Convert RAW Audio to FLAC — Free Online Converter

Raw PCM audio is the most elemental form of digital audio — an unbroken sequence of binary sample values with no container, no header, no codec information, and no metadata of any kind. The file is nothing more than numbers representing amplitude values at regular time intervals. Interpreting this data requires external knowledge of the sample rate, bit depth, byte order, and channel configuration. This format is produced by data acquisition systems, audio hardware test equipment, FPGA audio pipelines, and bare-metal embedded processors.

FLAC (Free Lossless Audio Codec) is the open-source standard for lossless audio compression, created by Josh Coalson. FLAC typically achieves 50-60% compression of PCM data while guaranteeing bit-perfect reconstruction — not a single sample is altered. It supports up to 32-bit samples, 655.35 kHz sample rates, 8 channels, and embeds Vorbis Comment metadata, cover art, and cue sheets. FLAC is the archival format of choice for audio engineers, music collectors, and scientific researchers worldwide.

Raw PCM files are space-inefficient and context-free. A one-hour stereo recording at 44.1 kHz / 16-bit is 635 MB of headerless data that no application can identify or catalog. FLAC compresses that same recording to approximately 250-380 MB while preserving every single sample value with mathematical precision. The FLAC container also embeds all the metadata that raw audio lacks — sample rate, bit depth, channels, total duration, MD5 checksum of the original audio, and arbitrary text tags.

For scientific data, audio engineering, and archival applications where lossless preservation is mandatory, FLAC is the definitive destination format. It is supported by every major operating system, audio player, and streaming service (Tidal, Amazon Music HD, Qobuz), while providing the error detection that raw PCM files entirely lack.

FFmpeg reads the raw PCM stream using explicit format flags: `-f s16le -ar 44100 -ac 2` for 16-bit signed little-endian stereo at 44.1 kHz. The decoder outputs planar audio that the FLAC encoder processes using linear prediction, residual coding, and Rice entropy coding. FLAC compression level (0-8) controls the encoder's effort — higher levels produce marginally smaller files at the cost of encoding time, but all levels produce identical decoded output. The output includes a STREAMINFO metadata block with the audio's MD5 signature for integrity verification.