The short answer
- FLAC is an open lossless digital audio compression format that preserves original PCM audio samples during compression and decoding, but is not suited to non-PCM audio.
- On Windows or macOS, select an application that explicitly supports FLAC and use its Open command to select the file. On a phone, choose a FLAC-capable audio app from the file manager's Open with or Share menu, if available. Support for unusual channel counts, sample depths or sample rates depends on the decoder. The official flac command-line tool can decode, test and analyze files; flac -t "file.flac" tests the stream.
- FLAC has a medium parser-related risk: malformed data can cause memory errors, arbitrary code execution or resource exhaustion. Cover metadata can refer to an external URI; fetching it can introduce tracking, malicious content or directory traversal risks. Applications should obtain explicit consent before fetching remote resources and must not execute code stored in audio or metadata.
FLAC files: opening, lossless conversion and safety
Free Lossless Audio Codec uses a native stream containing the fLaC marker, a required STREAMINFO metadata block, optional metadata and audio frames. It supports tags, cover pictures and fast seeking. Native FLAC uses audio/flac; audio/x-flac is a deprecated alias. FLAC inside Ogg or another container uses the container's media type.
Use flac -d "file.flac" with the official tool to decode to WAVE. Other documented decoding outputs include Wave64, RF64, AIFF and raw samples. Ordinary decoding preserves the audio samples; applying the tool's ReplayGain option changes output samples, so that conversion is no longer lossless.
How to open it
On Windows or macOS, select an application that explicitly supports FLAC and use its Open command to select the file. On a phone, choose a FLAC-capable audio app from the file manager's Open with or Share menu, if available. Support for unusual channel counts, sample depths or sample rates depends on the decoder. The official flac command-line tool can decode, test and analyze files; flac -t "file.flac" tests the stream.
On Windows or macOS, select an application that explicitly supports FLAC and use its Open command to select the file. On a phone, choose a FLAC-capable audio app from the file manager's Open with or Share menu, if available. Support for unusual channel counts, sample depths or sample rates depends on the decoder. The official flac command-line tool can decode, test and analyze files; flac -t "file.flac" tests the stream.
Use flac -d "file.flac" with the official tool to decode to WAVE. Other documented decoding outputs include Wave64, RF64, AIFF and raw samples. Ordinary decoding preserves the audio samples; applying the tool's ReplayGain option changes output samples, so that conversion is no longer lossless.
File safety
FLAC has a medium parser-related risk: malformed data can cause memory errors, arbitrary code execution or resource exhaustion. Cover metadata can refer to an external URI; fetching it can introduce tracking, malicious content or directory traversal risks. Applications should obtain explicit consent before fetching remote resources and must not execute code stored in audio or metadata.
An unknown sender, a name ending in two extensions, or contents that do not match the extension — check before you open it.
Converting it
Use flac -d "file.flac" with the official tool to decode to WAVE. Other documented decoding outputs include Wave64, RF64, AIFF and raw samples. Ordinary decoding preserves the audio samples; applying the tool's ReplayGain option changes output samples, so that conversion is no longer lossless.
Convert a copy, never the original, then compare quality, metadata, and layout against what you started with.
Common questions
What is FLAC audio used for?
FLAC compresses PCM digital audio without losing the original samples. Its open specification also supports tags, cover pictures and fast seeking.
How do I open a FLAC file for listening?
Choose an audio application that explicitly supports FLAC, then use Open to select the file. Format recognition does not guarantee support for every sample rate, sample depth or channel count.
How do I open FLAC on Windows?
In a FLAC-capable application, choose Open and select the .flac file. If playback fails, use the official flac tool's test mode to check the stream, where that tool is available.
How do I open FLAC on Mac?
Use Open in an application that explicitly supports FLAC. If the application rejects the file, check its support for the file's audio parameters; do not rely only on the extension.
How do I play FLAC on a phone?
Select a FLAC-capable audio app through the file manager's Open with or Share menu, if offered. Playback depends on the app's decoder and its support for the file's audio parameters.
What should I do if a FLAC file will not play?
Check that the application supports FLAC and the file's audio parameters. Run flac -t "file.flac" with the official tool to check for stream errors. A failed test alone does not identify the exact cause.
Should I choose FLAC or WAV for decoded audio?
Choose FLAC when you need lossless PCM compression. Choose WAV when your receiving workflow requires WAVE output; the official flac tool can decode FLAC to it without changing samples during ordinary decoding.
How do I convert FLAC to WAV without losing audio quality?
Use flac -d "file.flac" for ordinary WAVE decoding. Avoid applying ReplayGain during decoding if you need unchanged samples, because that option alters them.
What are the FLAC sample rate and bit-depth limits?
The format can represent PCM audio with 1–8 channels, 4–32 bits per sample and sample rates of 1–1048575 Hz. These format limits do not guarantee that every player supports every combination.
What safety risks can a FLAC file contain?
Malformed audio or metadata can exploit parser flaws or exhaust resources. Cover metadata may reference remote resources with tracking or malicious-content risks; allow remote fetching only with explicit consent.
Does a successful FLAC stream test prove that the file is safe?
No. Stream testing does not establish the trustworthiness of the source or external cover resources. The fLaC marker identifies a native stream but is not proof of safety.
Related formats
Sources
RFC 9639: Free Lossless Audio Codec (FLAC) · IETF 标准轨道规范 / RFC Editor
FLAC — FLAC command line tool · Xiph.Org Foundation 官方工具文档
FLAC — Features · Xiph.Org Foundation 官方格式资料