Free online FLAC to OMA converter

What the FLAC format is

FLAC (Free Lossless Audio Codec) compresses PCM audio without discarding information, usually reducing WAV size by 40–60%. It is commonly created by Exact Audio Copy, foobar2000, MusicBee, fre:ac, and CD-ripping software, and is supported by VLC, foobar2000, Audacity, and many modern media players. FLAC is suitable for archival copies and editing because decoding reproduces the original PCM samples exactly.

What the OMA format is

OMA is Sony’s OpenMG audio container, used mainly by SonicStage, older Sony Walkman products, and related ATRAC software. An OMA file normally contains ATRAC3 or ATRAC3plus audio and may include OpenMG DRM or device-specific encryption. Its main advantage is compatibility with older Sony hardware; it is not a general-purpose successor to FLAC and has limited support outside Sony-focused software.

How to actually convert FLAC to OMA

Using 101convert.com

1. Open 101convert.com and choose the audio converter.
2. Upload the FLAC file and select OMA as the output format.
3. Choose the ATRAC codec and bitrate offered by the converter. Use the bitrate supported by the destination Walkman or SonicStage version.
4. Start the conversion and download the resulting .oma file.
5. Test the file in SonicStage or on the Walkman before converting a large collection; some devices accept only particular ATRAC3 or ATRAC3plus profiles.

This option requires no installed conversion software and is available free on 101convert.com.

Using a Sony-compatible desktop workflow

For a local conversion, first create a lossless PCM intermediate with FFmpeg:

ffmpeg -i input.flac -c:a pcm_s16le output.wav

Import output.wav into SonicStage or another Sony ATRAC encoder, select ATRAC3 or ATRAC3plus and the required bitrate, then use its import, export, or transfer function to create the OMA track. SonicStage versions differ in their available import and export commands, and current Windows systems may not run the discontinued software reliably. FFmpeg is useful for decoding FLAC and creating WAV, but it should not be assumed to produce a Sony-compatible, DRM-enabled OMA file directly.

Quality, compatibility, and limitations

FLAC-to-OMA conversion is normally lossy because ATRAC3 and ATRAC3plus discard audio information. Converting to a higher ATRAC bitrate cannot restore information already removed; retain the original FLAC as the archival source. A WAV intermediate does not add quality loss, but it temporarily requires substantially more storage.

OMA files made by one tool may fail on a device because the player expects a particular ATRAC variant, bitrate, metadata layout, or OpenMG encryption state. DRM-protected OMA tracks may work only in the Sony account and library that created them, and an unencrypted OMA file is not guaranteed to be accepted by DRM-dependent hardware. If the device supports MP3 or AAC, those formats are generally easier to create and transfer than OMA.