⌘K

Key Numbers

Lossless cutoff22 kHz
320 CBR cutoff20.5 kHz
256 CBR cutoff20 kHz
V0 cutoff19.5 kHz
192 CBR cutoff19 kHz
V2 cutoff18.5 kHz
128 CBR cutoff16 kHz
MP3 shelf (all)16 kHz
Transparency192 kbps
V0 bitrate230–270 kbps
V2 bitrate180–210 kbps
Min lossy192 / V2
Lossless formatFLAC only
Human hearing20 Hz–20 kHz

Music Sources

Analog

  • Require analog-to-digital converter (sound card)
  • Vinyl records — always allowed
  • Cassette tapes — strict conditions

Digital

  • CDs, DVDs, SACDs — physical digital media
  • Web downloads — iTunes, Amazon (legitimate)
  • Web rips = lossy transcode of stream — bad

Audio Formats

CategoryDescriptionExamples
Uncompressed LosslessALL data, no compressionWAV, AIFF
Compressed LosslessSmaller, ALL data retainedFLAC, ALAC, APE
LossyRemoves inaudible freqMP3, AAC, WMA

Bitrate: kbps — higher = better. Transparency: 192 kbps CBR.

Allowed: FLAC (lossless) · MP3 ≥192 CBR/V2 · AAC (iTunes only) · AC3/DTS (DVD)

LAME MP3 Encoding

FormatTypeBitrateOK?
320 CBRConstant320 kbps✓
V0Variable~230–270✓
V2Variable~180–210✓ min VBR
192 CBRConstant192 kbps✓ min CBR
ABRAveragevaries✗

CBR — Constant Bitrate

Every second uses the same bits. Valid: 8, 16, 24, 32, 40, 48, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320.

VBR — Variable Bitrate

Adjusts per complexity. V0 (best) → V9 (worst).

ABR — Average Bitrate

Targets an average while varying. Not recommended.

Good Transcodes

Never converted to lossy, or lossy only once as the final step.

FromTo
Uncompressed losslessCompressed losslessOK
Compressed losslessUncompressed losslessOK
Compressed losslessCompressed losslessOK
Any losslessLossy (final step)OK

Bad Transcodes

Lossy more than once, or lossy→lossless (does NOT restore data).

FromTo
Higher lossyLower lossyNO
Same lossySame lossyNO
Any lossyAny losslessNO
Core rule: Never lossy→lossy. Never lossy→lossless. Lossy = once only, final step.

Spectral Analysis

Visual display of audio — frequencies (Hz/kHz) vs time. Human hearing: 20 Hz – 20 kHz.

FormatCutoff
Lossless (CD/FLAC/WAV)22 kHz
MP3 320 CBR20.5 kHz
MP3 256 CBR20 kHz
MP3 V019.5 kHz
MP3 192 CBR19 kHz
MP3 V218.5 kHz
MP3 128 CBR16 kHz

MP3 Shelf

ALL MP3 files display a shelf at 16 kHz regardless of bitrate.

How to Detect Transcodes

  • Lossy→lossless shows truncated cutoff matching original lossy source
  • FLAC @ 19.5 kHz → likely from V0 MP3
  • FLAC @ 16 kHz → likely from 128 kbps MP3
  • Metadata alone cannot reliably identify transcodes

Tools

Audacity · Adobe Audition · SoX · Audio Identifier · dbPowerAmp

CD Ripping & Burning

PlatformSoftware
Windows / LinuxExact Audio Copy (EAC)
macOSX Lossless Decoder (XLD)

.log files

Document the ripping process + errors. NEVER modify — results in warnings / account disabled.

.cue files

Table of contents / catalog. Used to burn an identical copy of the original CD.