Convert FLV to OPUS Online
Convert Flash FLV files to modern Opus audio, free and without uploading files.
.flv · up to 100 MB
Main use cases
Preserve audio from the Flash era
Pre-2015 YouTube
Convert your pre-2015 YouTube FLV downloads to modern Opus with full compatibility.
Flash games and animations
Extract audio from Flash videos on Newgrounds, Albino Blacksheep, and other Flash-era platforms.
Digital preservation
Convert to Opus, an open IETF standard with guaranteed long-term support. Perfect for historical archives.
100% local, no plugins
No Flash or external codecs needed. FFmpeg.wasm processes FLV entirely in your modern browser.
How it works
Three steps, no hassle
Upload your FLV file
Drag or select your .flv. Works with pre-2015 YouTube downloads, Flash game videos, Newgrounds archives, and other Flash-era content.
FFmpeg extracts and converts the audio
The MP3 or AAC audio inside the FLV is decoded and re-encoded to Opus using FFmpeg.wasm. 100% local processing.
Download your .opus file
Get modern Opus audio ready for Discord, digital preservation archives, and any current platform. No watermarks, no signup.
FAQ
Got questions?
YouTube FLV files from before 2015 primarily used MP3 (MPEG Layer III) at 128 kbps for lower quality streams or AAC-LC for higher quality streams. Starting in 2013, YouTube began transitioning to WebM+Opus for audio, completing the migration gradually by 2015. FLV files from 2005–2012 are the most common in archives and nearly always use MP3 or AAC in the FLV container.
Flash games published on Newgrounds between 2000 and 2020 embedded audio directly in the SWF file, but animations and videos exported to FLV from Flash Professional used MP3 or ADPCM (Adaptive Differential PCM, Adobe Flash's native audio format). ADPCM in FLV uses 22.05 kHz or 44.1 kHz samples at 4 bits, resulting in lower quality. FFmpeg correctly converts these to Opus 48 kHz.
Yes. The Internet Archive preserves millions of FLV videos from the Flash era (2000–2020). Converting them to Opus in OGG or MKV containers is standard digital preservation practice: Opus has guaranteed long-term support as an open IETF standard, while FLV player support declines year by year following Flash's end of life on December 31, 2020.
There is one transcoding generation since MP3 or AAC must be decoded to PCM and re-encoded to Opus. However, Opus is more efficient than MP3 and AAC: at 64 kbps, Opus matches or exceeds MP3 at 128 kbps in perceptual quality. For preserving Flash game audio or Newgrounds animations, Opus at 96–128 kbps delivers excellent fidelity.
Adobe Flash Player reached official end of life on December 31, 2020. From January 12, 2021, Adobe actively blocked Flash playback. Modern browsers (Chrome 88+, Firefox 85+) completely removed FLV and Flash plugin support. To play FLV content today you need VLC or must convert to a modern format.
You can convert FLV files up to 2 GB directly in the browser with FFmpeg.wasm. For very large files (over 1 GB), conversion may take several minutes depending on your device. On 64-bit browsers with more than 4 GB of available RAM, FFmpeg.wasm can handle larger files without issues.
Convert FLV to Opus: preserve pre-2015 YouTube and Flash-era audio in a modern format
FLV (Flash Video) was the dominant internet video format between 2003 and 2015. Adobe introduced FLV with Flash Player 6 in 2002, and YouTube adopted it as the primary format from its launch on February 14, 2005 until 2010–2012, when the progressive transition to MP4 and WebM began. During this period, all YouTube videos were stored and distributed in FLV format with MP3 audio (low-quality streams, itag 5 at 22.05 kHz and itag 6 at 44.1 kHz) or AAC-LC (higher resolution streams). Platforms such as Dailymotion, Metacafe, Veoh, and Vimeo also used FLV as their primary format until the rise of HTML5 video. The Flash ecosystem — with platforms like Newgrounds (founded 1995, with its Flash content peak between 2000 and 2015), Albino Blacksheep, and eBaum's World — produced tens of thousands of animations and videos in FLV or exported from Flash Professional to FLV. Adobe Flash Player reached official end of life on December 31, 2020, and Adobe actively blocked Flash execution on January 12, 2021. This made all FLV files formats requiring special software to play, creating an urgent need for conversion for digital preservation.
Audio in FLV files can be MP3 (MPEG Layer 3), AAC-LC, Speex (an open-source voice codec that preceded Opus, used in Flash video calls), ADPCM (Adaptive Differential PCM, Flash's native audio format at 5.5, 11, 22, or 44 kHz at 4 bits per sample), or uncompressed PCM. YouTube FLVs primarily used MP3 (itags 5, 6, 13, 17) and AAC (itag 18 for 360p MP4/FLV hybrid). Newgrounds Flash game FLVs frequently use ADPCM or embedded MP3. Opus, standardized as RFC 6716 in September 2012, technically supersedes all these formats: Speex was developed by the same principal author (Jean-Marc Valin) who later co-created Opus, and Opus outperforms Speex, MP3, AAC, and ADPCM in efficiency at all bitrates. For historical audio preservation, Opus at 128 kbps in OGG container delivers transparent quality and an open standard with long-term IETF-guaranteed support.
Convertir.ai runs the FLV→Opus conversion entirely in the browser using FFmpeg.wasm. The technical process varies by FLV audio: for FLV with MP3, FFmpeg decodes the MP3 stream (flv1 + mp3 is the most common combination in YouTube 2005–2010 archives) to float32 PCM at 44.1 kHz, resamples to 48 kHz, and re-encodes with libopus; for FLV with AAC, the process is identical but decoding AAC-LC; for FLV with Flash ADPCM, FFmpeg decodes the ADPCM (4-bit, typically 22.05 kHz) to PCM, resamples to 48 kHz, and encodes to Opus — significantly improving quality by moving from 4 bits/sample to Opus transform-based coding; for FLV with Speex (used in interactive Flash multimedia), FFmpeg decodes Speex to PCM at 16 kHz, resamples to 48 kHz, and re-encodes to Opus, benefiting from both codecs being voice-optimized and developed by Jean-Marc Valin. The result is a .opus file in OGG conforming to RFC 7845. The tool is completely free, no signup, no limits.