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Supported Formats
Convert between all major file formats with high quality
Common Formats
MPEG-1 Audio Layer III - the most universal audio format worldwide, using lossy compression to reduce file sizes by 90% while maintaining excellent perceived quality. Perfect for music libraries, podcasts, portable devices, and any scenario requiring broad compatibility. Supports bitrates from 32-320kbps. Standard for digital music since 1993, playable on virtually every device and platform.
Waveform Audio File Format - uncompressed PCM audio providing perfect quality preservation. Standard Windows audio format with universal compatibility. Large file sizes (10MB per minute of stereo CD-quality). Perfect for audio production, professional recording, mastering, and situations requiring zero quality loss. Supports various bit depths (16, 24, 32-bit) and sample rates. Industry standard for professional audio work.
Ogg Vorbis - open-source lossy audio codec offering quality comparable to MP3/AAC at similar bitrates. Free from patents and licensing restrictions. Smaller file sizes than MP3 at equivalent quality. Used in gaming, open-source software, and streaming. Supports variable bitrate (VBR) for optimal quality. Perfect for applications requiring free codecs and good quality. Growing support in media players and platforms.
Advanced Audio Coding - successor to MP3 offering better quality at same bitrate (or same quality at lower bitrate). Standard audio codec for Apple devices, YouTube, and many streaming services. Supports up to 48 channels and 96kHz sample rate. Improved frequency response and handling of complex audio. Perfect for iTunes, iOS devices, video streaming, and modern audio applications. Part of MPEG-4 standard widely supported across platforms.
Free Lossless Audio Codec - compresses audio 40-60% without any quality loss. Perfect bit-for-bit preservation of original audio. Open-source format with no patents or licensing fees. Supports high-resolution audio (192kHz/24-bit). Perfect for archiving music collections, audiophile listening, and scenarios where quality is paramount. Widely supported by media players and streaming services. Ideal balance between quality and file size.
MPEG-4 Audio - AAC or ALAC audio in MP4 container. Standard audio format for Apple ecosystem (iTunes, iPhone, iPad). Supports both lossy (AAC) and lossless (ALAC) compression. Better quality than MP3 at same file size. Includes metadata support for artwork, lyrics, and rich tags. Perfect for iTunes library, iOS devices, and Apple software. Widely compatible across platforms despite Apple association. Common format for purchased music and audiobooks.
Windows Media Audio - Microsoft's proprietary audio codec with good compression and quality. Standard Windows audio format with native OS support. Supports DRM for protected content. Various profiles (WMA Standard, WMA Pro, WMA Lossless). Comparable quality to AAC at similar bitrates. Perfect for Windows ecosystem and legacy Windows Media Player. Being superseded by AAC and other formats. Still encountered in Windows-centric environments and older audio collections.
Lossless Formats
Apple Lossless Audio Codec - Apple's lossless compression reducing file size 40-60% with zero quality loss. Perfect preservation of original audio like FLAC but in Apple ecosystem. Standard lossless format for iTunes and iOS. Supports high-resolution audio up to 384kHz/32-bit. Smaller than uncompressed but larger than lossy formats. Perfect for iTunes library, audiophile iOS listening, and maintaining perfect quality in Apple ecosystem. Comparable to FLAC but with better Apple integration.
Monkey's Audio - high-efficiency lossless compression achieving better ratios than FLAC (typically 55-60% of original). Perfect quality preservation with zero loss. Free format with open specification. Slower compression/decompression than FLAC. Popular in audiophile communities. Limited player support compared to FLAC. Perfect for archiving when maximum space savings desired while maintaining perfect quality. Best for scenarios where storage space is critical and processing speed is not.
WavPack - hybrid lossless/lossy audio codec with unique correction file feature. Can create lossy file with separate correction file for lossless reconstruction. Excellent compression efficiency. Perfect for flexible audio archiving. Less common than FLAC. Supports high-resolution audio and DSD. Convert to FLAC for universal compatibility.
True Audio - lossless audio compression with fast encoding/decoding. Similar compression to FLAC with simpler algorithm. Open-source and free format. Perfect quality preservation. Less common than FLAC with limited player support. Perfect for audio archiving when FLAC compatibility not required. Convert to FLAC for broader compatibility.
