Convert WebM to AAC — Free Online Converter

WebM files typically contain audio encoded as Opus or Vorbis — both high-quality open-source codecs. Opus is particularly notable for its exceptional performance across all bitrates, from speech (6 kbps) to transparent music (256 kbps). AAC (Advanced Audio Coding) is the MPEG-4 standard audio codec and the native format for Apple devices, playing on every iPhone, iPad, Android phone, and modern computer.

While Opus is technically superior to AAC at most bitrates, iOS does not support Opus in its native Music app, and many hardware audio players lack Opus support. AAC provides the closest quality match to Opus with truly universal device compatibility. This extraction is common when downloading YouTube audio (served as Opus in WebM) for mobile listening.

AAC at 256 kbps is perceptually transparent for virtually all content, making it the best lossy format for broad distribution from WebM sources.

FFmpeg demuxes the WebM container, extracts the Opus or Vorbis audio stream, decodes to PCM, and re-encodes to AAC-LC using the native or libfdk_aac encoder. Output is an ADTS-wrapped AAC file or M4A container. Opus at 48 kHz is resampled to 44.1 kHz if needed for compatibility. Quality-based (-q:a) or constant bitrate (-b:a) encoding modes are available.