Convert AVI to OPUS Online
Convert legacy AVI video audio to modern Opus, free, in your browser.
.avi · up to 100 MB
What it's for
From legacy AVI to the audio codec of the future
MP3 → Opus: modern quality
Opus at 64 kbps perceptually outperforms MP3 at 128 kbps. Modernize your DivX archive.
Efficient archiving
Reduce legacy audio file size by up to 50% with equal or better perceived quality.
100% private
Your AVI video never leaves your device. Local processing with FFmpeg.wasm.
No usage limits
No signup, no watermark. Digitize and modernize your entire AVI collection.
How it works
Three steps, no hassle
Upload your AVI file
Drag or select your .avi video. Compatible with DivX, XviD, and any standard AVI.
Legacy codec conversion
FFmpeg.wasm decodes the MP3 or AC-3 audio from the AVI and re-encodes it to modern Opus in your browser.
Download your modernized Opus
Get your .opus with up to 60% less size than the original MP3 at equal perceived quality.
FAQ
Got questions?
AVI (Audio Video Interleaved), defined by Microsoft in November 1992 as part of the Video for Windows API, supports multiple audio codecs, but DivX-era AVI files (1999–2008) almost universally use MP3 (MPEG-1 Audio Layer III, encoded with LAME) at 128 kbps or 192 kbps. Some DVD-rip AVI files use AC-3 (Dolby Digital) at 192 kbps. Newer AVI files may carry AAC or even PCM. AVI has intrinsic limitations: it does not properly support more than 2 audio channels, has a 2 GB file size limit in its original version (OpenDML extends this to 4 GB), and does not support embedded subtitles in a standard way.
DivX-era AVI files represent a personal and cultural video heritage. The MP3 audio at 128 kbps they contain was acceptable in 2001 but is clearly inferior to Opus at 64–96 kbps in perceptual quality per MUSHRA studies. Modernizing the audio to Opus preserves perceptual quality while reducing audio file size by up to 50%. This is especially relevant when the goal is to redistribute the extracted audio (uploading voice clips, sharing on Discord, creating podcasts from old recordings).
This tool extracts only the audio from the AVI, discarding the video. AVI A/V sync problems do not affect the extracted audio, which is simply the continuous audio track. If the AVI has AVI 1.0 interleaving with timestamp issues (a known problem in old-era AVI), FFmpeg applies timestamp correction during decoding. The resulting .opus is continuous audio with no temporal references to the video.
Yes. AVI files from VHS digitization with Pinnacle, Hauppauge, or consumer video capture cards from the 2000–2010 era are fully compatible. These AVIs typically have PCM audio at 44.1 kHz or MP3 at 128 kbps. For long-term archiving, consider using a high Opus bitrate (128–160 kbps) to preserve the source audio quality — even though it already has VHS tape degradation, there's no need to add further compression degradation.
No, in the sense that nothing lost in the original MP3 is recovered. The process is: decode the MP3 to PCM (with quantization noise already present from the original encoding) and re-encode that PCM to Opus. The resulting Opus is a representation of the PCM reconstructed by the MP3 decoder, not the original audio before MP3 compression. The advantage is smaller size at equal perception and better compatibility with modern platforms.
Technically yes, AVI supports multiple audio streams, but in practice almost all AVIs have a single audio track. DVD rips in AVI from the DivX era rarely include multiple languages; the single audio track is usually from the language of the group that ripped the DVD. For AVI files with multiple audio tracks (unusual), FFmpeg extracts the first track marked as default.
