kHz, 16-bit stereo):

~10 MB per minute
1 hour = ~600 MB

Container Compatibility

Primary: WAV (also supports: AVI)

Example Configuration

{
  "audioCodec": "pcm_s16le",
  "container": "wav",
  "audioChannels": "original"
}

WAV files are 5-10x larger than FLAC with no quality benefit. Use FLAC for archival unless you specifically need uncompressed audio.

AC3 (Dolby Digital)

Surround sound codec commonly used for home theater and DVDs.Codec ID: ac3

Use Cases

Surround sound (5.1/7.1) encoding
Home theater video files
DVD/Blu-ray compatibility
Legacy surround sound systems

Quality Settings

Recommended Bitrates:

128 kbps - Stereo minimum
192 kbps - Stereo standard (used in Frame’s Archive preset)
384 kbps - 5.1 surround standard
448 kbps - 5.1 surround high quality
640 kbps - Maximum (5.1/7.1)

Channel Support

Stereo (2.0)
5.1 surround (6 channels)
7.1 surround (8 channels)

Container Compatibility

Works with: MKV, MP4, MOV

Example Configuration

{
  "audioCodec": "ac3",
  "audioBitrate": "192",
  "audioChannels": "original"
}

Channel Configurations

Frame supports three audio channel configuration modes:

Original
Stereo
Mono

Original Channels

Setting: originalPreserves the source audio channel configuration.

Behavior

Mono source → Mono output
Stereo source → Stereo output
5.1 source → 5.1 output
7.1 source → 7.1 output

Use Cases

Preserving surround sound
Maintaining original audio characteristics
Multi-channel audio workflows
Default for archival presets

This is the recommended setting for most use cases to preserve the original audio experience.

Stereo Downmix

Setting: stereoConverts audio to 2-channel stereo.

Behavior

Mono source → Stereo (duplicated)
Stereo source → Stereo (unchanged)
5.1/7.1 source → Stereo (downmixed)

Use Cases

Mobile device playback
Headphone listening
Reducing file size (fewer channels)
Web video delivery
Social media uploads

Implementation

{
  "audioChannels": "stereo"
}

Frame uses FFmpeg’s default downmixing algorithm which intelligently combines surround channels into stereo.

Mono

Setting: monoConverts audio to single-channel mono.

Behavior

Mono source → Mono (unchanged)
Stereo/multi-channel source → Mono (mixed down)

Use Cases

Voice-only content (podcasts, audiobooks)
Minimizing file size
Phone calls and VoIP
When spatial audio is not needed

File Size Savings

50% smaller than stereo at the same bitrate
Allows lower bitrate for speech (32-64 kbps)

Implementation

{
  "audioChannels": "mono",
  "audioBitrate": "64"
}

Codec Selection Guide

Maximum Compatibility - MP3

Use MP3 at 192-320 kbpsWhen you need audio to play on any device:

Older devices and car stereos
DJ software and music production tools
Universal music libraries
Legacy system compatibility

Recommended settings:

Bitrate: 192 kbps (good), 320 kbps (maximum)
Channels: Stereo
Container: MP3

Modern Devices - AAC

Use AAC at 128-256 kbpsFor modern smartphones, tablets, and computers:

Mobile device playback
Streaming video audio
Apple ecosystem
General-purpose use (2010+)

Recommended settings:

Bitrate: 128 kbps (standard), 192 kbps (high quality)
Channels: Stereo
Container: M4A (audio-only) or MP4 (with video)

Web Streaming - Opus

Use Opus at 96-128 kbpsFor web-based audio/video:

YouTube uploads
Web streaming platforms
Browser-based playback
Best quality-to-size ratio

Recommended settings:

Bitrate: 96 kbps (excellent quality)
Channels: Stereo
Container: WebM (with VP9 video)

Archival & Perfect Quality - FLAC

Use FLAC (lossless)When you need perfect audio quality:

Music archival and preservation
Audiophile listening
Source files for future conversions
Professional audio work

Recommended settings:

No bitrate (lossless)
Channels: Original
Container: FLAC

Note: 50% smaller than WAV with identical quality

Apple Ecosystem - ALAC

Use ALAC (lossless)For Apple device libraries:

iTunes/Music app integration
iPhone/iPad/Mac playback
AirPlay streaming
Lossless within Apple ecosystem