Audio Interchange File Format - Apple's uncompressed audio format, equivalent to WAV but for Mac. Stores PCM audio with perfect quality. Standard audio format for macOS and professional Mac audio applications. Supports metadata tags better than WAV. Large file sizes like WAV (10MB per minute). Perfect for Mac-based audio production, professional recording, and scenarios requiring uncompressed audio on Apple platforms. Interchangeable with WAV for most purposes.
Modern Formats
Opus Audio Codec - modern open-source codec (2012) offering best quality at all bitrates from 6kbps to 510kbps. Excels at both speech and music. Lowest latency of modern codecs making it perfect for VoIP and real-time communication. Superior to MP3, AAC, and Vorbis at equivalent bitrates. Used by WhatsApp, Discord, and WebRTC. Ideal for streaming, voice calls, podcasts, and music. Becoming the universal audio codec for internet audio.
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Matroska Audio - audio-only Matroska container supporting any audio codec. Flexible format with metadata support. Can contain multiple audio tracks. Perfect for audio albums with chapters and metadata. Part of Matroska multimedia framework. Used for audiobooks and multi-track audio. Convert to FLAC or MP3 for universal compatibility.
Legacy Formats
MPEG-1 Audio Layer II - predecessor to MP3 used in broadcasting and DVDs. Better quality than MP3 at high bitrates. Standard audio codec for DVB (digital TV) and DVD-Video. Lower compression efficiency than MP3. Perfect for broadcast applications and DVD authoring. Legacy format being replaced by AAC in modern broadcasting. Still encountered in digital TV and video production workflows.
Dolby Digital (AC-3) - surround sound audio codec for DVD, Blu-ray, and digital broadcasting. Supports up to 5.1 channels. Standard audio format for DVDs and HDTV. Good compression with multichannel support. Perfect for home theater and video production. Used in cinema and broadcast. Requires Dolby license for encoding.
Adaptive Multi-Rate - speech codec optimized for mobile voice calls. Excellent voice quality at very low bitrates (4.75-12.2 kbps). Standard for GSM and 3G phone calls. Designed specifically for speech, not music. Perfect for voice recordings, voicemail, and speech applications. Used in WhatsApp voice messages and mobile voice recording. Efficient for voice but inadequate for music.
Sun/NeXT Audio - simple audio format from Sun Microsystems and NeXT Computer. Uncompressed or μ-law/A-law compressed audio. Common on Unix systems. Simple header with audio data. Perfect for Unix audio applications and legacy system compatibility. Found in system sounds and Unix audio files. Convert to WAV or MP3 for modern use.
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RealAudio - legacy streaming audio format from RealNetworks (1990s-2000s). Pioneered internet audio streaming with low-bitrate compression. Obsolete format replaced by modern streaming technologies. Poor quality by today's standards. Convert to MP3 or AAC for modern use. Historical importance in early internet audio streaming.
Specialized Formats
DTS Coherent Acoustics - surround sound codec competing with Dolby Digital. Higher bitrates than AC-3 with potentially better quality. Used in DVD, Blu-ray, and cinema. Supports up to 7.1 channels and object-based audio. Perfect for high-quality home theater. Premium audio format for video distribution. Convert to AC-3 or AAC for broader compatibility.
Core Audio Format - Apple's container for audio data on iOS and macOS. Supports any audio codec and unlimited file sizes. Modern replacement for AIFF on Apple platforms. Perfect for iOS app development and professional Mac audio. No size limitations (unlike WAV). Can store multiple audio streams. Convert to M4A or MP3 for broader compatibility outside Apple ecosystem.
VOC (Creative Voice File) - audio format from Creative Labs Sound Blaster cards. Popular in DOS era (1989-1995) for games and multimedia. Supports multiple compression formats and blocks. Legacy PC audio format. Common in retro gaming. Convert to WAV or MP3 for modern use. Important for DOS game audio preservation.
