usefulweb.site Universal Audio Converter

Audio, video & images

Universal Audio Converter

Convert MP3, WAV, FLAC, Ogg, Opus, M4A and AIFF with bitrate and sample-rate control.

MP3, WAV, FLAC, Ogg/Opus, M4A/AAC, AIFF or WMA (also the first audio track of a video), max 100 MB and 2 hours. Processed on our server in a private temporary folder that is deleted afterwards; the result can be downloaded for about 2 hours.

Used in fixed-bitrate mode. 128 kbit/s is fine for speech, 192–320 kbit/s for music.

Try an example: MP3 tone to Ogg Opus 64 kbit/s, mono · MP3 to lossless FLAC with tags

How it works

Converts audio between MP3, WAV, FLAC, Ogg Vorbis, Ogg Opus, M4A (AAC) and AIFF with ffmpeg. Choose constant bitrate or VBR quality, sample rate, mono/stereo and bit depth; tags and album covers are kept where the format supports them. Shows an ffprobe report before and after, with a player and a download.

  • The container is detected from the first bytes of the file (not the name) and passed to ffmpeg explicitly, so playlists or files that reference other files are never opened.
  • ffprobe reads codec, sample rate, channels, bitrate, duration and tags before conversion. ffmpeg then decodes the first audio track and encodes it with LAME (MP3), the native AAC encoder (M4A), libvorbis, libopus, FLAC or PCM (WAV/AIFF).
  • Lossy formats use either a fixed/average bitrate or a VBR quality level (MP3 -q:a, Vorbis -q:a; Opus/AAC use VBR at a matching target bitrate). Lossless formats ignore the bitrate.
  • Opus only supports 8/12/16/24/48 kHz and MP3 at most 48 kHz; other rates are resampled to the nearest supported rate and you get a warning.
  • Tags are copied with -map_metadata 0; album covers are copied for MP3, M4A and FLAC (Ogg/WAV/AIFF covers are not supported by ffmpeg muxers). Encoder version tags and timestamps are not written, so the same input always gives the same file.
  • ffprobe reads the result again for the before/after report.

Converting a lossy file (MP3, AAC, Ogg) to another lossy format or to a lossless format cannot restore lost quality.

Sources

For scripts and AI agents

  • JSON API: POST https://audioconverter.usefulweb.site/api/v1/calculate (same calculation as this page)
  • Interface description: OpenAPI 3.1 · AI guide: llms.txt
  • MCP server (Streamable HTTP): https://audioconverter.usefulweb.site/mcp · tool name audio_converter
Example request
curl -s -X POST https://audioconverter.usefulweb.site/api/v1/calculate \
  -H 'content-type: application/json' \
  -d '{…see OpenAPI examples…}'

Related tools

  • Audio Loudness Normalizer – Measure LUFS and true peak, then normalise to Spotify, podcast or EBU R 128 targets.
  • Audio Cutter & Merger – Trim audio, keep or remove ranges, fade in/out, or join up to 10 clips with crossfades.
  • MP3 Tag & Cover Editor – Edit MP3 ID3 tags (title, artist, album, year…) and add, replace or remove the cover.
Feedback