FLV to MP3 Converter

Extract MP3 Audio from an Archived FLV

FLV is a legacy Flash Video container, and Adobe ended Flash Player support on December 31, 2020 — so these files are archive material now: old screen recordings, downloaded lectures, webcam captures, and ripped streams. This tool decodes the audio track inside the FLV and writes it out as a standalone MP3 that plays on any phone, desktop player, or browser, discarding the video you don't need.

How to Convert FLV to MP3

1. Upload Your FLV File: Drag and drop your .flv onto the upload area, or click "Add Files" to browse. Several FLV files can be queued at once and they all use the same export settings.
2. Choose a File Compression Mode: Open Advanced Options. Quality Preset (Highest through Lowest) tracks the source; Constant Bitrate pins a fixed rate from a dropdown that starts at 128 kbps; Custom Bitrate takes a typed value (128 Kbps is prefilled); Specific file size takes a target in megabytes (8 MB is prefilled). The output codec is MP3 — it is the only codec this container accepts.
3. Set Channels, Sample Rate, or Trim (Optional): Audio Channel offers Original, Mono, and Stereo. Audio Sample Rate offers Original, 8000, 12000, 16000, 24000, 44100, and 48000 Hz. Trim takes a start time and a duration, in seconds or HH:MM:SS.sss, so you can export one segment instead of the whole recording.
4. Convert and Download: Click Convert and save the MP3. Files are uploaded over an encrypted connection, processed on our servers, and deleted automatically after a few hours. No sign-up, no watermark.

Which Bitrate to Pick

MP3 (MPEG-1 Audio Layer III, ISO/IEC 11172-3) tops out at 320 kbps. Match the rate to the material rather than maxing it out — the FLV's own audio bitrate is the real ceiling, and re-encoding a 64 kbps source at 320 kbps produces a bigger file, not a better one.

If you care about hitting a size rather than a quality level, use Specific file size and type the number of megabytes instead of guessing at a bitrate.

What Might Be Inside Your FLV

The FLV container carried several audio codecs over its life, which is why old files sound so different from each other. All of them are decoded and re-encoded to MP3 here, so the steps never change — but knowing what the source was tells you what to expect.

Frequently Asked Questions

Will extracting audio from FLV lose quality compared to the original?

There is exactly one re-encode. Our converter decodes the FLV's audio stream and re-compresses it to MP3 with LAME rather than lifting it across untouched, so the pass is lossy, and because FLV audio was almost always already lossy (MP3, AAC, Nellymoser, or Speex) you are going lossy-to-lossy. The practical rule is that the source bitrate is your ceiling: exporting a 128 kbps source at 192 kbps adds file size, not fidelity. If you want to avoid a second lossy pass entirely, export to FLV to WAV instead, which stores the decoded audio uncompressed.

Do all the audio codecs found in FLV files convert, or only some?

All of them. FLV files can carry MP3, AAC, Nellymoser Asao, Speex, ADPCM, or raw PCM audio, and each is decoded before being re-encoded to MP3, so you always get a standard MP3 out regardless of what was inside. The codec in the source does change how the result sounds — a Nellymoser microphone capture will never sound like a music track — but it does not change the steps or add failure modes.

Why does my old Flash screen recording sound thin and compressed?

Because it was probably recorded with Nellymoser Asao, the codec Flash used for live microphone and webcam audio. Nellymoser was tuned for low-latency real-time speech at very low bitrates, not for fidelity, so it discards a great deal of the frequency range at capture time. The conversion preserves exactly what is there, and no MP3 bitrate can restore detail that was never recorded. For this material, 64-96 kbps mono gives the same result as 320 kbps stereo in a fraction of the space.

Is FLV still usable now that Flash Player is gone?

The delivery runtime is gone, not the file. Adobe ended Flash Player support on December 31, 2020 and began blocking Flash content on January 12, 2021, so no current browser plays an .flv inline. The container itself is independent of that runtime — standalone decoders read FLV directly, which is why an archived Flash file can still be converted. Nothing about this conversion depends on Flash being installed.

Can I export just one section instead of the whole recording?

Yes. Under Trim, switch from Unchanged to Time Range and enter a start time and a duration, either in plain seconds or as HH:MM:SS.sss. Only that segment is decoded and written to MP3, which also makes the export faster on a long capture. If you need several separate pieces out of one recording, extract the whole thing first and then run the finished MP3 through the audio cutter, which is built for exactly that.

Should I change the sample rate, or leave it on Original?

Leave it on Original unless you have a reason. Original keeps whatever the FLV recorded, which avoids a resampling step. Dropping to 16000 or 24000 Hz is worth doing for narrowband voice recordings, where the source has no content above 8-12 kHz anyway and the smaller rate shrinks the file. Raising the sample rate above the source never adds detail, so going from a 22 kHz Flash capture up to 48000 Hz just makes a larger file.

Will switching Audio Channel to Mono halve the file size?

Not exactly halve it, but it will cut it substantially for anything genuinely single-voice. Mono encodes one channel instead of two, so at the same bitrate setting you get more bits per channel — meaning you can usually also drop the bitrate a step and keep the same perceived quality. For a lecture or sermon captured from one microphone, Mono at 64 kbps typically sounds identical to Stereo at 128 kbps. Leave it on Original for music or anything with real stereo imaging.

I actually need the video too — is this the wrong page?

Yes, this tool discards the picture entirely. If you want a playable modern video file, convert FLV to MP4 for H.264 that works on phones, browsers, and smart TVs, or convert FLV to MOV if the file is heading into Final Cut Pro or iMovie. Extracting the audio separately still makes sense alongside those — it is common to keep both a video copy and an MP3 you can listen to on the move.

Is the MP3 output good enough to share or archive?

For listening and sharing, yes — MP3 plays on effectively every device made in the last twenty-five years, and 192-256 kbps is transparent for most listeners. For long-term archiving you should keep a lossless copy as well, since every future re-encode compounds the loss; FLV to WAV gives you that. If the MP3 needs to fit under an email attachment cap, compress the MP3 afterward rather than re-running the extraction at a lower rate.

How are my files handled, and how long are they kept?

Your FLV is uploaded over an encrypted connection, processed on our servers, and deleted automatically a few hours after the conversion — no sign-up, no watermark, never shared or made public. The practical limit on a long recording is upload size and connection speed rather than anything in the conversion itself, so trimming a very large capture before uploading can save time.