Recommended settings:

No bitrate (lossless)
Channels: Original
Container: M4A

Surround Sound - AC3

Use AC3 at 384-640 kbpsFor multi-channel audio:

5.1/7.1 surround sound
Home theater systems
Movie/TV show encoding
DVD/Blu-ray compatibility

Recommended settings:

Bitrate: 384 kbps (5.1), 640 kbps (7.1)
Channels: Original
Container: MKV or MP4

Audio Codec Comparison

Codec	Type	Quality/Size	Compatibility	Best Bitrate	Use Case
AAC	Lossy	Excellent	Modern devices	128-192 kbps	General purpose
MP3	Lossy	Good	Universal	192-320 kbps	Maximum compatibility
Opus	Lossy	Outstanding	Web/modern	96-128 kbps	Web streaming
FLAC	Lossless	Perfect	Good	N/A	Archival
ALAC	Lossless	Perfect	Apple only	N/A	Apple ecosystem
AC3	Lossy	Good	Excellent	192-640 kbps	Surround sound
PCM	Uncompressed	Perfect	Universal	N/A	Professional work

Get Started

Features

Guides

Development

​Audio Codecs

​Lossy vs Lossless

​Lossy Audio Codecs

​Characteristics

​Supported Lossy Codecs

​When to Use Lossy

​Lossless Audio Codecs

​Characteristics

​Supported Lossless Codecs

​When to Use Lossless

​Supported Audio Codecs

​AAC (Advanced Audio Coding)

​Use Cases

​Quality Settings

​Channel Configurations

​Container Compatibility

​Example Configuration

​MP3 (MPEG Audio Layer 3)

​Use Cases

​Quality Settings

​Channel Configurations

​Container Compatibility

​Example Configuration

​Opus

​Use Cases

​Quality Settings

​Characteristics

​Container Compatibility

​Example Configuration

​FLAC (Free Lossless Audio Codec)

​Use Cases

​Characteristics

​File Size Expectations

​Container Compatibility

​Example Configuration

​ALAC (Apple Lossless Audio Codec)

​Use Cases

​Characteristics

​FLAC vs ALAC

​Container Compatibility

​Example Configuration

​PCM / WAV (Uncompressed)

​Use Cases

​Characteristics

​File Sizes

​Container Compatibility

​Example Configuration

​AC3 (Dolby Digital)

​Use Cases

​Quality Settings

​Channel Support

​Container Compatibility

​Example Configuration

​Channel Configurations

​Original Channels

​Behavior

​Use Cases

​Stereo Downmix

​Behavior

​Use Cases

​Implementation

​Mono

​Behavior

​Use Cases

​File Size Savings

​Implementation

​Codec Selection Guide

​Audio Codec Comparison

​See Also

Build docs developers (and LLMs) love

Audio Codecs

Lossy vs Lossless

Lossy Audio Codecs

Characteristics

Supported Lossy Codecs

When to Use Lossy

Lossless Audio Codecs

Characteristics

Supported Lossless Codecs

When to Use Lossless

Supported Audio Codecs

AAC (Advanced Audio Coding)

Use Cases

Quality Settings

Channel Configurations

Container Compatibility

Example Configuration

MP3 (MPEG Audio Layer 3)

Use Cases

Quality Settings

Channel Configurations

Container Compatibility

Example Configuration

Opus

Use Cases

Quality Settings

Characteristics

Container Compatibility

Example Configuration

FLAC (Free Lossless Audio Codec)

Use Cases

Characteristics

File Size Expectations

Container Compatibility

Example Configuration

ALAC (Apple Lossless Audio Codec)

Use Cases

Characteristics

FLAC vs ALAC

Container Compatibility

Example Configuration

PCM / WAV (Uncompressed)

Use Cases

Characteristics

File Sizes

Container Compatibility

Example Configuration

AC3 (Dolby Digital)

Use Cases

Quality Settings

Channel Support

Container Compatibility

Example Configuration

Channel Configurations

Original Channels

Behavior

Use Cases

Stereo Downmix

Behavior

Use Cases

Implementation

Mono

Behavior

Use Cases

File Size Savings

Implementation

Codec Selection Guide

Audio Codec Comparison

See Also