Convert FLV to FLAC Online
Convert Flash FLV videos to lossless FLAC for permanent archiving, free, in your browser.
.flv · up to 100 MB
What it's for
FLV to FLAC: lossless archiving of the Flash legacy
Pre-2015 YouTube preserved
Convert historically downloaded FLVs to lossless FLAC for permanent archiving without additional degradation.
Flash soundtracks archived
Preserve music from Flash games and Newgrounds animations in FLAC for retro audio collections.
Internet Archive compatible
Correct workflow for archiving FLVs from archive.org without unnecessary re-encodings.
No servers, 100% private
Your FLVs are processed locally in your browser with FFmpeg.wasm. No uploads, no registration.
How it works
Three steps, no hassle
Upload your FLV file
Drag or select your .flv. Pre-2015 YouTube videos, Flash games, streaming captures. Up to 500 MB.
Extraction and FLAC conversion
FFmpeg extracts the FLV audio (MP3, AAC, or Speex) and converts to lossless FLAC. No server uploads.
Download the FLAC
Lossless audio ready for permanent archiving, spectral analysis, or audiophile player playback.
FAQ
Got questions?
Yes in terms of the conversion, but the full quality chain deserves honesty. FLV audio comes in three formats: MP3 (most common in pre-2012 YouTube), AAC-LC (used in 2012–2015 YouTube and Twitch/Justin.tv streams), or Speex (VoIP audio in some videocall FLVs). All three are lossy codecs. Converting to FLAC decodes that lossy audio to PCM and re-encodes to FLAC: the result is lossless but inherits exactly the artefacts of the original codec. You don't recover frequencies or detail that MP3 or AAC discarded. What you get is the best possible copy of that Flash audio with no additional degradation.
From 2005 to 2015, YouTube distributed virtually all content in FLV format with MP3 or AAC audio. Many internet history archivists downloaded these FLVs using tools like youtube-dl before YouTube deleted or claimed rights to them. Converting these FLVs to FLAC is relevant for: preserving the soundtrack of historical videos (early virals, historical event commentary, ephemeral cultural content) in the best available quality; spectrally comparing FLV archive audio with later HD uploads (to verify whether YouTube re-encoded the audio); and archiving in the most long-term compatible format, since FLAC has guaranteed indefinite support as an open standard.
Flash games (.swf) from the 2000–2020 era contained music and sound effects generally in MP3 format embedded in the SWF or loaded from external FLV files as audio streams. Projects like Flashpoint (BlueMaxima's Flashpoint, the largest Flash game and animation archive, with over 180,000 games preserved as of 2024) and the Internet Archive preserve these games but don't always export audio separately. Extracting audio from a Flash game FLV to FLAC allows preserving the soundtrack at the best available quality, creating retro game music collections with archival quality, and facilitating remastering or re-release work by original authors or the community.
FLVs downloaded from YouTube between 2005 and 2011 use mostly MP3 at 128 kbps stereo or mono. YouTube FLVs from 2011 to 2015 use AAC-LC at 128–192 kbps. Twitch or Justin.tv stream FLVs use AAC-LC at 64–128 kbps. Videocall FLVs (Adobe Connect, some Ustream) use Speex at 16 kbps. The impact on FLAC: MP3 at 128 kbps has frequency response up to ~16 kHz and audible artefacts on transients; AAC-LC at 128 kbps has better perceptual quality at the same bitrate; Speex at 16 kbps is voice-only and the resulting FLAC will have very low audio quality.
The Internet Archive (archive.org) hosts millions of FLVs downloaded before the HTTPS and HD era on YouTube. To correctly archive audio from these FLVs: download the original FLV from archive.org (the .flv format, not the MP4 transcoded versions Archive auto-generates, which introduce an additional re-encoding); convert to FLAC with Convertir.ai or FFmpeg to get the audio at maximum available quality; document the original audio codec (ffprobe will show whether it's MP3 or AAC and the bitrate); and store the FLAC with the original Archive item metadata (URL, download date, Archive identifier) for archival traceability.
If you already have an FLV with MP3 audio, you can stream-copy the MP3 directly without re-encoding, getting the original MP3 with no additional loss. However, FLAC has specific advantages: FLAC is a permanent reference file from which you can generate any derived format (MP3, AAC, Opus) without generational loss, which is impossible if you only keep the MP3; spectral analysis tools (iZotope RX, Audacity) work better with FLAC to detect cuts, edits, or manipulations; and FLAC is more suitable for long-term institutional archiving since MP3 patents expired in 2017 but the format has less guaranteed multi-decade support than FLAC.
Convert FLV to FLAC: lossless preservation of Flash and pre-2015 YouTube legacy
FLV (Flash Video) was the dominant standard for internet video distribution for nearly a decade, from approximately 2005 to 2015. YouTube used FLV exclusively until 2011, when the gradual transition to MP4/H.264 began, and maintained FLV for some distribution streams until 2015. This era coincides with the cultural explosion of internet video: the first virals, real-time political and cultural debates, user-generated content in its purest state before YouTube's mass professionalisation. In parallel, Flash games and animations (.swf) that proliferated on Newgrounds, Kongregate, Miniclip, and thousands of independent sites used FLV as an external audio container for music and sound effects. Preserving this digital audiovisual heritage in FLAC format is the goal of archivists, digital historians, and communities like Flashpoint (BlueMaxima's Flashpoint, launched in 2018 and with over 180,000 games preserved as of 2024) and the Internet Archive.
Honesty about the quality chain is fundamental in FLV-to-FLAC conversion. Audio in historical FLVs is invariably lossy: MP3 at 64–128 kbps in 2005–2011 YouTube FLVs, AAC-LC at 128–192 kbps in 2011–2015 FLVs, and Speex at 8–16 kbps in voice-content FLVs (webinars, videocalls in Adobe Connect or Ustream). When converting to FLAC, FFmpeg decodes this lossy audio to 32-bit floating-point PCM and re-encodes to lossless FLAC: the resulting FLAC is perfectly faithful to the decoded FLV audio, but preserves exactly the compression artefacts of the original codec. There is no magic that recovers the 16+ kHz that MP3 at 128 kbps filtered out, the pre-echoes on transients, or quantisation noise modulation. What FLAC guarantees is no additional degradation: the FLAC file is the most solid possible starting point for any subsequent use.
Convertir.ai executes FLV-to-FLAC conversion entirely in the browser via FFmpeg.wasm, with support for all audio codecs that can appear in historical FLVs: the mp3 decoder from libavcodec for FLV with MP3 audio (the most common in the pre-2012 YouTube archive); the native aac decoder from libavcodec for FLV with AAC-LC (2012–2015 YouTube, Twitch/Justin.tv); and the libspeex decoder for FLV with Speex (voice content). In all cases the output is FLAC encoded by libFLAC at compression level 8, with duration and sample rate metadata correctly written. The resulting .flac file is playable in foobar2000, VLC, Winamp, Amarok, and any FLAC-compatible player, as well as on Astell&Kern, FiiO, and Sony NW-A portable players. No registration, no watermarks, no usage limits.