Convert WebM to AIFF — Free Online Tool
Convert WebM video files to AIFF audio by extracting the Opus or Vorbis audio track and re-encoding it as uncompressed PCM (pcm_s16be) — Apple's native lossless audio format. Ideal for macOS workflows, professional audio editing, and archiving web video audio at full fidelity.
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FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
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Note: Browser-based encoding uses approximate quality targets. For precise CRF compression, copy the FFmpeg command above and run it on your desktop.
Estimated output:
Conversion Complete!
DownloadHow It Works
WebM files typically carry audio encoded with Opus or Vorbis — both lossy compressed codecs optimized for streaming efficiency. AIFF does not support these codecs; it stores audio exclusively as uncompressed PCM. During this conversion, FFmpeg discards the VP9 video stream entirely and decodes the compressed Opus or Vorbis audio, then re-encodes it as 16-bit big-endian PCM (pcm_s16be) inside an AIFF container. This decode-then-re-encode step means the audio is decompressed from its lossy state into a lossless uncompressed format — the resulting AIFF captures everything the lossy codec preserved, but introduces no further compression artifacts. The output file will be significantly larger than the source WebM because PCM audio is uncompressed.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg program, the open-source multimedia processing engine that powers this conversion both in the browser (via FFmpeg.wasm) and on the desktop command line. |
-i input.webm
|
Specifies the input file — a WebM container that typically holds a VP9 video stream and an Opus or Vorbis audio stream. FFmpeg reads both streams but will only process the audio for this conversion. |
-c:a pcm_s16be
|
Sets the audio codec for the output to 16-bit signed big-endian PCM, which is the standard uncompressed audio encoding used in AIFF files. This decodes the compressed Opus or Vorbis audio from the WebM and re-encodes it as raw PCM suitable for the AIFF container. |
output.aiff
|
Specifies the output filename and format. The .aiff extension tells FFmpeg to wrap the PCM audio in an Audio Interchange File Format container, the uncompressed lossless audio format developed by Apple and natively supported across macOS applications. |
Common Use Cases
- Extracting a voice-over or narration from a WebM screen recording to import into Logic Pro or GarageBand for editing on macOS
- Archiving the audio commentary track from a WebM conference recording as an uncompressed AIFF master for long-term preservation
- Pulling audio from a WebM video downloaded from a web platform and converting it to AIFF for use in Final Cut Pro or other Apple-ecosystem editors that natively support AIFF
- Preparing a music or podcast recording that was exported as WebM from a browser-based recorder (like a web DAW) for further mastering in a professional audio application
- Converting WebM audio to AIFF to meet delivery requirements for Apple Podcasts, broadcast archives, or sound libraries that specify uncompressed audio formats
- Extracting the audio from a WebM animation or motion graphics file to use as a standalone sound effect or music asset in a macOS-based post-production pipeline
Frequently Asked Questions
No — the audio in a WebM file is encoded with a lossy codec (Opus or Vorbis), meaning some audio information was already discarded when the WebM was created. Converting to AIFF decompresses that audio into uncompressed PCM, which preserves exactly what the lossy codec retained, but it cannot recover what was lost during the original compression. The AIFF output will be larger and lossless going forward, but it is not higher quality than the WebM source.
WebM uses Opus or Vorbis audio compression, which dramatically reduces file size by discarding audio data the human ear is less sensitive to. AIFF stores audio as raw, uncompressed PCM — every sample is stored at full resolution with no compression. A one-minute stereo audio track at 44.1 kHz in 16-bit PCM takes roughly 10 MB uncompressed, whereas the same content in Opus might be under 1 MB. The size increase is expected and is a direct consequence of converting from a compressed to an uncompressed format.
This tool uses the pcm_s16be codec by default, which produces 16-bit AIFF audio — the same bit depth as a standard audio CD. If your source WebM audio was encoded at a higher fidelity and you need 24-bit or 32-bit output for professional mastering, you can modify the FFmpeg command locally by replacing pcm_s16be with pcm_s24be or pcm_s32be respectively. AIFF natively supports all of these PCM variants.
No. AIFF is a pure audio format and cannot contain video streams. FFmpeg automatically drops the VP9 video track from the WebM during this conversion and outputs only the audio. If you need to keep the video, you should convert to a container format that supports both audio and video, such as MP4 or MOV.
The flag -c:a pcm_s16be specifies the PCM encoding used in the AIFF output. You can replace pcm_s16be with another AIFF-compatible codec: use pcm_s24be for 24-bit signed PCM, pcm_s32be for 32-bit signed PCM, pcm_f32be for 32-bit floating-point, or pcm_f64be for 64-bit floating-point. For example: ffmpeg -i input.webm -c:a pcm_s24be output.aiff. Note that the sample rate and channel count are inherited from the source WebM unless you explicitly set them with -ar and -ac flags.
Yes, on the command line you can use a shell loop to process multiple files. On Linux or macOS, run: for f in *.webm; do ffmpeg -i "$f" -c:a pcm_s16be "${f%.webm}.aiff"; done. On Windows Command Prompt, use: for %f in (*.webm) do ffmpeg -i "%f" -c:a pcm_s16be "%~nf.aiff". This browser-based tool processes one file at a time, so the FFmpeg command shown here is especially useful for batch workflows on your local machine.
Technical Notes
AIFF uses big-endian byte ordering for its PCM data, which is why the codec is named pcm_s16be ('s' for signed, '16' for bit depth, 'be' for big-endian) — this reflects AIFF's origins on Motorola 68k-based Macintosh systems. The sample rate and channel layout of the output AIFF are inherited directly from the decoded WebM audio stream, so a stereo 48 kHz Opus track will produce a stereo 48 kHz AIFF. Opus audio in WebM is most commonly encoded at 48 kHz, which is fully supported by AIFF. Metadata support differs significantly between the formats: WebM can carry rich metadata in its Matroska-based container, but AIFF's metadata support is limited to its MARK, NAME, and ID3 chunk mechanisms — most WebM metadata tags will not transfer to the AIFF output. Subtitles, chapters, and multiple audio tracks present in the WebM are all silently dropped, as AIFF supports none of these features. If the WebM contains multiple audio tracks, FFmpeg will select the default or first audio track for the conversion.