Convert AVI to Opus: modernize legacy DivX and XviD audio with the most efficient codec
AVI (Audio Video Interleaved) was introduced by Microsoft in November 1992 as part of the Video for Windows SDK, designed for the multimedia hardware of the time: 486 processors at 33–66 MHz with 2x-speed CD-ROM drives. The format dominated digital video sharing between 1993 and 2006, especially after the DivX codec (a modification of Microsoft's MPEG-4 codec, later an independent implementation based on OpenDivX/FFmpeg) became popular in 1999–2001 for digital movie distribution on the internet. A typical DivX-era AVI file (2000–2006) combines DivX or XviD video (MPEG-4 Part 2) with MP3 audio encoded with LAME at 128 kbps, all in an AVI container with the OpenDML extension (AVI 2.0) to overcome the original 2 GB limit. Millions of personal video collections stored on hard drives from the early 2000s are in this format. The MP3 audio at 128 kbps they contain was the quality standard of 2001 (when the average copy was a CD ripped to 128 kbps on a 5 GB iPod), but is clearly inferior to what Opus offers at the same or lower bitrate according to Xiph.org's 2012 perceptual evaluation studies. MP3's psychoacoustic model, based on fixed-length subbands of 576 samples (granule mode), has known limitations in handling transients (pre-echo) and in the 16–22 kHz frequency range. Opus, designed with low-latency CELT for this type of content, handles transients and high frequencies more efficiently. Converting the audio of an AVI collection to Opus is an archive modernization process: the audio loses dependency on the AVI container and MP3 codec, and moves to a modern format compatible with all 2024 platforms.
The context of the MP3 audio codec in legacy AVI files is relevant to understanding the quality of the conversion output. LAME (Lame Ain't an MP3 Encoder), the dominant open-source encoder for MP3 creation in the DivX era, evolved significantly between versions 3.70 (1999) and 3.100 (2017). AVI files from 1999–2002 encoded with early LAME versions have specific artifacts: pre-echo on percussion attacks, distortion in high-frequency female voices, and quantization noise in the 15–20 kHz spectrum range. AVI files from 2004–2006 encoded with LAME 3.96+ (VBR mode 2 or CBR 128/192 kbps) have notably better quality, though still inferior to modern Opus. When extracting and converting the audio from these AVI files to Opus, the result is a representation of the PCM decoded by FFmpeg's MP3 decoder (libmpg123 or FFmpeg's native decoder), re-encoded to Opus. This means that artifacts from the original MP3 are present in the output Opus if they were in the source MP3 — no information lost by the original MP3 encoder is recovered. The advantages of converting to Opus are: distribution on modern platforms (Discord, Telegram, WebRTC) that expect native Opus; audio file size reduction (a 100 MB MP3 at 128 kbps can be represented with perceptually equivalent quality in Opus at 64–80 kbps, producing an approximately 50 MB file); and better future compatibility than MP3, whose patents began expiring in 2017 but whose support on some modern hardware manufacturers is uneven.
Convertir.ai performs the AVI-to-Opus conversion entirely in the browser with FFmpeg.wasm, requiring no server or software installation. The technical process: FFmpeg.wasm opens the AVI file using FFmpeg's AVI demuxer, which handles both AVI 1.0 (2 GB limit) and OpenDML AVI 2.0 (4 GB+ extension). It identifies the audio stream, which in AVI is specified via the fccHandler field of AVISTREAMHEADER (0x55 0x00 for MP3, 0x61 0x63 for AC-3, 0x00 0x01 for PCM). It decodes the audio with the corresponding codec (libmpg123/FFmpeg native decoder for MP3, liba52 for AC-3) to PCM at 44.1 kHz or 48 kHz. It applies resampling to 48 kHz if necessary with FFmpeg's Kaiser sinc filter (high-quality resampler with Kaiser-8 window by default, 0.97 rolloff, 80 dB out-of-band attenuation). It encodes the resulting PCM with libopus at the chosen bitrate and mode. AVI INFO metadata (INAM for name, IART for artist, ICRD for creation date) is transferred to Opus Vorbis Comment tags when available, though DivX-era AVI files rarely have populated INFO metadata. The output .opus file in OGG is compatible with all modern players and communication platforms that support Opus. The service is completely free, no signup, no file limit, and no watermark.