FLV to OPUS Converter

FLV to Opus Converter

Flash Video is the container that carried web audio and video through the 2000s, and Adobe ended Flash Player support on 31 December 2020, so .flv files today are archive material: lectures, screencasts, webcam captures, podcast rips and stream recordings. This page lifts the soundtrack out of one and re-encodes it to Opus, the IETF codec defined in RFC 6716. The video track is discarded — the output is an audio-only .opus file. Opus stays intelligible at bitrates where older codecs fall apart, which is exactly the right property for salvaged, already-compressed Flash audio.

Opus Format at a Glance

What Is Inside an FLV Soundtrack

How to Convert FLV to Opus

1. Upload Your FLV File: Drag your .flv onto the page or click "+ Add Files" to browse. Several files can be queued and converted with the same settings in one pass.
2. Pick a File Compression Mode: Open Advanced Options. Quality Preset runs from Highest down to Lowest; Constant Bitrate offers fixed steps from 8 kbps to 384 kbps; Custom Bitrate takes any number you type in bps, Kbps or Mbps; and Specific file size lets you name a target size instead.
3. Set Audio Channel, Audio Sample Rate, or Trim: Audio Channel offers Original, Mono or Stereo — Mono roughly halves a voice recording. Audio Sample Rate offers Original plus 8000 to 48000 Hz. Trim takes a Start time and a Duration in seconds or HH:MM:SS.sss.
4. Convert and Download: Click "Convert" and save the .opus file. No sign-up, no watermark.

Choosing a Bitrate for Salvaged Flash Audio

The one rule that beats all of these: do not set a bitrate far above what the FLV already contained. If the source was a 96 kbps MP3, encoding at 256 kbps produces a bigger file carrying exactly the same information.

Frequently Asked Questions

Does this keep the video, or only the sound?

Only the sound. Opus is an audio-only codec, so the Sorenson Spark, VP6 or H.264 video inside the FLV is decoded, discarded, and never written to the output — you get a .opus file containing the soundtrack alone. That is exactly what you want for rescuing a lecture, an interview or a music rip out of a Flash archive. If the picture matters too, convert FLV to MP4 instead.

Why did my 44.1 kHz audio come out at 48 kHz?

Because Opus does not define a 44.1 kHz mode. RFC 6716 specifies the codec at 8, 12, 16, 24 and 48 kHz, so a 44.1 kHz source cannot be stored at its original rate. We snap the requested rate to the nearest one Opus actually supports, which for 44.1 kHz means 48 kHz — including when you explicitly pick 44100 Hz from the Audio Sample Rate list. Resampling is not audibly damaging at these rates, but it is worth knowing so the number in your file inspector does not come as a surprise.

Will I lose quality extracting Opus from an FLV?

A little, because this is a re-encode rather than a copy. FLV audio is almost always already lossy — MP3, AAC, Nellymoser Asao, Speex or ADPCM — so this is a lossy-to-lossy generation. Opus is far more efficient than the codecs Flash shipped with, particularly Nellymoser and Speex, so it can carry what remains at a smaller size, but it cannot undo loss that was baked in at record time. Match or slightly exceed the source bitrate and the added loss is inaudible for most listeners.

What bitrate should I choose for an old lecture or screencast?

24–48 kbps in Mono is plenty. Speech was Opus's original design target — the SILK half of the codec came from Skype's speech work — and voice recordings from Flash-era screen captures were low-bandwidth to begin with. Downmixing to Mono is the single biggest saving on a talking-head recording, because a webcam or headset capture rarely holds real stereo information anyway.

Which players and devices actually handle .opus files?

Chrome, Firefox, Edge and Opera play Opus natively, as do Android, VLC, mpv and Discord, and recent Apple systems have added support. The gaps are the ones you would expect from a 2012 codec: older car head units, legacy portable players, and Windows installations older than 10 that need a decoder pack. If universal playback matters more than efficiency, convert FLV to MP3 instead — MP3 is worse per byte but plays on essentially anything with a speaker.

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

Yes. Set Trim to a Start time and a Duration, in seconds or HH:MM:SS.sss, and only that span is encoded. This is worth doing up front for long stream rips or multi-hour lecture captures, since it cuts both the processing and the size of the download. If you would rather cut the file after the fact, the Audio Cutter does the same job on the finished audio.

Why is the upload slow when the output file is tiny?

Because you are uploading the whole FLV, video track included, and the video is by far the larger part of it. A 200 MB Flash capture whose soundtrack is a 96 kbps MP3 still has to travel in full before the audio can be separated out — the resulting .opus may be a couple of megabytes. Nothing is wrong; the video simply has to arrive before it can be thrown away.

Does the .opus file keep the title, artist or chapter information from the FLV?

Not reliably. FLV stores loose metadata in an onMetaData script tag rather than in a standard tag format, and there is no direct mapping from that into the Ogg comment header an Opus file uses. Treat the output as untagged audio and add tags afterwards in a tag editor or your music library software if you need them.

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

Your FLV is uploaded over an encrypted connection, processed on our servers, and the .opus file is returned to you. Uploads and outputs are deleted automatically a few hours after conversion — no sign-up, no watermark, never shared or made public. The practical limit for a long Flash capture is upload size and time, since the file still carries its full video track on the way in.