Speex - open-source speech codec designed for VoIP and internet audio streaming. Variable bitrate from 2-44 kbps. Optimized for speech with low latency. Better than MP3 for voice at low bitrates. Being superseded by Opus. Perfect for voice chat, VoIP, and speech podcasts. Legacy format replaced by Opus in modern applications.
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How to Convert Files
Upload your files, select output format, and download converted files instantly. Our converter supports batch conversion and maintains high quality.
Frequently Asked Questions
What is SND format and where does it come from?
SND is generic Unix sound format, originally from NeXT computers (NeXTSTEP operating system, late 1980s/early 1990s). It's also called AU (Audio/Unix) format - SND and AU are essentially same thing with different file extensions. The format was designed by Sun Microsystems and adopted by NeXT, becoming standard audio format for Unix workstations before WAV and MP3 existed.
Technical basics: SND files contain PCM audio (uncompressed or compressed with μ-law/A-law), typically 8kHz or 8-bit for voice, though higher quality specs are supported. Simple header followed by audio data. The format's simplicity made it popular for Unix system sounds, telephony applications, and early internet audio.
Should I convert SND to WAV or MP3?
Strong reasons to convert SND:
Obsolete Format
SND is dead technology from 1980s Unix. Modern software barely supports it. Convert for compatibility.
Poor Quality Source
Most SND files are low-quality (8kHz, 8-bit, μ-law). Convert to WAV for editing, MP3 for distribution.
No Hardware Support
Phones, players, cars don't recognize SND. WAV and MP3 work everywhere. Conversion essential for playback.
Web Incompatibility
Browsers don't support SND. Streaming services reject it. Convert for web use and modern distribution.
Convert SND to WAV if preserving quality matters (archival, editing). Convert to MP3 for practical use (playback, sharing, storage). No reason to keep SND format in 2024.
What's the difference between SND and AU formats?
SND vs AU explained:
Same Format
SND and AU are identical - same file structure, same audio data. Only difference is file extension (.snd vs .au).
Naming History
.au was Sun Microsystems' original extension. .snd was NeXT's preference. Both refer to same format spec.
MIME Type
Official MIME type is 'audio/basic' for μ-law SND/AU. Web servers treat both extensions identically.
Playback Works
Software that plays .au files plays .snd files. Just rename extension if needed - internal format is same.
Platform Association
.au slightly more common on Sun/Solaris systems. .snd on NeXT/Mac. But truly interchangeable.
Conversion Identical
Converting SND to WAV is same process as AU to WAV. Tools treat them identically.
Modern Irrelevance
Neither extension is recognized by modern devices. Both obsolete. Distinction doesn't matter today.
SND and AU are same format with different names. Historical split between Sun and NeXT naming conventions. Completely interchangeable.
Does converting SND to WAV lose quality?
Depends on SND encoding. If SND contains uncompressed PCM, converting to WAV is lossless - you're just changing container format, audio data is identical. PCM SND to WAV is perfect quality preservation.
If SND uses μ-law or A-law compression (common for telephony/voice SND files), that audio is already lossy. Converting μ-law SND to WAV doesn't lose additional quality (decompression to PCM is standard) but you can't recover information lost in original μ-law encoding. You're getting best quality possible from lossy source.
Low sample rate issue: Many SND files are 8kHz/8-bit (telephone quality). Converting to WAV preserves this low quality exactly - you don't gain quality through conversion. SND's limitations (sample rate, bit depth, compression) are locked in. Conversion to WAV makes files usable but can't improve inherent quality.
What is μ-law (mu-law) audio compression?
μ-law (mu-law or u-law) is logarithmic audio compression developed for telephone systems. It compresses 16-bit audio to 8-bit using logarithmic scaling (human hearing is logarithmic). Provides reasonable voice quality at 1/2 file size. Used in North American/Japanese telephony and widely in SND/AU files.
Why it exists: Telephone networks had limited bandwidth (64 kbps per channel). μ-law compressed audio efficiently for voice calls. It's lossy compression but optimized for speech intelligibility, not music quality. Sounds terrible for music, acceptable for voice. Standard in telecom for decades.
