One file at a time. The first audio track is used. MP3 is a lossy format; conversion does not improve the source. 75 MiB · 30 minutes.
| Format | Audio codec | Before you convert |
|---|---|---|
| MP4 to MP3 | AAC LC, MP3 | MP4 is a container, not an audio codec. AAC LC and MP3 audio tracks are supported; silent videos cannot produce audio. |
| WAV to MP3 | PCM 16-bit, 24-bit, float 32-bit | Signed 16-bit and 24-bit PCM and 32-bit float WAV are supported. MP3 is lossy: it is not an archival replacement for your WAV. |
| M4A to MP3 | AAC LC, ALAC | M4A may contain lossy AAC or lossless ALAC. Converting either to MP3 is lossy. Protected M4P files are not supported. |
| FLAC to MP3 | FLAC 16-bit, 24-bit | 16-bit and 24-bit FLAC are supported. MP3 discards audio information; even 320 kbps does not preserve FLAC losslessly. |
| OGG to MP3 | Vorbis, Opus | OGG can hold different codecs. This tool accepts Vorbis and Opus audio, not every possible OGG stream. Re-encoding cannot restore lost detail. |
| AAC to MP3 | ADTS AAC LC | AAC LC in ADTS is supported. An AAC track inside M4A belongs in the M4A tool. Invalid duration or damaged frames may be rejected. |
| WebM to MP3 | Opus, Vorbis | WebM with Opus or Vorbis audio is supported. A screen recording without an audio track cannot be repaired by conversion. |
| MOV to MP3 | AAC LC, PCM | MOV with AAC LC or supported PCM audio is accepted. Only the first audio track is used; camera-specific or protected codecs may not work. |
| WMA to MP3 | WMA v1, WMA v2 | WMA v1 and v2 in ASF are supported. DRM, WMA Pro and WMA Lossless are outside the supported set. Renaming the extension does not remove protection. |
THE COMPLETE GUIDE
Read support as a precise file specification
The table above is the starting point. These explanations connect the extension, container, codec and limits so you can identify a useful input without trial-and-error renaming.
The container and codec must both fit
A container tells you how tracks are packaged; an audio codec tells you what must be decoded. MP4 with AAC LC is a tested case. MP4 with a different unsupported codec is not made equivalent by the extension. When checking a rejected input, inspect both properties and whether the first track is actually audio.
| File or concept | Relationship | What it means |
|---|---|---|
| An extension | suggests but does not prove | the actual container and audio codec |
| Published support | covers | the named tested codec variants |
What was actually checked
The local matrix contains 21 positive format-and-codec cases. They pass through real upload, queued processing, native FFmpeg, output probing and decoding. The checks include actual downloaded MP3 bytes. This evidence describes the named cases, not every encoder implementation or damaged media file that could produce the same extension.
Size, duration and audio properties are independent checks
Every source must stay within 78,643,200 bytes and 1,800 seconds. A compact compressed file can still be too long; a brief PCM recording can still be too large. The first audio track must be readable and have accepted properties. The tool does not silently trim overlong input or repair damaged frames to make the limits appear satisfied.
Continue with a practical guide
The output has its own specification
The result is one MP3 audio stream at 128, 192, 256 or 320 kbps CBR, with mono or stereo output. Automatic preserves mono/stereo and downmixes more channels to stereo. Sample rate can be normalized to an MP3-compatible rate. Source metadata, artwork, chapters, video and subtitles are not retained as part of the output package.
Unsupported tasks are not hidden settings
The current workflow has no URL downloader, batch processing, ZIP output, trimming, MP3-input compression, noise removal or DRM bypass. WMA Pro and WMA Lossless are outside the published WMA set. Use the dedicated supported tool for your existing file, and do not assume another page title unlocks a different backend capability.
Continue with a practical guide