Free online RTX to FLAC converter

Some older phones and ringtone tools store melodies as RTX files, while music players and audio editors commonly accept FLAC. Converting the ringtone lets you keep or share it as a lossless audio recording, but RTX may describe notes rather than contain recorded sound.

What the RTX format is

In audio contexts, RTX is used for ringtone data, commonly a text-based sequence of pitches and durations associated with RTTTL-style ringtones. It is not necessarily a waveform recording, and the extension alone does not establish which RTX variant a file uses. You may encounter it in files exported by older ringtone utilities or copied from mobile devices.

What the FLAC format is

FLAC stores digital audio using lossless compression: decoding reproduces the encoded audio samples exactly, unlike lossy formats such as MP3. It is useful for archiving, editing, and playback on software or devices that support FLAC. Converting a note sequence to FLAC requires rendering it as sound first; FLAC cannot preserve the editable ringtone instructions.

How to convert RTX to FLAC

Online on 101convert.com

1. Open the RTX-to-FLAC converter page on 101convert.com and upload the RTX file.
2. Choose FLAC as the output format and start the conversion.
3. Download the converted file when processing finishes. The page allows batch conversion; check its displayed per-file size limit before uploading.

Offline with desktop software

There is no broadly supported desktop audio editor that can decode every RTX variant directly. If the file is an RTTTL-style text ringtone, use an RTX/RTTTL-to-MIDI converter to make an intermediate MIDI file, then render that MIDI with the free, cross-platform FluidSynth and encode the resulting WAV with FFmpeg:

1. Convert the ringtone notation to MIDI with a converter that explicitly supports the RTX variant in your file. Confirm that the output MIDI contains the expected notes.
2. Render the MIDI using FluidSynth and a SoundFont file: fluidsynth -ni soundfont.sf2 output.mid -F rendered.wav -r 44100. The SoundFont supplies the instrument sound; without it, the melody cannot be rendered as audio.
3. Encode the rendered audio as FLAC with FFmpeg: ffmpeg -i rendered.wav output.flac.

FluidSynth and FFmpeg are available for Windows, macOS, and Linux. If your RTX file contains recorded audio rather than ringtone notation, this MIDI workflow is inappropriate; use a decoder that supports that specific RTX variant or the online converter.

Quality and limitations

FLAC encoding does not add audio detail that was absent from the source. For a ringtone note sequence, the rendered result depends on the SoundFont, MIDI conversion, and chosen sample rate; it will not reproduce an original recording unless the source encoded one. If the file is rejected or produces unexpected notes, verify its format rather than renaming the extension.