A-law alternative: Europe/international telecom used A-law compression (similar to μ-law but different curve). Both serve same purpose - voice compression for telephony. SND/AU files from different regions might use μ-law or A-law. Modern codecs (Opus, AAC) vastly outperform both.
How do I convert SND to WAV or MP3?
FFmpeg (best method): `ffmpeg -i input.snd output.wav` converts SND to WAV. For MP3: `ffmpeg -i input.snd -codec:a libmp3lame -q:a 2 output.mp3`. FFmpeg handles all SND variants (PCM, μ-law, A-law) automatically. Fast, reliable, command-line.
Audacity: Open SND file (File > Open), then Export as WAV or MP3 (File > Export). Audacity has excellent SND/AU support and gives GUI for users uncomfortable with command line. Can batch convert using Macros feature.
Online converters: Our converter and others support SND to WAV/MP3. Upload SND, choose format, download. Easy for occasional conversions. For batch processing old Unix archives, FFmpeg scripting is most efficient.
Why are my SND files such poor quality?
Historical context: SND format originated in era of expensive storage and limited bandwidth. 8kHz/8-bit audio was acceptable compromise for voice in 1980s/1990s. A minute of 8kHz μ-law audio is only ~480KB - crucial when hard drives were 100MB total. Quality was sacrificed for practicality.
Intended use: SND was designed for system sounds, voice memos, telephony - not music. Voice intelligibility at small file size was priority. For that purpose, 8kHz μ-law works fine. Playing music or expecting high fidelity from SND files is using format outside its design parameters.
Can't improve: If SND file is 8kHz/8-bit/μ-law, that's maximum quality possible. Converting to WAV or upsampling doesn't add information that wasn't recorded. Low quality is permanent characteristic of that specific recording. If audio is important, seek higher-quality source if available.
What software can play SND files?
SND playback options:
Audacity
Cross-platform audio editor. Excellent SND/AU support for playback and conversion. Free, reliable.
VLC Media Player
Plays almost everything including SND. Windows/Mac/Linux. Best universal media player option.
QuickTime (Mac)
macOS QuickTime Player handles SND natively (NeXT heritage). Built-in Mac support for legacy format.
ffplay
Command-line player from FFmpeg suite. `ffplay file.snd` plays SND files. Minimal but functional.
Windows Media Player
Doesn't support SND natively. Need codec pack or better player (VLC). Not recommended.
Modern software has limited SND support. VLC and Audacity are most reliable. For regular playback, convert SND to WAV/MP3.
Can I edit SND files or should I convert first?
Convert to WAV first! Modern audio editors (Audacity, Adobe Audition, Reaper) can technically open SND, but editing works better with WAV. WAV is standard editing format - all tools, plugins, and effects expect WAV. SND is input format only in practical workflow.
Why convert first: Better software compatibility, avoid format quirks, ensure plugins work properly, and make export easier (WAV to anything). Editing compressed SND (μ-law) is especially problematic - best to decompress to WAV, edit, then export to desired final format.
Workflow: SND → WAV (via FFmpeg or Audacity) → edit in DAW → export to WAV/MP3/FLAC. Don't edit SND directly and re-save as SND - that's requesting trouble. Treat SND as source material needing conversion to modern formats before serious work.
Are SND files used anywhere today?
Current SND usage (rare):
Legacy Systems
Old Unix servers, ancient telephony systems, vintage NeXT software. Maintained for compatibility, not by choice.
Retro Computing
NeXT emulation, vintage Mac software, retro gaming. Hobbyist/preservation contexts only.
Archival Collections
Universities, museums preserving 1990s internet content or NeXT materials. Historical documentation.
Embedded Systems
Some ancient industrial/telephony equipment still uses SND/AU. Replacement parts scenario, not new deployments.
Not for New Projects
Zero reason to create SND files in 2024. Use WAV (uncompressed), FLAC (lossless), or Opus (efficient modern).
Sun Microsystems Gone
Sun (SND's creator) was acquired by Oracle in 2010. Format has no active development or support.
NeXT History
NeXT merged into Apple 1997. macOS has NeXT DNA but doesn't promote SND format. Legacy support only.
Academic Interest
Computer science history, digital preservation research. Studying dead formats, not using them.
