Best Audio Format to Send for Restoration: What Professionals Need

When you're submitting audio for professional restoration, the format you send matters. Sending a compressed file when you have an uncompressed original, or sending at the wrong sample rate, limits what restoration can achieve — often unnecessarily.

This guide explains what formats work best for audio restoration, why the source quality matters so much, and how to prepare your files before submitting.

The Golden Rule: Send the Highest-Quality Original

Before any format specifics: the most important thing is sending the best quality version you have. If you recorded as WAV, send WAV — don't convert to MP3 first. If you recorded at 24-bit/96kHz, send that file, not a converted-down version.

Restoration cannot recover quality that was lost before you submitted the file. Every step that reduces quality before restoration limits what can be achieved.

Understanding Audio Formats

Uncompressed Formats (Best for Restoration)

WAV (Waveform Audio File Format)

• The gold standard for restoration submissions
• Uncompressed — no information is lost
• Preserves full dynamic range and frequency content
• File size: ~10MB per minute for 44.1kHz/16-bit stereo; ~35MB for 96kHz/24-bit
• Platform-universal — opens on any system without codec issues

AIFF (Audio Interchange File Format)

• Apple's equivalent to WAV
• Same technical quality as WAV — identical audio content
• Slightly larger file size due to metadata overhead
• Completely acceptable for restoration; functionally equivalent to WAV

Broadcast WAV (BWF)

• WAV with embedded metadata (timestamps, description, etc.)
• Common in professional broadcast and field recording
• Ideal if you have it — the metadata can be valuable for production context

Lossless Compressed Formats (Good for Restoration)

FLAC (Free Lossless Audio Codec)

• Losslessly compressed — identical audio content to WAV when decoded
• Typically 50-60% of WAV file size with zero quality loss
• Excellent for restoration — full quality preserved
• Slightly more compatibility considerations (not natively supported on all older hardware)

Apple Lossless (ALAC / .m4a)

• Apple's lossless format
• Same quality as FLAC, just a different container
• Common from iOS recordings and Logic Pro
• Fully acceptable for restoration

Lossy Formats (Acceptable Only When It's All You Have)

MP3

• Lossy compression discards audio information permanently
• At high bitrates (320 kbps): audible artifacts are minimal; restoration results close to lossless
• At medium bitrates (128-192 kbps): compression artifacts affect restoration quality
• At low bitrates (below 128 kbps): significant artifacts; restoration quality is compromised
• Important: If your original was recorded as MP3, send that original MP3 — don't convert to WAV first (WAV of an MP3 contains the same quality as the MP3)

AAC (.m4a, .aac)

• More efficient than MP3 at equivalent quality
• At 256 kbps (Apple Music standard): very close to lossless for most restoration purposes
• Acceptable when it's the original format
• Same principle: send the original, don't convert unnecessarily

OGG Vorbis

• Open-source lossy format
• Similar characteristics to AAC/MP3 at equivalent bitrates
• Less common but fully acceptable

Sample Rate Recommendations

What to send:

• 96kHz or higher: Excellent — send as-is. Maximum information for restoration processing.
• 48kHz: Standard for video and professional audio — fully appropriate, no conversion needed.
• 44.1kHz: CD quality, fully acceptable for restoration. No need to upconvert.
• Below 44.1kHz: Send as-is — don't try to upsample before sending (upsampling doesn't add information).

Do not: Convert from a lower sample rate to a higher one before sending (e.g., 44.1kHz → 96kHz). This creates a larger file without adding any real information — restoration engineers will see through this immediately.

Bit Depth Recommendations

24-bit: Preferred. Greater dynamic range means more headroom for processing without artifacts.

32-bit float: Some DAWs record at 32-bit float. Send it — this preserves even more dynamic range.

16-bit: CD standard, fully acceptable. Much restoration work is done at this bit depth.

8-bit: Low dynamic range creates limitations. Send as-is; converting up doesn't improve it.

Specific Scenarios

Old Cassette or Vinyl Transfer

If you transferred from analog yourself:

• Send the WAV or AIFF from your recording interface
• Include information about the source format (cassette, vinyl, reel-to-reel)
• Note whether you applied any processing during transfer (noise reduction, EQ) — this helps the restoration engineer understand what they're working with

Phone Recording

Smartphone recordings are typically AAC (iPhone) or AAC/OGG (Android):

• Send the original phone file — don't convert
• iPhone voice memos: .m4a at 44.1kHz AAC is what you'll have
• These are acceptable starting points; compression artifacts are relatively minor at smartphone recording settings

Video with Audio

If you need the audio from a video file restored:

• Option 1: Send the video file and let the restoration service extract audio
• Option 2: Extract the audio track yourself and send separately

To extract audio from video (free methods):

• VLC Media Player: File > Convert/Stream, choose audio-only output
• FFmpeg command line: ffmpeg -i input_video.mp4 -vn -acodec copy output_audio.aac
• Handbrake: Save audio-only

When extracting, use the same codec as the original embedded audio (usually AAC) rather than converting to MP3 (double lossy compression).

Multiple Audio Files

If sending multiple related files (podcast with separate host and guest tracks, multi-track recording):

• Send all tracks as separate files
• Use consistent naming that makes the relationship clear: session_host.wav, session_guest.wav
• A brief note explaining the relationship helps the engineer understand the project

File Size Considerations

Large files are completely normal for professional restoration:

• A 1-hour podcast interview at 24-bit/48kHz stereo WAV: ~500MB
• A 45-minute music recording at 24-bit/96kHz: ~1.8GB

WefixSound accepts files in all common formats via secure upload. File size is not a limiting factor — send the highest quality version you have.

What to Include with Your File

Along with the audio file, include:

1. Description of the problem: What noise, what quality issues, what's wrong with the audio
2. Source information: How it was recorded, original format if different from what you're sending
3. Intended use: Podcast, video, personal archive, legal use — this helps calibrate processing decisions
4. Priority sections: If certain parts are most important (the first 5 minutes, a specific speaker), note this

Quick Reference

Format	Quality	For Restoration
WAV 24-bit	Excellent	Ideal
AIFF 24-bit	Excellent	Ideal
FLAC	Excellent	Very good
WAV 16-bit	Good	Good
MP3 320 kbps	Good	Acceptable
AAC 256 kbps	Good	Acceptable
MP3 128 kbps	Fair	Limited results
MP3 < 128 kbps	Poor	Very limited

Related Articles

• Audio Restoration Service: What to Expect
• How to Prepare Audio Before Restoration
• How Long Does Audio Restoration Take?

Submitting the right format sets the foundation for the best possible restoration results. When in doubt, send WAV or AIFF in the highest quality you have — and upload to WefixSound to get a free 60-second sample showing exactly what's achievable from your specific file.