FLV to FLAC Converter

How to Convert FLV to FLAC Online

1. Upload Your FLV Files: Drag and drop or click "Add Files" to select one or more FLV (Flash Video) files. Batch conversion is supported, so a folder of legacy Flash recordings can be processed in one pass.
2. Set Audio Channel and Sample Rate: Use the "Audio Channel" dropdown to keep the source layout (Original) or downmix to Mono / Stereo. Set "Audio Sample Rate" to Original to inherit the source rate, or pick a fixed value (8000 / 12000 / 16000 / 24000 / 44100 / 48000 Hz). Keeping the original rate avoids an unnecessary resample step.
3. Choose a Compression level (Optional): FLAC's compression slider runs 1–12. All levels are lossless — they produce a bit-identical decoded waveform. Higher levels just take longer to encode and write a slightly smaller file. Level 5 (the encoder default) is the standard balance; level 8 is the practical max for typical music libraries.
4. Trim and Convert (Optional): Enter a start time and duration in seconds or HH:MM:SS.sss to extract a single segment. Click "Convert" and download. Files are processed in a browser session — no sign-up, no watermark, no upload to a third-party host.

Why Convert FLV to FLAC?

FLV (Flash Video) was the dominant streaming-video container of the mid-2000s — YouTube, Newgrounds, Hulu, and most Flash sites shipped video as FLV until HTML5 took over. The audio track inside an FLV is almost always lossy: MP3 was the common default, AAC arrived with Flash Player 9, and microphone-recorded FLVs typically used Nellymoser. Adobe ended Flash Player support on December 31, 2020, so FLVs are a legacy archive format now.

Converting that audio to FLAC (Free Lossless Audio Codec, formally specified in IETF RFC 9639, December 2024) repackages it into an open lossless container so no further generational loss occurs when you edit, re-tag, or re-encode later. Common reasons people pull FLAC out of an FLV:

• Archive Flash-era recordings before they rot. FLV playback is no longer native in any modern browser, and standalone FLV-aware players are dwindling. Pulling a FLAC out now means the audio survives even if FLV tooling disappears.
• Music and soundtracks from old uploads. Background music, game soundtracks, podcast intros, or remixes saved off Flash sites in the 2000s are often only available as FLV. FLAC keeps the audio in a format every modern player handles (VLC, foobar2000, Apple Music since macOS 10.13, Windows Media Player on Windows 10+).
• Lossless source for editing. Editing FLAC and re-saving incurs no codec loss. Editing the FLV's MP3/AAC track in place re-encodes it on every save and stacks artifacts.
• Library normalization. If the rest of your music library is FLAC, mixing in MP3-in-FLV files breaks tag, replay-gain, and metadata workflows. Standardizing on FLAC fixes that.
• Forensic / archival masters. A FLAC keeps the decoded waveform exact. If you later need to verify or reproduce the audio, the FLAC is bit-identical to what came out of the FLV decoder.
• Microphone recordings. Old screen-capture and webcam tools wrote audio into FLV via Nellymoser or Speex. Decoding once to FLAC lets every modern editor (Audacity, Reaper, Logic, Audition) read the file directly.

Need the reverse direction or a different output? See FLV to MP3 for a smaller lossy file, FLV to WAV for uncompressed PCM, or FLV to MP4 if you actually want to keep the video.

FLV Audio vs FLAC Output

Common FLV Audio Codecs (and What FLAC Does With Them)

Codec IDs above match the FLV file format spec (Adobe). The converter decodes whichever codec the FLV holds and re-encodes the resulting PCM stream into FLAC — quality is bounded by the lossy source.

FLAC Compression Level Quick Guide

Every level produces an identical decoded waveform. The slider only trades CPU time for a smaller file.

Frequently Asked Questions

Does converting FLV to FLAC actually improve audio quality?

No, and any tool that says otherwise is misleading you. The audio inside almost every FLV is already lossy (MP3, AAC, Nellymoser, Speex, or ADPCM), so data was permanently discarded at the original encode. FLAC preserves whatever the FLV decoder hands it bit-for-bit, but it cannot reconstruct what was thrown away. The benefit is that no further loss happens on subsequent edits — not that the audio gets cleaner.

Why pick FLAC instead of WAV when both are lossless?

Both store the same decoded waveform. FLAC compresses it losslessly to roughly 50–60% of the WAV size and supports rich tagging (Vorbis comments) for artist, album, replay-gain, cover art, and so on. WAV has no native tag system and is roughly twice the size on disk. FLAC is the better choice for music archives unless a tool you depend on rejects FLAC. See WAV to FLAC if you have the reverse situation.

What audio codecs does FLV actually contain?

The FLV file format defines audio codec IDs 0–15: Linear PCM (0), ADPCM (1), MP3 (2), Nellymoser 16 kHz mono (4), Nellymoser 8 kHz mono (5), AAC (10), Speex (11), and MP3 8 kHz (14). MP3 is the most common in YouTube-era files; AAC arrived with Flash Player 9 in 2007; Speex was added with Flash Player 10. The converter decodes any of them and outputs FLAC.

What sample rate and channel layout should I keep?

Leave both at "Original" unless you have a specific reason to change them. Resampling — for example forcing a 22.05 kHz Nellymoser source to 48000 Hz — does not add audio information; it only enlarges the file. The same goes for forcing a mono Nellymoser source to stereo: you get a duplicated mono track in two channels, not real stereo. Downmix to mono only when the source is genuinely identical on both channels and storage matters.

Can I extract just one song or segment from a long FLV?

Yes. Use the Trim controls to enter a start time and duration. Both fields accept either plain seconds (125.5) or HH:MM:SS.sss (00:02:05.500). Only the selected segment is decoded and written to FLAC, so the output is exactly the length you asked for. For more advanced cuts on the FLAC after conversion, see Trim FLAC.

Why is my FLAC file so much bigger than the FLV it came from?

The FLV's MP3 or AAC track is lossy and typically sits around 128–192 kbps. A lossless FLAC of the decoded audio at 44.1 kHz / 16-bit stereo runs roughly 800–1,000 kbps — five to eight times larger. That's the cost of preserving the decoded waveform exactly. If size matters more than re-edit safety, FLV to MP3 is the smaller option.

Is Flash still required to play FLV files?

No. Adobe ended Flash Player support on December 31, 2020, and started actively blocking Flash content in January 2021. FLVs still play in VLC, ffmpeg, and most modern media tooling because the container and its codecs are decoded in software — Flash Player itself is no longer in the chain. Converting to FLAC removes the FLV dependency entirely.

Does the compression level slider affect audio quality?

No. FLAC compression levels 1–12 are all lossless. Decoding any of them yields the identical PCM waveform. The slider controls how hard the encoder works to predict and pack the data — higher levels run slower and write a slightly smaller file. Level 5 (the encoder default) is fine for nearly every use case. If you're encoding a large batch and want to save a few percent on disk, level 8 is the practical ceiling.

Will the converter handle Nellymoser or Speex audio from old screen recordings?

Yes. Both legacy Flash voice codecs decode normally and re-encode to FLAC. Note that Nellymoser-8 is mono at 8 kHz and Speex is voice-optimized at 8/16/32 kHz, so the resulting FLAC will preserve the source's narrow bandwidth — it won't sound like studio audio, because the original wasn't.

Can I batch-convert a folder of old FLVs at once?

Yes. Drop multiple FLVs in the upload area; each one is converted to its own FLAC with the same settings. For huge libraries you may want to also run Compress FLAC afterwards if storage is tight, though that re-encodes the FLAC at a higher compression level rather than reducing audio fidelity.