Conversion Recommended
If you encounter SND, convert immediately. Don't preserve obsolete format - preserve audio content in modern format.
Internet Archaeology
Early 1990s websites sometimes have .au files. Converting these is preserving internet history.
What's the maximum quality possible for SND files?
Format technically supports: Up to 32-bit audio, various sample rates (though 8kHz was most common), multiple channels, and different encodings (PCM, μ-law, A-law, ADPCM). However, high-quality SND files are rare - format was used for low-quality applications (telephony, system sounds).
Practical reality: 99% of SND files you'll encounter are 8kHz/8-bit/μ-law (telephone quality) or 8kHz/16-bit (slightly better). High-quality SND files exist in theory but nobody used SND for quality recordings - WAV, AIFF, and later formats were preferred for that.
If you need quality: Don't use SND format. Use WAV (up to 192kHz/32-bit, universally compatible), FLAC (lossless compression), or ALAC (Apple lossless). SND is wrong choice for quality audio in any era. Its role was utility audio, not fidelity.
How do I batch convert SND files?
FFmpeg batch - Windows PowerShell: `Get-ChildItem -Filter *.snd | ForEach-Object { ffmpeg -i $_.Name -codec:a pcm_s16le "$($_.BaseName).wav" }` converts all SND to WAV. For MP3: use `-codec:a libmp3lame -q:a 2` instead.
Linux/Mac bash: `for f in *.snd; do ffmpeg -i "$f" "${f%.snd}.wav"; done` processes folder. Simple, effective. Adjust output format (wav, mp3, flac) as needed for your use case.
Audacity Macros: Create macro with Import > Export WAV. Apply to folder of SND files. GUI batch conversion for users who prefer avoiding command line. Good for small collections, FFmpeg better for thousands of files.
Why did SND format fail to stay relevant?
Better alternatives appeared: WAV (Microsoft/IBM, 1991) had better Windows support and became universal. MP3 (1993) offered compression that actually sounded good. FLAC (2000s) provided lossless compression. SND's niche (Unix system sounds, telephony) wasn't large enough to sustain it.
Unix decline in consumer market: Sun workstations and NeXT computers were expensive professional tools. When consumer computing shifted to Windows and Mac, Unix-specific formats lost relevance. Linux inherited SND support but never promoted it - Linux audio moved to modern formats.
Technical limitations: μ-law/A-law compression sounds terrible by modern standards. 8kHz/8-bit was acceptable in 1980s, unacceptable in 1990s, and laughable today. SND couldn't evolve fast enough - better formats captured mindshare before SND adapted.
Should I preserve SND files or just convert them?
For historical/archival purposes: Keep SND originals AND create modern conversions. If files are from vintage NeXT software, early internet, or computing history, original SND files are artifacts worth preserving. Convert to WAV/FLAC for usability, keep SND for authenticity.
For practical content: Convert and discard SND. If files are just voice memos, system sounds, or generic audio with no historical significance, convert to WAV/MP3 and move on. No practical reason to maintain obsolete format for common content.
Archival strategy: Convert to FLAC (if PCM source) or keep as WAV. Add metadata explaining origin ("Converted from NeXT SND file, 1992"). Document source format for future reference. Preserve content in accessible format rather than clinging to dead container.
SND vs AU vs WAV - what's the history?
SND/AU (1989-1990s): Sun Microsystems and NeXT created AU/SND for Unix audio. Simple format optimized for telephony and system sounds. Dominated Unix world before multimedia era. Used μ-law compression from telecom industry. Good for its time and purpose.
WAV (1991): Microsoft and IBM created WAV for Windows 3.1 multimedia. Based on RIFF container (also used for AVI video). Became universal standard due to Windows market dominance. Uncompressed PCM was default, making it large but compatible. Superior to SND in ecosystem support.
Outcome: WAV won through Windows ubiquity. SND/AU survived on Unix but never escaped niche. Today, WAV is standard for uncompressed audio, FLAC for lossless compression, MP3/AAC for lossy. SND/AU are historical footnotes. Use WAV for compatibility, FLAC for archival, MP3 for distribution. Never SND.