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Connections & formats

Lossless

Also called lossless audio, lossless streaming

Lossless audio is a file or stream that reproduces the original digital recording exactly, with no data discarded, unlike lossy formats such as MP3 and AAC. Any PCM audio stored in FLAC, ALAC or WAV without data removed is lossless, whatever its resolution.

OriginalStoredDecodedLosslessFLAC1,411 kbps~700 kbps1,411 kbpsidenticalLossyAAC1,411 kbps256 kbps1,411 kbpsdata lost
Lossless compression such as FLAC packs 1,411 kbps CD audio into about half the data and decodes it back bit for bit. A lossy format such as 256 kbps AAC discards data it judges inaudible, and decoding cannot restore it.

The word says nothing about resolution: a 16-bit/44.1 kHz stream and a 24-bit/192 kHz one are both lossless if nothing was removed. Services use "lossless" for CD quality and "hi-res" for anything above it. FLAC and ALAC are the usual containers.

Whether lossless is audibly better than a good 256 kbps lossy stream is a long-running test subject; most listeners struggle to tell them apart on most music, while some can on some tracks. Over Bluetooth, lossless is almost always lost again on the way to the headphone. The chain only stays lossless if it is also Bit-perfect.

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