PCM vs DPCM: Which Digital Audio Compression Method Wins?
PCM (Pulse Code Modulation) samples audio by recording exact amplitudes at fixed intervals. DPCM (Differential PCM) instead stores the difference between successive samples, cutting data size by predicting the next value from the last one.
People confuse the two because both end in “PCM” and claim “digital audio compression,” yet Spotify’s mobile stream sounds different from your old CD. One keeps every detail; the other guesses, so you wonder why your ripped vinyl hiss vanished.
Key Differences
PCM captures absolute levels, producing larger files ideal for mastering. DPCM encodes deltas, trimming 25–50 % space but risking compounding errors if prediction drifts. Think raw WAV versus ADPCM-encoded game sounds.
Which One Should You Choose?
Need pristine archiving? Stick with PCM. Building a low-bandwidth VoIP app or retro game? DPCM slashes bitrate while keeping speech or 8-bit SFX clear. The trade-off is fidelity versus storage.
Examples and Daily Life
CD-quality tracks are PCM at 1,411 kbps. Nintendo DS voice clips use DPCM at ~32 kbps. Your Zoom call likely rides a descendant of DPCM, while your FLAC library stays PCM for audiophile bragging rights.
Does DPCM always sound worse?
Not at high bitrates; errors stay tiny, and noise shaping masks them. Artifacts appear only when the difference predictor is starved.
Can I convert PCM to DPCM losslessly?
No. The delta step discards fine amplitude info, making perfect reversal impossible.
Which phones still use pure PCM recording?
Most flagships default to PCM in voice-memos; compression kicks in only when you choose a “compressed” format like AAC.