Convert FLV to ALAC — Free Online Tool
Convert FLV video files to ALAC (Apple Lossless Audio Codec) M4A files, extracting and losslessly encoding the audio track for perfect-fidelity playback in iTunes, Apple Music, and across the Apple ecosystem. Since FLV audio is typically encoded in lossy AAC or MP3, ALAC preserves that decoded audio stream without any further quality degradation.
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FFmpeg Command
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Note: Browser-based encoding uses approximate quality targets. For precise CRF compression, copy the FFmpeg command above and run it on your desktop.
Estimated output:
Conversion Complete!
DownloadHow It Works
During this conversion, FFmpeg reads the FLV container and discards the video stream entirely, focusing only on the audio track. The audio — typically AAC or MP3 inside the FLV — is decoded to raw PCM and then re-encoded using Apple's ALAC codec, storing the result in an MPEG-4 (.m4a) container. ALAC is lossless, meaning the encoded output is a bit-for-bit reconstruction of that decoded PCM — no additional quality is lost beyond what the original lossy FLV audio already discarded. The resulting M4A file is significantly smaller than uncompressed WAV or AIFF while remaining fully lossless, and it supports embedded metadata tags for artist, title, and album information.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg command-line tool, which handles all media reading, stream processing, codec decoding and encoding, and container muxing for this conversion. |
-i input.flv
|
Specifies the input FLV file. FFmpeg reads the Flash Video container and identifies its streams — typically a video stream (H.264 or Sorenson Spark) and an audio stream (AAC or MP3) — before processing begins. |
-c:a alac
|
Instructs FFmpeg to encode the audio stream using Apple's ALAC (Apple Lossless Audio Codec). The audio decoded from the FLV's lossy AAC or MP3 track is re-encoded losslessly into ALAC, producing a bit-perfect reconstruction of the decoded PCM audio. This flag appears twice in the command; the second instance overrides the first, but both specify the same codec so the result is identical to using it once. |
-c:a alac
|
A duplicate of the preceding audio codec flag. FFmpeg processes this as the active codec setting for the audio stream, confirming ALAC encoding. Since no video output codec is specified and the output is an audio-only M4A container, the video stream from the FLV is automatically dropped. |
output.m4a
|
Defines the output filename and container. The .m4a extension tells FFmpeg to wrap the ALAC-encoded audio in an MPEG-4 audio container, which is the standard and only supported container for ALAC files and ensures compatibility with iTunes, Apple Music, and all Apple devices. |
Common Use Cases
- Archiving audio from legacy Flash-era video content (tutorials, webcasts, early YouTube downloads) into a modern, lossless format before FLV players become completely obsolete
- Extracting a music performance or live concert recorded in FLV format to preserve the audio at the highest possible fidelity for long-term storage in an iTunes or Apple Music library
- Pulling the audio from a Flash-based e-learning or lecture recording into ALAC so it can be imported into GarageBand or Logic Pro for editing without generational quality loss
- Converting FLV audio commentaries or interview recordings to ALAC M4A for archival purposes, taking advantage of ALAC's chapter support to add navigation markers later
- Stripping and preserving the audio from FLV gaming highlight reels or streaming clips in a lossless format before further audio post-production in DAW software
- Migrating a collection of FLV files from an old Flash media server archive to ALAC for Apple TV or HomePod playback without re-encoding through a second lossy codec
Frequently Asked Questions
No — and this is an important distinction. FLV files almost always contain lossy audio (AAC or MP3), so some quality was already lost when the FLV was originally created. Converting to ALAC does not recover that lost information. What ALAC guarantees is that no additional quality is lost in this conversion step: the audio is decoded to PCM and then losslessly re-encoded, so the ALAC output is a perfect representation of what was in the FLV. Think of it as freezing the quality at its current state rather than improving it.
ALAC is Apple's proprietary lossless codec and it is stored exclusively in an MPEG-4 container, which uses the .m4a file extension for audio-only files. This is a fundamental property of the codec itself — ALAC cannot be stored in a WAV or Ogg container. If you need a more universally compatible lossless format, FLAC in an MKV or OGG container would be an alternative, but ALAC in M4A is the correct choice for Apple device compatibility and iTunes library integration.
Yes. The MPEG-4 container used by ALAC supports iTunes-style metadata tags including title, artist, album, genre, year, track number, and artwork. However, FLV files have very limited and often absent metadata, so the conversion tool will transfer whatever tags exist in the source FLV, which in most cases means the output will have minimal embedded tags that you may want to edit manually afterward using a tool like MusicBrainz Picard or iTunes itself.
The single-file command shown is 'ffmpeg -i input.flv -c:a alac -c:a alac output.m4a'. To batch process in a Unix shell, you can wrap it in a loop: 'for f in *.flv; do ffmpeg -i "$f" -c:a alac "${f%.flv}.m4a"; done'. On Windows Command Prompt, use: 'for %f in (*.flv) do ffmpeg -i "%f" -c:a alac "%~nf.m4a"'. This processes every FLV in the current directory and names each output after its source file.
This is a redundancy in the resolved command — '-c:a alac' appears twice, but FFmpeg simply applies the last valid codec specification for the audio stream, so the output is correctly encoded as ALAC regardless. In practice, a single '-c:a alac' flag is sufficient and produces identical results. The duplication is harmless and does not affect the output quality, file size, or compatibility of the resulting M4A file.
The output ALAC M4A will typically be larger than the original FLV because ALAC, while lossless and compressed, encodes raw PCM audio — which is inherently larger than the highly compressed AAC or MP3 audio inside the FLV. For a typical FLV with 128kbps AAC audio, the ALAC version of the same decoded audio might be 3–5x larger in terms of audio data alone. The video stream is removed entirely, so you lose those bytes, but the audio portion will grow noticeably compared to its lossy FLV counterpart.
Technical Notes
FLV containers support AAC and MP3 as their primary audio codecs, both of which are lossy formats. This means the audio decoded from an FLV and re-encoded to ALAC will be a lossless representation of already-lossy source material — a concept sometimes called 'lossy-to-lossless' conversion. The ALAC codec itself uses integer linear predictive coding and stores audio in the MPEG-4 container with full support for 16-bit and 24-bit depth and sample rates up to 384kHz, though FLV sources are almost always 44.1kHz or 48kHz at 16-bit. One notable advantage of the MPEG-4 container is its support for chapter markers, which can be added to the ALAC output after conversion — a feature absent from FLV entirely. FLV does not support multiple audio tracks, subtitles, or transparency, so none of those elements need to be handled during this conversion. The ALAC format is natively supported on all Apple platforms (macOS, iOS, tvOS, watchOS) and in iTunes and Apple Music without any additional codecs, making it ideal for Apple-centric workflows.